MATHEMATICAL MODELING OF HEAT-SHIELDING CHARACTERISTICS OF SAND FREE LIGHTWEIGHT CONCRETE WALL STONES

2013 ◽  
Vol 3 (4) ◽  
pp. 82-86 ◽  
Author(s):  
Yu. S VYTChIKOV ◽  
I. G BELYaKOV

The article reports on theoretical research results of sand free lightweight concrete wall stones thermal protective properties. Calculated values of resistance referred to stone wall masonrys thermal exchange on cement-sand and warm mortars are got using the method worked out by the article writersCalculation of three-dimension thermal fields in the external wall fragment was performed by using the method of finite elements provided in ANSIS software package.

2007 ◽  
Vol 5 ◽  
pp. 127-132
Author(s):  
N.A. Vaganova

To detect damage to the underground pipeline, a mathematical model, allowing to take into account the most significant Factors affecting the distribution of temperature on the day surface. To implement this model, a software package has been developed and results of numerical calculations. With the help of these calculations, in particular, It is established that modern thermal imaging equipment has a principal possibility to determine an unauthorized frame in the main pipeline at a depth of two meters in clay soil.


2015 ◽  
Vol 1753 ◽  
Author(s):  
Sergey Karabanov ◽  
Dmitriy Suvorov ◽  
Gennady Gololobov ◽  
Evgeny Slivkin ◽  
Dmitry Tarabrin

ABSTRACTThe paper presents the results of numerical modeling of thermomechanical stresses and thermal fields for conditions of erosion-resistant electrode coatings of magnetically controlled MEMS switches with W-Ti-Cu structure at local temperature and electric current influence in axially symmetrical approximation. It is shown that the introduction of titan interlayer (30-100 nm) in the coating with W-Ti-Cu structure results in considerable (more than two times) decrease of internal thermomechanical stresses between layers that increases coating resistance to delamination. It is established that there is an optimum value of Ti layer thickness at which the minimum thermomechanical stresses are provided.


2019 ◽  
Vol 9 (4) ◽  
pp. 27-32
Author(s):  
Olga A. BALANDINA ◽  
Svetlana M. PURING

The analysis of the values of the concentrations of the formed nitrogen oxides and the temperatures of the jet plume under various conditions of mixture formation is carried out. The plots of the distribution of torch temperatures and concentrations of nitric oxide in the calculated area for oxidizer temperatures of 20, 60, 100, 150, and 200 ° C were obtained and analyzed. Mathematical modeling of the gaseous fuel combustion process was carried out using the FlowVision software package. An analysis of the results showed that a decrease in the temperature of the air supplied as an oxidizing agent leads to a significant decrease in the concentration of nitrogen oxides in flue gases, while not significantly affecting the change in the flame temperature. The research results can be used to solve the problems of optimizing boiler plants, in order to reduce harmful flue gas emissions. Further modeling is planned to determine the dependence of the influence of various factors on the degree of formation of nitrogen oxides in the flue gases of boiler plants.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Irindu Upasiri ◽  
Chaminda Konthesingha ◽  
Anura Nanayakkara ◽  
Keerthan Poologanathan ◽  
Brabha Nagaratnam ◽  
...  

Purpose In this study, the insulation fire ratings of lightweight foamed concrete, autoclaved aerated concrete and lightweight aggregate concrete were investigated using finite element modelling. Design/methodology/approach Lightweight aggregate concrete containing various aggregate types, i.e. expanded slag, pumice, expanded clay and expanded shale were studied under standard fire and hydro–carbon fire situations using validated finite element models. Results were used to derive empirical equations for determining the insulation fire ratings of lightweight concrete wall panels. Findings It was observed that autoclaved aerated concrete and foamed lightweight concrete have better insulation fire ratings compared with lightweight aggregate concrete. Depending on the insulation fire rating requirement of 15%–30% of material saving could be achieved when lightweight aggregate concrete wall panels are replaced with the autoclaved aerated or foamed concrete wall panels. Lightweight aggregate concrete fire performance depends on the type of lightweight aggregate. Lightweight concrete with pumice aggregate showed better fire performance among the normal lightweight aggregate concretes. Material saving of 9%–14% could be obtained when pumice aggregate is used as the lightweight aggregate material. Hydrocarbon fire has shown aggressive effect during the first two hours of fire exposure; hence, wall panels with lesser thickness were adversely affected. Originality/value Finding of this study could be used to determine the optimum lightweight concrete wall type and the optimum thickness requirement of the wall panels for a required application.


