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Date submitted2023-12-07
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Date accepted2024-11-07
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Date published2025-04-07
Determination of the tangential component of cutting resistance during frozen sedimentary rock cutting using blocked, deeply blocked and cell cutting methods
Due to the insufficient accuracy of existing studies of frozen sedimentary rock cutting process for practical calculations, the article solves the problem of determining the tangential component cutting resistance for blocked, deep blocked and cell cutting, which are currently the most commonly used methods in earthmoving equipment. The cutting tool and rock mass force interaction is considered from the point of view of the emerging stresses, which act on the separated chip element. The analytical dependences for determining the tangential component of cutting resistance were obtained. The numerical explanation of the choice of cell cutting in relation to blocked and deeply blocked cutting is given. For all three methods of cutting, under equal geometrical parameters of the cutting tool and the physical and mechanical properties of the frozen rock, the numerical value of the tangential component of cutting resistance is obtained. The comparison of the cutting resistance estimated values has shown that cell cutting requires relatively less energy and is preferred during the process of frozen sedimentary rock excavation. During field and laboratory investigations with the use of a multi-purpose cutting stand, a sufficient convergence of the analytical statements with the physics of frozen sedimentary rock cutting process was established. The results of the research allow a more reasonable approach to the adjustment of existing methods for determining the required tractive force and power for the drive of an excavation machine, and, therefore, to the actual efficiency and profitability of work.
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Date submitted2023-10-31
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Date accepted2024-11-07
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Date published2025-01-24
Specifics of magnetotelluric studies in Antarctica
One of the priority areas of scientific research in Antarctica is the study of its deep structure. Most of the continent is covered with a thick ice sheet, so the main geoscientific data are acquired using geophysical methods, among which magnetotelluric (MT) ones have the greatest penetration depth and insignificant environmental impact. The possibility of acquiring high-quality MT data in the conditions of the sixth continent has long been questioned. The work is aimed at studying the specifics of magnetotelluric survey in Antarctica. The following tasks were set: to summarize the world experience of studying Antarctica using MT sounding methods; to identify factors that negatively affect the high-quality data acquisition; to determine methods for minimizing the influence of these factors. The article analyses geophysical studies conducted by the magnetotelluric sounding method in the Antarctic region from 1964 to the present. The application of the method is complicated by the following: extremely low temperature affects the drop in the batteries capacity, freezing of the non-polarizing electrodes solution, and changes in the strength properties of materials. Electromagnetic noise occurs during strong winds; proximity to the magnetotelluric field source can violate the plane wave principle on which the method is based. The ice sheet covering most of Antarctica does not allow acquiring optimal values of the contact resistance of the electrode grounding; the extended coastline distorts the acquired data. Studies of the influence of factors complicating the MT sounding method in the coastal and central parts of Antarctica made it possible to formulate recommendations for preparing equipment and adapting the work procedure, modifying the processing flow and a set of measures to ensure safety, the implementation of which will both allow safe performance of geophysical investigations and high-quality data acquisition.
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Date submitted2022-05-12
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Date accepted2022-09-15
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Date published2022-12-29
Problem solution analysis on finding the velocity distribution for laminar flow of a non-linear viscous flushing fluid in the annular space of a well
- Authors:
- Vasiliy I. Nikitin
Modern drilling fluids are non-linear viscous media with an initial shear stress. In classical scientific works on hydromechanical modeling of drilling fluids motion in pipes and annular channels the Shvedov – Bingham approximation and Ostwald – de Waale power-law model were used, which did not fully account for behavior of technological fluids in a wide range of shear rates. This article presents a numerical solution for a mathematical model of drilling fluid motion of the three-parameter Herschel – Bulkley rheological model in the annular space of the well. The Herschel – Bulkley model in the rheological equation takes into account the presence of initial shear stress and a tendency for viscosity to change with shear rate, which distinguishes it from the Ostwald – de Waale and Shvedov – Bingham models. The target function in solving the equation of motion is the velocity distribution in the radial direction of the upward flow of the flushing fluid. The analysis of obtained solution is based on the theory of velocity profile influence on quality of cuttings removal during wellbore cleaning. Due to peculiarities of mathematical statement of the task, which supposes necessity of differential equation of motion solution, Wolfram Mathematica computational software has been used as a calculation tool. The analysis of numerical solution allowed to draw conclusions about the possibility of its application in evaluation of velocity profile when drilling fluid moves in annular space of the well. The possibility for application of modified excess coefficient as a relative quantitative parameter for evaluation of velocity profile uniformity was substantiated.
