Showing papers by "Ternopil Ivan Pul'uj National Technical University published in 2015"
TL;DR: The cyclic linear random process is defined, that combines the properties of linearrandom process and cyclic random process and can be used as the mathematical model of the cyclic stochastic signals and processes in various fields of science and technology.
Abstract: Abstract In this study the cyclic linear random process is defined, that combines the properties of linear random process and cyclic random process. This expands the possibility describing cyclic signals and processes within the framework of linear random processes theory and generalizes their known mathematical model as a linear periodic random process. The conditions for the kernel are given and the probabilistic characteristics of generated process of linear random process in order to be a cyclic random process. The advantages of the cyclic linear random process are presented. It can be used as the mathematical model of the cyclic stochastic signals and processes in various fields of science and technology.
12 citations
TL;DR: In this paper, the authors applied the combined approach to study of deformation and fracture based on the following research parameters from nonlinear fracture mechanics: physical mesomechanics and numerical fractography.
Abstract: The majority of modern gas pipelines in Ukraine, Lithuania and Russia have been operating for more than 30–40 years. The problem of forecasting residual life-time of materials comprising such gas pipelines calls for study of their degradation kinetics as well as requires to determine its relationship with the strain-force loading parameters. The aim of the paper is to study the kinetics of fracture in order to range mechanisms of cyclic deformation of 17Mn1Si steel at nucleation and growth of a fatigue crack. Flat specimens were cut out from a fragment of 17Mn1Si steel pipe after 40 years of service. Microstructures of specimens were examined. In the paper, an attempt was made to apply the combined approach to study of deformation and fracture based on the following research parameters from nonlinear fracture mechanics: physical mesomechanics and numerical fractography.
12 citations
TL;DR: In this paper, an approach is proposed to perform a mathematical analysis of an ordered relief formed on the nanotitanium surface after laser shock-wave treatment, which enables one to obtain informative attributes and a quantitative estimate of parameters of morphological structures being formed with allowance for the stochastic and cyclic nature of this process.
Abstract: An approach is proposed to perform a mathematical analysis of an ordered relief formed on the nanotitanium surface after laser shock-wave treatment. This approach enables one to obtain informative attributes and a quantitative estimate of parameters of morphological structures being formed with allowance for the stochastic and cyclic nature of this process.
10 citations
03 Dec 2015
TL;DR: WSN is considered to be a distributed, self-organizing system of a large number of sensors and assistive devices that communicate with each other through the radio channel to enhance the security wireless sensor networks.
Abstract: Recent advances in the micro electromechanical systems technology MEMS, wireless communications and digital electronics allowed to create inexpensive, low-powered, multi-functional nodes. They are small and "talk" directly with each other. Wireless Sensor Network (WSN) is considered to be a distributed, self-organizing system of a large number of sensors and assistive devices that communicate with each other through the radio channel. Sensor networks are based on the joint work of a large number of tiny nodes that consist of data collection and processing modules and a transmitter or a transceiver. Such networks have significant advantages over the set of traditional sensors. The main problem in sensor networks is a short stint due to high power consumption and the incompatibility of various hardware. Because of the absence of a clear standardization in sensor networks, there are several different platforms. All platforms meet the essential basic requirements for sensor networks: low power consumption, long operating time, low-power transmitters and presence of sensors. Each platform is in its own interest substantiated and has its own peculiarities. They will transmit the observation data to the central nodes where data collection, storing, and processing will be performed. The main purpose is to enhance the security wireless sensor networks.
8 citations
TL;DR: In this paper, conditions for DNP realization in the test setup with pre-set rigidity have been found and strain velocities have been determined to be equal to 2.10 s − 1 in the processes of forming and developing a dissipative structure of heat resistant steel under the DNP (dynamic non-equilibrium process).
Abstract: Using an original experimental methodology and software for contactless investigation into strains applying the method of digital image correlation, conditions for DNP realization in the test setup with pre-set rigidity have been found. Strain velocities have been determined to be equal to 2...10 s–1 in the processes of forming and developing a dissipative structure of heat resistant steel under the DNP (dynamic non-equilibrium process).
7 citations
12 Nov 2015
TL;DR: It is proposed to investigate this problem via examination of criteria comparability by replacement and examine sensitivity the result of alternative architectures assessment as well, and optimization of trade-offs between quality criteria.
Abstract: The methods of software architectures examination are discussed in the paper. It is shown that this is multicriteria hierarchical problem. For its solution, modified Analytic Hierarchy Process (AHP) is applied. Nevertheless, general result of software architectures assessment hides influence of each quality criterion on the final value and correlations between criteria too. Therefore, it is proposed to investigate this problem via examination of criteria comparability by replacement and examine sensitivity the result of alternative architectures assessment as well, and optimization of trade-offs between quality criteria.
6 citations
TL;DR: In this article, a pseudostereopair is used to determine the geometry of the start zone of the brittle separation crack in OSL steel and the stretch zone of railway axis steel.
Abstract: The method for determining the height of the surface microirregularities by means of a pseudostereopair, which can be used to determine the geometry of the start zone of the brittle separation crack, is completed and automated. The possibility of using the proposed method for investigating the stretch zone of compact specimens of the OSL steel is considered. The stretch zone of the railway axis steel is investigated using the proposed technique.
6 citations
5 citations
TL;DR: In this paper, the effect of PTL modes on structural and mechanical regularities in material deformation at the crack tip using the parameters of fracture mechanics was studied, and the results are the basis for a more precise definition of the guaranteed strength of structural elements with crack-like defects.
Abstract: The article studies the effect of PTL modes on structural and mechanical regularities in material deformation at the crack tip using the parameters of fracture mechanics. The obtained results are the basis for a more precise definition of the guaranteed strength of structural elements with crack-like defects.
