bluuebunny/crossref_metadata_2025 huggingface dataset:
Perpendicular to steel reinforcing bars axis displacements of rebars for determination the torsional stiffness of reinforced concrete elements with normal cracks
Authors: Azyzov T , Kochkarev D , Tsyhanenko L , Tsyhanenko H , Srybniak N
Published: July 2021

The article provides a technology for determining the displacement of the end of the reinforcing bar embedded in concrete for measuring the shifting force in the longitudinal reinforcement. Dependences of the displacement of the end of the reinforcing bar on different protective layers are shown. A formula to define the displacement of steel reinforcing bars due to the shifting force is given. The formula was obtained by the numerical computation approximation using three-dimensional finite elements. A method for determining the torsional stiffness of reinforced concrete element with normal crack is presented. In this method the pliability of the reinforcement perpendicular to its axis is also considered.
Calculation of a multi-span frame for stability
Authors: Balduk P , Balduk H , Yaremenko O , Yaremenko N
Published: July 2021

The loss of stability of the first kind as applied to the longitudinal bending of the supports of a flat one-story free multispan frame under the action of vertical forces is considered. The elements of the frame have arbitrary stiffnesses constant along the length of the elements. The system of nonlinear equations of displacement method is solved. The matrix of coefficients of the system of equations is presented in block form. Formulas of generalized coefficients for each block of matrix are determined, and then one or another element of general stability equation matrix. A slight correction of generalized coefficients formulas makes it possible to extend the methodology to calculate the stability of non-free frames (overpasses). Compact notation of generalized coefficients of stability equation matrix makes it possible to considerably simplify development of algorithms and computer programs designed for solution of such tasks. The algorithm is implemented in Excel. To verify the obtained results, test calculations of stability frames for which the exact solution is known have been performed. Stability calculation of plane frame of periodic structure has been done by the suggested method. The diagram of the boundary curve has been made and the areas of frame stability and instability under the action of the given system of forces have been determined. Stability calculations of the model in the software package ANSYS, with subsequent comparison of the calculation results, have been performed.
Nonlinear problems of equilibrium for axisymmetric membranes
Authors: Bedov A , Vagapov R , Gabitov A , Salov A
Published: July 2021

The problems for equilibrium of circular and annular membranes made of elastic-orthotropic and elastoplastic isotropic materials are considered in this paper in a geometrically and physically nonlinear formulation meeting the Föppl-Karman assumptions. The outer contour is considered to be stationary, while the inner one being free, or reinforced by either an elastic ring or a fixed disk. The load is assumed to be uniformly distributed over the membrane surface.

The results of calculations of circular and annular membranes with large deflections in comparison with thickness, deformations and squares of angular displacement to be comparable with each other but small in comparison with the unit are presented in the first part thereof. The resulting boundary value problems are reduced to the Cauchy problem to be numerically integrated by the shooting method under the iterative Steffensen algorithm. For circular membrane structures an analytical solution as a power series similar to the Prescott series for a circular membrane is assumed either.

The results of numerical solutions of problems are presented as dimensionless characteristic functions. Analysis of this information will enable to solve the problem of the support, being optimal in a certain sense when the membrane is close to be equal in strength.

Problems of elastoplastic equilibrium of isotropic membranes are presented in the second part thereof. The idealized Prandtl diagram is used as the main characteristic of the mechanical properties of the membrane material. The Tresca-Sant-Venant and Huber-Mises-Hencky conditions were used as criteria for the transition of a material from an elastic state to a plastic one. Solutions of physically nonlinear equilibrium problems for axisymmetric membranes are also presented as dimensionless characteristic functions.
Study of the fracture surface of concretes reinforced with basalt fiber coated with titanium and zirconium dioxides. Fiber-reinforced concrete composites
Authors: Gots V , Berdnyk O , Maystrenko A , Palchik P , Amelina N
Published: July 2021

It is impossible to imagine the development of modern technologies without the use of efficient and affordable fibrous materials based on minerals, glass, and other fibers. The intensive development of the production of fibers and materials based on them worldwide determines the formulation of significant scientific and technical problems of obtaining them with a given set of properties and high-quality indicators, optimization of processing, and rational use. However, the possibility of modifying the composition of the rock with other components that could significantly improve the physical and chemical properties of the fibers is not always taken into account. For the first time, a study was conducted to research the coating of basalt fibers, such as TiO2, ZrO2 and their effect on the physical and chemical characteristics of aluminosilicate melts made from rocks, fiber formation processes, structure, and physical and chemical properties of fibers. Studies have shown that fibers modified with oxides of TiO2 and ZrO2 have higher chemical resistance in aggressive environments compared with unmodified fibers obtained from melts of similar component groups.
Contact heat transfer of a cutting diamond wheel with a boundary layerof air
Authors: Bespalova A , Faizulyna O , Lebedev V , Frolenkova O , Chumachenko T
Published: July 2021

