scholarly journals THEORETICAL RESEARCH OF THE POSSIBILITY OF JOINTLESS TRACK ARRANGEMENT IN CURVED SECTIONS OF RADIUS LESS THAN 350 METERS

2021 ◽  
Vol 1 (37) ◽  
pp. 86-96
Author(s):  
V. Tverdomed
Keyword(s):  
Theoretical Calculations ◽  
Operating Conditions ◽  
Theoretical Research ◽  
Track Structure ◽  
Method Of Determination ◽  
Traditional Structure ◽  
Transverse Stability ◽  
The Given ◽  
Current Operating

The traditional structure of the upper structure of the track on the main railways of Ukraine in curved sections with a radius of less than 350 m is a link structure of the track with wooden sleepers. This track design is not rational under current operating conditions. The use of a more advanced jointless track design in curves with a radius of less than 350 m is limited primarily by the condition of ensuring the transverse stability of the rail-sleeper lattice. To be able to expand the use of jointless track construction in curved sections with a radius of less than 350 m, it is necessary to know the values of the transverse forces of interaction of the structures of the upper track structure with the moving carriage. Knowing the forces of interaction, it is possible to estimate by what value the transverse stability of the rail-sleeper lattice will be provided and to make constructive decisions on its increase. The method of determination of transverse horizontal forces of interaction of track and moving carriage in curves of radius less than 350 m taking into account quasi-static compressive forces in a train is given. The reasons for these forces are related to the presence of eccentricity of the autoclutch shank in the horizontal and vertical planes. Theoretical calculations of horizontal transverse forces of interaction are carried out according to the given technique and coefficients of stability of a rail-sleeper lattice in curved sites are defined. The main conclusions concerning the possibility of operation of the jointless track structure in curved sections with a radius of 350 m and less are made.

INCREASING THE RESOURCE OF DIESEL CYLINDER HEADS BY IMPROVING THE TECHNOLOGY OF THEIR RESTORATION

2020 ◽  
Vol 15 (7) ◽  
pp. 950-957
Author(s):  
G.D. Mezhetskiy ◽  
◽  
V.A. Strelnikov ◽  
Keyword(s):  
Diesel Engines ◽  
Thermal Loading ◽  
Theoretical Calculations ◽  
Operating Conditions ◽  
Advanced Technology ◽  
Temperature Fields ◽  
Cylinder Block ◽  
Diesel Cylinder ◽  
Thermal Intensity

The article presents the results of studies of the thermal fatigue strength of diesel cylinder heads and their resource under operating conditions, by using the most advanced technology for their restoration. Based on the results of theoretical calculations of durability and operational studies, a restoration technology has been proposed, which makes it possible to increase the resource of cylinder heads by 2 ÷ 2.5 times. For this purpose, the non-uniformity of the temperature field on the firing bottom of the cylinder heads of YaMZ-238NB diesel engines was theoretically determined and experimentally confirmed. On the basis of theoretical calculations, the most heatstressed sections of the plane of the cylinder heads of diesel engines bonded to the cylinder block were determined, and the appearance of cracks in them. When developing a method for calculating the temperature fields of the fire bottom, the universal finite element method (FEM) was used. This method makes it possible to take into account the geometry and conditions of thermal loading of the cylinder heads quite accurately. For the determination of temperature fields, a well-founded assignment of the boundary conditions is crucial. With this in mind, a number of surfaces were determined that characterize the durability of the entire part during operation. As a result of calculations carried out on a computer, temperature fields have been obtained that make it possible to analyze the distribution of temperatures and temperature gradients at any point of the fire bottom. The highest temperatures (620...635K) are localized in the central part of the fire bottom, which is two times higher in thermal intensity than the peripheral one and confirms the appearance of cracks in these places during the operation of diesel cylinder heads.

scholarly journals Influence of rigidity of a flange ridge knot of a double hinged arch on the redistribution of efforts in its elements

