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Date submitted2023-07-07
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Date accepted2023-12-27
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Date published2024-08-26
Landslide hazard assessment in Tinh Tuc town, Cao Bang province, Vietnam using Frequency ratio method and the combined Fractal-frequency ratio method
Landslides are one of the most frequent natural disasters that cause significant damage to property in Vietnam, which is characterized by mountainous terrain covering three-quarters of the territory. In 17 northern mountainous provinces of the country, over 500 communes are at a high to very high landslide hazard. The main goal of this study was to establish landslide hazard maps and conduct a comparative evaluation of the efficiency of the methods employed in Tinh Tuc town, Cao Bang province. The landslide hazard assessment was carried out in this study using the combined Fractal-frequency ratio (FFR) and the Frequency ratio (FR) methods. The FR method is based on the actualist principle, which assumes that future landslides may be caused by the same factors that contributed to slope failure in the past and present. The FFR method is based on the determination of the fractal dimension, which serves as a measure of the landslide filling density in the study area. Eight landslide-related factors were considered and presented in cartographic format: elevation, distance to roads, slope, geology, distance to faults, land use, slope aspect, and distance to drainage. Determining the area under the receiver operating characteristic curve (ROC-AUC) and verification index (LRclass) was performed to assess the performance of prediction models and the accuracy of the obtained maps. As a result, five zones were identified for the study area, characterized by very low, low, moderate, high, and very high landslide hazards. The analysis of the reliability of the obtained landslide hazard maps using the AUC and LRclass indices revealed that the FFR model has a higher degree of reliability (AUC = 86 %, LRclass = 86 %) compared to the FR model (AUC = 72 %, LRclass = 73 %); therefore, its use is more effective.
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Date submitted2021-11-10
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Date accepted2022-05-25
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Date published2022-12-29
Predicting the permeability of the near-bottomhole zone during wave impact
The research reveals that during selection of a method to increase oil recovery it is necessary to take into account rheological features of fluid movement through the formation, effect of capillary forces and heterogeneity of reservoir properties of the productive formation in thickness and along the bedding. Low-frequency wave impact, which is used to increase production in oil fields, is considered. At low-frequency impact new fractures appear and existing fractures in rocks increase in size. The greatest increase in porosity and permeability of rocks occurs at an impact frequency up to 10 Hz. Dynamics of oscillation amplitude during wave's movement in saturated porous medium is studied in the paper: essential attenuation of amplitude occurs at distance up to 1 m from borehole axis. With increase of frequency from 1 to 10 Hz the intensity of amplitude's attenuation decreases. The technology was tested on a well in Perm region (Russia). The actual permeability value was 50 % higher than the predicted value. According to the results of hydrodynamic investigations processing, it was noted that the greatest increase of permeability took place near the wellbore, while away from the wellbore axis permeability remained almost unchanged. In order to refine the mathematical model for prediction of wave impact on rock permeability it is necessary to take into account interconnection of pore space structure, change of adhesion layer, as well as to study transfer of particles during vibration.
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Date submitted2020-10-22
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Date accepted2021-03-02
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Date published2021-04-26
Dynamic simulation of industrial-scale gibbsite crystallization circuit
- Authors:
- Vladimir O. Golubev
- Tatyana E. Litvinova
Population balance model is crucial for improving the method of aluminum hydroxide massive crystallization and enhancing the quality of control over industrial precipitation trains. This paper presents the updated population balance model, which can be used for simulation of industrial-scale precipitation. Processes of birth-and-spread and particle breakage are considered integral parts of the precipitation process along with secondary nucleation, growth and agglomeration of particles. The conceptual difference of the proposed system of equations is its ability to reproduce the oscillatory process that occurs in precipitation circuits as a result of cyclic changes in the quality of the seed surface. It is demonstrated that self-oscillations can occur in the system without any external influence. The updated model is adjusted and verified using historical industrial data. The simulation of seed-recycle precipitation circuit showed an exact correspondence between the calculated dynamic pattern of changes in particle size distribution of aluminum hydroxide and the actual data.
