Constant Moment Research Articles

Gadolinyum(III) Asetat İçeren Yeni Tetrapirazinoporfirazinin Sentezi ve Spektroskopik Özellikleri

A new tetrakis-(2-methylpyrazino)porphyrazinato gadolinium(III) acetate complex was synthesized. Elemental analysis, Fourier-Transform Infrared, Ultraviolet-visible, and fluorescence spectroscopy techniques clarified its structure. It can dissolve very well without aggregation in both Dimethyl sulfoxide and N, N-Dimethylformamide, which have high dielectric constant and high dipole moment from polar aprotic solvent type. Its aggregation property was also investigated in dimethyl sulfoxide at different concentrations, and it was determined to contain monomeric species. In addition, its fluorescence properties were investigated in Dimethyl sulfoxide and the effect of gadolinium(III) acetate metal ion as a heavy rare earth element was determined. According to the findings in this study, it may be used as an electronic and optical material and in various technological applications such as photocatalytic applications. In addition, these findings may be useful for systems that include changes in pyrazinoporphyrazine-like forms.

Load-Bearing Performance of Non-Prismatic RC Beams Wrapped with Carbon FRP Composites

This study investigated the influence of CFRP composite wrapping techniques on the load–deflection and strain relationships of non-prismatic RC beams. A total of twelve non-prismatic beams with and without openings were tested in the present study. The length of the non-prismatic section was also varied to assess the effect on the behavior and load capacity of non-prismatic beams. The strengthening of beams was performed by using carbon fiber-reinforced polymer (CFRP) composites in the form of individual strips or full wraps. The linear variable differential transducers and strain gauges were installed at the steel bars to observe the load–deflection and strain responses of non-prismatic RC beams, respectively. The cracking behavior of unstrengthened beams was accompanied by excessive flexural and shear cracks. The influence of CFRP strips and full wraps was primarily observed in solid section beams without shear cracks, resulting in enhanced performance. In contrast, hollow section strengthened beams exhibited minor shear cracks alongside the primary flexural cracks within the constant moment region. The absence of shear cracks was reflected in the load–deflection curves of strengthened beams, which demonstrated a ductile behavior. The strengthened beams demonstrated 40% to 70% higher peak loads than control beams, whereas the ultimate deflection was increased up to 524.87% compared to that of the control beams. The improvement in the peak load was more prominent as the length of the non-prismatic section increased. A better improvement in ductility was achieved for the case of CFRP strips in the case of short non-prismatic lengths, whereas the efficiency of CFRP strips was reduced as the length of the non-prismatic section increased. Moreover, the load–strain capacity of CFRP-strengthened non-prismatic RC beams was higher than the control beams.

Failure Mode of GFRP Bar RC Beams Using GFRP Sheet as Shear Reinforcement

The objectives of this study are to analyze the pattern crack and failure mode of the GFRP concrete beam by using GFRP sheet as shear reinforcement (GFB) compared with the two types of the conventional reinforced concrete beam (CB and GB). One of the conventional reinforced concrete beams is reinforced with the steel bar (CB) and the other is the GFRP bar (GB) as longitudinal reinforcement. The nine beams were cast from one concrete batch with dimensions of 150 mm width, 250 mm depth and 3300 mm length. This study focuses on a simply-supported beam using a roller and pinned supports at the end of the beam. Control beam (CB) that using steel reinforcement shows three phases of deformation based on the deflection load curve, ie before crack, after crack, and after yield, while GB and GFB beams that use GFRP bar reinforcement only show two phases of linear deformation namely the deformation phase before cracking and after cracking. From the crack pattern, CB beams experience the flexural cracks which starting from the mid-span on the tensile side of the constant moment region and propagated to the compression region along with the increase in load. All GB beams show the crack starts from the mid-span and then propagates towards the support. Whereas GFB beam show the flexural cracks that occur in the constant moment region and in the shear span, also diagonal cracks that divide the GFRP sheet occurred. From the failure mode, CB experienced flexural failure, while GB experienced compression failure and shear failure in all GFB beams.

