Wyniki wyszukiwania - Biblioteka Nauki

1

The nature and detection of unauthorized waste dump sites using remote sensing

100%

Vambol S. , Vambol V. , Sundararajan M. , Ansari I.

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nr 3

2

Substantiation of the choice of the cutter material and method of its hardening, working under the action of friction and cyclic loading

100%

Sokolov D. , Sobyna V. , Vambol S. , Vambol V.

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tom Vol. 94, nr 2

49--54

EN

Purpose: The main problem with the use of rescue instruments during emergency response is the low strength of the tool’s cutting edge. The consequence of this is the low efficiency of rescue operations. The purpose of this study is to substantiate experimentally the choice of material for the tool’s cutting edge and the method of surfacing it on the cutter of a hydraulic tool, operating under the simultaneous influence of friction and cyclic loading. Design/methodology/approach: The choice of material was carried out by the way of analytical analysis with subsequent experimental verification. For this purpose, specially made samples of cutters from various grades of alloyed steel were used. With these cutters the steel rod Ø 12 mm made of St3 steel was cut; the number of cutting cycles preceding blunting or destruction of the cutting edge of the tool was counted. Analytical study of the possibility of cutter’s surface hardening by fusing the cutting edge onto it was carried out by the way of analyzing scientific research in the area of improving the technical characteristics of a mechanized hydraulic tool. Findings: It has been experimentally established that Steel 30HGT gives the greatest number of working cycles before blunting, while steels of the manufacturer (Steel 65G and Steel 12M) are destroyed in 180 and 200 working cycles, respectively. Other steels are not destroyed, but can stand fewer number of cutting cycles. To reduce the cost and increase the efficiency of rescue operations, it is proposed to perform surface hardening of the tool cutter by fusing the cutting edge made of Steel 30 HGT steel (analogs: in Germany – 30MnCrTi; in the Czech Republic – 14231). Analytical research has shown that manual arc welding as a method of welding metals is widely tested, reliably reproducible, allows for surfacing in any conditions outside the fabrication facility and is carried out with non-bulky equipment. This will increase the life of the hydraulic rescue tool. Research limitations/implications: The study was conducted for steels that meet the requirements of national standards. Practical implications: Equipping rescue workers with a mechanized tool that has been upgraded by the proposed method improves the efficiency of rescue operations in emergency situations. Originality/value: It is proposed to increase the strength and reliability of a mechanized tool for rescue operations. For the first time, an attempt to substantiate the choice of method for hardening the cutting) edge of an instrument by applying reliably reproducible technologies was made.

3

Justification of the most rational method for the nanostructures synthesis on the semiconductors surface

88%

Suchikova Y. , Vambol S. , Vambol V. , Mozaffari N. , Mozaffari N.

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tom Vol. 92, nr 1-2

19--28

EN

Purpose: of this paper is to justification the most rational method for the nanostructures synthesis on the semiconductors surface, which is capable of providing high quality synthesized nanostructures at low cost and ease of the process. Design/methodology/approach: The choice of the optimal method of synthesis was carried out using the hierarchy analysis method, which is implemented by decomposing the problem into more simple parts and further processing judgments at each hierarchical level using pair comparisons. Findings: The article describes the main methods of synthesis of nanostructures, presents their advantages and disadvantages. The methods were evaluated by such criteria as: environmental friendliness, efficiency, stages number of the technological process, complexity, resources expenditure and time and effectiveness. Using the hierarchy analysis method, has been established that electrochemical etching is the most important alternative, and when choosing a nanostructures synthesis method on the semiconductors surface, this method should be preferred. Such studies are necessary for industrial serial production of nanostructures and allow reducing expenses at the realization of the problem of synthesis of qualitative samples. Research limitations/implications: In this research, the hierarchy analysis method was used only to select a rational method for synthesizing nanostructures on the semiconductors surface. However, this research needs to be developed with respect to establishing a correlation between the synthesis conditions and the nanostructures acquired properties. Practical implications: First, was been established that the optimal method for the nanostructures synthesis on the semiconductors surface is electrochemical etching, and not lithographic or chemical method. This allowed the theoretical and empirical point of view to justify the choice of the nanostructures synthesis method in the industrial production conditions. Secondly, the presented method can be applied to the synthesis method choice of other nanostructures types, which is necessary in conditions of resources exhaustion and high raw materials cost. Originality/value: In the article, for the first time, the choice of the nanostructures synthesis method on the semiconductors surface is presented using of paired comparisons of criteria and available alternatives. The article will be useful to engineers involved in the nanostructures synthesis, researchers and scientists, as well as students studying in the field of "nanotechnology".

