MATHEMATICAL MODEL AND EXPERIMENTAL ESTIMATION OF THERMAL PROCESSES IN HEATING MODULE AS A PART OF STEAM ABLATION DEVICE FOR VARICOSE VEINS TREATMENT

2021 ◽  
pp. 117-125
Author(s):  
Дина Владимировна Кривоносова ◽  
Евгений Сергеевич Ермолаев
Keyword(s):  
Mathematical Model ◽  
Varicose Veins ◽  
Thermal Power ◽  
Thermal Characteristics ◽  
Steam Injection ◽  
Heating Element ◽  
Vein Wall ◽  
Tissue Heating ◽  
Comparison Of The Results ◽  
The Mathematical Model

На сегодняшний день в России для лечения варикозного расширения вен часто проводятся малоинвазивные операции методами радиочастотной или лазерной облитерации, при этом метод паровой облитерации при лечении варикозной болезни не применяется совсем. Однако метод паровой облитерации обладает существенными преимуществами: малый объём и биоинертность рабочей среды - водяного пара, его невысокая температура - 120 °С, исключающая вероятность образования нагара и перфорации венозной стенки. Целью данной работы является разработка математической модели для расчёта тепловых характеристик блока нагревания, входящего в устройство для лечения варикозной болезни методом паровой облитерации. Модель описывает теплообменные процессы в гидравлической трубке блока нагревания и может быть полезна при расчёте размеров нагревательного элемента, обеспечивающих нагрев и парообразование определённой порции воды. С целью верификации математической модели результаты моделирования были сопоставлены с экспериментальными данными. Была проведена серия экспериментов, в ходе которых были получены значения энергии, содержащейся в одной инжекции пара, и объём воды в одной инжекции, а также оценена фактическая тепловая мощность нагревателя. Сравнение результатов имитационного моделирования и значения фактической тепловой мощности пара, полученной экспериментальным путем, показала работоспособность математической модели. Разработанная математическая модель позволяет подбирать геометрические параметры нагревательного элемента в зависимости от требуемой тепловой мощности, которая должна быть обеспечена блоком нагревания, а также варьировать параметры нагревательного элемента для разной степени нагрева тканей Today in Russia minimally invasive varicose veins treatment is often performed using radiofrequency or laser ablation, while the method of steam ablation is not used at all. However, the steam ablation method has significant advantages: a small volume and biological inertness of the working substance - sterile water vapor, its low temperature - 120 °C, excluding the carbon deposits and perforation of the vein wall. The purpose of this work is to develop a mathematical model for calculating the thermal characteristics of the heating module as a part of the device for varicose veins treatment using steam ablation. The model describes heat exchange processes in the hydraulic circuit of the heating module and can be applied to calculate the dimensions of the heating module which provides heating and vaporization of a certain portion of water. In order to verify the mathematical model, the simulation results were compared with experimental data. A series of experiments were carried out in which the energy contained in one steam injection and the volume of water in one injection were estimated, as well as the actual thermal power of the heating module. Comparison of the results of simulation and the value of the actual thermal power of steam obtained experimentally showed the efficiency of the mathematical model. The proposed mathematical model allows to select the geometric parameters of the heating element depending on the required thermal power, which must be provided by the heating module, and also to vary the parameters of the heating element for different degrees of tissue heating

Valve Gear Refinement

2000 ◽  
Vol 124 (1) ◽  
pp. 86-90 ◽  
Author(s):  
Jurij Avsec ◽  
Milan Marcic ◽  
Maks Oblak
Keyword(s):  
Mathematical Model ◽  
Cam Design ◽  
Cam Follower ◽  
New Type ◽  
Cam Profile ◽  
Profile Design ◽  
Comparison Of The Results ◽  
The Mathematical Model ◽  
Valve Gear ◽  
Lubrication Properties

This paper describes a new type of valve gear cam—MULTICAM—which consists of seven curves and allows an optimum cam profile design. In order to calculate the cinematic and dynamic values and to assess the minimum oil film thickness in the valve gear, the mathematical model of an ideal valve gear was used. In addition, the comparison of the results between the polysine cam and the new MULTICAM cam design was made. By means of the new cam design the Hertz pressures were reduced at the point of contact between the cam and the cam follower and the lubrication properties at the top of the cam improved.

scholarly journals Ways of Improvement of Safety and Efficiency of Endovenous Laser Coagulation in Treatment of Lower Limb Varicose Vein Disease

