Rectilinear Sections Research Articles

An Image Processing-Based Method to Analyze Driver Visual Behavior Using Eye-Tracker Data

This paper presents a practical method for analyzing drivers’ eye movements, providing a valuable tool for understanding their behavior during driving simulations. The method, which utilizes an image processing technique, addresses the challenges when the driver’s attention is on points without information about the image depth. The screen image changes or moves with the simulation. It allows us to identify the gaze position relative to the road, determining whether the glance is inside or outside. This is achieved by transforming RGB images (frames) collected by the eye-tracker video camera into a b/w image using the Canny filter. This filter can identify objects’ contours by evaluating the change in color of their surfaces. A window is then applied to these new images to extract information about the gaze position in the real world. Four drivers were used as a sample for the method’s testing. The findings demonstrate various driver variations and a disparity between driving in curved and rectilinear segments. The gaze is typically inside the road in curved sections, whereas in rectilinear sections, the gaze is frequently outside.

Relevance of monitoring residual stresses and the need to reduce them

The objective of the study is to show the significant impact of taking into account the actual values of residual stresses on the strength and resource of safe operation of nuclear power facilities. Generally accepted approaches of strength physics and fracture mechanics were used to determine strength and service life. The degree of influence of residual stresses on the strength and service life of pipeline elements in the case of a cyclically acting load, under static load, when there is a danger of brittle fracture, and in the case of corrosion is investigated. The objects of the study were pipelines of nuclear power plants. It is noted that the current state of science and technology has made it possible to create a technique for non-destructive testing of mechanical stresses acting in metal structures based on the use of the acoustoelasticity method. Currently, on the basis of this method, a method for measuring residual welding and installation stresses in pipelines has been developed and certified for use in the field of atomic energy use. The measurement technique provides for the determination of membrane and bending stresses in annular sections located on rectilinear sections of pipelines. The values of stresses in the structural elements of pipelines and residual welding stresses in the deposited metal of welded joints are determined using ratios based on the use of the balancing principle. The relevance of introducing into the procedure for monitoring the technical condition of pipelines and equipment of nuclear power plants the procedure for determining the actual level of residual stresses, which significantly increases the reliability of the assessment of their strength and service life, is shown. It is proved that in order to implement the procedure for determining the actual level of residual stresses, it is necessary to use a non-destructive testing system for residual welding and installation stresses using the acoustoelasticity method based on a measurement technique that allows determining the actual values of residual stresses with established error characteristics.

Модель проходження повороту автомобілем

The car turning model is considered, in particular at an X-shaped intersection with an arbitrary intersection angle of the tracks. The conditions and restrictions that are imposed when the car enters a turn are analyzed. It is shown that, when the car moves from straight to curved sections, angular accelerations acting relative to its vertical axis have a significant influence on the redistribution of the forces of interaction between the wheels and the road surface and, accordingly, on the stability and controllability of the car. The analysis of motion trajectories, which consist of conjugate rectilinear and curvilinear sections and are described by the equations of a circle, a parabola, and a hyperbolic cosine, is provided. It is shown that choosing a trajectory according to the law of parabola and hyperbolic cosine slightly reduces the turning radius of the car, but significantly reduces the curvature gradient in the conjugation zone and, accordingly, reduces angular accelerations and increases the resistance of the car to rotation relative to the vertical axis. For a smooth transition from a straight path to a curved one, a special logistic dependency was used to connect (stitch) different sections of the route. This made it possible to describe the trajectory of the car by a smooth function, the first and second derivatives of which are also smooth functions. For the selection of the trajectory of passing turns with a slight curvature of the route, a dependence in the form of a fourth-degree polynomial, the curvature of which at the point of conjugation is equal to zero, is proposed, which ensures a smooth transition from a straight to a curved section and ensures passing a turn with minimal dynamic loads. 
 The developed model allows you to design the trajectory of turning for various types of intersections in real time and can be used to build dynamic models of car movement along given trajectories, as well as to build simulators for unmanned vehicles.