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Date submitted2022-03-24
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Date accepted2022-07-21
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Date published2022-12-29
A probabilistic study on hole cleaning optimization
- Authors:
- Seyyed Shahab Tabatabaee Moradi
Hole cleaning is considered as one of the most important drilling fluid functions. An efficient hole cleaning ensures a reliable well drilling practice with minimum troublesome problems. In this study, two main steps of hole cleaning, i.e., cuttings removal from under the bit and cuttings transport to the surface are discussed based on the drilling data of a shale formation. The traditional models for optimization of each step are presented. As the models require variety of input data, which are usually subjected to some extent of errors and uncertainties, the output of the model is also an uncertain parameter. Using Monte Carlo simulation, a simple probabilistic study was conducted to quantify the certainty level of the obtained results. Based on the result of this study, it is shown that for the proposed well, a good hole cleaning is expected. However, a more reliable decision for further hole cleaning optimization should be made considering the results of uncertainty analysis.
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Date submitted2021-12-19
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Date accepted2022-07-21
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Date published2022-11-10
Increasing the content of coarse fractions in the mined coal mass by a combine using paired cuts
The main volume of coal is mined underground using shearers. In modern shearers, auger actuators are mainly used, which are distinguished by the simplicity of design, manufacturability and reliability. However, in the process of separating coal from mass by cutting, the yield of fine grades is 40-50 % of the total production volume. Therefore, the search and development of technical solutions that provide an increase in the yield of large fractions in the process of coal mining with auger shearers is an urgent task. Traditionally, this problem is solved by increasing the thickness of the slices, which is achieved by installing cutters with a larger radial reach and increasing the shearer feed rate. An unconventional way to increase the cross section of slices by forming energy-efficient paired and group slices with mutual superposition of stress fields in the mass from the action of neighboring cutters is considered. The results of modeling the process of cutting coal confirm that an increase in the efficiency of destruction of the rock mass by the cutters of the auger executive bodies of the shearer can be achieved by a complex technical solution, including the formation of paired cuts and combined stress zones in the rock mass. As a result, the output of large fragments when cutting with paired cutters increases by 1.3-1.8 times compared with cutting with a single cutter.
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Date submitted2021-04-30
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Date accepted2021-11-30
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Date published2021-12-27
Methodology for testing pipeline steels for resistance to grooving corrosion
- Authors:
- Viktor I. Bolobov
- Grigoriy G. Popov
The methodology for testing pipeline steels is suggested on the assumption that for the destruction of pipes in field oil pipelines by the mechanism of grooving corrosion the simultaneous fulfillment of such conditions as the occurrence of scratches on the lower generatrix of the pipe, eventually growing into a channel in the form of a groove, emulsion enrichment with oxygen, presence of pipe wall metal in a stressed state, presence of chlorine-ion in the oil-water emulsion is required. Tests are suggested to be carried out in 3 % aqueous solution of NaCl with continuous aeration by air on bent plates 150×15×3 mm, made of the analyzed steel, the middle part of which is under the action of residual stresses σ res , close to the level of maximum equivalent stresses σ eqv in the wall of the oil pipeline, with the presence of a cut on this part on the inner side of the plate as an initiator of additional mechanical stresses. Using the value of the modulus of normal elasticity of the analyzed steel, the degree of residual strain of the elastic-plastic body from this material, corresponding to the value σ res ≈ σ eqv is calculated, based on which the plates are bent to the required deflection angle, after which the cut is applied to them. After keeping the plates in the corrosive medium for each of them the increase in depth of the cut as a result of corrosion of the walls by the corrosive medium is analyzed, from which the rate of steel K by the mechanism of grooving corrosion is calculated taking into account the duration of tests. Corrosion rate values for two pipe steel grades determined by the suggested procedure are given. The comparison of K values obtained leads to the conclusion about the higher resistance to grooving corrosion of 09G2S steel.