5 citations
TL;DR: In this paper, the suitability of CoMoCrSi and WC-NiMoCrFeCo applied by high velocity oxygengen fuel technology from point of view of their suitability for renovation of sink roll in hot dip galvanizing line was evaluated.
Abstract: The paper deals with the evaluation of coatings CoMoCrSi and WC-NiMoCrFeCo applied by High Velocity Oxygen Fuel technology from point of view of their suitability for renovation of sink roll in hot dip galvanizing line. The structure of the coatings was evaluated by metallographic analysis. The adhesion of the coatings as-sprayed and after thermal cyclic loading was determined by pull-off test. Wear resistance of the coatings was evaluated by pin-on-disc test in the corrosive environment of 1M aqueous solution of NaCl.
4 citations
TL;DR: In this article, the dismantled tubes of the steam-boiler operated by the Kalush Heat and Power Plant were investigated and the suitability of the proposed methods for the calculation of Shannon entropy of the surface analyzed was tested.
Abstract: The dismantled tubes of the steam-boiler operated by the “Kalush Heat and Power Plant” were investigated. Defects of various nature, pitting of the indefinite shape were found during the examination. Since pitting is a deepening in the material and contains dark products of the corrosion process. It looks like a darkened area that stands out against the light background of the non-damaged surface in the optical images. The efficiency of such processing for identification of the corrosion defects is analyzed. The suitability of the proposed methods for the calculation of Shannon entropy of the surface analyzed was tested, as well as for determining the area and number of pitting defects.
TL;DR: In this paper, the relationship between the energy parameters of fracture (impact toughness) and the deformation response of the material (the height of shear lips) of the specimens from the pipe steel is established.
Abstract: By example of steel 17G1S, the regularities in the impact fracture of Charpy specimens at normal and low temperatures are described. The relationship between the energy parameters of fracture (impact toughness) and the deformation response of the material (the height of shear lips) of the specimens from the pipe steel is established. The micromechanisms of impact fracture of the material are described. At 20 °C and –30 °C, focal splitting of the material was observed on the fracture surface of specimens; at –60 °C, the material failed in a brittle manner by the mechanism of cleavage.
TL;DR: In this paper, the S and J - methods of pipe laying tend to increase the brittle fracture component in the material, however, they have practically no effect on the residual life-time of metal under low amplitude cyclic loading (260 MPa).
Abstract: The S and J - methods of pipe laying tend to increase the brittle fracture component in the material, however, they have practically no effect on the residual life-time of metal under low amplitude cyclic loading (260 MPa). An increase in the stress range up to 320 MPa enhances the negative effect of preloading, which is more pronounced in case of using the S - method of pipe laying as compared to the J - one. Within the high amplitude range (420 MPa) the process of preliminary deformation causes the activation of relaxation processes and longitudinal splitting in the material, giving rise to an abnormal increase in the cyclic life of the plastically deformed material.
TL;DR: In this paper, the peculiarities of deformation and failure of heat resistant 25Cr1Mo1V steel with a network of thermal fatigue cracks are investigated within the concept of physical mesomechanics of materials and fracture mechanics.
TL;DR: In this paper, the peculiarities of the accumulation of structural and mechanical defects on the surface of the D16chT aluminum alloy under significant plastic strains are analyzed, and the geometrical parameters of the relief formations are described.
Abstract: The peculiarities of the accumulation of structural and mechanical defects on the surface of the D16chT aluminum alloy under significant plastic strains are analyzed. The peculiarities of the surface strain hardening are found, and the geometrical parameters of the relief formations are described. The relationship between multiple cracking and specimen deformation is established. It is proved that the deformation relief parameters can be used to assess damage of the D16chT alloy under static deformation.
TL;DR: In this article, the optimal modes and parameters for surface layer modification are determined being a certain compromise between strength/ductility of the layer and its thickness etc., which may give rise to localized development of plastic deformation or fracture.
Abstract: Surface modification is an effective way both to protect structural materials and to improve their mechanical properties. However under mechanical loading the distinction of elastic moduli of a modified surface layer and adjacent bulk material causes the stress concentrators to occur, whose relaxation may give rise to localized development of plastic deformation or fracture [1]. Under cyclic loading such distinction of the properties brings to multiple microcracking of strengthened surface layer, to act as structural micronotches [2, 3]. Therefore, optimized modes and parameters for surface layer modification are to be determined being a certain compromise between strength/ductility of the layer and its thickness etc.
02 Nov 2015
TL;DR: VHDL-AMS model of MEMS capacitive accelerometer with delta-sigma analog to digital converter (ADC) has been developed and can be used to conduct the analysis of the device at the behavioral level of computer-aided design.
Abstract: In the paper, VHDL-AMS model of MEMS capacitive accelerometer with delta-sigma analog to digital converter (ADC) has been developed. The proposed model allows to simulate capacitance changes, change of output voltage of the sensor, digitizing the output signal from the sensor using delta-sigma A/D converter depending on the applied acceleration. The model can be used to conduct the analysis of the device at the behavioral level of computer-aided design.
01 Sep 2015
TL;DR: Techniques for the improvement of the metrological and functional characteristics of the tracking antenna system due to designed optoelectronic smart angle sensor with built-in functions of detection and compensation of errors in mechanical constructions is considered.
Abstract: Techniques for the improvement of the metrological and functional characteristics of the tracking antenna system due to designed optoelectronic smart angle sensor with built-in functions of detection and compensation of errors in mechanical constructions is considered. Performance characteristics and results of experimental research of dual-channel optoelectronic angle sensor are described.