2016 ◽  
Vol 23 (3) ◽  
Author(s):  
Roman Kohan ◽  
Volodymyr Goshchynsky
Keyword(s):  
Mathematical Model ◽  
Laser Radiation ◽  
Varicose Vein ◽  
Lower Limb ◽  
Linear Density ◽  
Varicose Veins ◽  
Laser Coagulation ◽  
Light Pipe ◽  
The Mathematical Model ◽  
Vein Disease

Nowadays endovenous laser coagulation is the priority method of treatment of lower limb varicose vein disease. However, there are a number of specific complications that reduce efficiency of its usage.The objective of the research was to decrease specific postoperative complications after endovenous laser coagulation due to the introduction of its mathematical design.Materials and methods. The study included 168 patients with lower limb varicose vein disease. Prior to surgery the mathematical calculation of the basic parameters of laser coagulation such as density of laser irradiation and rate of reverse movement of the light pipe depending on the diameter of varicose veins was made. The control group consisted of 146 patients with varicose vein disease; the aforementioned parameters were established according to the instruction of using a laser device.Results.  The analysis of complications such as induration of skin over coagulase great or small saphenous vein, phlebitis in the projection of the great or small saphenous vein, ecchymosis or dermatomelasma in the early postoperative period, pain syndrome showed the reduction in the number of complications while applying the mathematical model of calculation of linear density of laser radiation and the speed of reverse traction of the light pipe with its transfer to the graphic image.Conclusions.  The application of the mathematical model of calculation of linear density of laser radiation and the speed of reverse traction of the light pipe with its transfer to the graphic image allows us to improve the results of endovenous laser coagulation for varicose veins due to the reduction in specific complications.

The Numerical Mathematical Modeling of Gradient Hardening Processes under Conditions of Complex Local Loading of the Center of Deformation

2020 ◽  
Vol 989 ◽  
pp. 615-621
Author(s):  
Vyacheslav A. Golenkov ◽  
Daniil O. Dorokhov ◽  
Sergey Y. Radchenko
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Experimental Work ◽  
Local Loading ◽  
Comparison Of The Results ◽  
Number Of Passes ◽  
The Mathematical Model

The paper considered the peculiarities of the numerical mathematical modeling of gradient hardening processes under conditions of complex local loading of the center of deformation. The authors described the mathematical model. They presented the results of modeling in the form of a picture of the change in Odkvist parameter with an increase in the number of passes. Data were given on the comparison of the results of experimental work and mathematical modeling.

scholarly journals Improving the Efficiency of the Three-Stage Technique of Mathematical Model Identification of Complex Thermal Power Equipment

2020 ◽  
Vol 209 ◽  
pp. 03002
Author(s):  
Vitalii Alekseiuk
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Thermal Power ◽  
Great Part ◽  
Model Identification ◽  
Identification Accuracy ◽  
Model Parameters ◽  
Power Equipment ◽  
Operation Conditions ◽  
The Mathematical Model

The problems of state estimation of thermal power system operation and identification of mathematical model parameters have not been acceptably solved due to the complexity of studied objects and their mathematical models, and the lack of effective methods, algorithms and computer programs to solve the required mathematical problems. The results of solving the indicated problems are of importance as such, and play a great part in the qualitative solution to the problems of thermal power equipment control, e.g., the problems of optimal load dispatch among thermal power plant units and optimal control of thermal power equipment operation conditions. The paper describes an effective three-stage technique of mathematical model identification of complex thermal power equipment. The technique allows us to more effectively detect gross errors in measurements of control parameters used for identification of the mathematical model of the studied equipment, to evaluate correctness and rectify errors in the mathematical model construction, and to improve identification accuracy. The article presents a new formulation of the optimization problem for more efficient identification of mathematical models of heat power equipment. An effective three-stage technique of mathematical model identification of complex thermal power equipment was tested on a detailed mathematical model of the present-day 225 MW generating unit that was constructed by the author. The paper presents results of solving the identification problem of mathematical model parameters of a generating unit.

scholarly journals An improved technique for identification of mathematical model parameters of thermal power equipment and assessment of its performance

