Results Of Experimental Research Research Articles

Determining infrared radiation intensity characteristics for the exhaust manifold of gas turbine engine ТВ3-117 in МІ-8МSB-B helicopter

The object of this study is the screen-exhaust device in the TV3-117 engine of the Mi-8MSB-B helicopter. To reduce visibility in the thermal range, a system of mixing hot engine exhaust gases with ambient air is used; this technique makes it possible to reduce the infrared radiation of engines. For this purpose, a new sample of screen-exhaust device was designed for testing. A thermal imaging survey of the helicopter was conducted. Three variants of thermal images were acquired: a helicopter without installation of a thermal visibility reduction system, a helicopter with standard exhaust shields installed, and a helicopter with newly developed shield exhaust devices installed. Based on the obtained experimental results, the characteristics of the intensity of infrared radiation were determined for three variants of research in the range of thermal waves of 3–5 μm. The study uses a comprehensive approach to solving the tasks, which includes a statistical analysis of known and promising ways to protect a helicopter from guided missiles with infrared homing heads based on reduced radiation forces and a theoretical method for calculating flow and temperature fields. The advantages of placing the section of the exhaust channel of the designed screen-exhaust device in the horizontal plane for complete shielding of infrared radiation in the lower hemisphere have been experimentally proven. The benefits of directing the flow of exhaust gases from the screen-exhaust device into the space above the helicopter propeller and dividing this flow into four separate flows were shown. The results of experimental research could be used to design new or improve existing screen-exhaust devices by the developers of military aviation

Preliminary microstructural research of clay solid bricks taken from historic buildings located in Poland

The article presents the results of the preliminary experimental research and analysis of the structure of samples of clay solid bricks from six historical buildings erected in Poland in the years 1300 to 1910. Images obtained with a scanning electron microscope; parameters characterizing the pore space of the ceramic material, which were obtained using mercury porosimetry; and chemical composition identified using an energy dispersive X-ray spectroscopy, were analyzed. The test results showed that as the age of the brick increases, the homogeneity of its structure decreases, the chemical composition of all samples is quite similar, and in the tested samples, large disproportions in the percentage of pore width in individual ranges can be observed. An indicator P-index useful in comparing the studied structures was proposed, based on the knowledge of the share of the pores’ width within the adopted ranges.

Modeling of Yb:YAG Laser Beam Caustics and Thermal Phenomena in Laser-Arc Hybrid Welding Process with Phase Transformations in the Solid State.

This paper focuses on the mathematical and numerical modeling of the electric arc + laser beam welding (HLAW) process using an innovative model of the Yb:YAG laser heat source. Laser energy distribution is measured experimentally using a UFF100 analyzer. The results of experimental research, including the beam profile and energetic characteristics of an electric arc, are used in the model. The laser beam description is based on geostatistical kriging interpolation, whereas the electric arc is modeled using Goldak's distribution. Hybrid heat source models are used in numerical algorithms to analyze physical phenomena occurring in the laser-arc hybrid welding process. Thermal phenomena with fluid flow in the fusion zone (FZ) are described by continuum conservation equations. The kinetics of phase transformations in the solid state are determined using Johnson-Mehl-Avrami (JMA) and Koistinen-Marburger (KM) equations. A continuous cooling transformation (CCT) diagram is determined using interpolation functions and experimental research. An experimental dilatometric analysis for the chosen cooling rates is performed to define the start and final temperatures as well as the start and final times of phase transformations. Computer simulations of butt-welding of S355 steel are executed to describe temperature and melted material velocity profiles. The predicted FZ and heat-affected zone (HAZ) are compared to cross-sections of hybrid welded joints, performed using different laser beam focusing. The obtained results confirm the significant influence of the power distribution of the heat source and the laser beam focusing point on the temperature distribution and the characteristic zones of the joint.