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Date submitted2021-04-19
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Date accepted2021-10-18
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Date published2021-12-16
Mutual spectral densities calculation of the moments of resistance on the peat milling unit working bodies
- Authors:
- Konstantin V. Fomin
When performing technological operations in the peat industry, various units with milling-type working bodies are used. They differ in design, layout, number and type of cutting elements, operating modes, and may have one or more working bodies. During operation, random forces and moments act on the cutters, which have a dramatically variable nature, which is associated with the periodic interaction of the knives with the peat deposit, its structural heterogeneity, variations in the milling depth, physical and mechanical properties of peat, the rotational speed of the cutter and the movement speed of the machine. In this case, significant dynamic loads arise in the structural elements, which leads to a decrease in their reliability, deterioration of the energy characteristics of the engine operation and technical and economic indicators of use. In the dynamic analysis of drive elements, when using machines with several working bodies, it is necessary to know both spectral and mutual spectral load densities. For their calculation, expressions were obtained that take into account the physical and mechanical properties of peat, the operating modes of the unit and their probabilistic characteristics, as well as the design features of the working body. The expressions are obtained for the case when there are several working bodies with the same diameters and the number of knives in the cutting plane. In this case, the number of planes, width, type of cutting element and type of cutting (locked, semi-locked, etc.) may differ. As an example of using the developed approaches, the calculation of spectral and mutual spectral densities of moments on cutters and loads in the drive elements of the machine for surface-layer milling MTF-14 is presented.
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Date submitted2021-03-05
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Date accepted2021-10-18
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Date published2021-12-16
Physical and mathematical model of rock destruction by a milling machine cutter
As a result of the analysis of the work on rock destruction by cutters of milling of machines, it was found that the existing developments do not allow us to proceed to the derivation of calculation d dependencies for determining fracture resistance, or can be used only in preliminary calculations of the known by design parameters of milling machines. To eliminate these disadvantages, a combined physical and mathematical model of the process of interaction of a single milling cutter with a spherical tip with the rock has been developed. Consideration of the physical picture of the action of forces and stresses acting from the cutter with spherical tips on the separating rock element in the limiting condition allowed to describe analytically the components of total resistance, which are the mathematical part of the physical and mathematical model of rock destruction by cutters. Analytical dependences for determining the tangential and normal components of fracture resistance of rocks of medium hardness have been obtained. The adequacy of the physical and mathematical model to the physical process of destruction of rocks of different hardness by cutters on a universal stand was tested both in the field and in the laboratory conditions. Technical evaluation of the results of experimental studies confirms the reliability of the developed physical and mathematical model.
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Date submitted2020-05-13
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Date accepted2021-05-21
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Date published2021-09-20
Increasing the efficiency of technological preparation for the production of the manufacture components equipment for the mineral resource complex
An increase of components production for the equipment intended for oil and gas production is a key factor for analyzing existing technological processes and searching for new technological solutions to improve the efficiency of the production process and the quality of components. The article presents a simulation model designed to determine the rational technological processing parameters for the production of the “Centralizer shell” part. The basis for optimizing the working cycle of a production line is synchronization based on the principle of proportionality, which involves equalizing the duration of all technological operations with the rhythm of the production line. Synchronization of technological operations on the production line is carried out by choosing rational cutting parameters for each technological transition (cutting speed, feedrate, number of working passes). The “Centralizer shell” part is made of titanium alloy VT16, which has high strength, corrosion resistance and ductility. For the part under consideration, the permissible values of the cutting parameters were determined based on the calculation of the total processing error, as well as the frequency of replacement of the worn cutting tool. The simulation model described in the article made it possible to increase the efficiency of the production process due to the synchronization of technological operations and the search for rational technological parameters, as well as to improve the manufacturing quality of the “Centralizer shell” part by analyzing the processing error at various parameters of the technological process.