Size-effects of metamaterial beams subjected to pure bending: on boundary conditions and parameter identification in the relaxed micromorphic model

AbstractIn this paper we model the size-effects of metamaterial beams under bending with the aid of the relaxed micromorphic continuum. We analyze first the size-dependent bending stiffness of heterogeneous fully discretized metamaterial beams subjected to pure bending loads. Two equivalent loading schemes are introduced which lead to a constant moment along the beam length with no shear force. The relaxed micromorphic model is employed then to retrieve the size-effects. We present a procedure for the determination of the material parameters of the relaxed micromorphic model based on the fact that the model operates between two well-defined scales. These scales are given by linear elasticity with micro and macro elasticity tensors which bound the relaxed micromorphic continuum from above and below, respectively. The micro elasticity tensor is specified as the maximum possible stiffness that is exhibited by the assumed metamaterial while the macro elasticity tensor is given by standard periodic first-order homogenization. For the identification of the micro elasticity tensor, two different approaches are shown which rely on affine and non-affine Dirichlet boundary conditions of candidate unit cell variants with the possible stiffest response. The consistent coupling condition is shown to allow the model to act on the whole intended range between macro and micro elasticity tensors for both loading cases. We fit the relaxed micromorphic model against the fully resolved metamaterial solution by controlling the curvature magnitude after linking it with the specimen’s size. The obtained parameters of the relaxed micromorphic model are tested for two additional loading scenarios.

A Novel Method for Deflection Calculation of Reinforced Concrete Stair Slabs considering Step Stiffness

Stair slabs are some of the most common structural members with zigzag shapes in various buildings. However, the calculated deflection is usually overestimated during the design of stair slabs. In this article, the overestimated deflection is amended by utilizing step stiffness. To this end, it is assumed that the stress distribution of a unit cell in stair slabs is linear or bilinear under a constant bending moment. Stair slabs can be approximately regarded as flat slabs to derive the equivalent thickness based on the same bending strain energy. Subsequently, finite element (FE) models are established to verify that the obtained equivalent thickness can be applied to reinforced concrete (RC) stair slabs. To improve computational efficiency, the normalized models of stair slabs are adopted for further analysis. On this basis, a novel design method is proposed considering step stiffness for RC stair slabs. Furthermore, numerical examples are presented to compare the improved design method with the FE method and the conventional method. The results demonstrate that the design method considering step stiffness can not only ensure structural safety but also reduce concrete and steel consumption, making the design of stair slabs more economical and reasonable.

Radiation of a Solitary Polarization Pulse Moving at the Speed of Light

Photons have zero rest mass and always travel at the speed of light in a vacuum, but have no dipole moment. Atoms and molecules, which may have a constant or variable dipole moment, have mass and therefore cannot move at or above the speed of light. As a result, the radiation from such systems moving at the velocity of light was not considered. However, it is possible to create many artificial objects (light spots, effective charges, current pulses, etc.) that can travel at the speed of light and even exceed it. In this case, they become a source of electromagnetic radiation. In this work, the radiation of a solitary polarization pulse that travels at the speed of light and has a variable or constant amplitude is discussed. It is shown that if the amplitude does not change, then such an object does not radiate outward; i.e., the field emitted by it remains completely localized inside the moving polarization pulse. If the amplitude changes over time, then it begins to radiate backwards. In this case, unipolar pulses of an unusual shape, such as a rectangular one, can be obtained.