2020 ◽  
Vol 305 ◽  
pp. 00038
Author(s):  
Serhii Cheberyachko ◽  
Yurii Cheberyachko ◽  
Dmytro Radchuk ◽  
Oleg Deryugin ◽  
Olha Nesterova

The purpose is to substantiate theoretically the design of elastomeric half mask and canister of respirator of long-term protection. To develop the models for theoretical calculations of protective properties of dust masks the theory of non-stationary filtration and hydro aerodynamics was applied. To develop the digital model of a head the downhill simplex method was applied reflecting separate face features considering sex or age; to determine the halfmask surface the free energy equation for bowed plate being described by two-dimension spline surface was used with its unknown coefficients determined by method of proportional parts based on three-dimension coordinates of anthropometric face features. The main anthropometric face features influencing halfmasks design were determined to develop polygonous 3D model of head. According to its determined basic coordinates the surface of halfmask was determined using method of interpolation. Considering the mathematical model describing the movement of dust flows near a halfmask and in canister the dependences of distribution of air flow speed in a canister of variable geometry were set and kinematic parameters of dust-laden airflow according to a canister volume were determined. Reasonable geometric parameters of canister were determined; transient modulation from filter to inlet valve hole is performed as a contractor.


2013 ◽  
Vol 325-326 ◽  
pp. 480-485
Author(s):  
Petrin Drumea ◽  
Corneliu Cristescu ◽  
Catalin Dumitrescu ◽  
Iulian Dutu ◽  
Ioana Ilie

The paper presents the theoretical results of extensive research on the dynamic behavior of linear hydraulic motors, carried out in INOE 2000-IHP, in the framework of the NUCLEU Programmer. The research has been conducted both theoretically and experimentally, but, in this paper, is presented only the theoretical research. Theoretical research has taken place with the modern means of mathematical modeling and computer numerical simulation. The article presents some theoretical interested results obtained in the research, results that are of real scientific interest, but, also, with practical value through their use in the design of fluid power components and equipments.


Author(s):  
V. Gorobey

Purpose. Improvement of the quality of spreading seed of grain seeds by technologies with minimal tillage due to the theoretical based of the interconnection the range of the seeds sowing coulter by a mechanical roller-diffuser in the underpass space of and cultivator type coulter with this design parameters and technological modes. Methods. The research is based on analytical methods and mathematical modeling of agricultural machines and technological operations using the laws of mechanics. Based on the obtained theoretical dependencies, numerical simulation was performed on a computer, graphs were constructed using MathCAD. Results. The cultivator type coulter is developed for subsoil-spread sowing by technologists with minimal tillage with roller spreader in the under-floor space. From the seeding apparatus, the seed enters the socket of the coulter and through the roller-diffuser is distributed to the seed bed in the underpass space. For the studies, an equivalent circuit of the coulter and the trajectory scheme of the seed movement after descent from the roller of the diffuser with the most characteristic cases of movement of the seeds were developed: the seed falls immediately on the surface of the disk of the roller-diffuser; the seed falls on the conical surface of the roller-diffuser, slides on it to the disk, moves on it to the edge, and is sown after leaving the disk. Description of the movement of seeds on the conical surface of the roller-diffuser is made by the differential equation of relative motion in two coordinate systems. One inseparably linked to the cone is inertial and is located so that the ordinate axis is aligned with the axis of rotation of the working body, and the abscissa axis passes through the initial position of the seed on the cone, the second – non-inertial coordinate system is the axis of the natural trihedron , п, b. The solution of the system of differential equations of movement of seeds on the working surface of the cone of the roller-diffuser in the sub-space space of the cultivator-type coulter along the axes of the rectangular Cartesian coordinate system was obtained. According to the obtained theoretical equations, with the help of MathCAD program, plots of the sowing range of seeds by roller-diffuser, depending on the radius of initial hit on the roller at a speed of gradual movement of the seeder 2 m/s are constructed: when the seeds fall on the roller disk; when the seeds fall on the roller cone. Analysis of the graphs showed that the range of sowing seeds by roller-diffuser, depending on the radius of initial contact with the roller, varies from 0,005 to 0,011 m. Conclusions. Conclusions. The dependence of the relative speed of movement of seeds on the conical surface of the roller-diffuser from the modes of its operation is established. By specifying the beginning and end of the seedlings from the conical surface of the roller diffuser, as well as the speed of emergence at certain points, it is possible to determine the flight distance of the seeds from any point in the cone. Mathematical modeling of the technological process will allow to substantiate the geometrical parameters and technological characteristics of the cultivator type coulter. Keywords: cultivator type coulter, paw, roller-diffuser, mathematic model, technology, seeds, trajectory, theoretical dependence.


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