Experimental Study of Direct Shear Properties of Anisotropic Reservoir Shale

Understanding the shear mechanical properties of shale reservoirs is of great significance in the study of the formation stability around horizontal shale wells and the propagation and evolution of fractures for shale fracturing. However, the existing direct shear test results are limited due to small sample sizes and low shear rates. Based on previous experimental research results, the mechanical properties of anisotropic reservoir shale in direct shear tests with different experimental conditions were explored in this study. It was found that the shear mode, shear strain rate, and normal stress have a significant impact on the deformation and failure characteristics of shale. The peak shear displacement, peak shear strength, and shear stiffness of shale present an increasing trend of fluctuation, with an increase in the bedding angle. The peak shear strength of shale decreases with an increase in the shear strain rate, and this decrease trend descends with an increase in the shear strain rate. The shape of the shear fracture zone and the shear fracture mode of shale exhibit bedding effect characteristics. The fractal dimension of the shale shear fracture surface morphology shows a trend of fluctuation with the variation in the bedding angle. Further, the shear strain rate was found to play a dominant role in the fractal dimension of the shear fracture surface. The larger shear strain rate strengthens the bedding effect of the roughness for the shear fracture surface morphology. The results of this study provide a theoretical reference for determining the engineering geomechanics characteristics of shale reservoirs.

Results of experimental research of the process of forming reinforced concrete products by the centrifugation method

The method of conducting an experimental study of the process of forming reinforced concrete products is disclosed. The key factors influencing the quality indicators of the product being formed are defined and considered. On the basis of the conducted active, factorial experiment, a regression equation was compiled, graphical dependences of the influence of these factors on the process were obtained, rational parameters of the centrifugation process were determined, which are decisive in the manufacture of reinforced concrete products by the centrifugation method. Based on the results of laboratory experiment data processing, recommendations were developed for optimizing the operating parameters of industrial equipment for forming reinforced concrete products by the centrifugation method. Problem. When forming reinforced concrete products by the centrifugation method, some problems may arise, uneven distribution of the mixture in the mold body and of reinforcement, formation of voids or cracks, insufficient compaction of the mixture. If the parameters of the centrifugation process are not properly controlled, the quality of the products may vary, which may lead to deviations from specifications and standards. Problems with the deformation of the molds after forming the product can lead to damage to the product or difficulties in its removal. Goal. Based on the results of the conducted factorial experiment, recommendations are developed regarding the rational parameters of the process of forming columns of reinforced concrete supports for power transmission lines by the centrifugation method in the conditions of an operating technological line. Methodology. The basis of the research is the method of conducting a planned factorial experiment with further statistical processing of the obtained results using a computer program. Results. Based on the processing of the obtained results of the conducted factorial experiment, the following recommendations are suggested regarding the rational parameters of the process of forming reinforced concrete pillars for power lines by the centrifugation method in the conditions of an operating technological line.

STUDY OF DEFORMABILITY OF THE LARGE-SPAN ROOF STRUCTURAL SYSTEM IN THE FORM OF AN ASYMMETRICAL SHELL

The scientific article is devoted to a complex study of deformability of saddle-type shell of negative Gaussian curvature of a public object that has been in operation for a long time for further general restoration of the building’s roofing system. The authors have developed a specific algorithm for conducting experimental research, providing additional static load on a shell at the lower point of the gentle axial line of the supporting arches. To smoothly carry out the loading procedure, we mounted containers in barrel form on the roof surface and gradually filled them with water. We carried out an experimental evaluation of the bearing capacity of the shell with the determination of the redistribution of forces along the length of the section in the lower zone of the conventionally outlined arch. The experimental test results revealed that the deformability of the shell surface under short-term loading did not exceed 2.0 mm, and, under long-term loading, it was no more than 4.0 mm. Analysis of the qualitative features of structure deformation shows that the displacement of the roof’s points, located symmetrically to the vertical axis, has the opposite sign to the sign of the displacement of the actual ‘saddle’ point (the case of symmetrical deformation). We conducted a numerical verification of the behaviour of the investigated structure by forming a detailed finite element spatial model of the shell. Comparison of the results of numerical calculation with the results of field tests shows the coincidence of qualitative and quantitative parameters, which, in turn, characterises the developed theoretical model as fully adequate and suitable for analysing the stress-strain state of similar large-span structural systems. Based on the results of comprehensive theoretical and experimental research, we made proposals for the further restoration of the roofing structure with the limitation of the self-weight of the covering to 1 kN/m2. Engineers and scientists can use the research results to reconstruct similar authentic structural systems. Keywords: calculation, restoration, loading, deflection, shell, negative Gaussian curvature.