2021 ◽  
pp. 236-246
Author(s):  
Volodymyr Romanіuk ◽  
Volodymyr Suprunіuk
Keyword(s):  
Theoretical Calculations ◽  
Operating Conditions ◽  
Bolted Joints ◽  
External Loading ◽  
Parameter Method ◽  
Geometrical Parameters ◽  
Theoretical Determination ◽  
Design Rules ◽  
Current Design

The theoretical determination of the actual stiffness of the ridge knot of a steel perforated arch was carried out using the initial parameter method, which made it possible to calculate the stress in the upper reference section of the structure belt. The application of the proposed calculation method makes it possible to determine the rigidity of the bolted flange connection, taking into account its actual operation, and to change it by changing the geometrical parameters of the nodal details, that is, the diameter of the bolts or the thickness of the flanges.It is marked that in the calculation of building constructions an important value has exact determination of boundary conditions of connection of nodal elements, that substantially influences on the redistribution of efforts in the separate elements of constructions on their length and rigidity of knots. Especially it touches of flange bolted joints. Current design rules use idealized schemes of nodal joints, which, according to numerical researches, do not fully correspond to the actual operating conditions of nodal joints and constructions on the whole. For realization of aim of researches, that is, theoretical determination of rigidity of ridge knot of the steel preliminary tense perforated arch, the method of initial parameters is used, which allowed to define theoretical tensions in the supporting cut of fastening upper belt to the ridge knot of arch. Divergence in the values of actual tensions in the cuts of beam and theoretical, calculated according to the current design rules, is explained by the flexibility of the flanged bolted joints, that due to the actions in the knot of bending moment opens up, although in theoretical calculations this joint is accepted by absolutely rigid. Rigidity depends on the thickness of flanges, diameter of bolts, the distances between them, the values of the previous tension of the bolts and external loading. The conclusion is set forth, that the application of the offered methodology of calculation allows to define the rigidity of the bolted flanged joint taking into account its actual work, and which, according to experimental researches and theoretical calculations, differs from the idealized calculation schemes. In addition the proposed methodology allows to change the rigidity of the bolted jont, changing the diameter of the bolts or the thickness of the flanges, and also to use the additional resource of material due to some reduction of the maximum tensions in weak cuts of elements.

scholarly journals Determination of the features and effectiveness of the pivot sprinkler with corner irrigation system

2020 ◽  
Author(s):  
O. Mitrofanov ◽  
◽  
V. Sidorenko ◽  
S. Sidorenko
Keyword(s):  
Capital Investment ◽  
Irrigation System ◽  
Operating Conditions ◽  
Theoretical Research ◽  
Irrigated Agriculture ◽  
Irrigation Systems ◽  
Term Operation ◽  
Irrigated Area ◽  
The Cost

Introduction. Circular-action sprinklers, as shown by the practice of their long-term operation and previous studies, have significant advantages over front-end machines: maintenance is minimized, the ability to fully automate irrigation processes and network power supply, a one-hydrant water supply system, etc. At the same time, pivot irrigation leaves the corner sections of the field without irrigation, which account for up to 20% of its area - and this is a significant drawback of pivot irrigation machines. Foreign manufacturers of irrigation machines produce and sell additional swivel fenders for pivots that irrigate the corners of the field. They are also called "corner irrigation systems". Since 2018, such systems began to appear in Ukraine. Specialists of the South-Ukrainian branch of L. Pogorilyy UkrNDIPVT investigated the corner irrigation system of the company "Valley" by testing in the conditions of economic operation. Research goal. Determination of parameters and characteristics of the corner irrigation system "V-Flex Corner Valley", assessment of its effectiveness and prospects for widespread implementation. Research methods. Theoretical research was carried out by analyzing the studied information resources. Laboratory and field studies were carried out by testing the irrigation system under operating conditions. System parameters and characteristics were determined according to standardized methods. Results. The design features and principles of the irrigation system functioning have been investigated and described. The tests determined the main operational characteristics of the irrigation system in comparison with the characteristics of the pivot sprinkler (using materials from previous studies). The economic indicators of the irrigation system and the circular machine are determined in comparison. The factors of increasing/decreasing efficiency and their quantitative indicators have been investigated. The analysis of the results obtained and the reasons that hinder the widespread introduction of corner irrigation systems into the practice of irrigated agriculture in Ukraine are identified. Сonclusions. Tests and studies of the pivot sprinkler with corner irrigation system have proven the functional excellence and high operational reliability of the irrigation system. The use of a corner irrigation system made it possible to increase the irrigated area by 21.86 % without changing the basic infrastructure and borders of the irrigated field. Implementing a corner irrigation system requires significant capital investment: the cost of a corner wing, which irrigates 21.86 % of the field, is 79 % of the cost of a basic pivot, which irrigates 59.72 % of the field.. The increase in gross income due to an increase in the irrigated area provides a basis for predicting the return on investment when growing highly profitable crops.