Результаты гидравлических расчетов каналов Черноземельской обводнительно-оросительной системы

Purpose: hydraulic calculations of the current water supply network of the Chernozemelskaya irrigation system channels. Materials and methods. The materials for the calculations were: operational records of the Chernozemelskaya irrigation system, the results of field surveys of channels and data from instrumental measurements of water levels, velocities and water discharges in the surveyed discharge section lines of distributary channels. The field work was carried out according to the generally accepted rules and methods of surveys, hydrometric measurements and assessment of the reclamation facilities state. Channel hydraulic calculations were performed for the conditions of constant water flow in their channels on rectilinear sections. Calculations of the main elements of the water cross-section of the Chernozemelskaya irrigation system channels were carried out using passport data and the results of field surveys of these channels. Results. Calculations of the main elements of the water cross-section of the channels for the control stations on the Yashkul and Gashun distribution canals of the Chernozemelskaya irrigation system were performed, rating curves of discharge and average water flow velocity in channels from the depth of their filling were constructed; permissible (non-eroding and non-silting) velocities of water flow in the channels were determined. Conclusions. It was found for the discharge section line on the Gashun distribution canal, that siltation of the channel will occur at a water flow discharge of Q < 2.75 m³/s and channel filling of h < 1.0 m. When assessing the channel of the Gashun canal for the susceptibility to erosion, it was determined that the channel in the control station section can pass the specified discharge without being eroded. Checking the channel of the Yashkul distribution canal in the control section for siltation and erosion showed that its channel will not be eroded in the considered range of water flow velocities from 0.62–1.14 m/s.

From strain to displacement: using deformation to enhance distributed acoustic sensing applications

SUMMARY Over a period of less than a decade, distributed acoustic sensing (DAS) has become a well-established technology in seismology. For historical and practical reasons, DAS manufacturers usually provide instruments that natively record strain (rate) as the principal measurement. While at first glance strain recordings seem related to ground motion waveforms (displacement, velocity and acceleration), not all the seismological tools developed over the past century (e.g. magnitude estimation, seismic beamforming, etc.) can be readily applied to strain data. Notably, the directional sensitivity of DAS is more limited than conventional particle motion sensors, and DAS experiences an increased sensitivity to slow waves, often highly scattered by the subsurface structure and challenging to analyse. To address these issues, several strategies have been already proposed to convert strain rate measurements to particle motion. In this study, we focus on strategies based on a quantity we refer to as ‘deformation’. Deformation is defined as the change in length of the cable and is closely related to displacement, yet both quantities differ from one another: deformation is a relative displacement measurement along a curvilinear path. We show that if the geometry of the DAS deployment is made of sufficiently long rectilinear sections, deformation can be used to recover the displacement without the need of additional instruments. We validate this theoretical result using full-waveform simulations and by comparing, on a real data set, the seismic velocity recovered from DAS with that recorded by collocated seismometers. The limitations of this approach are discussed, and two applications are shown: enhancing direct P-wave arrivals and simplifying the magnitude estimation of seismic events. Converted displacement provides better sensitivity to high velocity phases, improves broadside response and permits the direct application of conventional seismological tools that are less effective when applied to strain (rate) data.