MATHEMATICAL MODELING OF THE HOLLOW PROFILES FORMING PROCESS

Steel alloys containing manganese and boron are increasingly being used in mechanical engineering, including automotive and agricultural sectors. Products of critical application made from such steels, including hollow ones, have a high level of mechanical properties, surface hardness, and wear resistance. These products are obtained by profiling of previously electrically welded round pipes with a hot sheet stamping or pressure treatment (drawing, cold rolling, stamping). Technological parameters of combined processing methods are determined by the results of experimental research, which, due to the complexity and cost of materials, leads to significant expenses. The application of mathematical modeling can reduce the number of experiments and forecast the quality of finished products. The research focuses on investigating the possibility of obtaining square hollow profiles by means of push-pulling through one stand of a pipe welding unit and defining the requirements for geometric parameters of the billet.

Implication of viruses in the etiology of preeclampsia.

Preeclampsia is one of the most common disorders that poses threat to both mothers and neonates and a major contributor to perinatal morbidity and mortality worldwide. Viral infection during pregnancy is not typically considered to cause preeclampsia; however, syndromic nature of preeclampsia etiology and the immunomodulatory effects of viral infections suggest that microbes could trigger a subset of preeclampsia. Notably, SARS-CoV-2 infection is associated with an increased risk of preeclampsia. Herein, we review the potential role of viral infections in this great obstetrical syndrome. According to in vitro and in vivo experimental studies, viral infections can cause preeclampsia by introducing poor placentation, syncytiotrophoblast stress, and/or maternal systemic inflammation, which are all known to play a critical role in the development of preeclampsia. Moreover, clinical and experimental investigations have suggested a link between several viruses and the onset of preeclampsia via multiple pathways. However, the results of experimental and clinical research are not always consistent. Therefore, future studies should investigate the causal link between viral infections and preeclampsia to elucidate the mechanism behind this relationship and the etiology of preeclampsia itself.

Bплив ранньовесняних строків сівби насіння ромашки лікарської на польову схожість та виживання рослин в умовах правобережного лісостепу України

An important place in the effective technology of growing medicinal chamomile (Matricaria recutita L.) is occupied by the early spring sowing period. Therefore, they provide a dense emergence of seeds, as evidenced by many conducted scientific studies in the field of plant breeding. The article presents the results of experimental research on the effect of early spring sowing dates of medicinal chamomile on field seed germination and plant survival. It was established that medicinal chamomile plants depended on weather and climatic conditions, sufficient amount of moisture in the soil, soil crust, which as a result led to variation in the passage of growth and development phases, and therefore, a question arose in the study of agrotechnical techniques aimed at the productivity of medicinal raw materials. The cultivation of tetraploid of medicinal chamomile variety Perlyna Lisostepu and Zloty Lan in the conditions of the Right-Bank Forest-Steppe of Ukraine during the period of research (2018-2023) in the early spring sowing period was studied. It was established that the investigated varieties of medicinal chamomile had the highest field germination of seeds due to the content of productive moisture. The highest field seed germination rates of 74.16% were recorded during the early spring (15-18.04) sowing period of the Perlyna Lisostepu variety, and the Zloty Lan variety was 72.68%, respectively. According to six-year research data, the highest field seed germination of 68.00% on the control variant (1-3.04) according to the sowing dates was noted in the Perlyna Lisostepu variety, and the lowest 67.00% – in the Zloty Lan variety. The maximum rate of plant survival at the end of the growing season was 88.96%, which was obtained in the variant of the early spring (15-18.04) sowing period of the Perlyna Lisostepu variety, the minimum rate was 69.15% in the control (1-3.04) of the Zloty Lan variety. The germination rate on average over six years exceeded the control by 6.14%, and the survival of chamomile plants on average over the years of research exceeded the control option by 1.5%. The difference in factors was insignificant (2-3%)