Cutting of natural and artificial building materials is most often carried out with diamond cutting wheels on a metal base at cutting speeds of about 50-80 m/s. The intensity of the cutting process causes a significant heat release, as a result of which the wheel temperature rises to unacceptable values. The value of these unacceptable temperatures is about 600 - 650°C

At these temperatures, graphitization of diamond grains occurs, i.e. loss of diamond layer and loss of cutting properties. In addition, a thin diamond wheel (thickness 1 - 3 mm) is deformed, which leads to jamming and its tensile strength at these temperatures is reduced by half, which creates the risk of rupture by centrifugal forces. In this work, it is taken into account that during the rotation of the wheel, a boundary layer of air is created around it, which is stationary relative to the wheel. Consequently, contact heat transfer occurs between the wheel and the boundary layer, and then convective heat transfer occurs between the boundary layer and the surrounding air. This scheme allows you to more accurately determine the time of safe operation of the diamond wheel. Contact heat transfer between the wheel and the boundary layer is not effective enough to lower the temperature. When air with a negative temperature is introduced into the boundary layer by means of a Rank-Hillsch tube, the wheel temperature decreases by about 10%.

When a sprayed coolant (fog cooling) is introduced into the boundary layer by means of an ejector tube, the wheel temperature decreases by 25%, which ensures an increase in the time of continuous operation.
VIBROABRASIVE TREATMENT OF ULTRA-HARD CERAMICS
Authors: Burlakcov V I , Burlakova G U , Mazur V A , Manoylov O V
Published: July 2021

The article reveals a possibility of treating ultra-hard nitride ceramics by means of vibro-abrasive treatment. It was proved that the value of residua; stresses of the second kind in ceramic samples sufficiently reduced after such treatment. Also it was confirmed experimentally that material removal increased with time. The article contains Difractograms of the surfaces. The surface quality of nitride ceramics was thoroughly analyzed. The grade of abrasive material was determined practically.
The influence of the process-induced deformed state on straightness of prestressing strands after manufacture
Authors: Ozerianskyi B M , Chaiun I M
Published: July 2021

Based on the study of elastic-plastic deformation, the expressions of longitudinal force Nt
, bending Mb
and torque Mt
moments in wire-cross sections subject to the process parameters of rope torsion are obtained: wire tensioning efforts, untwisting and preformation.

A technique for determining the technological internal force factors (TIFF) in the rope cross-sections: the longitudinal forces

N
x
T

(

N

t
i

)

; bending

M
y
T

(

N

t
1

;

M

b
i

;

M

t
i

)
,

M
z
T

(

N

t
i

;

M

b
i

;

M

t
i

)

and torque

M
x
T

(

N

t
i

;

M

b
i

;

M

t
i

)

moments. Being guided by the theorem on unloading and FEM, the external deformed state of the rope unloading from TIFF is studied. The expression of the rope unloading deformations vector

|
D
K
|
=
|
ε
,
θ
,
χ
,
ζ

|
T

as a function of the

F
=
(

N
x
T

;

M
x
T

;

M
y
T

;

M
z
T

)

TIFF vector using the global stiffness matrix of 4×4 rope cross-section corresponding to the elastic deformation is obtained.

Based on the bending deformations, an expression was χ and ζ obtained, the parameter h (h is the segment arrow at the chord length of 1 m), which, according to the regulatory standard, characterizes the degree of the rope straightness after manufacture. The connection between the parameters of torsion (tension, untwisting, and preformation) and the parameter h of straightness is established. It is determined that the unstraightness is directly affected only by the deviation from the uniformity of tension. The developed theory allows to determine the permissible deviation from the non-uniformity of tension with the permissible value of the parameter h of straightness. For example, a prestressing strand of a structure 1+6, having a diameter of 6.9 mm is considered to be of high quality according to the standard, if h ≤ 25mm. This value h corresponds to the deviation of the tension of Δκ = 0,8 one of the 6 wires of the layer. With an increase in deviation of tension, h increases almost rectilinearly to Δκ ≃3. With further increase, a loop is Δκ formed – the loss of stability.

The obtained theory of the external deformed state of unloading provides further opportunity to study the internal deformed-stress state of the rope wires due to process-induced forces, which opens the prospect of even a deeper study of operational strength and durability of ropes.
Effect of alloying elements on structure, metastability and properties of Fe-Cr-Mn (Ni-free) corrosion-resistant austenitic-ferritic steels
Authors: Cheylyakh Y , Cheiliakh A , Kaiming W
Published: July 2021