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Date submitted2020-05-21
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Date accepted2020-10-05
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Date published2020-11-24
Method of calculating pneumatic compensators for plunger pumps with submersible drive
- Authors:
- Eduard O. Timashev
One of the most promising ways to improve the efficiency of mechanized oil production is a plunger pump with a submersible drive, which allows obtaining harmonic reciprocating movement of the plunger. In the pumping process of well products by plunger pumps, oscillations in the velocity and pressure of the liquid in the lifting pipes occur, which lead to an increase in cyclic variable loads on the plunger, a decrease in the drive life period and the efficiency of the pumping unit. To eliminate the pulsation characteristics of the plunger pump and increase the reliability indicators of the pumping unit (in particular, the overhaul period), pneumatic compensators can be used. A method for calculating the optimal technological parameters of a system of deep pneumatic compensators for plunger pumping units with a submersible drive, based on mathematical modeling of hydrodynamic processes in pipes, has been developed. Calculations of the forming flow velocity and pressure in the lifting pipes of submersible plunger units equipped with pneumatic compensators (PC) have been carried out. Influence of the PC technological parameters on the efficiency of smoothing the oscillations of velocity and pressure in the pipes has been analyzed. Non-linear influence of the charging pressure and PC total volume on the efficiency of their work has been established. Optimal pressure of PC charging, corresponding to the minimum pressure in the tubing during the pumping cycle for the considered section of the tubing, is substantiated. Two ultimate options of PC system placement along the lifting pipes are considered. In the first option, PC are placed sequentially directly at the outlet of the plunger pump, in the second - evenly along the lift. It is shown that the first option provides the minimum amplitude of pressure oscillations at the lower end of the tubing and, accordingly, variable loads on the pump plunger. Nature of the pressure and flow velocity oscillations in the tubing at the wellhead for both options of PC placement has similar values .
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Date submitted2019-03-31
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Date accepted2019-08-25
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Date published2020-02-25
Cascade frequency converters control features
The structures of systems with high-voltage cascade frequency converters containing multi-winding transformers and low-voltage low-power converters connected in series at each output phase of the load are considered. Low-voltage blocks contain three-phase diode or active rectifiers, DC capacitor filters, single-phase stand-alone voltage inverters and block disconnecting devices in partial modes (in case of failure when part of the blocks are disconnected). The possibilities of operation of cascade converters are determined, equations for correcting tasks to units in partial modes are given, tables of correction of tasks with estimates of achievable load characteristics are proposed. The results of experiments on the model of a powerful installation with a cascade frequency converter are presented, confirming the possibility of ensuring the symmetry of the load currents when disconnecting part of the blocks and the asymmetry of the circuit.
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Date submitted2019-05-05
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Date accepted2019-07-03
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Date published2019-10-23
Scraper Face Conveyors Dynamic Load Control
- Authors:
- E. K. Eshchin
The task of controlling the dynamic loading of scraper face conveyors (SC) is considered and the unsatisfactory state of loading of mechanical and electrical components of the SC is recorded. The possibility of the appearance of a self-oscillatory nature of the entire system load due to the peculiarities of the movement of the traction chain along the lattice frame of the SC is indicated. The property of the system is noted – the cyclic nature of the loading of the circuit during movement, which causes energy exchange processes between the mechanical and electromotive components of the conveyor (when using the head and tail electric drives) through the common cable network of the power supply system of the SC. A high level of dynamic loading of the electromechanical system causes the problem of eliminating the self-oscillating operating mode of the SC that generates it which is proposed to be solved by changing the angular rotation speeds of the SC drive sprockets. Angular speeds can be changed by applying frequency control of asynchronous electric motors. The efficiency of setting the frequency of electric motor stator currents of the head and tail drives of the conveyor is established in proportion to the frequency of rotors rotation to eliminate self- oscillating modes of operation in the main operating mode. The possibility of reducing the starting shock values of the electromagnetic moments of electric motors is considered. The results of the calculation of the start-up and liquidation of the self-oscillating operating mode are presented on the example of the scraper face conveyor Anzhera-34. The results of calculations of the start-up modes and the main operational transportation of coal in an uncontrolled mode of operation and after the introduction of control are compared, based on which it is concluded that it is advisable to use active control of the dynamic loading ofSC.
