scholarly journals Determination of working parameters of measure to ensure metrological research tribological characteristics of plain bearings

2017 ◽  
Vol 6 (2) ◽  
pp. 123-129
Author(s):  
Серебрянский ◽  
Aleksey Serebryanskiy
Keyword(s):  
Experimental Study ◽  
Experimental Studies ◽  
Design Parameters ◽  
Laboratory Equipment ◽  
The Real ◽  
Metrological Research ◽  
Real Size ◽  
Working Parameters ◽  
Conditions Of Work

The characteristics of plain bearings used in the industry are given in the article. The directions that increase their ser-vice life are defined. The need for experimental studies of bearing is justified, and laboratory equipment is offered. Experimental study of bearings is necessary to verify calculations and to determine the effect of changing some design parameters on their work as well. It is usually difficult or even impossible to experience the bearing in the real size and under conditions identical to real conditions of work.

EXPERIMENTAL STUDIES OF REINFORCED CONCRETE STRUCTURES WITH CROSS-SHAPED SPATIAL CRACK UNDER TORSION WITH BENDING

2020 ◽  
Vol 92 (6) ◽  
pp. 13-25
Author(s):  
Vl.I. KOLCHUNOV ◽  
◽  
A.I. DEMYANOV ◽  
M.M. MIHAILOV ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Determination ◽  
Calculation Method ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Design Parameters ◽  
Reinforced Concrete Structures ◽  
Experimental Scheme

The article offers a method and program for experimental studies of reinforced concrete structures with cross-shaped spatial crack under torsion with bending, the main purpose of which is to check the design assumptions and experimental determination of the design parameters of the proposed calculation method. The conducted experimental studies provide an opportunity to test the proposed calculation apparatus and clarify the regularities for determining deflections, angles of rotation of extreme sections, and stresses in the compressed zone of concrete. For analysis, the article presents a typical experimental scheme for the formation and development of cracks in the form of a sweep, as well as characteristic graphs of the dependence of the angles of rotation of end sections.

Deaf and Hard-of-hearing Users Evaluating Designs for Highlighting Key Words in Educational Lecture Videos

2021 ◽  
Vol 14 (4) ◽  
pp. 1-24
Author(s):  
Sushant Kafle ◽  
Becca Dingman ◽  
Matt Huenerfauth
Keyword(s):  
Experimental Study ◽  
Key Words ◽  
Hard Of Hearing ◽  
Experimental Studies ◽  
Design Parameters ◽  
Educational Video ◽  
Word Level ◽  
Sentence Level ◽  
First Occurrence ◽  
Educational Videos

There are style guidelines for authors who highlight important words in static text, e.g., bolded words in student textbooks, yet little research has investigated highlighting in dynamic texts, e.g., captions during educational videos for Deaf or Hard of Hearing (DHH) users. In our experimental study, DHH participants subjectively compared design parameters for caption highlighting, including: decoration (underlining vs. italicizing vs. boldfacing), granularity (sentence level vs. word level), and whether to highlight only the first occurrence of a repeating keyword. In partial contrast to recommendations in prior research, which had not been based on experimental studies with DHH users, we found that DHH participants preferred boldface, word-level highlighting in captions. Our empirical results provide guidance for the design of keyword highlighting during captioned videos for DHH users, especially in educational video genres.

Determination of the Real Size of Fundus Objects from Fundus Photographs

1996 ◽  
Vol 5 (6) ◽  
pp. 433???435 ◽  
Author(s):  
Anne L. Coleman ◽  
Julia A. Haller ◽  
Harry A. Quigley
Keyword(s):  
The Real ◽  
Real Size ◽  
Fundus Photographs

scholarly journals MATHEMATICAL MODELING OF VERTICAL OSCILLATIONS OF A CUTTING MACHINE FRONTLY MOUNTED ON AN ARABLE-TILL TRACTOR

2021 ◽  
pp. 39-56
Author(s):  
Volodymyr Bulgakov ◽  
Valeriy Adamchuk ◽  
Grigory Kaletnіk ◽  
Ivan Golovach
Keyword(s):  
Differential Equation ◽  
Vibration Amplitude ◽  
Experimental Studies ◽  
Vertical Plane ◽  
Soil Surface ◽  
Design Parameters ◽  
Analytical Determination ◽  
Surface Irregularities ◽  
Rotary Cutting