Radiation of a Solitary Polarization Pulse Moving at the Speed of Light

Photons have zero rest mass and always travel at the speed of light in a vacuum, but have no dipole moment. Atoms and molecules, which may have a constant or variable dipole moment, have mass and therefore cannot move at or above the speed of light. As a result, the radiation from such systems moving at the velocity of light was not considered. However, it is possible to create many artificial objects (light spots, effective charges, current pulses, etc.) that can travel at the speed of light and even exceed it. In this case, they become a source of electromagnetic radiation. In this work, the radiation of a solitary polarization pulse that travels at the speed of light and has a variable or constant amplitude is discussed. It is shown that if the amplitude does not change, then such an object does not radiate outward; i.e., the field emitted by it remains completely localized inside the moving polarization pulse. If the amplitude changes over time, then it begins to radiate backwards. In this case, unipolar pulses of an unusual shape, such as a rectangular one, can be obtained.

A study of electrothermomechanical converter for technological purposes with nonlinear changes in the loading and cooling medium

Heavy temperature processes with high-temperature loads require optimisation of technological processes, ensuring high reliability and combining rotating parts of electric machines with actuators to achieve greater efficiency of electromechanical converters. The research aims to provide a theoretical justification and experimental confirmation of the effect of higher harmonics in the air gap under nonlinear changes in the temperature of the medium. The research is based on the basic principles of electrodynamics, heat and mass transfer, mathematical modelling by the finite element method, and experimental verification of multi-physical parameters. Based on the analysis of the differential equation for determining the increase in the surface temperature of a ferromagnetic rotor under conditions of nonlinear temperature changes in the environment surrounding the electromechanical converter, the regularities of the formation of the free and forced components of the instantaneous temperature values of the massive rotor are established. Depending on the mode of interaction between the load-cooling medium and the electromechanical part of the screw units, kinematic diagrams of single-mass and two-mass systems with variable or constant moments of inertia and stiffness were formed. According to the size of the electromagnetic system of the experimental sample, a mathematical model for studying thermal and electromagnetic processes was built. The regularities of the spatial distribution of the temperature of the screw electromechanical unit are determined. The spectra of higher harmonics of voltage and current in the frequency range from 0 to 50 kHz have been experimentally determined, which confirms the presence of the effect of generating higher harmonics when the temperature of the medium surrounding the rotor screw changes. The detected harmonic spectrum affects both the formation of the dynamics of the rotating system and additional thermal power while increasing the overall efficiency of the screw electromechanical converter. The practical value of the obtained results lies in the possibility of predicting the optimal indicators of interrelated electromagnetic and heat exchange processes in screw electromechanical converters for technological purposes

Improved magnetic and dielectric quality factors with low losses in rare earth (Eu) substituted Co-Ni-Zn ferrites for high frequency devices

Co0.2Ni0.5Zn0.3EuxFe2-xO4 (CNZEFO) composites were synthesized by the conventional double sintering technique, where x = 0.00, 0.02, 0.04, and 0.08. Rietveld refined x-ray diffraction indicates the spinel cubic structure (Fd-3 m space group) of the samples. The refined XRD pattern also mentioned the Fe2O3 secondary peak for x = 0.04 and 0.08 samples. The structural lattice constant was initially increased, but after that it decreased with the Eu concentration. The bulk density of the samples was always lower than the x-ray density, where the densities were increased with the enhancement of Eu concentration. FTIR analysis confirmed the metal–oxygen bonds in ferrite with spinel cubic structure. FESEM micrographs provide the average grain size of the samples, which varies between 105.1 nm and 169.9 nm. EDX analysis was used to carry out the compositional verification and confirm that the elements were present in the required ratios. Magnetic hysteresis loop measurements were studied at room temperature, where the magnetization demonstrates the decline with the substitution of Eu ions. The addition of Eu concentration also changed other fundamental properties of the ferrites, such as coercivity (Hc), retentivity (Mr), anisotropy constant (K), and magnetic moment (nB). The permeability measurements show that the real permeability of the samples was decreasing at lower frequency region further they became high at higher frequency region. The magnetic loss tangent (tanδM) and dielectric loss tangent (tanδD) were reduced with the addition of Eu concentration, where the Eu doped samples show higher dielectric and magnetic quality factor than the pure sample. The enhancement of resistivity and impedance were also noticed for the addition of Eu content in Co0.3Ni0.2Zn0.5Fe2O4 sample. These europium doped cobalt–nickel-zinc ferrites may be strong candidates for potential high frequency applications.