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Date submitted2019-03-13
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Date accepted2019-05-18
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Date published2019-08-23
Improving the Operation of Pump-ejector Systems at Varying Flow Rates of Associated Petroleum Gas
- Authors:
- A. N. Drozdov
- Ya. A. Gorbyleva
Application of pump-ejector systems for the utilization of associated petroleum gas reduces the negative environmental impact of its flaring, and also allows the implementation of a promising method of water-gas stimulation of the formation, which effectively increases oil recovery. Equally feasible is the use of pump-ejector systems in the operation of oil wells with a high gas factor, low bottomhole pressures to increase production rates and increase the turnaround period. A significant change in the flow rate of associated petroleum gas over time is a serious problem for the efficient operation of pump-ejector systems for the utilization of associated petroleum gas. To ensure the rational operation of the pump-ejector system under the condition of a variable flow rate of associated petroleum gas, experimental studies of a liquid-gas ejector characteristics were carried out. The article presents the results of the research, obtained pressure-energy characteristics of the investigated jet apparatus at various values of the working stream pressure before the ejector nozzle. The possibility of adapting the operation of pump-ejector systems to changes in the flow rate of the pumped gas, regulated by the working pressure and fluid flow rate through the nozzle is revealed. To successfully change the operation of the pump-ejector system, the possibility of frequency regulation of the pump shaft's rotation at changing gas flow rates in a small range of values is considered. With a large difference in the values of the possible flow rate of associated petroleum gas, it is recommended that frequency regulation should be supplemented by periodic short-term operation. The possibility of increasing the efficiency of the pump-ejector system when using salt solutions with a concentration that contributes to the suppression of bubble coalescence is noted.
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Date submitted2018-09-07
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Date accepted2018-11-10
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Date published2019-02-22
Justification of the technological parameters choice for well drilling by rotary steerable systems
- Authors:
- Vladimir S. Litvinenko
- M. V. Dvoinikov
Paper presents the analysis of the investigation results of vibrational accelerations and beating amplitudes of the downhole drilling motor, which help to define the ranges of optimum energy characteristics of the gerotor mechanism, ensuring its stable operation. Dependencies describing the operation of the «drilling bit – rotary steerable system with power screw section – drilling string» system and the values of the self-oscillation boundaries and the onset of system resonance when it is used jointly, were defined as a result of computational and full-scale experimental research. A mathematical model is proposed, which allows determining the optimal range of technological parameters for well drilling, reducing the extreme vibration accelerations of the bottomhole assembly by controlling the torque-power and frequency characteristics of the drilling string, taking into account the energy characteristics of the power screw section of the rotary steerable system. Recommendations on the choice of drilling mode parameters were given.
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Date submitted2018-07-18
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Date accepted2018-08-25
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Date published2018-12-21
Development of vibroacoustic module for fine filtration of drilling muds
- Authors:
- G. B. Fedorov
- O. L. Dudchenko
- D. S. Kurenkov
The issue of drilling mud multiple use is problematic. To reuse, the solution must be efficiently cleaned from solid particles according to the class of 0.04-0.07 mm. An analysis of existing technologies and equipment has shown that drilling mud regeneration schemes are rather difficult to operate and expensive. In world practice there has been a tendency to create universal equipment, which allows most complete cleaning cycle for a drilling mud in fine grades. The paper proposes an innovative vibroacoustic module for cleaning drilling muds from sludge. The creative element of the proposal is the impact of vibroacoustic oscillations on the drilling mud passing through the mesh element. At the same time, specific effects arise around the mesh, which increase the productivity and efficiency of the process. The design of the vibroacoustic apparatus and the principle of its operation are presented. An important element of the proposal is that the oscillation is created by pistons interconnected by rods and located on opposite sides of the mesh. This dipole system provides the excitation of variable pressures of different polarity before the mesh and after it. The results of industrial tests of the vibroacoustic module when servicing the BU-75-BrE drilling rig are presented. The dependence of the installation performance and efficiency on the amplitude of oscillations was found. The optimal dynamic range of exposure (from 5.5 to 6.5 mm) was determined. Analysis showed that in the composition of the cleaned drilling mud, the maximum particle size of the solid phase did not exceed 0.04 mm. The conducted industrial tests confirmed the possibility of using the vibroacoustic module for cleaning the washing fluid and developing a pit-free drilling technology on its basis.
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Date submitted2017-09-03
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Date accepted2017-11-04
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Date published2018-02-22
Development of sensorless vector control system for permanent magnet synchronous motor in Matlab Simulink
- Authors:
- V. Ya. Frolov
- R. I. Zhiligotov
In last 20 years segment of electric drives with permanent magnet synchronous motors has increased. This type of motors has better technical characteristics compared to induction motors, but has problems in actual implementation, one of which is the requirement of rotor position data. It is possible to implement with use of sensors or without them by means of motor state observer. The paper describes problems of sensorless vector control system for permanent magnet synchronous motors. The vector control system with state observer for permanent magnet synchronous motors is described. Synthesis of sliding mode observer for rotor speed and position is presented. The algorithm is implemented by development of model in Matlab Simulink environment with support by Texas Instruments processors support blocks. Experimental comparison of results of rotor angle state calculation and the data obtained by rotor position sensors was conducted. Research objective is a development of control algorithm, which has required precision for calculation of rotor start angle, high range of speed regulation and resistance to drift of motor parameters.
