scholarly journals Determination of the beginning the Steady-State for controlled processes in monitoring systems with limited resources

2018 ◽  
Vol 245 ◽  
pp. 10002 ◽  
Author(s):  
Vladimir Leontiev ◽  
Alexander Sorokin ◽  
Sergey Saradzhishvili

This paper describes the basic approach for determination of the steady-state conditions of physical processes such as boiling or other phase transitions in control systems with limited resources. In this research, we consider the particular case of a control system that should determine the moment when the water temperature reaches boiling point. In different systems, the accurate determination of the boiling point is important, because it results in other functions such as switching off or transitioning to other states. Hence, we explore the possibility of applying our approach in systems with limited resources, using cheap temperature inertial sensors. During the investigation, we encountered a delay in identifying the boiling point, caused by inertia. These issues demonstrate the need for the further improvement of the suggested approach in this particular case. However, generally our results indicate the applicability of this approach for control systems.

Author(s):  
ALİ AKPEK

Accurate determination of the viscosity behavior of fluids is extremely important, especially for biomedical and clinical applications. For example, blood viscosity is used to detect cardiovascular diseases in patients. Like blood, all body fluids and biochemical solvents used in biomedical studies are very limited resources. Therefore, a viscometer that is especially focused for biomedical and clinical applications should have the ability to obtain viscosity results from a reservoir as small as possible, in a range as wide as possible and in a period of time as short as possible. The measurements must be accurate even when the fluid temperatures shift swiftly and the test fluids pass throughout the viscometer continuously. Thus, it would be a huge advantage if a viscometer had the capability to measure simultaneously dynamic viscosity, kinematic viscosity, static viscosity, and density. However, there is no viscometer in the world that can achieve these goals. In this study, a novel electromagnetically levitated vibrational viscometer is designed to solve this problem.


Author(s):  
C. Andreau ◽  
F. Ferdi ◽  
R. Ville ◽  
M. Fillon

Safe operation of a rotating line shafting needs to use proper tools and methodology for an accurate determination of its static and steady state behavior in running conditions. Taking into account properly the characteristics of shaft environment is of primary importance. These characteristics are mainly bearing material behavior, oil film dynamic coefficients (stiffness and damping), flexibility and deformations of structure supporting line shafting bearings. Global non linear behavior of the entire system needs to be analyzed to get an accurate solution, as oil film dynamic coefficients depend on steady state location of shaft inside the considered bearing, which depends itself on oil film stiffness, and also on flexibility and deformations of supporting structure. Calculations of structure flexibility and deformations, as well as line shafting stiffness characteristics are performed straightforwardly using finite element method. Solving global matrix equilibrium equation needs to solve elastohydrodynamic (EHD) problem on each bearing. A specific finite element method is developed for this purpose. This method is attractive for taking into account thick and flexible bearing materials such as multi layer synthetic materials. It can also support further developments (effects of geometry defects on bearings, solving thermoelastohydrodynamic problem). The application of the method to the propulsion line shafting of a large LNGC ship (Liquid Natural Gas Carrier) is presented, the final target being the determination of the most optimum bearing offsets for operating safely the vessel in all relevant conditions.


1923 ◽  
Vol 123 (0) ◽  
pp. 2953-2963 ◽  
Author(s):  
Kazimierz Jabłczyński ◽  
Stanisław Kon

2020 ◽  
pp. 53-62
Author(s):  
Yuriy Kachan ◽  
Vladyslav Mishchenko

Analysis of recent research and publications. Problematic issues of theory and technology of production of ferroalloys, improvement of structures of ore-thermal electric furnaces, optimization of electric modes of melting are constantly discussed at the relevant international congresses. For a more accurate reflection of the actual physical processes occurring in the working space of the bath, it is necessary to take into account that when the mixture is heated its density changes and occurs between the phase transition.The aim of the study. The purpose of this work is to simulate the process of transition of the charge in the melt, with the subsequent possibility of more accurate determination of some its parameters in the dynamics.Presentation of the main research material. Bath OTF is complex in its structure. It contains a mixture of various physical and chemical conditions (from solid pieces to doughy magma), slag and metal. The physical processes that take place are very different. Some of them are continuous, and others, which are carried out before full melting of single-loaded materials.In order to simulate the process of formation of a melt in a bath of an ore-thermal furnace it is proposed to break its inner space into elementary volumes. We have chosen and slightly modified the method based on the system of cylindrical coordinates, according to which the furnace bath is regarded as a cylinder. We will place further calculation points in the geometric centers of these volumes.The transition of the charge from the solid to the liquid phase is determined by the temperature at which the melting of different types of ferroalloys occurs. If this is the case, knowing the mass and density of the liquid melt and slag at a given temperature, we calculate their real volume, obtained as a result of these phase transitions, in one elementary volume. Thereafter, the total melt volume and charge formed over a given period of time is calculated.During the phase transition, the charge is converted into a melt and slag resulting in its settling down to the bottom of the ore-thermal furnace bath. The maximum permissible amount of charge settling near the electrodes is strictly regulated by the technical documentation of the furnace, so if the calculated value has reached this value, the charge of the charge under the electrodes should be made.It is also possible to compare the calculated volume of the formed melt over the melting interval with its predetermined value. If these indicators are already the same, then it is necessary to merge the melt and slag, otherwise we go to the next period of time and perform these calculations until the specified condition is fulfilled.Conclusions. With a comprehensive approach to the process of modeling the operation of OTF, one of the tasks is to determine the amount of molten metal in the bottom of the bath. This question is solved by the presented methodology and algorithm, which give an opportunity to find out how much melt there is at one or another time during the operation of the furnace.


2013 ◽  
Vol 113 (21) ◽  
pp. 213705 ◽  
Author(s):  
J. A. Giesecke ◽  
F. Schindler ◽  
M. Bühler ◽  
M. C. Schubert ◽  
W. Warta

2021 ◽  
Vol 65 (1) ◽  
pp. 74-78
Author(s):  
A.S.A. Elmaryami ◽  
Hafied M.B. Khalid ◽  
Abdulhakim Alamaria ◽  
Osama Alashebe ◽  
S.S. Ali ◽  
...  

The effect of thermal cycling was carried out on steel bars (0.4 C %). A single run was performed at a lower temperature of 32℃ and an upper temperature of 500℃ cooled in water, seawater (previous results) and oil (new results). For several numbers of cycles up to 30 cycles for an accurate determination of heating and cooling times. The effect of thermal cycling on the corrosion rate was evaluated. The effect of thermal cycling on the following properties was evaluated the corrosion rate. The comparison between the effect of thermal cycling on carbon steel (0.4 C %) seawater and water-cooled (previous results as shown in references [1, 2]) and the effect of thermal cycling on carbon steel (0.4 C %) water-cooled (new results) has been studied. From the obtained test results (previous and in this paper, it was found that: the type of corrosion is uniform attack; corrosion rate of the first stage gradually increases with the number of thermal cycling up to 15 cycles, then it takes steady-state up to 30 cycles. It was found that the rate of corrosion (previous results, seawater and water-cooled) is more than the rate of corrosion of the new results, oil-cooled respectively.


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