Mathematical substantiation of mine locomotive braking efficiency under pulsiting braking torque

Purpose. Determination of braking torque parameters that provide high braking performance of a mine locomotive by mathematical modeling of the braking of a mine locomotive by a disc brake that creates a pulsating braking torque. The methods. Forced vibrations of the elements of the wheel-motor unit (WMU) of a mine locomotive in the process of braking with a disc brake are studied by the methods of differential calculus and mathematical modeling. Integration of the system of differential equations is performed by the Runge-Kutt method. Findings. A comparative analysis of a mine locomotive braking by a disc brake, which creates a constant and pulsating sinusoidal braking torque with a different number of sinusoid periods per revolution of the wheel pair, is carried out. It has been proved that the pulsating sinusoidal braking moment generated on the axle of the wheel pair equal to the sum of the constant component and the amplitude of the oscillations of the variable component multiplied by the sine of the product of the number of sinusoid periods per revolution of the wheel pair by its angular coordinate provides higher braking characteristics than the constant braking moment. It is shown that pulsating braking torque reduces the braking time and braking distance of the mine locomotive. The values of the amplitude of oscillations, which depend on the average value of the braking torque, and the number of periods of the sinusoid per one revolution of the wheelset, at which the greatest effect is achieved, are determined. The originality. For the first time, a mathematical model has been developed for braking a mine locomotive by a disc brake, which creates a pulsating braking torque on the axle of the wheel pair, depending on its angular coordinate, taking into account the nonlinear dependence of the adhesion coefficient on relative slip, on the basis of which the efficiency of a disc brake with a multi-sector disc is shown in comparison with a disc brake with a homogeneous disk under various conditions of the rail track. Practical implementation. The research results make it possible to determine the parameters of a disc brake with a multi-sector disc located on the wheelset axle and on the engine shaft, which provide the highest braking efficiency.

Influence of dissipative asymmetry on the of rotation stability in a resisting medium of a asymmetric rigid body under the action of a constant moment in inertial reference frame

Assuming that the center of mass of an asymmetric rigid body is located on the third main axis of inertia of a rigid body, the influence of dissipative asymmetry on the stability of uniform rotation in a medium with resistance of a dynamically asymmetric rigid body is estimated. A rigid body rotates around a fixed point, is under the action of gravity, dissipative moment and constant moment in an inertial frame of reference. The stability conditions are represented by a system of three inequalities. The first and second inequalities have the first degree with respect to the dissipative asymmetry, and the third inequality has the third degree. The third inequality is the most difficult to study. Analytical studies of the influence of small and large dissipative asymmetries, restoring, overturning and constant moments on the stability of rotation of a rigid body are carried out. Conditions for asymptotic stability are obtained for sufficiently small values of the dissipative asymmetry and conditions for instability for sufficiently large values of the asymmetry. The stability conditions are written down to the second order of smallness with respect to the constant moment and the first - with respect to the restoring or overturning moments. Stability conditions for the rotation of a rigid body around the center of mass are studied.

A numerical study towards shape memory alloys application in orthotic management of pediatric knee lateral deviations

Exerting a constant load would likely improve orthosis effectiveness in treating knee lateral deviations during childhood and early adolescence. Shape memory alloys are potential candidates for such applications due to their so called pseudoelastic effect. The present study aims to quantitatively define the applicable mechanical loads, in order to reduce treatment duration while avoiding tissular damage and patient discomfort. This is essential for performing a more efficient design of correction devices. We use a patient-specific finite elements model of a pediatric knee to determine safe loading levels. The achievable correction rates are estimated using a stochastic three-dimensional growth model. Results are compared against those obtained for a mechanical stimulus decreasing in proportion to the achieved correction, emulating the behavior of conventional orthoses. A constant flexor moment of 1.1 Nm is estimated to change femorotibial angle at a rate of (7.4 ± 4.6) deg/year (mean ± std). This rate is similar to the achieved by more invasive growth modulation methods, and represents an improvement in the order of 25% in the necessary time for reducing deformities of (10 ± 5) deg by half, as compared with conventional orthoses.