EXPERIMENTAL RESEARCH CHARACTERISTICS OF TRANSFORMATION BY THE OPTIC-ELECTRONIC MODULE OF THE AUTOMATIC CONTROL SYSTEM

Simulators of environmental state sensors are used to set up and control the efficiency of automatic process control systems. In some cases, it is convenient to use a voltage-resistance converter with an optoelectronic output module based on a controlled photoresistor as a simulator of potentiometric sensors.
 An optical-electronic voltage-to-resistance converter, which has a galvanic isolation of the output and has a linear characteristic in a given range of output resistance is developed. The developed converter allows to set the angular and free coefficients of the linear equation arbitrarily that describes the response function of the converter and correctly simulate the operation of a potentiometric state sensor of the controlled parameter. An operating model of the converter was developed and manufactured, experimentally determination of its response function for different values of the free coefficient, supply voltage and different options for the circuit design of the optoelectronic module was carried out.
 The principle of operation of the converter is based on a change in the resistance of photoresistors under the influence of optical radiation coming from a controlled source. The model of the converter consists of optical and electronic blocks. The optical block consists of an optical radiation source and two photoresistors simultaneously directed at it. The signal from one photoresistor is the output, and the signal from the second photoresistor is analyzed by the control circuit, which synchronously changes the illumination on the light-sensitive areas of the photoresistors through the brightness controller in accordance with the voltage level of the control and corrective signals.
 The experimentally determined response function of the converter in the initial section has a non-linearity in the zone of low input voltages, which is determined, foremost, by the limitation of the lamp brightness and depends on the scheme of its inclusion. The non-linearity zone in the researched converter can be significantly reduced by increasing the supply voltage. Within the given range of change of the output resistance of the rectilinear section of the response function, the output resistance of the converter is linearly related to the input voltage, according to the results of experimental measurements in natural laboratory conditions, the conversion error hasn’t exceeded 0.3%.

TECHNOLOGICAL INDICATORS OF THE CATHODIC PROCESS IN THE REGENERATION OF USED SULFO-ACID SOLUTIONS FOR ETCHING STEEL

The current state of regeneration of sulfate solutions was analyzed, it was established that the existing physico-chemical methods do not solve the problem of regeneration of sulfuric acid, but only neutralize it, for transfer according to the standards of the MPC to neutralization and into the sewage system with subsequent disposal. It has been confirmed that it is advisable to carry out the regeneration by an electrochemical method using a three-chamber electrolyzer, when the solution is fed into the middle chamber, the concentration of regenerated sulfuric acid increases to 180-200 g/l, with simultaneous iron deposition, with a current yield of 65-70%. This method reduces waste and allows switching to a closed cycle on sulfuric acid. It was found that in the process of digestion, the concentration of sulfuric acid decreases from 2.0 to 0.5 mol·dm-3, and the concentration of iron (II) sulfate increases accordingly. Under the conditions of a decrease in the concentration of sulfuric acid, its chemical activity also decreases when interacting with iron oxides and hydroxides. To increase the reactivity of pickling solutions, an increase in the temperature of the entire process is used. The kinetic regularity of combined cathodic processes in model solutions of iron (II) sulfate with sulfuric acid was established. Platinum, copper and carbon steel were used as cathode material. The choice of the cathode material was based on the different electrochemical properties of these selected metals with respect to the hydrogen reaction. The main process at the platinum cathode is hydrogen release in a wide range of current densities. At current densities greater than 0.1 A/cm2, a sharp increase in potential was observed due to the incorporation of Fe2+ into the composition of the cathode-electrolyte interface, but Fe2+ reduction potentials were not reached. When replacing the cathode material from platinum to carbon steel, a significant inhibition of hydrogen release was observed, which made it possible to reach the potentials for the simultaneous reduction of hydrogen and iron, however, the maximum current of the rectilinear section of the electrochemical process with electrochemical control was reduced from 10 at 20 0C to 3 times at 80 0C. The use of a copper cathode made it possible to reveal the influence of the hydrogen reaction on the course of Fe2+ reduction. The release of hydrogen at the copper cathode was accompanied by a significant inhibition of the hydrogen ion discharge. When using an iron cathode, electrochemical desorption is the limiting stage, which leads to the existence of layers of adsorbed hydrogen firmly attached to the surface of the iron cathode. A comparative analysis of the voltage-current dependences for the final investigated temperatures indicates a significant effect of an increase in temperature from 20 0C to 80 0C by approximately 120-150 mV. The cathodic process at 20 0C takes place in the mode of increased kinetics for both combined processes. At 80 0С, rectilinear sections of electrochemical control of the cathodic process appear on the voltage–voltage dependences, at Fe2+ concentrations of 1.0 and 1.5 mol/dm3. These areas range from 20 to 60 mA/cm2. The concentration of iron ions and the temperature of electrolysis have a significant effect on the process of electrochemical reduction of Fe2+, which was confirmed experimentally. Since the target process in the electrochemical regeneration of spent pickling solutions is the regeneration of sulfuric acid itself, and not the removal of Fe2+ from this solution, the cathodic mode of operation of the electrode unit was determined according to the technological indicators of the anodic process.