2019 ◽  
Vol 114 ◽  
pp. 06009
Author(s):  
Aleksandr Kler ◽  
Vitalii Alekseiuk ◽  
Aleksei Maksimov
Keyword(s):  
Mathematical Model ◽  
Thermal Power ◽  
Identification Accuracy ◽  
Model Construction ◽  
Model Parameters ◽  
Power Equipment ◽  
Control Parameters ◽  
Accuracy Of Measurements ◽  
Improved Technique ◽  
The Mathematical Model

The problems of state estimation of thermal power system operation and identification of mathematical model parameters have not been acceptably solved due to the complexity of studied objects and their mathematical models, and the lack of effective methods, algorithms and computer programs to solve the required mathematical problems. The results of solving the indicated problems are of importance as such, and play a great part in the qualitative solution to the problems of thermal power equipment control, e.g., the problems of optimal load dispatch among thermal power plant units and optimal control of thermal power equipment operation conditions. The paper describes a technique improved by the author for identification (adjustment, verification) of mathematical model parameters for complex thermal power equipment. The technique allows us to more effectively detect gross errors in measurements of control parameters used for identification of the mathematical model of the studied equipment, to evaluate correctness and rectify errors in the mathematical model construction, and to improve identification accuracy. An improved technique for identification of mathematical model parameters was tested on a detailed mathematical model of the present-day 225 MW generating unit that was constructed by the author. The paper presents results of solving the identification problem of mathematical model parameters of a generating unit and an example of the optimization calculation of the real operation condition in order to reduce specific fuel consumption for electricity generation. In addition, the paper discusses an issue of assessing the identification accuracy of mathematical model parameters of thermal power equipment that depends on the accuracy of measurements of control parameters used to adjust the model, as well as on the correctness of the mathematical model construction and the calculation technique applied.

scholarly journals Modeling and Hourly Time-Scale Characterization of the Main Energy Parameters of Parabolic-Trough Solar Thermal Power Plants Using a Simplified Quasi-Dynamic Model

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 221
Author(s):  
Ignacio Arias ◽  
Eduardo Zarza ◽  
Loreto Valenzuela ◽  
Manuel Pérez-García ◽  
José Alfonso Romero Ramos ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Power Plants ◽  
Thermal Power ◽  
Thermal Power Plants ◽  
Parabolic Trough ◽  
Solar Thermal Power ◽  
Simulation Results ◽  
Solar Field ◽  
The Mathematical Model

A simplified mathematical model of parabolic-trough solar thermal power plants, which allow one to carry out an energetic characterization of the main thermal parameters that influence the solar field performance, was evaluated through a comparison of simulation results. Two geographical locations were selected to evaluate the mathematical model proposed in this work—one in each hemisphere—and design considerations according with the practical/operational experience were taken. Furthermore, independent simulations were performed using the System Advisor Model (SAM) software, their results were compared with those obtained by the simplified model. According with the above, the mathematical model allows one to carry out simulations with a high degree of flexibility and adaptability, in which the equations that allow the plant to be energetically characterized are composed of a series of logical conditions that help identify boundary conditions between dawn and sunset, direct normal irradiance transients, and when the thermal energy storage system must compensate the solar field energy deficits to maintain the full load operation of the plant. Due to the above, the developed model allows one to obtain satisfactory simulation results; referring to the net electric power production, this model provides results in both hemispheres with a relative percentage error in the range of [0.28–8.38%] compared with the results obtained with the SAM, with mean square values of 4.57% and 4.21% for sites 1 and 2, respectively.

Numerical Study of the Dynamics of Particles Motion with Different Sizes from Coal-Based Thermal Power Plant

2019 ◽  
Vol 20 (2) ◽  
pp. 223-241 ◽  
Author(s):  
Alibek Issakhov ◽  
Ruslan Bulgakov ◽  
Yeldos Zhandaulet
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Mathematical Model ◽  
Power Plant ◽  
Thermal Power Plant ◽  
Thermal Power ◽  
Numerical Results ◽  
Simulation Results ◽  
Turbulent Models ◽  
The Mathematical Model

AbstractIn this paper, the propagation of particles with different sizes from a coal-based thermal power plant was investigated. It was found that the deterioration of the environment is due to the release of a large amount of SOx, NOx and the volatile particles of Suspended Particulate Matter and Respirable Suspended Particles matter, which cause human and animal diseases. This paper presents the numerical simulation results of air pollution by particles which having different sizes from thermal power plants in real sizes using a 3D model. For the adequacy of the mathematical model, a test problem was solved using different turbulent models. To assess the applicability of the mathematical model, the numerical algorithm and the choice of the optimal turbulent model, experimental data and numerical results of other authors were used. The obtained numerical simulation results are in good agreement with the experimental results and the numerical results of other authors. And to obtain more accurate numerical results for the experimental data for turbulent models ($k - \varepsilon $,$k - \omega $), there were certain corresponding boundary conditions for kinetic energy. Also, profiles of all flow characteristics were compared with and without particles and some effects of the particle on the flow were identified.