4

Substantiation of expedience of application of high-temperature utilization of used tires for liquefied methane production

88%

Vambol S. , Vambol V. , Kondratenko O. , Koloskov V. , Suchikova Y.

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tom Vol. 87, nr 2

77--84

EN

Purpose: The purpose of this investigation is to substantiate by means of numerical simulation the expedience of high-temperature utilization of used tires with subsequent methanation of fuel gases and separation of multicomponent hydrocarbon mixtures to drain the liquefied methane. Design/methodology/approach: The investigation was carried out by means of numerical simulation. In mathematical description of gas processes relations of thermodynamics and heat and mass transfer were used. To determine the coefficients of thermal and physical parameters of working bodies the Peng-Robinson equation of state was used through the computer program REFPROP. The system of equations is represented as the interrelations between the functional elements according to the principle "output from the element A – input into the element B". Its solution was obtained by the method of successive approximations, namely by the Newton-Raphson iteration method. Using this method we have determined the values of temperature, pressure, mass flow rate and mass content of the hydrocarbon gas mixture components in each reference cross-section of the power facility. Findings: As a result of numerical simulation, it is determined that when the multicomponent hydrocarbon mixtures are separated, three flows of energy resources may be obtained: with a high mass content of methane of 91.5% and 83.4%, which may be used as motor fuel, and a gas flow suitable for maintaining the process of waste gasification. However, to remove heat in the condenser of the rectification column, it is necessary to use expensive liquid nitrogen. The cost of methane production may be reduced if the condenser is removed from the rectification column. However, such approach reduces the overall yield of commercial products almost in four times and significantly reduces the methane with the third product (molar percentage of 35%). Research limitations/implications: The investigation was carried out for the material of used tires without a metal frame. Practical implications: The implementation of the technology of high-temperature recycling of used tires gives the opportunity to use the generated synthetic gas to maintain the process of utilization, and gives the opportunity to produce liquefied methane, suitable for storage. Originality/value: The main problem of high-temperature recycling of tires is the emission of toxic gas to the atmosphere. It is proposed to allocate methane energy resource from this gas. For the first time an attempt was made to justify the expedience of the technology of high-temperature utilization of tires for liquefied methane production.

5

Physical modelling of changes in the energy impact on a worker taking into account high-temperature radiation

63%

Ragimov S. , Sobyna V. , Vambol S. , Vambol V. , Feshchenko A. , Zakora A. , Strejekurov E. , Shalomov V.

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tom Vol. 91, nr 1

27--33

EN

Purpose: The purpose of this investigation is development of an experimental installation and definition the intensity of thermal irradiation at workplaces to ensure safety under condition of increased thermal radiation. This purpose is justified as follows. Human health and well-being depend to a large extent on conditions of the internal environment of the premises, which affect the heat exchange of workers with the surrounding surfaces. With this the spectral composition and intensity of irradiation are also important for assessing the effect of thermal radiation. Design/methodology/approach: The investigation was carried out using special experimental device. Uniformly lit semitransparent screen was used as a source of thermal radiation source. We used photo film with heat flow sensor ДТП 02 – ДТП 03 developed by Institute of Engineering Thermophysics under Academy of Science of Ukraine as model of the elementary surface of human body. Findings: Based on results of conducted research and optimization, we propose protective compositors that are nonflammable. This fact allows the increase in safety of facilities during operation and evacuation routes in emergency case due to high-temperature effects. Research limitations/implications: In this study, was focused on the dependence of the local angular coefficient of irradiation and maximum thermal loads, as well as the transition from indirect measurements to direct ones. This allows us to predict working conditions by the thermal factor in the workplace. Practical implications: The results of this study can be recommended to the Ministry of Health and the Ministry of Industry for the development to reduce the incidence of occupational morbidity among workers who work under conditions of exposure of thermal radiation. Originality/value: It was disclosed that it is possible to determine the distance to the source of thermal radiation from the point of measurement and the angle at which the source of thermal radiation is visible with high accuracy. Moreover, measurement point may be located at a distance safe for the researcher.