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Date submitted2020-07-04
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Date accepted2021-03-29
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Date published2021-09-20
Transition between relieved and unrelieved modes when cutting rocks with conical picks
In the modern theory of rock cutting in production conditions, it is customary to distinguish two large classes of achievable cutting modes – relieved and unrelieved. The kinematics of rock-breaking machines in most cases determines the operation of the cutting tool in both modes in one cycle of the cutting tool. The currently available calculation methods have been developed for a stable, usually unrelieved cutting mode. In this article, the task is set to determine the conditions for the transition between cutting modes and the modernization of the calculation method for determining the forces on the cutting tool. The problem is solved by applying methods of algebraic analysis based on the search for the extremum of the force function on the cutter, depending on the ratio of the real cut spacing to the optimal spacing for the current chip thickness. As a result of solving the problem, an expression is obtained for determining the chip thickness, for which, at the specified parameters, the transition between the relieved and unrelieved cutting modes is provided. The obtained result made it possible to improve the method of calculating the forces on the cutting tool in the areas of the cutter movement with relieved cutting.
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Date submitted2019-11-04
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Date accepted2020-01-12
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Date published2020-10-08
PDC cutter pressure on plastic-brittle rock in the process of its destruction
- Authors:
- Oleg B. Trushkin
- Hamzja I. Akchurin
Presently, there are no methods for calculating the parameters of the drilling practices with rock-cutting tools equipped with polycrystalline diamond composite (PDC cutters). To create such a method requires the studying their work. The article presents the results of bench studies of the PDC cutters in the process of a rock sample breakdown when reproducing the actual layout of the cutters on the working surface of the bit. An important parameter of PDC cutters operation, which is necessary for the bit load analysis, is the pressure of the cutters on the rock during its breakdown. The total pressure of a cutter on the rock can be broken into two mutually perpendicular components: the forcing pressure and the cutting pressure. It is proposed to evaluate the PDC cutters loading at breakage of rocks of different hardness using relative values of forcing and cutting pressures, which are calculated relative to the yield strength of the rock by the die. It is established that the variability of the average relative pressures of forcing and cutting is significantly influenced by drifting per bit turnover and the radius of the cutter on the bit. The dependences of the maximum relative pressures of PDC cutters at the plastic-brittle rock breakdown on the drifting per bit turnover and the radius of the cutter location on the bit are obtained. It has been established that when drifting up to 0.4 mm per turn, the main mechanism of breakdown is cutting, and with the increase of the breakdown depth, the process of forcing becomes decisive.
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Date submitted2019-06-19
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Date accepted2019-09-11
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Date published2020-02-25
Method for estimating the spectrum density of the resistance moment on the working body of a peat milling unit
- Authors:
- K. V. Fomin
The main source of dynamic loads in the drive elements and the design of the peat milling unit is the working body. The forces of external resistance arising in the process of performing a technological operation are sharply variable, random in nature. The article proposes a model of formation of the moment of resistance on the mill when interacting with peat. The case when there are several cutting planes with the same radius at the ends of the cutting elements is considered. When developing the model, it was taken into account that the operating conditions of the knives, determined by the type of cutting (blocked, semi-blocked, etc.), their width and type in each cutting plane can vary. Factors that determine the nature of loading, such as the frequency of interaction of the cutting elements with the fallow and the randomness of the operating conditions of the unit, lead to the presentation of the loads in the form of a sequence of pulses with random parameters. Expressions are obtained for determining the spectral density of the moment of resistance on the mill at the design stage, taking into account its design, operating modes, physico-mechanical properties of peat and their probabilistic characteristics. To illustrate the application of the developed approaches, a technique is presented for determining the spectral density of the moment on the working body of deep milling machines and in their drive elements based on a linear model. An example of calculation is given, and the obtained expressions are verified on the basis of experimental data. The probabilistic characteristics of the loads on the mill serve as initial information for the dynamic analysis of the drive system and the design of the unit, its strength analysis, the selection of optimal parameters and operating modes.