Flexural performance of high-strength lightweight concrete beams made with hybrid fibers

This paper reports on the flexural response of lightweight high strength concrete beams, (LWHSC) reinforced with different combinations of discrete, discontinuous and randomly distributed steel, crimped polypropylene and recycled plastic fibers. All the LWHSC beams tested failed in a typical flexural failure mode, in which flexural vertical cracks appeared within the constant moment zone. Analysis of the test results indicated that the fiber reinforced LWHSC beams exhibited significant increase in load carrying capacity, flexural toughness and ductility indices compared to control LWHSC beams without fibers. Among all the beams tested, the ones reinforced with 0.5% of 60 mm long steel fibers and 0.25% of crimped polypropylene fibers exhibited the largest increase, about 18% in load carrying capacity and flexural toughness compared to control beam specimens without fibers. While, the beams reinforced with 0.5% (50/50 blend) of short steel fibers (30 mm and 60 mm long), and 0.25% of recycled plastic fibers outperformed the flexural toughness of similar beams containing equal content of steel fibers and 0.25% of crimped polypropylene fibers by about 6%. Furthermore, test results indicated that an eco-friendly locally produced recycled plastic fibers could be successfully used for enhancing the flexural performance of LWC beams without compromising their load carrying capacity. Moreover, finite element software ABAQUS was used for predicting numerically the flexural response and crack progression of the beams investigated. The numerical predictions compare fairly well with the experimental test results

Moment gradient factor for steel I-beams with sinusoidal web openings

The moment gradient factor is an important parameter to be considered in the design of beams subjected to failure by Lateral-torsional Buckling. The analytical formulation to obtain the critical moment for the LTB is based on the assumption of applying a constant bending moment along the free span of the structural element. This loading situation is not usual in engineering projects, so it is necessary to correct the value of the critical moment according to the different loading situations that can be found in practical cases. Thus, many design codes worldwide assign values to perform this correction. The moment gradient factor, Cb, is determined by comparing the elastic critical moment of a beam subject to varying moment condition with that subject to a constant moment condition. When considering beams with web openings, there are currently no recommendations or proposals for calculating the moment gradient factor, considering loads applied outside the shear center. There are also no explicit recommendations in standards regarding the design of this type of structure. Recent research deals with the influence of cellular beam parameters on the moment gradient factor; however, they do not present explicit proposals for its calculation in structures of this nature. The research scenario in the literature becomes even more scarce when considering beams with sinusoidal web openings. Thus, the paper investigates this for a wide range of I-beams with openings, with the goal of analyzing the influence of the openings on the Cb, as well as proposing formulae for usual design situations. The proposals were obtained through prediction models derived from an extensive parametric study using the ABAQUS finite element software, in which 34,020 models were developed.

Elucidating the Effect of Pressure on Structural, Electronic, Magnetic, Mechanical and Thermal Properties of Mn2ZrZ (Z=Ge and Si): DFT Overview