Investigated was chromium influence within 15-21.4 wt.% and manganese influence within 8-11.4 wt.% upon phase transformations, formation of structure and mechanical properties of corrosion resistant nickel-free (Fe-Cr-Mn) steels of austenite-ferrite structural class. It was found out that by the variation of chromium and manganese content it was possible to modify efficiently the content of ferrite and austenite in the structure, the degree of deformation metastability of austenite and control the mechanical properties of steels. An improved complex of strength, plasticity properties and impact toughness is reached at optimal content of alloying elements (Cr, Mn) in new nickel-free steels, it can be explained by positive impact of deformation induced martensite γ→α’ transformation at testing during their formation.
The use decorative concretes with the addition of highly dispersed chalk for volumetric and spatial elements of urban space
Authors: Chepurna Svitlana , Popova Olha , Ryshchenko Tetiana , Dudka Olena
Published: July 2021

In recent years, the attitude to the external appearance of the urban environment and its elements has changed dramatically. Interest in new constructive solutions, style of urban space design and modern materials which improve the quality of urban space has increased. Installed that the most effective material is decorative concrete, which is used to create a variety of volumetric and spatial elements of engineering improvement, architectural and urban design. The possibility of creating decorative concrete with the addition of highly dispersed chalk and the natural pigment that is distinguished by high operational, decorative, aesthetic properties and solves environmental and economic problems has been considered in the article. The results obtained indicate the possibility of combined use of highly dispersed chalk and yellow natural pigment (ocher) to create colored concrete with high corrosion resistance, frost resistance and decorative and aesthetic properties. The relationship between the durability and corrosion resistance of the test concrete on the size and nature of the pores has been established.
Method for calculating the shape of rolls for helical rolling
Authors: Gorbatyuk S M , Deniskina T V , Balakhnina E E , Chicheneva O N
Published: July 2021

The paper is devoted to solving the problem of determining the shape of the rolls of helical rolling mills, depending on the specified profile of the deformation zone. A universal calculation method has been proposed, thanks to which it is possible to determine the shape of the working surface of a roll for all types of helical rolling mills (with mushroom-shaped, cup-shaped, barrel-shaped and disc rolls), any relative arrangement of the rolling axis and rolls axes, and various locations of the deformation zone on the rolling axis. The proposed method is implemented as a standalone exe-application with a simple intuitive interface. The application allows you to output the calculation results into txt-files, which can then be imported into CAD systems to create 3D roll models.
The problem of plane bending a direct composite beam of arbitrary cross-section and the prerequisites for its approximate analytical solution
Authors: Koval’chuk S B , Goryk O V , Antonets A V
Published: July 2021

The approach to the reduction of the spatial problem of plane bending a composite discrete-inhomogeneous beam of arbitrary cross-section to the approximate two-dimensional bending problem of the equivalent multilayer beam has been discussed here. The result is represented in the form of relations for determination the characteristics of the equivalent multilayer structure by physical and mechanical materials characteristics of the original beam’s phases and the system of static, geometric and physical relations of the corresponding two-dimensional problem. The obtained equations are similar to the plane problem equations of the elasticity theory, but instead of stresses, they contain internal efforts consolidated to the main plane of the beam. The equations of the approximate two-dimensional problem were used to solve the problem of static bending a composite console of arbitrary structure with a load on the free end, taking into account the uniform change of the temperature field. The given system of equations and relations is the starting point for the construction of non-classical deformation models and solving a wide range of problems concerning the deformation of a direct composite beams.
Features of production and application of glued wooden beams in cottage construction
Authors: Guzii S G
Published: July 2021

This paper discusses the technological features of the production and use of laminated veneer lumber in cottage construction. The main properties of aluminosilicate glue for gluing pine lamellas have been determined. Changes in both the dynamic and plastic viscosity of aluminosilicate glue are given depending on the spindle rotation speed and shear rate. Equations describing these dependencies are given. These dependencies influence the choice of the method for applying the aluminosilicate glue to the substrate surface. It has been shown that a change in dynamic viscosity from 1662 to 1268 cP in the operating speed range from 20 to 30 RPM and shear rate from 4.2 to 6.3 1/s provides a small shear force from 69.9 to 79.88 dynes/cm2, which makes it easy to apply the glue with a brush or a special roller.

It is noted that aluminosilicate glue with a density of 1.54 g/cm3 has a low surface tension of 54 mN/m, which affects the contact angle and the tendency to spread on a pine base. It has been found that an increase in the spreading coefficient results in more complete wetting. It is shown that with an increase in the curing time of the glue joints, the shear strength along the fibers and the elastic modulus on the 28th day increase by 1.63/1.1 times as compared with the seven-day age. An increase in strength and elastic modulus is associated with the passage of crystallization processes in an aluminosilicate gel with the subsequent formation of zeolite-like formations. It is noted that the increase in the value of the breaking load of the samples at the age of 28 days is 1.63 times higher than after 7 days of curing, for determining the values of the shear modulus and elasticity does not have such a decisive importance and this decrease is 5.1%.
Application of parallel computing in finite element analysis of constructions
Authors: Homenyk S I , Kozub V Yu
Published: July 2021