Algorithms for Planning Smoothed Individual Trajectories of Ground Robots

The article is devoted to the development of an algorithm for constructing the trajectory of a robotic platform moving in an environment with obstacles. This algorithm is based on the application of a special local optimization procedure at each planning step and allows us to obtain feasible program trajectories without increasing the computational complexity of algorithms compared to existing methods. The algorithm is based on the application of the improved method of potential fields and subsequent smoothing of the resulting trajectory. The improving of the potential field method consists in a new way of detecting and avoiding local minima. When a local minimum is detected, it is added to the map as an additional obstacle, which makes it possible to avoid it during further trajectory planning. To circumvent obstacles that can be approximated by polygons, the method of the effective point to the obstacle is proposed, which is the equivalent of the latter in relation to the current location of the moving robotic platform when using this planning method. A two-stage technique for smoothing piecewise linear trajectories is proposed. It is assumed that there is some initial suboptimal curve found by any planning method. This curve is optimized using a functional that includes the length of the trajectory and the deviation of the optimized curve from the original curve. At the second stage, the linear segments of the planned straight line are conjugated with second-order curves. As a result, the planned trajectory of motion is a quadratic-linear curve with a smooth function of the trajectory velocity. At the same time, the proposed method of coupling rectilinear sections of the trajectory does not require sudden changes in speed when passing turns. Simulation results confirming the effectiveness of the proposed method of planning the trajectories of robots are considered and discussed.

EXPERIMENTAL STUDIES OF INFORMATION SIGNAL-TO-RESISTANCE CONVERTER FOR AUTOMATIC CONTROL SYSTEM

Potentiometric sensors are widely used in the construction of automatic and automated process control systems. In potentiometric sensors, resistance is the output signal and its magnitudes depend on the magnitude of the input signal. voltage, current, digital code, angle of rotation, displacement or other signal is usually used as the input signal. In practice, the task of simulating of the signal which coming from the built-in potentiometric sensor is often appeared. An additional potentiometric sensor can be used to simulate the signal of the built-in sensor that allows setting the required resistance magnitude by changing any external parameter.
 The model of the voltage-to-resistance converter is made. This model allows simulating the potentiometric state sensor of the controlled system. The experimental determination of its transfer characteristic at different ambient temperatures is carried out. This model is based on a two-channel conversion circuit, which includes a source of optical radiation and two photoresistors optically connected to it. One of photoresistors is connected to a current stabilizer, while the voltage on it is analyzed by a tracking circuit that changes the brightness of the optical radiation source according to the magnitude of the control voltage. The transfer characteristic of the converter in the initial section has an insensitivity zone, following by a rectilinear section. Within the insensitivity zone, a change in input voltage does not change the output resistance. The magnitude of the insensitivity zone is determined by the maximum voltage on the incandescent lamp that determines its brightness, as well as the minimum possible resistance of the using illuminated photoresistor. Within the rectilinear section, the output resistance of the converter is linearly related to the magnitude of the input voltage. The conversion error does not exceed 0.6 % at an ambient temperature of 20° C. When the temperature decreases to -20° С, the conversion error increases to 7 %, which is due to differences in temperature errors of the photoresistors using in the model.

Axial Load Enhancement of Lightweight Aggregate Concrete (LAC) Using Environmentally Sustainable Composites