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Date submitted2015-08-18
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Date accepted2015-10-06
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Date published2016-04-22
Energy- efficient control of asynchronous motor drive with current refinement of the loss minimum on the basis of fuzzy logic
- Authors:
- O. B. Shonin
- V. S. Pronko
Currently, asynchronous electric drive on the basis of semiconductor frequency converters is widespread because of the relative simplicity and reliability of the design, the use of digital control systems, providing the accuracy and flexibility of process control, which allows for a significant increase in product quality, reduction in energy consumption and improvement of the enterprise profitability. In spite of these advantages, the problem of ensuring high energy efficiency of the drive in wide range of its operational modes is still not solved in full scale. The paper is devoted to the reduction of losses in the asynchronous drive on the basis of en-ergy-saving control algorithms that aim to ensure the desired mode of the driven mechanism while minimizing losses in copper and steel of the motor. On the basis of the motor model, taking into account magnetic losses, dependences of losses in the copper and steel, as well as the total loss from the absolute slip have been derived for different operating points of the drive. The optimal values of the absolute slip for different speeds of the rotor have been obtained for use in the con-trollers ensuring operation of the drive at maximum efficiency, highest power factor and minimum of the stator current. For minimizing the losses in the drive when changing the motor parameters it has been offered the combined method based on the method of loss model and iterative method of searching the minimum of power consumption. The effectiveness of the proposed control system using fuzzy logic is confirmed by comparing the graphs of losses and efficiency, obtained at using a traditional control law and the optimal control law.
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Date submitted2014-12-27
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Date accepted2015-03-01
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Date published2015-12-25
Minimization of energy losse when starting a variable frequency drive through application of a genetic algorithm of optimization
- Authors:
- O. B. Shonin
- V. S. Pronko
In the face of energy lack and rising energy prices one of the priorities of current researches is to improve energy efficiency of electric drives, which are widely used in modern industrial plants. Existing methods of minimizing losses are mainly designed for stationary regimes. At the same time, the development of algorithms for reducing losses in transient and in particular starting conditions is given little attention. Due to the high complexity of the description of the multivari-ate dynamic processes determining the optimal control laws is advantageously to be carried out us-ing stochastic optimization methods. The work seeks to substantiate the optimal starting character-istics of an asynchronous drive based on a genetic algorithm. A feature of the proposed method of optimization is the use of multiple simulation experiments to find start-up characteristics which provide a minimum energy loss. Automation of the search is performed using the developed pro-gram, which includes a module of a genetic algorithm and a module for interfacing with the elec-tric model in the MATLAB/Simulink environment. The program allows choosing the parameters of the genetic algorithm along with controlling the process of optimization. Application of the proposed method allowed obtaining the optimal starting characteristics «voltage – frequency» in a tabular form with consequent linear approximation of the data. Increase in efficiency due to the proposed start up law has been confirmed by comparing the simulation re-sults under conditions of using a traditional linear characteristic and derived optimal law. The es-timation of losses reduction has been carried out at the drive load of different kind in a wide range of its variation.
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Date submitted2010-07-15
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Date accepted2010-09-13
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Date published2011-03-21
Experimental setup for research Influence of vibromechanical treatment on mechanical properties of welded joints
- Authors:
- O. F. Khafizova
- V. I. Bolobov
The description of developed experimental setup for welding product that made of pipeline steels with application of applying vibration with intended frequency approximating to natural-vibration frequency of welded construction unit of pipelines during the welding cycle is presented.
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Date submitted2010-07-19
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Date accepted2010-09-22
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Date published2011-03-21
Simulation of swinging movement autoresonant electric drive with nonsymmetric excitation
- Authors:
- A. N. Fomenko
Mathematical and simulation models of drill bit oscillations. Method for calculating the model works elastic, electromagnetic and load torques has been developed. Simulation results of autoresonant regimes with asymmetric excitation oscillations of dynamically counter balanced drilling string on the cargo-carrying cable drill bit are represented.
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Date submitted2010-07-06
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Date accepted2010-09-14
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Date published2011-03-21
Electromechanical processes in electric drives of mountain equipment on the basis of the synchronous electric motor
- Authors:
- A. O. Sviridenko
The description is given and the function chart of the bench installation is resulted, allowing to reproduce static and dynamic modes of adjustable electric drives of an alternating current. The modes considered during experimental researches of the electric drive on the basis of the synchronous electric motor, working in a mode of ventilniy electric motor are listed. Conclusions are drawn on character of course of dynamic modes, comparison of the electric drive to the synchronous electric motor and the electric drive of a direct current with the subordinated regulation is given.