To optimize finite elements computational processes of the “MIRELA +” computing complex, parallel programming algorithms have been developed for creating stiffness matrices of finite elements and calculating the stress-strain. The parallel data processing is implemented using OpenMP library. On the basis of computational methods of experiments, the use of parallel computing algorithms at the beginning of solving problems with traditional finite element algorithms for large-dimensional grids has been established.
Effect of critical speed in machining of the main shaft of cone crushers on accuracy of treated surfaces
Authors: Kondratenko V E , Devyatiarova V V , Sedykh L V , Madgoziev F U
Published: July 2021

One of the industry development factors is the advancement of design and technological solutions of production applications. Mining industry makes heavy use of cone crushers, with the main shaft being one of the main components under serious loads, thus requiring repair or replacement. The paper suggests the method to determine the critical speed of the main shaft of cone crushers in machining and the effect, which the type of fixing on metal-cutting machines has on the accuracy of its surfaces.
Study of Stress-Strain Behavior of the Laminated Plate Damaged by Delamination
Authors: Kondratiev A , Smovziuk L , Shevtsova M , Nabokina T , Tsaritsynskyi A
Published: July 2021

The process of manufacturing of the structures of polymeric composite materials is accompanied by various technological defects. Delamination defects have the greatest impact on the bearing capacity of the composite structures. The method for assessment of the stress-strain behavior of a panel structure made of polymeric composite materials, which is damaged by delamination, has been developed. This method allows determining the degree of stress concentration in the area of step change in thickness and identifying the most dangerous point where the structural failure may start. In contrast to the classical theory of laminated plates, the proposed model gives an opportunity to simplify three-dimensional problem by setting the displacement field on the interfaces of layers and their linear interpolation over the plate thickness, taking into account the transverse shear deformation. Stress-strain behavior of the plate with delamination was determined according to the computational model of the plate with a cut for the case when the layers in the defect area cannot take up the applied load. According to the results obtained, distribution of stresses over the plate thickness changes significantly in the area of step transition to the delamination and near it. At the distance, it approaches the stress distribution in a plate of the uniform thickness. It allowed confirming the previous conclusions that maximum rise in stresses may occur in the weakened layer near the delamination, initiating the failure of the structure. Reliability of the developed mathematical model is confirmed by comparison with the results of experimental studies. The resulting maximum error does not exceed 7% and demonstrates good convergence of results. With the use of the developed method, it is possible to solve the important practical tasks of studying the loss of performance of the panel structures made of polymeric composite materials with delaminations and determining the optimal methods for repair of such defects.
An analytical solution to the problem of thermoelastic bending of a multilayer beam with different temperature of longitudinal faces
Authors: Koval’chuk S B , Goryk O V
Published: July 2021

An exact analytical solution of the quasistatic problem of thermoelasticity is presented for a section of a narrow multilayer beam with different temperatures of the longitudinal lower and upper faces and a heat flow of arbitrary height across the sections through the lateral faces. The solution was obtained for the entire package of layers by sequentially solving the heat equation for an inhomogeneous beam, taking into account the ideal thermal contact of the layers and the system of equations of the plane problem of the theory of elasticity under the assumption of a rigid connection of the layers. To take into account the inhomogeneity of the beam, a continuum approach is used, in which the multilayer material is considered continuous with variable physical and mechanical characteristics. The resulting relations take into account the orthotropy of the physico-mechanical properties of the materials of the layers and their compliance with the transverse shear and compression strains. An example of implementation of a solution for a five-layer beam with combined rigid and articulated fastening of the ends is given.
Stress-strain state of elastomeric vibroseismic insulators
Authors: Kozub Yu G , Dyrda V I , Kozub G A
Published: July 2021

A method for solving problems of viscoelastic deformation of structures made of weakly-compressible elastomers, based on the application of the hereditary Boltzmann-Volterra theory, is considered. To consider the weak compressibility and eliminate the “false shift” effect, the moment scheme of the finite element is used.
Modeling of Transformation of Quality Indicators in the Process of Mechanical Processing of Products with High Physical and Mechanical Properties
Authors: Parshyna Olena , Parshyna Marharyta , Parshyn Yurii , Gurenko Anna , Savchenko Iurii , Shapoval Alexander
Published: July 2021

Complex technologies are technologies which consist of a certain set of stages and technological processes. Using the theoretical basis of the systemic and synergetic approaches, the technological process of manufacturing of such parts has been represented as a process of qualitative and quantitative changes of the object. Taking into account the phenomena of technological heredity, it has been assumed that physical and mechanical properties, in particular, tensile strength, proportionality limit, relative narrowing and resilience, as well as characteristics of the quality of the treated surfaces and processing accuracy can be transformed during the complex technological process. To describe the transformation processes of quality indicators, a set of experimental studies of the roughness of the treated surface during machining of parts with high physical and mechanical properties has been carried out and mathematical models have been obtained. To determine the conditions of the integrated technology, it has been proposed to use a complex of dimensionless characteristics - relative changes of the coefficients of the mathematical model. The obtained mathematical models of the processes of mechanical treating of steel 38HN3MFA make it possible to determine the processing conditions that ensure the formation of a given set of quality indicators.
Features of the structure formation processes and synthesis of strength for Portland cement compositions modified with nanocarbonate additives
Authors: Pushkarova K. , Hadaichuk D. , Honchar O. , Kushnierova L , Кaverin К. , Ionov D.
Published: July 2021