Determination of the orientation of internal linear defects in isotropic optical crystals

2019 ◽  
Vol 85 (2) ◽  
pp. 29-32
Author(s):  
V. N. Cheredov ◽  
A. E. Petrakov
Keyword(s):  
Crystallographic Orientation ◽  
Material Science ◽  
Rapid Determination ◽  
Optical Microscope ◽  
Rapid Procedure ◽  
Linear Defects ◽  
Method Of Determination ◽  
Optical Crystals ◽  
The Given

Study of the structure of optical crystals and defects in them is one of the most important problems in crystal physics, crystallography and material science. Nowadays, study of the nanostructures, including the linear defects in crystals is of particular importance. Defects, and first and foremost linear imperfections of the crystal structure, significantly reduce the operational physical properties of optical crystals. Analysis of the properties of those defects, their orientation in the crystal lattice, as well as developing of the methods for determination of the crystallographic orientation of linear defects are the most important in view of the possibility of improving the properties of optical crystals. A method for rapid determination of the crystallographic orientation of linear defects (dislocations, clusters, linearly extended bulk inclusions, etc.) in optical crystals is presented. The orientation of a linearly extended micropore in an isotropic optical transparent fluorite crystal was determined using an optical microscope. The readings of the scale of the eyepiece drum were recorded when rotating the crystal fixed in the crystal holder of the microscope. Corrections for the refraction of light in the bulk of the crystal were taken into account analytically. The crystallographic orientation of the microporous in a transparent fluorite crystal was studied in detail. Crystallographic indices of micropore orientation corresponded to [100]. We developed an efficient rapid procedure for determination of the orientation of internal linear defects (imperfections) in optically isotropic crystals using an optical microscope. The restrictions imposed on the angles of crystal rotation depending on the value of the refractive index are considered for the given method of determination.

Determination of Modal Deformations by Means of In Situ Accelerations

1986 ◽  
Vol 108 (1) ◽  
pp. 32-38 ◽  
Author(s):  
S. Braun ◽  
J. Levran
Keyword(s):  
Operating Conditions ◽  
Modal Parameters ◽  
Normal Operating ◽  
Machining Conditions ◽  
The Given

Described is a method of extracting modal deflection patterns by means of acceleration measurements only. This enables the testing of systems/machines under normal operating conditions with many potential advantages. A single inertance measurement can be used in conjunction with these results to estimate true modal parameters. The method is demonstrated for a drill under machining conditions. Error associated with the proposed method are discussed, and estimated for the given example.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

The Role and Place of Budget Procedure in the System

2003 ◽  
pp. 42-49 ◽  
Author(s):  
E. Bushmin
Keyword(s):  
Budget Process ◽  
Public Expenditures ◽  
Principal Role ◽  
Process Trends ◽  
The Given ◽  
Rules Of The Game

The article is devoted to the analysis of improving budget process trends. The author offers the concept of "financial technologism". Its usage should promote an essential improvement of the budget process. The given concept is based on the fact that the regulation of budget procedure is the process of determination of "rules of the game", and the order of interaction of different institutions within the framework of the budget process, and the trends and volumes of expenses are the strategy of institutions. The procedure within the budget process plays a principal role as compared with the trends and volumes of public expenditures.

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