scholarly journals DETERMINATION OF DEFECTS SIZES AND THEIR POSITION DURING ULTRASONIC CONTROL BY METHODS OF MATHEMATICAL AND COMPUTER SIMULATION

2020 ◽  
Vol 42 (3) ◽  
pp. 93-98 ◽  
Author(s):  
V.P. Babak ◽  
I.V. Bogachev ◽  
V.V. Khaidurov
Keyword(s):  
Average Frequency ◽  
Geometric Shape ◽  
Computational Experiments ◽  
Sound Waves ◽  
Metal Structures ◽  
Modern Computer ◽  
Mathematical And Computer Simulation ◽  
Homogeneous Wave ◽  
Simple Geometric Shape

The use of sound waves to study the integrity of various metal structures is the most relevant method. The relevance is traced, in particular, in the ease of conducting such experiments, as well as its cheapness. The design of various parts requires the use of modern computer technology, which, using a mathematical apparatus that describes the process, allows you to determine the actual characteristics of the material to determine durability. This approach makes it possible to effectively create design solutions in order to create new parts and upgrade existing materials to extend their service life. The purpose of this work is to build mathematical models of homogeneous wave processes and their analysis in the form of computational experiments to control the passage of sound signals through the surface of the studied materials of objects. This approach is used to determine the influence of geometric parameters of defects in the form of cracks through which the signal passes, on its characteristics, which it describes after passing through these defects to the signal receiver, in particular, is the amplitude and frequency. For computational experiments, a point exciter of harmonic oscillations and a point receiver were chosen, which are located on different sides relative to the defect of a simple geometric shape. It should be noted that even minor defects affect the amplitude of the received signal, which passed through such defects. When a signal passes through defects of a simple geometric shape, the amplitude of such a signal decreases by 5–8 times and the average frequency decreases by 2–3 times.

scholarly journals Determination of the region of the limiting states occurrence in RVS-20000 with the subsidence of the external bottom contour

2018 ◽  
Vol 239 ◽  
pp. 06002
Author(s):  
P.V. Chepur ◽  
A.A. Tarasenko ◽  
A.A. Gruchenkova
Keyword(s):  
Technical Condition ◽  
Element Analysis ◽  
Metal Structures ◽  
Software Complex ◽  
Managerial Decisions ◽  
The Finite Element Analysis ◽  
Steel Tank ◽  
Intrinsic Stiffness ◽  
Bottom Contour

The problem of the limiting states occurrence in the structures of a vertical steel tank is investigated in this work. To study the SSS of the metal structures of the object, the authors created a numerical model of the RVS-20000 tank in the ANSYS software complex. The model considers the maximum number of elements with their geometry and connections affecting the tank SSS under non-axisymmetric loading, including beyond the elasticity of steel. Dependences between the parameters of intrinsic stiffness of the VST are obtained. The results of the finite element analysis made it possible to develop a technique for assessing the technical condition of the structure with the development of irregular subsidence of the external bottom contour. The proposed technique can be used by both operating and design organizations in making managerial decisions regarding the repair of RVS-20000 subjected to the base subsidence.

scholarly journals A thermo-mechanical machining method for improving the accuracy and stability of the geometric shape of long low-rigidity shafts

2021 ◽  
Author(s):  
Antoni Świć ◽  
Arkadiusz Gola ◽  
Łukasz Sobaszek ◽  
Natalia Šmidová
Keyword(s):  
Heat Treatment ◽  
Cross Section ◽  
Mechanical Treatment ◽  
Geometric Shape ◽  
Different Dimensions ◽  
Thermo Mechanical Treatment ◽  
Mechanical Machining ◽  
Simultaneous Heat ◽  
Accuracy And Stability

AbstractThe article presents a new thermo-mechanical machining method for the manufacture of long low-rigidity shafts which combines straightening and heat treatment operations. A fixture for thermo-mechanical treatment of long low-rigidity shafts was designed and used in tests which involved axial straightening of shafts combined with a quenching operation (performed to increase the corrosion resistance of the steel used as stock material). The study showed that an analysis of the initial deflections of semi-finished shafts of different dimensions and determination of the maximum corrective deflection in the device could be used as a basis for performing axial straightening of shaft workpieces with simultaneous heat treatment and correction of the initial deflection of the workpiece. The deflection is corrected by stretching the fibers of the stock material, at any cross-section of the shaft, up to the yield point and generating residual stresses symmetrical to the axis of the workpiece. These processes allow to increase the accuracy and stability of the geometric shape of the shaft.