Passive bandpass filters for modern microwave communication systems

Background. Bandpass filters are an integral part of any radio engineering systems and modern communication systems. Research and development of new passive components is due to growing need for such elements for modernization and creation of new modern communication systems.
 Aim. A brief overview of passive bandpass filters. Their classification according to the type of implementation is given.
 Methods. Results of experimental research and design of different passive bandpass filters are considered.
 Results. Lumped elements filters, microstrip filters, filters on high-temperature superconductor films, filter on dielectric resonators, surface acoustic wave filters, bulk acoustic wave filters are considered. At a qualitative level, the main advantages and disadvantages are considered from point of view of electrical parameters and size indicators. Examples of topological and constructive implementation are given.
 Conclusion. The passive bandpass filters considered in the paper make it possible to implement frequency selection devices at operating frequencies up to 6 GHz and higher, taking into account modern system trends and requirements for devices of this type.

Digital Transformation of Socio-Technological Reality: Problems and Risks

The research is devoted to a discussion of social and humanitarian problems associated with tectonic changes in human life against the backdrop of total digitalization. The author's attention is focused on the uniqueness of the modern situation: never before have innovative technologies had the ability to penetrate so rapidly and deeply into the foundation of modern society, have they become so widespread and accessible to almost all peoples and cultures. At the same time, the undeniable public good and the most serious threats to society that digital reality technologies bring with them are in a very close relationship. This is especially true for artificial intelligence systems. Innovations transform the entire world order, bringing radical changes not only to the material sphere of life, but also to the spiritual and moral state of a person. The research notes that the introduction of information and communication technologies into the life of modern society occurs without reliable support on the results of preliminary experimental research, without taking into account a deep professional and responsible assessment of the social and psychological consequences of their impact on the individual and on society as a whole. As a result, at this stage, society is constantly faced with many negative aspects of the impact of high-tech means. The work examines some of them: a decrease in cognitive and analytical abilities, the devaluation of human labor, the criminalization of cyberspace, the spread of Deepfake technology. Particular attention is paid to the problem associated with the possibility of using information technology as a tool of psychological influence. Information and psychological warfare is implemented on the basis of social networks and artificial intelligence technologies, which provides the enemy with the opportunity to achieve superiority without the use of military force. Information and humanitarian actions in cyberspace, carried out by Western countries in order to destabilize our society, destroy its value foundations, reformat the consciousness, worldview and spiritual and moral qualities of citizens, are becoming increasingly large-scale and aggressive. The work notes that digitalization is gaining momentum, plunging society deeper into new circumstances and requiring decisive action aimed at overcoming the many threats specific to the modern high-tech era.

THE IMPACT OF SOCIAL COMPARISON ON NEGATIVE PSYCHOLOGY AND IMPULSIVE BUYING BEHAVIOR OF CUSTOMERS IN VIETNAM

Purpose: This study consolidates core theories pertaining to social comparison, particularly upward comparison, impulsive buying behavior and notions associated with social characteristics such as envy, self-esteem, negative mood, depression and self-efficacy. At the same time, provide hypotheses and study models connected to the impact of social comparison on negative psychology and impulsive purchase behavior of customers in Vietnam. Method: Furthermore, this subject employed qualitative research methods such as group discussions and in-depth interviews with experts to reach a consensus on the definition of components, as well as to refine and enhance the measuring scales used to assess these factors. Subsequently, establish a foundation for carrying out initial quantitative investigation in order to finalize the official questionnaire, and subsequently proceed with the official quantitative study. A representative survey was conducted with a sample size of 647 customers who utilize social networks and engage in online shopping on e-commerce platforms. The study was conducted in major cities in Vietnam, including Ho Chi Minh, Hanoi, Da Nang, Hue, Can Tho and Bien Hoa. Result: Experimental research results have indicated that upward social comparison has a negative influence on self-esteem but a favorable impact on envy and negative mood. Simultaneously, increased self-esteem decreases depression and impulsive buying tendencies, whereas feelings of envy and negative mood have a beneficial effect. Conclusion: Additionally, the research findings demonstrate the influence of self-efficacy as a moderator and dedepression as a mediator. These findings provide a foundation for the researcher to suggest managerial recommendations for organizations to enhance client purchasing behavior.