Salient features of lightweight aggregate concrete (LAC) include noticeable fire resistance, high strength-to-weight ratio, and low magnitude of dead loads. Further, LAC has a low cost, eases construction practices, and possesses an environment-friendly nature. On the downside, LAC has substandard mechanical properties in comparison to normal aggregate concrete. Natural fiber-reinforced polymers (FRPs) have shown their potential in ameliorating the mechanical properties of natural aggregate concrete. So far, no study has been conducted to assess the efficacy of hemp rope confinement to strengthen lightweight aggregate concrete especially comprising rectilinear sections. This study aimed to overcome the substandard nature of LAC. A low-cost, sustainable, and environmentally green solution in the form of natural hemp rope layers is proposed. Twenty-four square concrete specimens were tested in three groups depending upon the presence and quantity of lightweight aggregates. It was found that concrete constructed with lightweight aggregates demonstrated lower ultimate compressive strength and strain as compared to normal aggregate concrete. Hemp rope-confined LAC showed enhanced ultimate compressive strength and strain. This enhancement was found to increase with the number of hemp rope layers. Several existing ultimate stress models were assessed to predict the ultimate compressive strength of the hemp rope-confined specimens. Only a single model was able to predict the ultimate compressive strength of the hemp rope-confined specimens with reasonable accuracy.

COMPOSITE GEOMETRICALLY SMOOTH CUBIC HERMITE CURVES IN SPACE AND ON THE PLANE

The article considers constructive algorithms for creating compound curves using parametric cubic equations. The possibilities of modern computer technology and systems of computer mathematics make it possible to implement algorithms of graph analytics using fractional rational parametric equations of the fifth, seventh and higher orders. The article considers a constructive algorithm for creating a compound cubic curve passing through given points with direction vectors specified in these points. Direction vectors can be used for monitoring the shape of a constructed curve. At the junction points of the cubic curve segments, second order geometric flatness is ensured, due to the equicontinuity of the camber and curvature. The required curve is made sequentially by attaching a new segment to the previous segment. Each segment must comply with the same group of geometric conditions: frequency at boundary points, contact with direction vectors, fixed curvature at one or both boundary points. The article proposes a constructive algorithm for constructing a three-dimensional or flat cubic Hermite segment that satisfies this group of conditions. The problem of constructing a compound geometrically smooth curve boils down to sequential construction of cubic segments using the proposed algorithm. The method proposed in the article for constructing a smooth compound curve allows: to shape a spatial curve with a given curvature at the starting point; to construct a plane curve with given radii of curvature at the nodes (in particular, with zero curvature at the nodal points); insert a cubic segment into a break in a curved line; find a smooth (without a break in a curve) conjugation of curvilinear and rectilinear sections of the constructed line. A distinctive feature of the algorithm is the significant use of reference tools and design capabilities of three-dimensional computer graphics. All necessary actions are performed using a desktop calculator and any software product that supports three-dimensional graphics (Compass-3D, AutoCAD, etc.). Five transparent examples of constructing flat and spatial composite cubic curves of the second order of smoothness are considered.

Structural, Electrical and Optical Properties of CuO Thin Films Obtained by Reactive Magnetron Sputtering

CuO thin films were produced by the method of reactive magnetron sputtering at direct current in a universal vacuum system Leybold-Heraeus L560 on glass substrates, the temperature of which was: 300 K and 523 K. The structural, electrical and optical properties for the obtained samples of CuO thin films were studied, namely: elemental composition, distribution of elements on the surface, which are part of these films, grain size, activation energy, optical band gap, refractive index, analysis of curves of transmission and reflection spectra for CuO thin films deposited on glass substrates. The elemental composition of the thin films and the surface morphology were performed using a scanning electron microscope (MIRA3 FEG, Tescan) equipped with a reflected electron detector (BSE) and an energy-dispersed X-ray detector (EDX). It was found that the grain size for films obtained at a lower substrate temperature D is ~ 16 nm, and for films obtained at a higher temperature - D ~ 26 nm. On the diffractograms of CuO thin films, a higher peak intensity is observed for thin films obtained at higher CuO no. 2 substrate temperatures, which may be due to better structural perfection of thin films and larger grain size. From the study of electrical properties, it was found that the temperature dependences of the electrical resistance for CuO thin films have a semiconductor character, ie the resistance decreases with increasing T. The surface resistance of the films was measured by the four-probe method: no. 1- ρ = 18,69 kΩ/¨, sample no. 2 – ρ = 5,96 kΩ/¨. Based on independent measurements of the reflection and transmission coefficients, the optical band gap was determined for the two samples by extrapolation of the rectilinear section of the curve (αhν)2 = f (hv) to the hv axis. For the sample CuO №1 Egop = 1.62 eV; for the sample CuO no. 2 Egop = 1.65 eV. For CuO no. 2 thin films, the envelope method was also used to determine the basic optical coefficients Egop = 1.72 eV, and the obtained Egop values determined by the two methods correlate well with each other.

