scholarly journals Simulation of Coagulable Mixtures Dynamics in Incompressible Liquid Considering Clot Cluster Formation

2020 ◽  
pp. 15-28
Author(s):  
В. А. Галкин ◽  
Т. В. Гавриленко ◽  
А. В. Галкин
Keyword(s):  
Simulation Model ◽  
Cardiovascular System ◽  
Blood Circulation ◽  
Incompressible Liquid ◽  
Cluster Formation ◽  
Simulation Models ◽  
Entire Body ◽  
Human Cardiovascular System ◽  
Mixture Dynamics ◽  
Formation System

Одной из ключевых проблем, на решение которой направлены ресурсы общества по преодолению заболевания, вызванного новым коронавирусом COVID-19, является проблема нарушения кровотока, связанная, в частности, с процессом тромбообразования. Это явление существенно ограничивает кровоток, снижая доставку кислорода в целом по всему организму. В статье рассмотрены результаты создания математической модели динамики коагулирующих смесей в несжимаемой жидкости c учетом явления формирования кластеров-тромбов. Создание математических моделей процессов коагуляции и тромбообразования в сердечно-сосудистой системе человека обеспечит разработку эффективного управления этими явлениями. В статье описана математическая модель для процессов коагуляции в дисперсных системах — тромбообразования. Представлены результаты численного решения задачи и визуализация аналитического решения задачи, включая такие важнейшие параметры для тромбообразования, как распределение концентрации примеси в жидкости и распределение поля давления. Указанная модель может служить основой для построения иерархической системы образования тромбов в сердечно-сосудистой системе от микроскопического уровня до макроскопических структур. В том числе модель позволит сделать выводы об эффективности использования антикоагулянтов при поступлении пациентов в отделения неотложной помощи и при положительном результате теста на COVID-19. One of the key problems associated with COVID-19 is blood circulation impairment, particularly caused by thrombosis. The impairment significantly reduces the blood flow and restricts oxygen delivery to the entire body. The paper covers the simulation model for the coagulable mixture dynamics in an incompressible liquid considering clot cluster formation. Simulation models for the thrombosis and coagulation processes in the human cardiovascular system will help efficiently manage these phenomena. The study proposes a simulation model of the coagulation processes in disperse systems, i.e., the thrombosis process. The paper presents the numerical solution results and the visualization of the analytical solution. The key thrombosis properties such as impurity concentration distribution in the liquid, and the pressure field 16 В. А. Галкин, Т. В. Гавриленко, А. В. Галкин О математическом моделировании динамики коагулирующих смесей в несжимаемой жидкости c учетом явления формирования кластеров-тромбов distribution, were estimated. The simulation model can become a foundation for developing a multi-tier clot formation system in the cardiovascular system: from the microscopic level to the macroscopic structures. Besides, the model can estimate the efficiency of anticoagulants administered to COVID-19 positive patients at emergency care departments.

scholarly journals Simulating Dynamics of Circulation in the Awake State and Different Stages of Sleep Using Non-autonomous Mathematical Model With Time Delay

2021 ◽  
Vol 11 ◽  
Author(s):  
Anatoly S. Karavaev ◽  
Yurii M. Ishbulatov ◽  
Mikhail D. Prokhorov ◽  
Vladimir I. Ponomarenko ◽  
Anton R. Kiselev ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Cardiovascular System ◽  
Healthy Subjects ◽  
Blood Circulation ◽  
Control Loops ◽  
Awake State ◽  
Proposed Model ◽  
Human Cardiovascular System ◽  
First Time

We propose a mathematical model of the human cardiovascular system. The model allows one to simulate the main heart rate, its variability under the influence of the autonomic nervous system, breathing process, and oscillations of blood pressure. For the first time, the model takes into account the activity of the cerebral cortex structures that modulate the autonomic control loops of blood circulation in the awake state and in various stages of sleep. The adequacy of the model is demonstrated by comparing its time series with experimental records of healthy subjects in the SIESTA database. The proposed model can become a useful tool for studying the characteristics of the cardiovascular system dynamics during sleep.

scholarly journals Analytical modeling of the human cardiovascular system with real-time implementation using NI ELVIS-II