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Date submitted2019-07-06
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Date accepted2019-08-25
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Date published2019-12-24
Improving the efficiency of technological preparation of single and small batch production based on simulation modeling
Technological preparation of production is an integral stage of the production process, which is characterized by high complexity, which is largely felt in the conditions of single and small-scale types of production. The effectiveness of technological preparation of production is increased through automation with the use of simulation modeling. The objective of the study is to develop a simulation model that allows you to determine a rational version of the process for processing a batch of parts. The simulation model described in the article allows to analyze the production schedule of the enterprise, build processing routes, evaluate options for using various types of workpieces and technological equipment, determine the acceptable values of cutting conditions, and choose a rational variant of the technological process of processing a batch of parts. The developed simulation model is based on the principles of modular technologies, the part is considered as a combination of individual elementary surfaces. Each elementary surface contains information about the technological processing route, technological equipment and the type of technological equipment used in its manufacture, cutting conditions and the size of the allowance for each processing stage. The rational choice of the technological process is selected on the basis of multicriteria analysis according to three criteria: the value of variable costs, the production time of a batch of parts and the value of the processing error. The analysis of these criteria is made and the parameters that have the greatest impact on their value are determined. The developed classification of surface elements is described: design elements, technological elements, basic elements, as well as a mathematical model based on which the calculation of the values of the criteria for choosing a rational option.
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Date submitted2019-07-23
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Date accepted2019-09-19
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Date published2019-12-24
Estimation of abrasiveness impact on the parameters of rock-cutting equipment
Development of equipment, which provides access to underground mineral deposits and their extraction, requires the use of all the accumulated experience and advanced scientific research in the area of mechanical rock cutting. The most important issues of using mechanical rock cutting tools are their wearability and consumption, which have an impact on technical and economic indicators of project efficiency. The paper describes Russian and foreign practices of estimating tool wear resistance, expressions to determine critical cutting speed, methods to evaluate tool consumption. It is demonstrated that wearability of mechanical tools and associated effects are to a large extent defined by rock abrasiveness. It is highlighted that in Russia the index is calculated using Baron-Kuznetsov method, which is briefly described in the paper. In many countries with a highly-developed mining industry, rock abrasiveness is estimated with a Cerchar Abrasiveness Index (CAI), recommended by the International Society for Rock Mechanics. Its description is also presented in the paper.
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Date submitted2018-11-03
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Date accepted2019-01-16
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Date published2019-04-23
Interpretation of the tracer investigation results considering convective mass transfer
- Authors:
- V. A. Korotenko
- S. I. Grachev
- A. B. Kryakvin
The paper discusses the results of interpreting well tracer studies. It is shown that from the law of mass conservation it follows that when filtering a volume of an indicator, part of the injected tracer flows into the matrix. With the flow of fluid containing the indicator from the low-filtration resistance channel (LFR) into the surrounding matrix, the linear dimensions of the flow area depend on the permeability and porosity properties of the high-permeability channel and the matrix. While another part of the tracer moves toward the production well, its mass is lost due to diffusion processes. From the solution of the diffusion equation, it follows that the initial concentration of the tracer decreases in the course of filtration along the LFR channel. To interpret the results of the tracer studies, different cases of the LFR channels' location in the volume of the productive formation are considered. The varied parameter w allows characterizing the presence of several peaks in the concentration of the indicator and calculation the filtration parameters of the LFR channels. Depending on the known technological indices, several methods for determining pore volumes in the LFR channels have been proposed. To reduce the water cut in producing wells and to apply the technology of changing or aligning the injectivity profiles, calculations of the pore channels' radii in the mass of highly permeable seams are presented. It is shown that the volume of the chemical reagent pumped into the injection well to isolate the LFR channel is affected by the linear dimensions of the drainage area for the aqueous solution of indicator. Examples of the calculation for the permeability and porosity parameters of the LFR, the volume of pore channels necessary to isolate water inflow, and the radii of pore filtration channels, which influence the selection of the size of chemical reagent molecules, are given.