The work shows the results of studying the features of the structure formation process when nano-carbonate additives of different physical states are added to Portland cement and the establishment of the appropriate technology for their introduction, which provides the best conditions for the synthesis of artificial stone. It was found that the introduction of nanocarbonate additives in the form of dispersion provides better kinetics of the cement stone strength gain, and the effect of the introduction of dispersion exceeds the effect of the introduction of powder on 7th day by (43 … 48)%, on 28th day - (27… 30)% and 365th day by (25… 29)%. The using of the dispersion is more economically efficient, while preventing the aggregation of particles provides a directed synthesis of crystal-chemically similar compounds. The nanocarbonate additive acts as a substrate for the directional formation of hydrosilicate phases, providing microreinforcement and the formation of a more homogeneous and improved structure of artificial stone at both nano- and micro-levels.
Restriction of Cl- and SO4
2- Ions Transport in Alkali Activated Slag Cement Concrete in Seawater
Authors: Kryvenko P , Rudenko I , Konstantynovskyi O , Boiko O
Published: July 2021

The relevance of alkali activated slag cement (AASC) concretes for structures operated in seawater is due to their enhanced resistance in aggressive environments. The application of high consistency fresh concretes is accompanied by negative changes in their structure with higher penetration of aggressive environments. Thus, the methods to prevent corrosion of steel reinforcement in plasticized AASC concrete are actual for investigations. It is shown, that modification of plasticized AASC concrete (consistency class S4) by the complex «alumina cement - portland cement - clinoptilolite - trisodium phosphate (Na3PO4·12H2O)» restrict the transport of aggressive Cl- and SO4
2- ions. The results of DTA, XRD, electron microscopy, microzond analysis show that mentioned complex limits transport of the mentioned aggressive ions due to their binding by AFm phases in hydration products, exchange with OH- ions in the structure of clinoptilolite, formation of hydrated products of apatite group Ca5(PO4)3(OH, Cl). This was confirmed by qualitative reaction on Cl- and SO4
2- ions in concrete structure, as well as by assessing of surface and mass loss of steel bars embedded in AASC concrete after 9 months in seawater. It was ensured the advanced crystallization with densification of microstructure, which increases corrosion resistance of artificial stone.
To the problem of transverse anisotropy effect on the distribution of contact stresses in a beam-strip loaded with a rigid stamp
Authors: Shvabiuk V.I , Rotko S.V. , Svabiuk V.V. , Hryshkova A.V.
Published: July 2021

The contact interaction of an orthotropic bar-beam loaded with a rigid stamp. The nature of contact stresses distribution along contact surface of beam and the size of the contact region depending on the beam material orthotropy degree is studied. Analytical expressions for contact pressure under the stamp, dimensionless force, size of contact region and stamp settlement depending on contact region size are derived. Numerical results of calculations are given.
Corrosion-resistant epoxy coating for protection of structural glued-laminated timber in high humidity conditions
Authors: Skripinets A , Saienko N , Danchenko Y , Cherkashina A
Published: July 2021

The article presents a solution to practical problem - the development of epoxy coating of low combustibility with corrosion-resistant properties for the protection of glued-laminated timber in conditions of high humidity. Based on the test results obtained, it was found that when using the developed epoxy polymer protective coating, the resistance of wooden beams to distilled and seawater increases by more than two orders of magnitude, ensuring the integrity of wood products and structures, protecting the ends and not causing warping of the material. In conditions of medium aggressiveness of the environment i.e. 10% H2SO4, 10% NaOH, 10% NaCl, the application of the developed epoxy polymer coating to glued-laminated timber provides their high indicators of bio- and chemical corrosion protection (water resistance, resistance to sea water and aggressive aqueous solutions). The developed protective coating has fungicidal properties, protecting structures from the appearance of blue stains, mold and wood-destroying fungi. Revealed a good correlation between the concentration of biocide and fungicidal coating properties. A comprehensive assessment showed that the developed epoxy coatings have increased biocorrosion-resistant properties and can be used as protective coatings for glued-laminated timber structures exposed to mold fungi, high temperatures and high humidity.
Improvement of technology of application of wood as a floor covering
Authors: Tsapko Y , Vasylyshyn R , Horbachova O , Bondarenko O
Published: July 2021