2018 ◽  
Vol 7 (3.3) ◽  
pp. 628
Author(s):  
Sisir Chettri ◽  
Akash Kumar Bhoi ◽  
Gyoo Soo Chae ◽  
Nilas Gurung ◽  
Ashis Sharma
Keyword(s):  
Cardiovascular System ◽  
Real Time ◽  
Human Body ◽  
Blood Circulation ◽  
Lumped Parameter Model ◽  
Blood Flows ◽  
System A ◽  
Lumped Parameter ◽  
Electrical Analogy ◽  
Human Cardiovascular System

Cardiovascular System, which consists of the heart, the systematic circulation and the pulmonary circulation is said to be the transport system for the human body. Modeling of cardiovascular system has become important for clinical researchers and for deeper understanding of blood circulation in the human body. This paper uses the lumped method which is also known as an electrical analogy for modeling and simulation of human cardiovascular system. A simplified complete lumped parameter model of the Human Cardiovascular System has been developed with real time implementation focusing mainly on blood flows. A resistor, an inductor and a capacitor are used to model every blood vessel, ventricles, atrium and set of all veins and capillaries. A pulse generating circuit is also modeled which acts as a power supply for the heart that controls the contraction of heart muscles.   

Bifurcation in a Simple Model of the Cardiovascular System

2000 ◽  
Vol 39 (02) ◽  
pp. 118-121 ◽  
Author(s):  
S. Akselrod ◽  
S. Eyal
Keyword(s):  
Nonlinear Dynamics ◽  
Blood Pressure ◽  
Heart Rate ◽  
Fixed Point ◽  
Cardiovascular System ◽  
Modified Model ◽  
Mayer Waves ◽  
Sustained Oscillations ◽  
Human Cardiovascular System ◽  
Physiological Values

Abstract:A simple nonlinear beat-to-beat model of the human cardiovascular system has been studied. The model, introduced by DeBoer et al. was a simplified linearized version. We present a modified model which allows to investigate the nonlinear dynamics of the cardiovascular system. We found that an increase in the -sympathetic gain, via a Hopf bifurcation, leads to sustained oscillations both in heart rate and blood pressure variables at about 0.1 Hz (Mayer waves). Similar oscillations were observed when increasing the -sympathetic gain or decreasing the vagal gain. Further changes of the gains, even beyond reasonable physiological values, did not reveal another bifurcation. The dynamics observed were thus either fixed point or limit cycle. Introducing respiration into the model showed entrainment between the respiration frequency and the Mayer waves.

scholarly journals Guidelines to Calibrate a Multi-Residential Building Simulation Model Addressing Overheating Evaluation and Residents’ Influence

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 242
Author(s):  
Christoph Schünemann ◽  
David Schiela ◽  
Regine Ortlepp
Keyword(s):  
Simulation Model ◽  
Time Window ◽  
Residential Building ◽  
Simulation Models ◽  
Building Simulation ◽  
Night Time ◽  
Building Performance Simulation ◽  
Starting Point ◽  
3D Simulation Model ◽  
Building Physics

Can building performance simulation reproduce measured summertime indoor conditions of a multi-residential building in good conformity? This question is answered by calibrating simulated to monitored room temperatures of several rooms of a multi-residential building for an entire summer in two process steps. First, we did a calibration for several days without the residents being present to validate the building physics of the 3D simulation model. Second, the simulations were calibrated for the entire summer period, including the residents’ impact on evolving room temperature and overheating. As a result, a high degree of conformity between simulation and measurement could be achieved for all monitored rooms. The credibility of our results was secured by a detailed sensitivity analysis under varying meteorological conditions, shading situations, and window ventilation or room use in the simulation model. For top floor dwellings, a high overheating intensity was evoked by a combination of insufficient use of night-time window ventilation and non-heat-adapted residential behavior in combination with high solar gains and low heat storage capacities. Finally, the overall findings were merged into a process guideline to describe how a step-by-step calibration of residential building simulation models can be done. This guideline is intended to be a starting point for future discussions about the validity of the simplified boundary conditions which are often used in present-day standard overheating assessment.