Newgrange — Science or Symbolizm

1994 ◽  
Vol 60 (1) ◽  
pp. 85-96 ◽  
Author(s):  
Andrew B. Powell
Keyword(s):  
Scientific Discourse ◽  
Geometric Shape ◽  
Mortuary Practices ◽  
Political Control ◽  
Spatial Relationships ◽  
Left And Right ◽  
Unit Of Length ◽  
Simple Geometric Shape

The Newgrange passage tomb is examined for evidence of ‘Neolithic science’. Claims that it incorporated an astronomical alignment, and was constructed using Pythagorean geometry and the megalithic yard are reviewed as are scientific interpretations of its art. A new analysis of the tomb's structure reveals that it was based on a simple geometric shape measurable by a 13.1 m unit of length. The locations of particular motifs and decorated surfaces are shown to conform to the spatial relationships evident in the tomb's form. These are defined in terms of oppositions between left and right, front and back, inside and outside, visible and hidden, as well as making reference to symbols found in the art of the neighbouring passage tomb at Knowth.These features are interpreted, not as evidence of a specificically scientific discourse in the Irish Neolithic, but as the elaboration of elements common to the passage tomb ritual discourse. Competition for political control, in the context of mortuary practices, resulted in the increasing formalization and rigid interpretation of passage tomb symbolizm, and the ritualization of new areas of knowledge.

scholarly journals EVALUATION OF THE VITALITY OF A FLANGED CONNECTION WITH A STEEL TOWER STRUCTURE WITH ACCOUNT OF EXPERIMENTAL DETERMINATION OF AERODYNAMIC COEFFICIENTS

2020 ◽  
Vol 82 (2) ◽  
pp. 215-224
Author(s):  
V.I. Erofeev ◽  
I.A. Samokhvalov
Keyword(s):  
Bearing Capacity ◽  
Numerical Study ◽  
Wind Load ◽  
Aerodynamic Coefficients ◽  
Metal Structures ◽  
Equivalent Stresses ◽  
Tower Structure ◽  
Calculation Results ◽  
Design Calculations

A numerical study of the survivability of the flange assembly is carried out upon reaching a critical load and in the presence of a defect in one of the design areas, taking into account the calculated values of the aerodynamic coefficients. An experiment is being carried out to determine the values of the wind load acting on the supporting legs of a metal tower. The calculation of the stressstrain state is performed using software system as SCAD Office and IDEA StatiCa 10.0. After calculating the forces in the core model of the structure, a threedimensional plate model of the assembly is formed and prepared for calculation. According to the results of the experiment, a graph was compiled with the values of aerodynamic coefficients, which were used in calculating the stressstrain state of the node. The analysis of the calculation results revealed that in the design (defectfree) state of the structure, the safety factor of the bearing units and elements is 35-40% (equivalent stresses were 165 MPa). If there is a defect in the metal structures of the belt in the region of the flange, the equivalent stresses increase to 247.6 MPa in the region of the cleavage (defective hole), thus, the margin in bearing capacity drops to 0.4%. As a result of the assessment of the survivability of the flange connection, it was revealed that the connection has a high potential survivability, in turn, the flange itself is able to work in the presence of some defects without reducing its bearing capacity to a critical level. The aerodynamic coefficients obtained in this work will determine the wind load on this type of profile and can be used in design calculations of tower structures for wind loads.

Strategic analysis of the competitiveness of the enterprise

2021 ◽  
pp. 35-46
Author(s):  
Yuliia Grynchuk ◽  
Andrii Muzychenko ◽  
Kseniia Prykhod’ko
Keyword(s):  
Price Policy ◽  
Strategic Analysis ◽  
Competitive Advantages ◽  
Macroeconomic Factors ◽  
Modern Computer ◽  
Study Results ◽  
Essential Components ◽  
Selection Of

The purpose of the article is to develop a methodology of strategic analysis of enterprise competitiveness. The methodological basis of the research is the use of general scientific methods: the method of analysis and synthesis, theoretical generalization and comparison, and the means of modern computer technology for data visualization. The scientific novelty of the received results consists of developing a logical and linguistic methodology of competitiveness analysis in the long term. The article is devoted to the development of strategic analysis of the competitiveness of the enterprise. Relevance of research is caused by enterprises management in the modern markets that use innovations of products or technologies, constantly face competition, and according to its condition, should make decisions on strategic development in conformity with the country’s development market inquiries the society. Thus, the problem is not only for new companies but also for those that already function in the market and carry out planning of economic activity to become the market leader, not to lose leadership, to keep the positions. The given methodology can be used by any enterprise irrespective of the type of activity, form of ownership, or strategic goals. Conclusions. According to the study results, the methodology of strategic analysis, which is based on the study of potential internal development of the enterprise, taking into account the influence of external factors, which include macroeconomic factors of influence and market conditions. The basic approaches to the analysis of the competitiveness of the enterprise of foreign and domestic researchers are investigated in the article. The essential components of competitive advantages, which include price and non-price factors, are considered. Peculiarities of carrying out the analysis of the competitiveness of the enterprise after Porter are defined. The methodology of competitiveness analysis in the long term is developed. The main components of the strategic analysis are the estimation of activity scale in a long-term prospect, determination of strategic aims of the company, determination of aims of market coverage, selection of strategy type, selection of basic subjects of influence on competitive advantages, assessment of future relations with suppliers and buyers, assessment of cost price level, assessment of the quality of products and services and unique properties of products, formation of internal price policy. Key words: strategy, strategic analysis, competitiveness, competitive advantages.