In this work, structural, electronic, magnetic, thermal and mechanical properties of Mn2ZrZ (Z=Ge and Si) under pressure up to 50 GPa is studied using state of the art density functional theory. In structural properties, under pressure ground state optimizations are performed to check the thermodynamic stability of studied alloys. Furthermore, enthalpy of formation and elastic stability criteria affirms the thermodynamic stability in studied alloys. Pugh ratio suggests that Mn2ZrGe and Mn2ZrSi remain ductile and brittle in nature, respectively throughout pressure up to 50 GPa. Moreover, large elastic anisotropic response is observed for both alloys. In electronic properties density of states and band gaps are discussed in detail which affirms the ferromagnetic half metallic nature of alloys. Our computed results, such as optimized ground state lattice constant, band-gap and magnetic moment are consistent and have matched excellently with available literature at ambient conditions. In mechanical properties, Debye temperature factor, minimum thermal conductivity and melting temperature is observed to increase with pressure while, Grüneisen anharmonicity factor decreases. However, to date, there are no reports available in literature with under pressure results up to 50 GPa. Therefore, this work illustrates new findings of Mn2ZrZ under pressure for potential applications in thermal actuators and spintronic devices.

Structural performance of reinforced concrete beams with self-healing cover zone

In the current study, experiments were carried out to investigate the structural performance of reinforced concrete (RC) beams with a self-healing cover zone. The cover zone consists of a 1.5-cm-thick layer of bacteria-embedded strain hardening cementitious composite (SHCC) for a combination of crack width control and crack healing. The aim is to bring together two emerging technologies (i.e., self-healing and strain-hardening) that show great potential for realizing highly efficient concrete structures. RC beam without the self-healing cover was also prepared as the control specimen for comparison purposes. The experimental program includes loading the beams to failure in four-point bending configuration and sawing the beams to segments for crack pattern analysis and crack healing. Results show that the beams with selfhealing cover exhibited a 45-60% improvement in structural capacity. The crack patterns of the hybrid beams were also largely modified. While the reference beam formed only a few major cracks, the hybrid beams formed around 40 fine cracks in the constant bending moment region with an average crack width smaller than 0.2 mm even at maximum load. By having an improved cracking behavior and an enhanced self-healing capacity, it is expected that the beams with a self-healing cover will possess an extended service life at the expense of minimal additional cost.

Перспективи розвитку методів діагностики в перехідних режимах роботи прокатних станів

The issue of using the parameters of vibrodynamic processes in rolling mills, primarily during the gripping of the strip by rolls, to determine the technical condition of the equipment is considered. Examples of typical transient processes of the moment of elastic forces on the spindles and the motor shaft and vibration of the equipment along the drive line are noted. Examples of developed methods of diagnosing the actual technical condition of rolling cage equipment are provided. In particular, with the use of such a new indicator as the time delay of the reaction of the areas to the impact load in the cage. On the basis of the obtained industrial measurements and mathematical modeling, the directions for the search and development of new methods and methods are proposed and substantiated. It is recommended to use the correlation fields constant moment - the maximum moment of elastic forces during strip capture, coefficients of variation, purposeful creation of special modes of rolling and operation of equipment and installation of continuously operating strain gauges and use of regular sensors.

ВПЛИВ ДИНАМІЧНОЇ НЕСИМЕТРІЇ НА СТІЙКІСТЬ ОБЕРТАННЯ У СЕРЕДОВИЩІ З ОПОРОМ ТВЕРДОГО ТІЛА ПІД ДІЄЮ ПОСТІЙНОГО МОМЕНТУ У ІНЕРЦІАЛЬНІЙ СИСТЕМІ ВІДЛІКУ

Under the assumption that the center of mass of an asymmetric rigid body is located on the third principal axis of inertia of a rigid body, the previously obtained conditions for the asymptotic stability of uniform rotation in a medium with resistance of a dynamically asymmetric rigid body are investigated. A rigid body rotates around a fixed point, is under the action of gravity, dissipative moment and constant moment in an inertial frame of reference. The stability conditions are presented as a system of three inequalities. The first and second inequalities have the first degree relative to the dynamic unbalance, and the third inequality has the third degree. The first and third inequalities are of the second degree with respect to the overturning or restoring moment, and the second inequality is of the first degree. The first and third inequalities are of the fourth degree with respect to the constant moment, and the second inequality is of the second degree. The third inequality is the most difficult to study. Analytical studies of the influence of dynamic unbalance, restoring and overturning moments on the conditions of asymptotic stability are carried out. Conditions for the asymptotic stability of uniform rotation in a medium with resistance to an asymmetric rigid body are obtained for sufficiently small values of dynamic unbalance. Sufficient stability conditions are written out up to the second order of smallness with respect to the constant moment and the first order of smallness with respect to the restoring and overturning moments. Instability conditions are obtained for sufficiently large dynamic unbalance. The effect of dynamic unbalance on the stability conditions for the rotation of a rigid body around the center of mass is studied. It is shown that in the absence of dissipative asymmetry, it is sufficient for asymptotic stability that the axial moment of inertia of a rigid body be greater than the double equatorial moment and that the well-known necessary stability condition for a symmetric rigid body be satisfied.