Settings, Experimentation and Evaluation of the Simulation Models

2013 ◽  
Vol 309 ◽  
pp. 366-371 ◽  
Author(s):  
František Manlig ◽  
Radek Havlik ◽  
Alena Gottwaldova
Keyword(s):  
Simulation Model ◽  
New Technology ◽  
Simulation Models ◽  
Manufacturing Processes ◽  
Customer Requirements ◽  
Evaluation Functions ◽  
Operational Management ◽  
Minimum Number ◽  
User Friendly ◽  
Setting Parameters

This paper deals with research in computer simulation of manufacturing processes. The paper summarizes the procedures associated with developing the model, experimenting with and evaluating the model results. The key area is of experimentation with the simulation model and evaluation using indicators or multi-criteria functions. With regards to the experiment the crucial variables are the simulation model. The key ideas are to set the number of variables, depending on what a given simulation will be. For example, when introducing new technology into production, modify the type of warehouse, saving workers, thus economizing. The simulation models for the operational management uses simplified models, if possible, a minimum number of variables to obtain the result in shortest possible time. These models are more user friendly and the course will be conducted mostly in the background. An example of a criteria function is the number of parts produced or production time. Multi-criteria function has given us the opportunity to make better quality decisions. It is based on the composition of several parameters, including their weight to one end point. The type of evaluation functions, whether it is an indicator or criteria function is selected and based on customer requirements. In most cases it is recommended to use the multi-dimensional function. It gives us a more comprehensive view of the results from the model and facilitates decision-making. The result of this paper is a display of setting parameters for the experimentation on a sample model. Furthermore, the comparisons of results with a multi-criteria objective function and one-criterion indicator.

A Method to Define the Best Weld Sequence Using a Limited Number of Welding Simulation Analysis

2015 ◽  
Author(s):  
Mahyar Asadi ◽  
Ghazi Alsoruji
Keyword(s):  
Simulation Model ◽  
Surrogate Model ◽  
Simulation Analysis ◽  
Combinatorial Problem ◽  
Fem Analysis ◽  
Simulation Models ◽  
Computational Time ◽  
Optimal Sequence ◽  
Welded Structure ◽  
Welding Sequence

Weld sequence optimization, which is determining the best (and worst) welding sequence for welding work pieces, is a very common problem in welding design. The solution for such a combinatorial problem is limited by available resources. Although there are fast simulation models that support sequencing design, still it takes long because of many possible combinations, e.g. millions in a welded structure involving 10 passes. It is not feasible to choose the optimal sequence by evaluating all possible combinations, therefore this paper employs surrogate modeling that partially explores the design space and constructs an approximation model from some combinations of solutions of the expensive simulation model to mimic the behavior of the simulation model as closely as possible but at a much lower computational time and cost. This surrogate model, then, could be used to approximate the behavior of the other combinations and to find the best (and worst) sequence in terms of distortion. The technique is developed and tested on a simple panel structure with 4 weld passes, but essentially can be generalized to many weld passes. A comparison between the results of the surrogate model and the full transient FEM analysis all possible combinations shows the accuracy of the algorithm/model.

Rotorcraft Lateral-Directional Oscillations: The Anatomy of a Nuisance Mode

2021 ◽  
Author(s):  
Dheeraj Agarwal ◽  
Linghai Lu ◽  
Gareth D. Padfield ◽  
Mark D. White ◽  
Neil Cameron
Keyword(s):  
Simulation Model ◽  
Simulation Models ◽  
Flight Test ◽  
Flight Simulation ◽  
Stability And Control ◽  
Systems Research ◽  
Control Derivatives ◽  
Research Aircraft ◽  
Level Of Understanding ◽  
And Control

High-fidelity rotorcraft flight simulation relies on the availability of a quality flight model that further demands a good level of understanding of the complexities arising from aerodynamic couplings and interference effects. One such example is the difficulty in the prediction of the characteristics of the rotorcraft lateral-directional oscillation (LDO) mode in simulation. Achieving an acceptable level of the damping of this mode is a design challenge requiring simulation models with sufficient fidelity that reveal sources of destabilizing effects. This paper is focused on using System Identification to highlight such fidelity issues using Liverpool's FLIGHTLAB Bell 412 simulation model and in-flight LDO measurements from the bare airframe National Research Council's (Canada) Advanced Systems Research Aircraft. The simulation model was renovated to improve the fidelity of the model. The results show a close match between the identified models and flight test for the LDO mode frequency and damping. Comparison of identified stability and control derivatives with those predicted by the simulation model highlight areas of good and poor fidelity.

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