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Date submitted2018-11-05
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Date accepted2019-01-01
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Date published2019-04-23
Features of elementary burst formation during cutting coals and isotropic materials with reference cutting tool of mining machines
- Authors:
- V. V. Gabov
- D. A. Zadkov
- Khac Linh Nguyen
The paper considers the cutting of brittle coals and rocks by a single cutter of a mining machine, in contrast to the generally accepted integral approach, different from the standpoint of the formation of successive elementary bursts that make up the cut. The process of the formation of an elementary bust in time is viewed as successive phases. Due to the complexity and multi-factor nature of the process, preference is given to experimental bench studies using reference cutters, isotropic materials, and real rock blocks. The bursting parameters values greatly influence the time of static forces action, the peculiarities of the formation of stress fields in the undercutter zone of the rock mass and the conditions for the emergence and development of main cracks in the near-cut zones during the cutting process. The accepted phase-energy method of analyzing the process, which most closely matches the structure of the studied process, revealed a more significant, than previously expected, effect on the cutting process, variability of cutting speed and potential energy reserve in the cutter drive. The paper discusses the possibility of purposeful formation of the parameters of elementary bursts. It describes new ways to improve the efficiency of cutting coal and rocks, in particular, reducing the maximum loads and specific energy consumption. It also considers the possibility of reducing the grinding of the rock mass and dust formation.
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Date submitted2018-05-21
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Date accepted2018-07-14
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Date published2018-10-24
Increasing the wear resistance of adapters and drill pipes by elec-tromechanical processing
The directions of the research on increasing the wear resistance of drill pipe locks, threaded joints and casing drill string have been defined: application of drill pipes from the nose-resistant surfacing to the lock with Russian and foreign materials (hardbanding); hardening of the surface layer of drill pipe locks by electromechanical processing; hardaning of the external and internal locking thread of drill pipes by electromechanical processing. Comparative tests of the wear resistance of various hardening materials (hardbanding) of Russian and foreign production and the drill pipe lock without surfacing have been made. The recommendations for increasing the wear resistance of threaded joints by the method of electromechanical processing are developed, which determine the ways of increasing the resource and reliability of drill pipes and sub-assemblies, the formation of unique properties of parts, reducing the labor-capacity of manufacturing and restoring parts, increasing the efficiency of enterprises and organizations, protecting the environment and creation of competitive products. The materials of the article are of practical value for specialists of various fields engaged in the issues of increasing the reliability of technological equipment. The production success of using wear resistant surfacing technology on the body of a drill pipe joint is due to the possibility of using relatively simple and mobile welding equipment, carrying out work in the places of use of a drilling tool or temporary (permanent) production bases with a small transport arm from the field, re-depositing surfacing materials restoration of drill pipe locks; a wide and growing list of companies that receive accreditation for the production of these works.
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Date submitted2017-11-22
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Date accepted2018-01-04
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Date published2018-04-24
Justification of a methodical approach of aerologic evaluation of methane hazard in development workings at mines of Vietnam
- Authors:
- V. V. Smirnyakov
- Nguen Min' Fen
The methods of evaluation of the aerological conditions to be performed for the purpose of normalization of mining conditions are provided in the present review; the location of possible accumulations of explosive gases during the drift of the development workings are taken into account. To increase the safety of the development working regarding the gas factor, a complex evaluation of a working was developed with respect to the dynamics of methane emission and air coursing along the working which is strongly affected by the character of the leakages from the ventilation ducting. Thereby, there occurs a necessity of the enhancement of a methodical approach of calculation of ventilation of a working which consists in taking into consideration a total aerodynamic resistance of the booster fan including the local resistances of the zones of the working. An integer simulation of the gas-air flows realized on the basis of a software package FLowVision allows to evaluate a change in the methane concentration in the zones of local accumulations.
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Date submitted2017-09-17
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Date accepted2017-11-06
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Date published2018-02-22
Collaborative interpretation of the data obtained by resistivity and ground penetrating radar methods for assessing the permeability of sandy clay soils
- Authors:
- D. A. Lalomov
- V. V. Glazunov
A method for estimating the filtration factor of sandy clay soils is considered on the basis of a joint interpretation of the data of a set of methods of engineering electrical exploration, including electrical resistivity tomography and ground penetrating radar studies. The solution of this problem is based on the use of known empirical connections between the imaginary and real parts of the complex dielectric permittivity, specific electrical resistance, and Q factor. An example of the effective joint use of the ground penetrating radar and non-contact electrical resistivity tomography shows how to obtain qualitative and quantitative estimates of a changing filtration factor in a draining road layer. It is necessary to use precise engineering geological information in order to provide the required estimates. The proposed approach makes it possible to describe continuous profiles of a pavement and underlying layers by ground penetrating radar and electrical resistivity tomography, as well as to assess soil properties when conducting an electrical survey from the surface of asphalt concrete pavement. Recommendations for the implementation of the developed methods of complex engineering and geophysical research are given for solving issues of repair work design, supervision, and quality control of road construction.