The analysis of wood flooring has been made and it has been found that the manufacture of wood flooring poses certain difficulties in ensuring resistance to destruction. Thermally modified wood is one of the promising uses of flooring. Therefore, knowledge of the physico-mechanical featutes of wood composites, their quality indicators, adhesion with organic adhesives, allows to make a choice taking into account economic indicators, duration and safety of application. Experimental studies have found out that a floor covering with an upper layer of thermally modified oak wood is less resistant to abrasion. The additional moisture effect showed a better result for the thermally modified oak samples than for the ash and oak samples. The test pieces with an upper layer of thermally modified oak are found to have the lowest measure of power. The results of the research will enable the further development of new composites of thermally modified wood and the conditions under which they are operated at different sites.
Physicochemical and physicomechanical studies of dolomite binder
Authors: Vinnichenko V I , Riazanov A N , Rakhimov R Z , Riazanov A A , Vinnychenko O V
Published: July 2021

To obtain dolomite cement, it is proposed to use screenings of dolomite stone and coal waste. Both physicochemical and physicomechanical studies of cement samples are carried out. It is shown that, in contrast to the existing dolomite binders, the proposed cement has the ability to harden when mixed with water.
The transportation of a particle by a vertical auger with a coaxial cylinder which rotate together around the common axis
Authors: Volina Tatiana , Pylypaka Sergiy , Pavlenko Olexandr , Klochko Oleksii , Hryshchenko Iryna
Published: July 2021

Differential equations of relative movement of a particle on the periphery of a vertical auger bounded by a movable coaxial cylinder are compiled. Both surfaces form a single whole and rotate around a common axis. A partial case, when the surfaces are stationary, is considered. A qualitative analysis of the obtained equations is made and on this basis, the regularities of the particle movement along the helical line – the curve of the intersection of the auger with the cylinder are found. Structural and kinematic parameters in which the particle moves upwards during sliding along the helical line, or falls downwards are found. The relative and absolute trajectories of the particle movement are constructed.
Characteristics of the limit state of the rope
Authors: Vovk P , Chaiun I
Published: July 2021

According to the Rules, in the calculation of ropes for strength, one characteristic is used, and it is the same regardless of the loading scheme. In the calculation method for permissible stresses, two strength characteristics are used: the yield strength or the tensile strength of the material of the part. It’s proposed the method for the theoretical determination of the characteristics of the ultimate elastic Pe
and ultimate elastic-plastic state PH
under four loading schemes, and taking into account the operational breaks of the wires (two characteristics of tension with winding on a drum with a weight in guides and with a free suspension and two when stretching a straight rope.) The ultimate elastic state is determined by the longitudinal force in the section of the rope, at which the longitudinal deformation of one of the wires reaches the yield point εT
according to the schematized wire tension diagram σ – ε. The criterion for the ultimate elastic-plastic state of the rope is the achievement of one of the wires of the ultimate uniform deformation according to the diagram σ – ε. It is assumed that on the basis of the characteristics Pe
of the stretching of the rope according to the ultimate elastic state, it is possible to construct a method for calculating the strength of the ropes, which will have advantages over the existing one. Advantage arguments:

– strength characteristics Pe
are directly related to the rope loading scheme

– the values Pe
take into account all geometric parameters of single and double lay, as well as deformation properties of wires

– characteristics Pe
allow to take into account the effect of wire breaks during the operation of the ropes.
Structural organization and operation of the structure-system
Authors: Vyrovoy Valerii , Korobko Oksana , Pishchev Oleg , Varych Hanna
Published: July 2021

The main factor is presentation of the building construction as open complex self-organizing system. The initial theoretical provisions on processes of self-organization of the construction both during its production period and during operational loads action period are formulated. The active elements of structure material are selected. Representation of the construction as system allows determining the conditions for safe functioning of the construction-system in the system of similar constructions.
Experimental studies of the deformation properties of concrete based on sulfate-resistant slag Portland cement as a material for hard coatings of agricultural airfields
Authors: Yanin O , Yemelianova T , Novikova S
Published: July 2021

The paper presents the results of experimental studies of the deformation properties of concretes based on sulfate-resistant slag Portland cement intended for hard coatings of agricultural tracks and airfields. The effect of concrete hardening conditions on the value of its relative shrinkage deformation has been studied. The role of surfactants (plasticizers) as an additional ingredient to concrete is also investigated. Based on these experimental tests, the regularities of the development of plastic deformations formed in concrete in time at a constant load are revealed. The results of the two series of experiments have made it possible to demonstrate the influence of concrete hardening conditions on the values of creep deformation that are also described and analyzed. This article analyzes the kinetics of concrete shrinkage deformations without additives, comparing the results with those for concrete with the addition of a lignosulfonate superplasticizer and also taking into account various modes of heat and humidity treatment of concrete. A comparison of the deformation properties in concrete with sulfate-resistant Portland slag cement with the deformation properties of concrete based on ordinary Portland cement is carried out. The conclusion is made about suitability of concrete with Portland slag cement for use in construction of hard coating for agricultural tracks and airfield runways.
Application of improved gradient projection method to parametric optimization of steel lattice portal frame
Authors: Yurchenko V V , Peleshko I D , Biliaiev Nikita
Published: July 2021