Experimental studies and production experience show that the most productive and high-quality collection of sugar beet haulms without soil impurities, is possible only when a continuous, carbonless cut of its main mass at the root is carried out. However, the use of haulm toppers with rotary haulm cutters, which are carried out without a guide cut, frontally mounted on energy resources, as well as a significant increase in the working speeds of harvesting, cause intense vibrations of these haulm toppers in the longitudinal-vertical plane, which not only reduces the quality of trimming the heads of root crops, but causes, in general, significant losses of tops. Therefore, there is a need for an analytical determination of the influence of the kinematic and design parameters of a topper, frontally mounted on a wheeled tractor, on the magnitude of the amplitude of oscillations in the longitudinal-vertical plane of its haulm topper. Taking this need into account, in this work we have constructed a computational mathematical model of the movement of a topper front-mounted on a wheeled tractor, based on the use of the original equation of dynamics in the form of Lagrange of the second kind. According to the developed equivalent circuit and the implementation of the necessary mathematical transformations, a nonlinear differential equation was obtained, which describes the oscillations of the rotary cutting device of the topper in the longitudinal-vertical plane when its pneumatic gauge wheels move over the unevenness of the soil surface. According to the compiled program and the numerical solution on the PC of the specified differential equation, rational constructive and kinematic parameters of the topper frontally mounted on the tractor have been determined which reduce the indicated oscillations. So, with the forward speed of movement of the topping unit equal to = 3,0 m∙ s–1, the vibration amplitude of the topper rotor decreases 1,2 ... 1,5 times in comparison with the height of the field surface irregularities, equal to = ± 0.04 m. With the vibration amplitude of the lower ends of the knives of the rotary cutting apparatus up to 4 cm, the loss of haulms does not increase significantly. However, with an increase in the amplitude of these fluctuations to 7 cm and more, the loss of tops increases significantly, the maximum values of which exceed 12%.

Calculated-Experimental Determination of Values Natural Frequencies Oscillations of the Case and Parameters of the Case Determining these Values

2019 ◽  
pp. 89-104
Author(s):  
A.V. Proskurin ◽  
A.V. Shlishevskiy
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Experimental Determination ◽  
Analytical Solutions ◽  
Natural Frequencies ◽  
Experimental Studies ◽  
The Body ◽  
Design Parameters ◽  
The Finite Element Method

The task of studying the behavior of various structures under the influence of intense pulsed (shock) loads that arise during the operation of many modern structures, machines and devices remains relevant for many years. One of the stages of this study is to find the values of the natural frequencies of vibrations and design parameters that determine these values. To find the natural frequencies of oscillations of the body, which are four flanges connected by cylindrical shells, the finite element method and analytical solutions were used. An analysis of experimental studies. Determination of natural frequencies values and design parameters determining these values will allow evaluating the response of the structure to the loads acting during its operation, and making corrections to the structure that change the response of the structure, as well as will help to more accurately select the installation sites of piezoelectric accelerometers for recording drums accelerations.

Durability Study of a Machine Shaft Based on the Material Behavior of 41Cr4 Steel Subjected to Rotating Bending

2012 ◽  
Vol 188 ◽  
pp. 256-261
Author(s):  
Lorand Kun ◽  
Cristian Sorin Nes ◽  
Ion Dumitru ◽  
Nicolae Faur
Keyword(s):  
Equivalent Stress ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Material Behavior ◽  
Load Spectrum ◽  
Premature Failure ◽  
The Real ◽  
Durability Analysis ◽  
Rotating Bending

This paper presents the durability analysis of a machine shaft subjected to bending with torsion, based upon the stress analysis at a notch which joins segments of different cross-sections (circular and square respectively) of the shaft. During the specific operating conditions of the equipment which’s part the shaft is, this notch has proven to be critical, causing premature failure. The durability analysis is carried out based on the real loading conditions, allowing the stress state evaluation at the base of the notch for different radii, using ABAQUS 6.9-3 finite element analysis program. The experimental studies carried out on the shaft’s material, 41Cr4 steel, resulted in the determination of material properties and of torsion fatigue curves in case of two different heat treatments. The cycles composing the equivalent stress spectrum are counted using the rainflow algorithm. The number of loading blocks to failure (number of load spectrum repetitions), considering the real operating conditions, is obtained using Miner’s rule, based on the rotating bending fatigue curve, corrected corresponding to the shaft’s specific characteristics. The proposed calculation method, based on the variation in time of the stress tensor during operating conditions, leads to the determination of the optimal notch radius for which the shaft’s durability falls between prescribed limits.