scholarly journals Frequency of mentum deformity in Chironomus sancticaroli (Diptera: Chironomidae) in a laboratory culture

2019 ◽  
Vol 14 (2) ◽  
pp. 1
Author(s):  
Mariana Silveira Guerra Moura e Silva ◽  
Ana Lúcia Silva Marigo ◽  
William Viveiros ◽  
Mônica Luisa Kuhlmann
Keyword(s):  
Aquatic Ecosystems ◽  
Low Frequency ◽  
Average Frequency ◽  
Laboratory Culture ◽  
Inorganic Pollutants ◽  
Ecotoxicological Tests ◽  
Research And Teaching ◽  
Dilution Water

The midge Chironomus sancticaroli (Diptera: Chironomidae) has been used in ecotoxicological tests because it is sensitive to a variety of inorganic pollutants. Among the parameters used to evaluate the toxicity of a substance is the frequency of mentum deformity, which is part of the oral system of this organism. However, there is still no consensus on the baseline level (percentage) of acceptable deformities in laboratory cultures not exposed to pollutants. The determination of this variable is important to ensure the validity of bioassays and to compare cultures from different research and teaching institutions. Once this value is established, it will also be used to monitor the quality of organisms cultured, since factors such as inbreeding could increase the frequency of mentum deformity. Thus, the objective of this study was to quantify the percentage of mentum deformity in the fourth instar of C. sancticaroli larvae from the culture of the Laboratory of Aquatic Ecosystems, at Embrapa Meio Ambiente. The average frequency of mentum deformity obtained was 6,63%. It is believed that factors such as the renewal of the culture with the inclusion of spawns from the laboratories of other institutions, as well as the control of the quality of the dilution water and the sediment of the breeding may have contributed to a low frequency of mentum deformity of the culture observed in this study.

Calculation and Experimental Technique for Determining the Damping Properties of Composite Materials

2018 ◽  
Vol 938 ◽  
pp. 46-53 ◽  
Author(s):  
Sergey I. Koryagin ◽  
O.V. Sharkov ◽  
Nikolay L. Velikanov
Keyword(s):  
Experimental Technique ◽  
Polymer Coatings ◽  
Engineering Systems ◽  
Damping Properties ◽  
Metal Structures ◽  
Experimental Specimen ◽  
Adhesive Compositions ◽  
Improved Accuracy ◽  
Damping Capability

Polymer coatings are widely used for effective vibration damping of sheet or hull structures of different engineering systems. The article presents a calculation and experimental technique that enables improved accuracy and validity of damping properties determination of polymer coatings. Mathematical models to determine the parameters of the experimental specimen having a homogenous strain state of the polymer coating are obtained. Experimentally confirmed that the use of coatings based on adhesive compositions such as "Sprut" increases by 18...28 times the damping capability in metal structures. An addition of fillers in adhesive compositions "Sprut" type in a proportion of 30...50% of its weight reduces by 2.4 times the damping properties of metal structures.

scholarly journals Laser System for Testing Early Shrinkage of Concrete Elements in Conjuction with the Deterioration of the Setting Time

2016 ◽  
Vol 16 (2) ◽  
pp. 25-34
Author(s):  
Jacek Gołaszewski ◽  
Tomasz Ponikiewski ◽  
Grzegorz Cygan ◽  
Małgorzata Gołaszewska
Keyword(s):  
Concrete Beams ◽  
Setting Time ◽  
Laser System ◽  
Scratch Resistance ◽  
Sound Waves ◽  
Concrete Elements ◽  
Speed Propagation

Abstract The paper presents a method for testing the shrinkage of concrete beams with dimensions of 10x10x50cm. Measurements followed from setting into the form until 24 hours after setting. It was used modified TLS system, which originally was meant for the determination of changes in the length of thin-mortar. Simultanously measured were the changes of speed propagation of sound waves by Vikasonic, what allows to specify the setting time of binders. It could be a base for determining the scratch resistance of the concrete in the first 24 hours after casting.

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