The paper has proposed a mathematical model for parametric optimization problem of the steel lattice portal frame. The design variable vector includes geometrical parameters of the structure (node coordinates), as well as cross-sectional dimensions of the structural members. The system of constraints covers load-carrying capacities constraints formulated for all design sections of structural members of the steel structure subjected to all ultimate load case combinations. The displacements constraints formulated for the specified nodes of the steel structure subjected to all serviceability load case combinations have been also included into the system of constraints. Additional requirements in the form of constraints on lower and upper values of the design variables, constraints on permissible minimal thicknesses, constraints on permissible maximum diameter-to-thickness ratio for the structural members with circle hollow sections, as well as the conditions for designing gusset-less welded joints between structural members with circle hollow sections have been also considered in the scope of the mathematical model. The method of the objective function gradient projection onto the active constraints surface with simultaneous correction of the constraints violations has been used to solve the formulated parametric optimization problem. New optimal layouts of the steel lattice portal frame by the criterion of the minimum weight, as well as minimum costs on manufacturing and erection have been presented.
A method for solving boundary value problems of mathematical theory of thick transversely isotropic plates
Authors: Zelensky A G , Demianenko A G
Published: July 2021

A method for solving the boundary value problems of a variant of the mathematical theory of thick transversely isotropic plates has been developed. Systems of high-order equilibrium differential equations are reduced by this method to second-order differential equations. The constructed version of the theory makes it possible to solve three-dimensional boundary value problems with any high accuracy. All components of the stress-strain state and boundary conditions are considered functions of three coordinates. They are represented by infinite mathematical series in transverse coordinate with the help of Legendre polynomials. The three-dimensional boundary-value problem is reduced to two-dimensional using the Reisner variational principle. The transverse normal and tangential stresses are displayed in such a way that the boundary conditions on the horizontal faces of the plate are exactly satisfied. Boundary value problems for semifinite transversely isotropic plates of arbitrary thickness with different boundary conditions are considered. Boundary effects are taken into account. The analysis of the stress-strain state is performed.
Characterization of Ti6Al4V powders produced by different methods for selective laser melting
Authors: Xie Bo , Fan Yazhuo , Zhao Sanchao
Published: July 2021

A comparative investigation was made into Ti6Al4V powders produced by electrode induction melting gas atomization (EIGA), plasma spheroidization (PS), and plasma atomization (PA) in terms of particle size distribution, shape, element distribution, microstructure, flowability and forming properties. The powders were characterized by a laser particle size and shape analyzer, a scanning electron microscopy (SEM), an energy dispersive spectrometer (EDS), an x-ray diffraction (XRD), a Hall-flow meter and SLM machine, respectively. Image analysis was used to quantitatively analyze the elongation and roundness of these Ti6Al4V powders. The results indicate that PA produces the smoothest powder with the lowest satellite sphere. The microstructure of the powders is composed of HCP-α‘ phase. The average elongation and roundness of EIGA Ti6Al4V powder is similar to those of PA Ti6Al4V powder. The flowability of the PA powder (26.23 s/50 g) is better than that of EIGA powder (32.16 s/50 g) and PS powder (35.30 s/50 g). The SLM Ti6Al4V samples produced by EIGA powder exhibit a well-balanced combination of strength (1047 MPa) and ductility (16.2%). In regard to the process of SLM, the PA and EIGA Ti6Al4V powders are more suitable than PS Ti6Al4V powder. The EIGA method is found to be the best choice among these three methods on account of cost and performance.
Mechanical and durability characteristics of sustainable coconut fibers reinforced concrete with incorporation of marble powder
Authors: Ahmad Jawad , Zaid Osama , Siddique Muhammad Shahid , Aslam Fahid , Alabduljabbar Hisham , Khedher Khaled Mohamed
Published: July 2021

‘Concrete needs some tensile reinforcement to enhance tensile strength and avoid unacceptable brittle nature. This study is supported out to estimate the characteristics of coconut fibers reinforced concrete with the incorporation of marble slurry. Marble waste used as binding materials in percentage of 0 to 30% in 5.0% increment by weight of cement to enhance compressive capacity while coconut fiber was used in proportion of 0.5%, 1.0%, 1.5%, 2.0%, 2.5% and 3.0% by weight of cement to enhance tensile capacity of concrete. Mechanical performance was evaluated through compressive, flexure, and split tensile strength. To assess durability characteristics of all mix, different parameters such as acid attack resistance, carbonation resistance and water absorption are examined. Experiment findings indicate that marble slurry and coconut fiber decrease the workability of fresh concrete. Furthermore, Concrete specimens’ tests indicate that marble slurry up to 20% and coconut fiber addition 2.0% tend to improve the mechanical performance of hardened Concrete. It also indicates that durability aspects such as water absorption, carbonation resistance and acid attack resistance significantly improved with the substitution of marble waste and coconut fibers. Response surface methodology (statistically models) is used to optimize combine dosage of marble slurry and coconut fiber and verified through experimental tests’.
Experimental investigation on ductility and hardness of squeeze cast Al–Si–Cu alloy using response surface methodology and excel-solver
Authors: Manikandan C , Amirthagadeswaran K S , Gunasekaran N
Published: July 2021