The Impact of Computational Accuracy on the Quality of Direct Drive Control

One of the main aspects of the control system development process for direct drives is the selection of the required computational accuracy while establishing its impact on the quality of the control. Understanding this relationship allows designers to consciously determine the system structure at the early stages of controller development, which enables the optimal usage of hardware resources. This paper analyzes the results of experimental research on the influence of computational accuracy on the quality of control of direct drives. During the carried-out research, several vector controllers with different computational precision were implemented using Field-Programmable Gate Arrays (FPGAs). The experiments were carried out on a dedicated research stand for testing direct drives. Test scenarios included position and trajectory monitoring under various torque loads. To assess the control quality, the measures based on the deviations from the value set by the controller were proposed. In this paper, the results of experiments have been presented in the form of values of the measures in relation to the computational accuracy. The obtained results proved that satisfactory drive operation parameters can be obtained despite the relatively low accuracy of calculations in the control algorithm.

Research on the possibility of manufacturing aerated-foam concrete with a variatropic structure based on aluminum powder and eabassoc foaming agent

This article presents some experimental research results on the composition and properties of aerated-foam concrete with a variable structure using available materials in Vietnam. To obtain concrete products containing anisotropic pores from the central area to the periphery, this study proposed fabricating cubic wooden molds with four perforated mold walls. The diameter of the pores is 1.5 mm and the distance between these pores is 10 mm. The pre-punching of hollow holes in the four mold wall panels is to remove excess gas and liquid phases during the setting and solidification process and form the internal variable structure of the air-foam concrete product. Experimental research results have shown that it is possible to produce anisotropic aerated-foam concrete with an average dry density of about 1459 kg/m3; the average compressive strength at the ages of 7 days, 14 days, and 28 days are 18.2 MPa; 21.2 MPa and 28.7 MPa, respectively. Besides, this study also compares the properties of anisotropic aerated-foam concrete with conventional foam concrete and aerated concrete. The obtained results show that the physical and mechanical properties of aerated-foam concrete with the variable structure are better than conventional foam concrete and aerated concrete with the same density.

Flexural Behavior of a New Precast Insulation Mortar Sandwich Panel

This article introduces the experimental and analytical research results of two precast insulation mortar concrete sandwich panels (PIMSP) and two precast concrete composite panels as one-way slabs under bending load. Obtaining a prefabricated floor slab that can balance thermal insulation and structural performance can reduce material consumption and increase inter-story usage height. As the sandwich material for PIMSP, insulation mortar with a strength of 6 MPa was used. Truss-shaped shear connectors were used for shear force transfer. Then, finite element analysis was used to analyze and study the unidirectional flat plate model. The results showed that the tested PIMSP achieved a complete composite effect in the elastic stage and a semi-composite effect in the plastic stage. The PIMSP crack pattern resembles that of a precast concrete slab when utilized as a one-way slab. The load transfer capacity of truss-shaped shear connectors is relatively small, and it is mainly used as a connection between floors. Experiments have demonstrated that PIMSP panels can serve as a structural substitute for regular concrete floors in residential buildings.