Research of Operational Properties of Household Fabrics for Production of Protective Masks

2021 ◽  
Vol 1038 ◽  
pp. 221-232
Author(s):  
Serhii Cheberiachko ◽  
Ivan Knysh ◽  
Dmytro Pustovoi ◽  
Olena Sharovatova
Keyword(s):  
Experimental Study ◽  
Protective Action ◽  
Experimental Studies ◽  
Breathing Resistance ◽  
Paraffin Oil ◽  
Two Samples ◽  
Physiological Impact ◽  
The Relationship ◽  
Penetration Coefficient

Experimental studies have been conducted to determine the operational properties of fabrics used for the manufacture of protective masks. For the experimental study, 22 different fabrics were used, which are available in everyday life. Determination of the operational properties was carried out according to three indicators: the penetration coefficient of the test aerosol, paraffin oil (filtering property), breathing resistance (ergonomic property), resistance to dusting (protective action period) in accordance with the requirements of DSTU EN 149-2017 standard. According to the results of the experimental study to determine the operational properties of fabrics: breathing resistance, penetration coefficient and resistance to dust, it was found that out of the twenty-two samples tested, only eight can be used for the manufacture of protective masks, since their characteristics are able to provide a sufficient level of protection from minimal physiological impact on human (wool, two-thread cloth, velor, tricotin, jersey, frieze and satin). Theoretical calculation of the operational properties of protective masks, which can be made of these fabrics, based on experimental data allowed to make their compliance with the first class of protection according to the requirements of DSTU EN 149-2017. The scientific novelty is to clarify the relationship between the operational properties of fabrics and the operational properties of protective masks.

scholarly journals EXPERIMENTAL DETERMINATION OF THE LEVEL OF INCIPIENT TURBULENCE IN THE WORKING PART OF THE T-1 WIND TUNNEL OF IVAN KOZHEDUB KHARKIV NATIONAL AIR FORCE UNIVERSITY

2021 ◽  
Vol 5 (2) ◽  
pp. 98-102
Author(s):  
Віталій Бездєльний ◽  
Сергій Шевченко ◽  
Ілля Грідасов
Keyword(s):  
Experimental Study ◽  
Pressure Drop ◽  
Wind Tunnel ◽  
Experimental Determination ◽  
Air Force ◽  
Normal Condition ◽  
Aerodynamic Drag ◽  
Experimental Studies ◽  
The Subject

The subject of the article is to determine the level of incipient turbulence in the wind tunnel T-1 which is based on the method of measuring the pressure drop. The purpose is to experimentally determine the level of incipient turbulence in the working part of wind tunnel T-1 of Ivan Kozhedub Kharkiv National Air Force University in preparation for aerodynamic testing of aircraft models. Research methods: the method of pressure drop on the surface of the sphere by drainage. The following results of experimental determination of the level of incipient turbulence in the wind tunnel T-1 were obtained. It is established that the wind tunnel T-1 has a level of incipient turbulence 0,5…0,9 %, which corresponds to the normal condition for further experimental studies. Conclusions. According to the results of studies of the incipient turbulence in the wind tunnel T-1 by the method of pressure drop, the main dependences are obtained, and the incipient turbulence of the flow for the wooden sphere x = 0,9 %, and for the metal sphere x = 0,5 %, is determined. Determining the pressure distribution and aerodynamic drag does not involve measures to balance the aerodynamic scales and their certification, which determines the necessary role in the obtained reliable results of the experimental study, and this favors the drainage method.

scholarly journals Determination of drying behaviour in industrial type convectional dryer and mathematical modelling

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 1935-1950 ◽  
Author(s):  
Ahmet Akan ◽  
Derya Ozkan
Keyword(s):  
Experimental Study ◽  
Mathematical Modelling ◽  
Diffusion Model ◽  
Diffusion Coefficients ◽  
Experimental Studies ◽  
Activation Energies ◽  
Second Law ◽  
Hot Air ◽  
Drying Behaviour

In this study, the performance of a stenter (ram machine) that enables the drying of textile products with hot air is theoretically modelled with a diffusion model derived from Fick?s second law. The experimental study was conducted in a 10 chamber stenter with three different drying temperatures (110-130-150?C) and three different fabric speeds (10-20-30 m per minute.) by using a fabric consisting of 95% cotton + 5% lycra. The drying behaviour of the dryer was determined by utilizing the data obtained from the studies. With the help of the utilized model, the values of diffusion coefficients and activation energies were obtained, the conformity of data between the model and the experimental studies were compared by using regres

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

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