Магнитная система одноосного инерционного магнитожидкостного акселерометра

Today, a physical problem of engineering design of inertial magnetic fluid accelerometers to measure dynamic processes is relevant. The main drawback of modern sensors is the nonlinear characteristic of the forced response, which limits the application area of the sensors to the case of quasi-static action (tilt angle sensor). The reason of nonlinearity is the design of the magneto-mechanical system of the elastic suspension of the inertial mass made in the form of a pair of permanent ring magnets. This drawback can be eliminated by designing an axisymmetric electromagnetic system that generates a magnetic field with a linear intensity gradient along the symmetry axis. Thus, the paper is devoted to this problem and experimental approvement of the results on a laboratory sensor prototype. The Monte Carlo algorithm is used to calculate electromagnetic system containing permanent magnets and magnetizing coils. The algorithm is implemented using the C++ programming language. Measurements of the most important parameters of the magnetic field from the point of view of the purpose of the study are carried out on the assembled model of the electromagnetic system of the accelerometer. The calculation of electromagnetic system that generate permanent magnetic field with linear intensity gradient along the symmetry axis is carried out. The applicability of the Monte Carlo method to solve similar engineering problems is shown. The measurements of the magnetic field strength of a given configuration have been made. The force of the magnetic field acting on the test sensitive element with a constant magnetic moment is measured. A comparison of the calculated magnetic field with the field of a real system is carried out. It shows satisfactory agreement between the calculated data and the real ones. A linear dependence of the restoring force on the displacement coordinate of a body with a constant magnetic moment from the equilibrium position is shown. The linearization of the response of the mechanical part of the magnetic fluid accelerometer is achieved by choosing the desired configuration of its electromagnetic system, which allows making reliable measurements of both static and dynamic quantities.

OBTAINING DECORATIVE ALKALINE-ACTIVATED CEMENT BY USING SLAGS WITH A HIGH CONTENT OF IRON OXIDE

The soft start device is designed to control the process of starting, operation and stopping of electric motors and enables smooth acceleration, smooth stopping, reduction of the starting current of the motor and coordination of the motor torque with the load moment. The article the control system of the triac device of the smooth start of an asynchronous motor with a constant load moment is considered. The control provides a reduction in the starting current and starting torque of the asynchronous motor. The principle of operation and the main technical parameters of the soft start device are described. The method of reducing power losses in power semiconductor elements of the soft start device is considered. The study of electromechanical processes in the soft start device when working with an asynchronous motor was carried out due to simulated computer modeling in the Matlab / Simulink software environment. The results of simulation modeling are given: oscillograms of input currents of the soft start device, dynamics of speed change and starting torque of an asynchronous motor. In the course of the simulation, it was established that the operation of the soft start device allows to reduce the starting current and starting torque by almost half. It is shown that the adjustment of the time to reach the full opening angle of the power switches of the soft start device and the starting angle of the opening of the power switches, which determines the acceleration dynamics of the asynchronous motor, significantly affects the value of the maximum amplitude value of the current and torque. The results of theoretical studies were implemented in a real physical prototype of the soft start device. The image of the boards of the developed soft start device is shown and its technical characteristics are indicated.