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Date submitted2014-10-09
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Date accepted2014-12-26
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Date published2015-08-25
Improving the precision of manufacturing power hydraulic cylinders of powered roof supports based on a vibration-damping tooling system
- Authors:
- V. V. Maksarov
- Yu. Olt
The article deals with a new system of a vibration-damping tool, the effect of which is achieved by a combination of the multi-layer principle and the use of anisotropic properties of sheet metal. Operation of such tool systems in turning operations can reduce high-frequency vibra-tions arising in the process of cutting due to the ordered disorientation of anisotropic plate texture of a multilayer modular tool holder that allows you to efficiently dissipate oscillatory wave energy at the boundary of transition between the plates of the tool holder. This method allows increasing the resistance of the tool cutting edge significantly and expanding the technological capabilities for the effective selection of cutting modes to ensure compliance with requirements for dimensional and geometric accuracy, quality of processed surfaces of powered roof supports, hydraulic units, mining machinery and equipment.
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Date submitted2010-07-16
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Date accepted2010-09-06
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Date published2011-03-21
The aboveground oil pipeline temperature regimes calculation
- Authors:
- S. Yu. Trapeznikov
The theoretical and experimental investigations of the highviscosity oil transportation temperature regimes to improve the pipeline efficiency are caused by the insufficient knowledge of its heat transfer process. The dependencies for the hydraulic resistance coefficient and the dimensionless heat transfer coefficient of Nusselt are proposed.
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Date submitted2010-07-14
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Date accepted2010-09-07
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Date published2011-03-21
Substantiation of pumped volumes of flow angularity compositions in injection wells
- Authors:
- A. R. Mavliev
- M. K. Rogachev
- D. V. Mardashov
The method of calculation pumped volumes of flow angularity compositions in injection wells, which based on combination of the seepage theory, laboratory investigation and field experience is developed.
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Date submitted2010-07-10
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Date accepted2010-09-04
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Date published2011-03-21
Experimental research of the train aerodynamic resistance
- Authors:
- V. A. Pleskunov
In paper the technique of definition of aerodynamic resistance of the train, a being main component of a piston pressure is resulted. The urgency of the given theme is caused by essential influence of a piston pressure on distribution of fresh air on a tunnel and accordingly on safe operation of railway tunnels.
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Date submitted2009-09-25
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Date accepted2009-11-15
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Date published2010-06-25
Studies of resistance micro-welding modes for dentistry applications
- Authors:
- A. B. Tsyganov
- A. S. Mustafaev
Various modes of resistance welding between steel and Ni-Ti-extracting electrodes and fractures of endodontic files were investigated. It was demonstrated that in close to real clinical situations there is most suitable a sequence of a number of pulses of a steepened welding current. As a result, detachment force limit of 15-50 N is achievable which is sufficient for the fracture extraction in most cases.
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Date submitted2009-09-26
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Date accepted2009-11-22
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Date published2010-06-25
Use of mosfet for the control of dielectric characteristics
- Authors:
- N. S. Pshchelko
- A. S. Mustafaev
In this work a device for measurement on a constant voltage of the basic electric characteristics of high-resistance dielectric materials and products from – their electric capacitance and resistance – is developed. The principle of work of the device is based on use of transients in connected in sereies elements having electric capacity and resistance. In the electric circuit of the device the MOSFET with high entrance resistance is used. The device on the basis of the MOSFET for measurement of surface potential of dielectrics is considered also. Use of this device is especially effective at measurement of electret surface potential. Results of research of electrets on a basis of silicon dioxide are discussed.