An Enhanced Mathematical Model for Investigating the Dynamic Loading of a Slewing Crane

2006 ◽  
Vol 220 (4) ◽  
pp. 421-433 ◽  
Author(s):  
B Jerman
Keyword(s):  
Mathematical Model ◽  
Dynamic Loading ◽  
Power Transmission ◽  
Steel Structure ◽  
Main Bearing ◽  
Air Resistance ◽  
Spatial Oscillation ◽  
Comparison Of The Results ◽  
The Mathematical Model

A fatigue analysis of a structure is nowadays a common part of the design process. One of the fundamental pieces of information for ensuring the high quality of the analysis is details of the dynamic loading of the structure. This information can be provided by means of a simulation using an appropriate mathematical model. In this article, a new mathematical model of a slewing crane is presented on the basis of the experiences gained with a previously developed model. Only the slewing motion that produces the spatial oscillation of the payload is considered, as this motion has received less attention than the translation of the suspension point. The mathematical model takes into account the non-linear nature of the swinging motion for large angles and the non-linearity of the power transmission to ensure sufficient accuracy. The structure's elasticity and damping, the friction in the main bearing, and the air resistance were also taken into account. The angles of swinging of the payload and the dynamic forces acting on the steel structure of the crane during payload transport were obtained. Measurements on an actual model of a crane were carried out for the purpose of confirmation of the mathematical model. The comparison of the results was executed and a good greement between the predicted and the measured values was observed.

scholarly journals Two-dimensional mathematical model of autowave process in thin surface layer of liquid dispersed nanosystem (magnetic fluid)

2021 ◽  
Vol 2131 (2) ◽  
pp. 022012
Author(s):  
V Chekanov ◽  
A Kovalenko ◽  
E N Diskaeva ◽  
E Kirillova
Keyword(s):  
Mathematical Model ◽  
Magnetic Fluid ◽  
Process Modeling ◽  
Comsol Multiphysics ◽  
System Of Equations ◽  
Two Dimensional ◽  
Electrode Layer ◽  
Autowave Process ◽  
Comparison Of The Results ◽  
The Mathematical Model

Abstract In this work, a two-dimensional mathematical model of an autowave process taking place in a thin near-electrode layer of a magnetic fluid is constructed. The model is represented by a boundary value problem, which consists of a solution domain, a system of equations, initial and boundary conditions. The mathematical model is implemented in the COMSOL Multiphysics physical process modeling system. Comparison of the results of the numerical solution with experimental data prove the adequacy of the developed model.

scholarly journals Features of the Multi-Criteria Optimization Mathematical Model of the Thermal and Electrical Loads Distribution at a Combined Heat and Power Plant with a Mixed Equipment Composition

2021 ◽  
Vol 2090 (1) ◽  
pp. 012012
Author(s):  
E K Arakelyan ◽  
A V Andryushin ◽  
S V Mezin ◽  
A A Kosoy
Keyword(s):  
Mathematical Model ◽  
Power Plant ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Combined Heat And Power ◽  
Mixed Composition ◽  
Environmental Friendliness ◽  
Electrical Loads ◽  
The Mathematical Model

Abstract The features of the mathematical model of multi-criteria optimization of the distribution of current thermal and electrical loads at a combined heat and power plant with a mixed composition of equipment based on traditional heating units and a heating CCGT are considered. The previously proposed mathematical apparatus for solving the problem of multi-criteria optimization at a thermal power plant is analyzed. It is shown that with a mixed composition of equipment, along with the criteria of efficiency and environmental friendliness, it is also necessary to take into account the factors of reliability and mobility (maneuverability). The substantiation of the choice of reliability and mobility criteria for optimizing the operation modes of a thermal power plant is given. Approaches to solving the multi-criteria task are considered. The description of the features of the algorithm for solving the optimization problem is given in relation to thermal power plants with a mixed composition of equipment, including heating turbines of the T type and PGU.

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