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Date submitted2010-07-20
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Date accepted2010-09-14
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Date published2011-03-21
The physical breadboard model of dynamically counterbalanced drilling string with swinging movement with the asynchronous electric drive powered by inverter laboratory experimental researche
- Authors:
- V. V. Ivanik
The laboratory experimental stand for research of the asynchronous resonant electric drive on a physical breadboard model of dynamically counterbalanced drilling string is developed. The asynchronous electric drive with swinging movement the autoresonant oscillation mode is realized.
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Date submitted2010-07-21
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Date accepted2010-09-28
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Date published2011-03-21
Swinging movement autoresonant electric drive with nonsymmetric excitation of dynamically counter-balanced drilling string on carrying cable
- Authors:
- E. A. Zagrivnyi
- A. N. Fomenko
Considered nonsymmetric mode of drill bit oscillations when forming a unipolar electromagnetic torque on each cycle oscillations of dynamically balanced drill . Developed a method for estimating speed of rotation drill around its axis when working in the nonsymmetric mode at first approximation .
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Date submitted2010-07-08
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Date accepted2010-09-02
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Date published2011-03-21
The autoresonant asynchronous electric drive of dynamically counterbalanced drilling string on carrying cable with swinging movement fluctuations amplitude stabilization
- Authors:
- E. A. Zagrivnyi
- V. V. Ivanik
The algorithm of resonant fluctuations amplitude stabilization of dynamically counterbalanced drilling string on carrying cable with swinging movement of jackbit is developed. Imitating modeling of the resonant asynchronous electric drive with swinging movement of jackbit with the frequency converter in various operating modes is resulted.
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Date submitted2010-07-26
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Date accepted2010-09-14
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Date published2011-03-21
Algorithm of control of the electric drive with ventilniy electric motor and the converter of frequency with the active rectifier
- Authors:
- A. P. Emelyanov
- A. O. Sviridenko
Advantages of application of the active rectifier as a part of converters of frequency for powerful drives with ventilniy electric motors are considered. The mathematical description of the processes proceeding in a power part of the active rectifier is given. The scheme of a drive with a vector control system with the gage of position of a rotor and the active rectifier is presented, schedules of power consumption and a current by a drive with the active rectifier are resulted.
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Date submitted2009-09-01
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Date accepted2009-11-19
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Date published2010-06-25
Structural features of gas-liquid mixture
- Authors:
- Yu. D. Muraev
- V. L. Shkryabin
- Sh. Z. Guseinov
the effectiveness of the foam flush drilling connects of foam ability to reduce the friction force and drilling shaft oscillation. The main factors are foam viscosity and foam bubble’s diameter.
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Date submitted2009-09-26
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Date accepted2009-11-14
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Date published2010-06-25
Automatic bulk solids moisture in stream control system
- Authors:
- S. S. Galushkin
- B. A. Vishniak
- V. N. Smirnov
Automatic moisture in fine-dyspersated stream control system based on microwave frequency method is presented. Minimizing means of interrupting factors peculiar to this method of measurement are produced and systematically proved.
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Date submitted2009-08-17
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Date accepted2009-10-25
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Date published2010-02-01
Compensation of supply station reactive power by means of the mine main fan electric drive
- Authors:
- V. V. Sobolev
- O. B. Shonin
On the basis of comparative analysis of the mine main fan electric drive input voltage-current characteristics, a frequency-variable drive with pulse width modulation (PWM) rectifier and PWM inverter is shown to be the most competitive one because of its capability to independently implement the substation power factor correction and the mine air flow energy-saving control.
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Date submitted2008-10-15
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Date accepted2008-12-17
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Date published2009-12-11
Low frequency inductive airborne electromagnetic system em-4h
Nearly all existing airborne EM-survey systems have been tested in Russian Federation. And for today the most popular EM-system is the frequency-domain one, called EM-4H. The article gives the description of the EM-4H system, that have been developed by «Geotechnologies» JS. This instrument allows effective conductivity mapping on a 1:25000 scale. It provides performing of 100 kilometers of survey per hour on the average.
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Date submitted2008-10-29
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Date accepted2008-12-06
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Date published2009-12-11
Data collection and processing system of low-frequency electrical method with artificial source
- Authors:
- A. I. Geraskin
Review of the basic components of elaborating system is presented. The basic trends of application of these components and software products created on their basis are shown. The concept of a processing graph is entered and shown its dynamic features. Specific examples of the successful practical application of the system are considered.