Al–Si–Cu alloy oil pump casings used in heavy automotive were produced through gravity die casting process. The customer requirement of 80–125 BHN with a ductility of 3% was not attainable with gravity die casting process. To acquire required level of ductility and hardness, heat treatment process was applied as post-processing, which increases the production cost and time. The squeeze casting technique is a process suitable to enhance the mechanical properties. A set of experiments was designed based on Box-Behnken method of Response Surface Methodology (RSM) to find the optimal parameter settings for squeeze casting process. Squeezing pressure, pouring temperature and dwelling time were considered as process parameters and a model for the process was created. Analysis of variance (ANOVA) results revealed that the model created is acceptable. Excel Solver was used to determine the optimal parameter settings to obtain maximum ductility and hardness. Confirmation tests were carried out to validate settings. The squeeze casting process, with the recommended settings, enhanced the mechanical properties and the heat treatment operation was eliminated.
Fast and powerful conditional randomization testing via distillation
Authors: Liu Molei , Katsevich Eugene , Janson Lucas , Ramdas Aaditya
Published: July 2021

We consider the problem of conditional independence testing: given a response $Y$ and covariates $(X,Z)$, we test the null hypothesis that $Y {\perp\!\!\!\perp} X \mid Z$. The conditional randomization test was recently proposed as a way to use distributional information about $X\mid Z$ to exactly and nonasymptotically control Type-I error using any test statistic in any dimensionality without assuming anything about $Y\mid (X,Z)$. This flexibility, in principle, allows one to derive powerful test statistics from complex prediction algorithms while maintaining statistical validity. Yet the direct use of such advanced test statistics in the conditional randomization test is prohibitively computationally expensive, especially with multiple testing, due to the requirement to recompute the test statistic many times on resampled data. We propose the distilled conditional randomization test, a novel approach to using state-of-the-art machine learning algorithms in the conditional randomization test while drastically reducing the number of times those algorithms need to be run, thereby taking advantage of their power and the conditional randomization test’s statistical guarantees without suffering the usual computational expense. In addition to distillation, we propose a number of other tricks, like screening and recycling computations, to further speed up the conditional randomization test without sacrificing its high power and exact validity. Indeed, we show in simulations that all our proposals combined lead to a test that has similar power to most powerful existing conditional randomization test implementations, but requires orders of magnitude less computation, making it a practical tool even for large datasets. We demonstrate these benefits on a breast cancer dataset by identifying biomarkers related to cancer stage.
α-Synuclein Selectively Impairs Motor Sequence Learning and Value Sensitivity: Reversal by the Adenosine A2A Receptor Antagonists
Authors: He Yan , Huang Linshan , Wang Ke , Pan Xinran , Cai Qionghui , Zhang Feiyang , Yang Jingjing , Fang Gengjing , Zhao Xinyue , You Feng , Feng Yijia , Li Yan , Chen Jiang-Fan
Published: July 2021

Parkinson’s disease (PD) is characterized pathologically by alpha-synuclein (α-Syn) aggregates and clinically by the motor as well as cognitive deficits, including impairments in sequence learning and habit learning. Using intracerebral injection of WT and A53T mutant α-Syn fibrils, we investigate the behavioral mechanism of α-Syn for procedure-learning deficit in PD by critically determining the α-Syn-induced effects on model-based goal-directed behavior, model-free (probability-based) habit learning, and hierarchically organized sequence learning. 1) Contrary to the widely held view of habit-learning deficit in early PD, α-Syn aggregates in the dorsomedial striatum (DMS) and dorsolateral striatum (DLS) did not affect acquisition of habit learning, but selectively impaired goal-directed behavior with reduced value sensitivity. 2) α-Syn in the DLS (but not DMS) and SNc selectively impaired the sequence learning by affecting sequence initiation with the reduced first-step accuracy. 3) Adenosine A2A receptor (A2AR) antagonist KW6002 selectively improved sequence learning by preferentially improving sequence initiation and shift of sequence learning as well as behavioral reactivity. These findings established a casual role of α-Syn in the SN-DLS pathway in sequence-learning deficit and DMS α-Syn in goal-directed behavior deficit and suggest a novel therapeutic strategy to improve sequence-learning deficit in PD with enhanced sequence initiation by A2AR antagonists.