Movement of the particle on the surface of the conveyor belt, arbitrarily oriented in space

The movement of the material on the inclined belt of the conveyor takes place during transportation or its frictional cleaning. For an inclined moving plane (slide), the angle of its inclination to the horizontal plane is decisive. The absolute motion of a particle is the sum of two motions - the portable belt and the relative particle along the belt, so it is affected by the angle between the vectors of the greatest inclination of the plane and the transfer velocity of the plane (tape). The purpose of the study is to determine the motion of a material particle on the conveyor belt for the case when the angle between the vector of the line of greatest inclination of the conveyor plane and the direction of its transfer speed is arbitrary. To do this, the conveyor belt element was depicted as a rectangle with an axis of symmetry drawn along the direction of translational movement. In the initial position, the plane was placed horizontally, so the angle of greatest inclination is absent. In the future, the plane was given an arbitrary location in space due to alternate rotation around the sides bounding its compartment or around the axes of symmetry of the compartment, which is equivalent. The relative and absolute motions of the material particle along the moving web of the conveyor are considered for the case when the line of the greatest inclination of the web plane makes an arbitrary angle with the direction of the portable motion of the web. A system of differential equations of motion is compiled and solved. The obtained results are illustrated graphically. It is established that the nature of the relative motion of a particle on an inclined plane moving rectilinearly and uniformly depends on the direction of the vector of the line of the greatest inclination and the value of the angle of inclination of this plane. If the angle of inclination is less than the angle of friction, then the lateral feed of the particle will eventually stop either on the curved section of the trajectory or on a straight line that is parallel to the line of greatest inclination. The stopping place of the particle depends on the value of the initial velocity. At an angle of inclination of the plane equal to the angle of friction, the particle during the movement along the curved section of the trajectory reduces its initial velocity by half and then moves in a straight line and evenly. If the angle of inclination of the plane is greater than the angle of friction, the particle in relative motion along the curvilinear section of the trajectory first reduces the velocity, and when approaching a rectilinear section, its velocity increases and continues to increase on a rectilinear section of the trajectory. Key words: material particle, conveyor, inclined plane, plane inclination angle, particle velocity

Improving the navigational preparation of a bridge crew for entering/leaving a port, including activities in case of emergency

Statistical analysis of the causes of ship accidents showed that 10 % of accidents are due to the influence of irresistible force, about 15 % are the result of technical imperfection and sudden failure of ship equipment, and the remaining 75 % account for the «human factor» regardless of the cause of the accident. A detailed analysis of the causes of accidents reveals that they are caused by the actions of individuals, dominated by organizational errors by a group of operators in the preparation and execution of the maneuvering control process. At the same time, there is a gap between the complexity of modern equipment and the psychological capabilities of the human operator as an element of the human-machine system. Analysis of accidents in the Bugsky-Dnestrovsky Liman Canal over the past 20 years has shown that 58.5 % of accidents occurred in the dark and under conditions of limited visibility. There were two causes of accidents: grounding and allision, 84.3 %; collisions, 28.8 %. This indicates the insufficient preparation of bridge crews for navigating the canal. This paper has considered a procedure of bridge crew navigation training for planning safe motion coordinates while entering/leaving a port along the trajectory points, as well as actions in case of a pre-emergency and techniques to predict it. The coordinates of the travel points are determined at the intersection of rectilinear segments of the recommended safe rectilinear path on a chart. It is a relevant task to use new methods of planning the path and controlling the movement along it, taking into consideration the area for maneuvering, maneuverable properties of the vessel, as well as external influences, for timely detecting the deviation of parameters from those planned. The calculation of the planned coordinates is performed for the center of gravity of the vessel for the characteristic points of the path of movement (the beginning and end of a turn, the onset of braking) and trajectory points (rectilinear segments of the path through 0.2 cables, and curvilinear sections through 10 degrees). Coordinates of the assigned path are represented in the form of the linear matrices of the path rectilinear and curvilinear sections. The navigational motion control system consists of the devices to automatically determine deviations from planned coordinates and decision support systems to correct deviations detected. The proposed method to plan and control motion was investigated by computer simulation, the test was carried out under natural settings. Their results showed that the calculated optimal assigned trajectory enables accident-free guidance of the center of gravity along the predefined path by ship’s control means and meets the established criteria of optimality. The proposed method could be used in the development of controls for automated vessels and is the only possible one for vessels with unattended operation