Continuous ultrasonic ozone coupling technology-assisted control of ceramic membrane fouling coupled enhanced multiphase mixing to treat dye wastewater and CFD flow field simulation

In this study, ozone catalysts (hydrogenation-modified red mud, HM-RM) successfully prepared by hydrogenation-modification of industrial hazardous solid waste red mud (RM) as a raw material in accordance with the viewpoint of treating waste with waste and using waste. Meanwhile, as for the common phenomenon of membrane fouling, uneven distribution of multiphase solid catalysts and ozone in liquids, the addition of ultrasound can not only disperse materials, but also play a role in online cleaning of ceramic membranes and catalysts. The optimum treatment conditions for Rhodamine B (RhB) solution with volume of 2 L and concentration of 40 mg/L were catalyst concentration of 0.4 mg/L, reaction temperature of 45 °C, ultrasonic time of 1 h, ultrasonic intensity of 600 W, removal rate of RhB was up to 90 %. In addition, the computational fluid dynamics (CFD) simulation method was used to investigate the fluid flow between the two gas-liquid phases and the effect of the negative pressure of the membrane pump on the fluid by the analysis of flow, pressure and ozone flux of the ceramic membrane(CM) reaction apparatus. The CFD simulation results showed that at the inlet gas-liquid flow rate of 3 m/s and the negative pressure of 20,000 Pa, the maximum flow rates of CM-1 were 3 m/s, 0.752 m/s for CM-2, and 0.228 m/s for CM-3, respectively. Vortices, which are beneficial to solid-liquid mixing and gas-liquid mass transfer, formed between the suction port CM-1 of CM-1 and the inlets of CM-2 and CM-3. This discovery is consistent with relevant experimental research results. Significantly higher concentrations of both •OH and dissolved ozone were observed in the US/HM-RM/O3 system compared to other systems, indicating the significant improvement in ozone utilization rate through the application of ultrasound. The superiority of the US/HM-RM/O3 device was demonstrated. The real dye effluent was tested under optimum operating conditions and the results showed that COD and TOC were reduced by 81.34 % and 60.23 % respectively after 180 min of treatment. The above research can provide technical support for the treatment of dye wastewater using Ultrasound-enhanced ozone oxidation ceramic membranes.

Vision‐based probabilistic post‐earthquake loss estimation for reinforced concrete shear walls

AbstractIn this paper, a probabilistic methodology based on image analysis is proposed for earthquake‐induced loss estimation in rectangular reinforced concrete shear walls (RCSWs) in compliance with FEMA P‐58. The methodology is developed using a databank of 285 surface crack patterns gathered from the result of experimental research on 99 rectangular RCSWs with wide‐ranging structural and geometric characteristics. For the complexity extraction, three fractal geometry indices of the damaged specimens are taken into consideration. Fragility functions are generated to determine the probability of exceeding a FEMA P‐58 compliant damage state based on the various methods of repair for specific complexity indices. The fragility functions are obtained using four common probabilistic distributions including lognormal, Weibull, gamma, and beta. The fitness of the fragility curves is examined by two goodness‐of‐fit tests, namely the Kolmogorov–Smirnov test and Lilliefors test. Results show that the Weibull is the best‐fitting distribution for the majority of damage states and succolarity possesses the best results in goodness‐of‐fit tests among fractal geometry indices. Empirical loss indices are also derived in this paper aimed at optimizing the goodness‐of‐fits. Finally, the proposed procedure is utilized for a sample specimen from the databank at various damage levels.

Using the wavelet transform to process data from experimental studies of the discontinuous plastic deformation effect

Vast number of theoretical and experimental works has been devoted to the study of discontinuous plastic deformation (the Portevin-Le Chatelier effect), which manifests itself for most widely used alloys in certain ranges of both temperatures and strain rates. Due to the statistical nature of this phenomenon, difficulties arise in processing, qualitative analysis and quantitative comparison of test results and calculations. Using of statistical methods for these purposes makes it possible to get only some averaged characteristics of the obtained data (usually - moments of the first and second orders in amplitudes and frequencies). A possible alternative for processing of experimental and theoretical results of this effect research is wavelet analysis using. The results of experimental studies of the Portevin–Le Chatelier effect, realized during the deformation of thin-walled tubular specimens made of aluminum alloy AMg6M at certain strain rates at room temperature are presented. Diagrams of deformation under uniaxial tension, shear, proportional and disproportionate loading of specimens were obtained. The inhomogeneity of strain fields and their rates is shown, illustrating the manifestation of the Portevin – Le Chatelier effect under conditions of complex loading of thin-walled tubular specimens made of AMg6M alloy. A brief overview of existing methods and means of non-destructive testing is presented that make it possible to non-contactly record the spatial heterogeneity of plastic yielding. Some possibilities of using the wavelet transform to process certain types of non-monotonic stress-strain diagrams obtained for the specimens made of the aluminum alloy in question are discussed. Using wavelet analysis, a compact presentation of data from field experiments in the form of amplitude-frequency characteristics was obtained. The scalograms analysis of specimen loading diagrams was carried out.