Combined anode processes in sulfuric acid solutions

Etching of carbon steel products in sulfuric acid solutions is, on the one hand, a common process in mechanical engineering and, on the other hand, harmful to the environment. As the concentration of H2SO4 decreases and the solution becomes saturated with Fe2SO4, the etching rate of the oxide film on the steel surface decreases. Therefore, while reducing the H2SO4 concentration to 25-30 g/l etching process is stopped, and replacing the etching solution. In this case, the concentration of Fe2SO4 reaches 400 g/l. During etching, two processes are observed: dissolution of oxides and dissolution of iron, which is located under the layer of oxides. These two processes can run simultaneously. The study of electrode processes in sulfuric acid solutions containing inorganic and organic impurities is the basis for the development of technological parameters for the regeneration of spent sulfate solutions. For the study used a little wear anode materials - platinum and lead oxide (IV). To determine the kinetic regularities of the anode process in selected anode materials, voltammetry was used with the construction of the obtained dependences in Tafel coordinates. The polarization dependences consist of two rectilinear sections with an inflection at logia ≈ -1,8 (ia, A · cm-2). The slope of the first section does not depend on the H2SO4 concentration and is 120 mV. The slope of the second section, for solutions with an H2SO4 concentration of 0,05 ... 0,37 mol/dm-3, is 60 mV, and for a concentration of 2,5 mol/dm-3 - 71 mV. A change in the concentration of sulfuric acid has practically no effect on the polarization of the anode. At a concentration of 5,0 mol·dm-3, in the area of high current density (≥ 1500 A∙m-2), the potential of the anode exceeds the PZCh for lead dioxide. This promotes the adsorption of sulfate ions on the surface of the composite anode and the onset of active oxygen formation. Under these conditions, the evolution of hydrogen peroxide is observed on the platinum anode. The polarization dependences consist of two straight sections with different slopes. For the entire range of sulfuric acid concentrations, at low current density portion is observed with a slope of 120 mV. Concentration of sulfuric acid at this site does not affect the kinetics of the process that corresponds to the literature data for platinum. The zero order in pH and independence from the concentration of sulfuric acid for this site indicates that the most probable mechanism of oxygen evolution is water rarefaction. The obtained values of the effective activation energy of the oxygen evolution process on the LOTC are close to the results obtained on platinum – 41,8 kJ mol-1 at Ea = 1,95 V. The value of the effective activation energy indicates the electrochemical nature of polarization, and its decrease with an increase in the anodic potential indicates a decrease in the strength of the bond between oxygen and the LOTC surface.

Glass Cutting Technology Combining Two Different Lasers

A new technology for laser cutting of glass along a curvilinear contour is described. This technology combines the use of two different methods of cutting in a single technological cycle: laser-controlled thermal splitting on rectilinear sections of the cutting contour and filamentation using a picosecond laser on curvilinear sections of the contour. The proposed technology makes it possible to significantly increase the productivity of the cutting process along curvilinear contours without compromising the strength characteristics of the glass products.

Curvilinear Section Radius and Rectilinear Section Length of the Mixing Chamber and Their Influence on the Ejector Characteristics

The paper presents the calculation results for ejectors with curvilinear and subsequent rectilinear sections of a mixing chamber. The reasons for choosing the curvature radius of a curvilinear section and the length of a rectilinear section in the mixing chamber are given. The effect of the flow separation in the mixing chamber on the ejector operation is analyzed.

Modeling of stress-strain state of piping systems with erosion and corrosion wear

The problems of modeling the stress-deformed state of erosion or corrosion-worn rectilinear sections and the ball-shaped bends of pipeline systems are proposed to solve in a cylindrical coordinate system. For this purpose, formulas of Christophell type II, non-zero components of the strain tensor and a system of equilibrium equations in the framework of linear torsional theory are given. The system of equilibrium equations is reduced to one equation, which is the basic equation of the Lame’s problem. Formulas for the calculation of ring stresses that occur in the wall of erosion or corrosion worn rectilinear sections, and the removal of pipelines from the action of internal pressure are derived. The influence of the change in the wall thickness of the pipeline bends in the place of their erosion or corrosion wear on the amount of ring stresses is determined.

Buckling of a drill-string in two-sectional bore-holes

The nature of the phenomena of drill-strings buckling in channels of deep curvilinear bore-holes is essentially complicated by complex combination of acting distributed forces (gravity, contact and friction), large length of the string (leading to a virtual loss of its bending stiffness), and its intricate geometry. Therefore, theoretical modelling of these effects turns out to be difficult to implement. In this article, the touched problem is stated with the use of the curvilinear flexible rods theory, differential geometry concepts, basic foundations of channel surfaces theory, and methods of numerical mathematics. The elaborated software is applied to the global analysis of the incipient stage of the drill-string buckling inside a deep bore-hole consisting of two nearly rectilinear sections bridged with curvilinear interjacent part. To solve the problem, firstly, the critical stress-strain state of the drill-string (eigenfunction) is established, and then, the shape of the buckled drill-string (eigenmode) is built. It is shown that the stated problem refers to the singularly perturbed type and so, depending on the knee angle and friction coefficient, the mode of stability loss represents a short wavelet localized at the lower end of the lower section or it is shifted to the knee zone of the bore-hole. The features of critical behavior of the drill-strings associated with the values of the knee angle of the bore-hole, system clearance, and friction coefficient, as well as critical loads and buckling mode wavelets are discussed.

Кривые течения нитратцеллюлозных растворов на вискозиметре Гепплера

For the first time a possibility of an application of a Hoppler viscosimeter with the pressing ball for obtaining of the flow curves of 5-50% bipolymeric cellulose nitrates – polyvinyl nitrate (NC-PVN) solutions based on the measurements of the stationary velocity of a ball displacement along the wall of the cylindrical vessel has been checked experimentally. The relationships, rearranging the equations of the shear stress and rate by means of the correlation coefficients, underlie the method. The time of the ball immersion into the polymeric solution has been used as the main parameter, which is experimentally determined. The rheological flow law and the rheological parameters of reprocessing of 5-50% NC-PVN solutions in EA: a flow index, a consistency coefficient, have been established. It has been shown that 30-50% NC-PVN solutions in EA display properties of the non-Newtonian liquid to a greater degree and they are more structural ones in comparison with 5-20% NC-PVN solutions; the greater deviation of the flow index from 1 indicates on it. The values of the limit shear stresses that characterize the plastic (strength) properties of the polymeric compositions and allow to evaluate preliminary a possibility of a reprocessing of the nitrocellulose solutions, including the solutions, which are filled to the powders using the aqueous-dispersing, the lacquer-extrusion and the extrusion technologies, were found by the extrapolation of the rectilinear section of the flow curve to the axis of stresses. In the course of reprocessing of NC-PVN solutions in EA according to the aqueous-dispersing, the lacquer-extrusion and the extrusion technologies, the limits of a plasticity, corresponding to 90-1950 Pa, 1950-2750 Pa and 2750-5600 Pa, have been established. It has been shown, that the plasticity of NC-PVN die (50:50), filled with the octogen in the amount of 40 % by mass, increases ~1.7 times in comparison with the die, which is not filled, and it results in descreasing of a “brittleness” of the filled NC-lacquer.