Применение термически поврежденной древесины в деревоклееных балочных конструкциях

This paper deals with the experimental research results of laminated wood beam structures made using lamellas produced from the pine trees, partially damaged in forest plantations. The purpose of the research has been to study the stress-strain state of laminated wood beam structures utilizing the wood damaged by the thermal exposure caused by a forest fire. Previously, the authors have carried out a significant amount of research into the physical, mechanical and strength properties of thermally damaged pine wood. They have established the dependence of the strength properties of the wood on the degree of fire damage and the wood sampling points according to the height of the stem. Prior to the experiment on the large-scale models in the “Lira 10.12” software complex, numerical studies of four series of single beams with a span of 6.0 m and a section of 140×500 mm produced from the 1st grade pine wood in the upper and lower parts of the section and from thermally damaged pine wood in the middle part of the section. A comparative analysis of the beams has been performed with varying percentages of replacement of the healthy pine wood with the one weakened by the fire along the height of the section: 76, 62, 51 and 36 %. As a result of the numerical calculation of the beams under study using the derived safety factor equaling 1.136, their actual load-bearing capacity has been determined. It has been established that a decrease in the load-bearing capacity of the СB-2 beams equals 12.2 kN, which is 16.05 % relative to the reference beam CB-5, made entirely of the 1st grade pine wood. For the CB-4 beams a decrease in the load-bearing capacity equals 7.4 kN, which is 9.74 % relative to the reference beam CB-5. The difference between the calculated and experimental breaking loads is 9.5 to 14.3 %. The introduction of the safety factor equaling 1.136 in the numerical calculation ensures sufficient convergence of the calculated and experimental data (the measurement error is 3 %). The load-bearing capacity of the reference beam СB-5, made entirely of the 1st grade pine wood, is 12.38 kN/m. For beams CB-1 to CB-4 it equals from 8.53 to 12.06 kN/m. The relative decrease in the load-bearing capacity did not exceed 31.1 to 32.5 %. It has been established that the CB-4 beam, made using 34 % of lamellas produced from thermally damaged pine wood, allows for the load-bearing capacity of 97.5 % relative to the beams made entirely of the 1st grade pine wood.

The results of experimental research of a rotor seed-metering unit for sowing non-free-flowing seeds

The production and cultivation of new high-quality seed varieties are linked to the sowing of various crops with diverse physical and mechanical seed properties. Efficient seed-metering unit operation is critical during the technological process of fodder crop cultivation, predominantly when sowing non-free-flowing seeds. The quality of seed sowing and crop yield significantly rely on the design precision of seed-metering devices, technical maintenance and appropriate calibration. A rotary seed metering device was incorporated to ensure that non-friable seeds are uniformly sown, thus maintaining consistent seed supply and consumption at all stages of circulation. The study of the proposed device's productivity dependence on its operating parameters is justified because these variables affect crucial indicators such as the capacity to achieve and sustain the desired seeding rate over the entire operational duration. The study presents findings from an experimental investigation on sowing non-free-flowing (non-flowing) and finely dispersed seeds using a rotor seed-metering unit. The tests aimed to ascertain the precision and evenness of sowing such crops. It was observed that the speed of rotation of the seed-metering unit's vane disk is a key factor in the uniformity and supply of sown seeds. The limits of variation in rotor rotation speed and rotor seed-metering unit productivity per second were established to guarantee the desired seeding rate for various crops, including alfalfa, Agropyron, and Bromus inermis.