A mathematical model for the freezing process in biological tissue

1988 ◽  
Vol 234 (1276) ◽  
pp. 343-358 ◽  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Blood Vessel ◽  
Vascular System ◽  
Mechanical Damage ◽  
Thermal Conditions ◽  
Damage Mechanism ◽  
Freezing Process ◽  
Unit Structure ◽  
Krogh Cylinder

A mathematical model has been developed to study the process of freezing in biological organs. The model consists of a repetitive unit structure comprising a cylinder of tissue with an axial blood vessel (Krogh cylinder) and it is analysed by the methods of irreversible thermo­dynamics. The mathematical simulation of the freezing process in liver tissue compares remarkably well with experimental data on the structure of tissue frozen under controlled thermal conditions and the response of liver cells to changes in cooling rate. The study also supports the proposal that the damage mechanism responsible for the lack of success in attempts to preserve tissue in a frozen state, under conditions in which cells in suspension survive freezing, is direct mechanical damage caused by the formation of ice in the vascular system.

Numerical Simulation and Calculation of Freezing Time of Soil

2012 ◽  
Vol 246-247 ◽  
pp. 327-330
Author(s):  
Yan Hui Jiao ◽  
Zhong Gui Ren
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Mathematical Model ◽  
Freezing Process ◽  
Freezing Time ◽  
Practical Engineering ◽  
Explicit Finite Difference ◽  
The Mathematical Model ◽  
Perform Computer Simulation ◽  
Explicit Finite Difference Method

The mathematical model based on temperature formulation for describing freezing course of soil is presented and the explicit finite difference method is used to perform computer simulation of freezing time of soil in this paper. It seems to be satisfactory by comparing the numerical results by the method of TDMA with experimental data. It is significant for freezing process and freezing units, optimum design of practical engineering.

scholarly journals Spectral Analysis and Invariant Measure in Studies of the Dynamics of the Hemostasis of a Blood Vessel

2021 ◽  
Vol 66 (3) ◽  
pp. 221
Author(s):  
V.I. Grytsay
Keyword(s):  
Mathematical Model ◽  
Invariant Measure ◽  
Blood Vessel ◽  
Physical State ◽  
Vascular System ◽  
Low Density Lipoproteins ◽  
Metabolic Process ◽  
Atherosclerotic Plaques ◽  
Low Density ◽  
First Time

A mathematical model of atherosclerosis of a blood vessel is advanced with regard for the entry of low-density lipoproteins (LDLs) into blood. For the first time, the influence of cytokines on the inflammation of a blood vessel at the formation of atherosclerotic plaques is taken into account. With the help of the expansion in a Fourier series and the calculation of an invariant measure, the scenario of the appearance of strange attractors depending on a change in the parameter of the dissipation of cholesterol is studied. The conclusion is made about the interconnection of the dynamics of the metabolic process in a blood vascular system and its physical state.

scholarly journals Revascularization After Traumatic Spinal Cord Injury

2021 ◽  
Vol 12 ◽  
Author(s):  
Chun Yao ◽  
Xuemin Cao ◽  
Bin Yu
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Blood Vessel ◽  
Vascular System ◽  
Mechanical Damage ◽  
Pathological Process ◽  
Secondary Injury ◽  
Traumatic Spinal Cord Injury ◽  
Physical Stimulation ◽  
Cord Injury

Traumatic spinal cord injury (SCI) is a complex pathological process. The initial mechanical damage is followed by a progressive secondary injury cascade. The injury ruptures the local microvasculature and disturbs blood-spinal cord barriers, exacerbating inflammation and tissue damage. Although endogenous angiogenesis is triggered, the new vessels are insufficient and often fail to function normally. Numerous blood vessel interventions, such as proangiogenic factor administration, gene modulation, cell transplantation, biomaterial implantation, and physical stimulation, have been applied as SCI treatments. Here, we briefly describe alterations and effects of the vascular system on local microenvironments after SCI. Therapies targeted at revascularization for SCI are also summarized.

The substantiation of the formalized estimation of effectiveness of technological and production systems

2018 ◽  
Vol 15 (1) ◽  
pp. 169-181
Author(s):  
M. I. Sidorov ◽  
М. Е. Stavrovsky ◽  
V. V. Irogov ◽  
E. S. Yurtsev
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Production Systems ◽  
Van Der Pol

Using the example of van der Pol developed a mathematical model of frictional self-oscillations in topochemically kinetics. Marked qualitative correspondence of the results of calculation performed using the experimental data of researchers.

scholarly journals Exhaust Noise Reduction by Application of Expanded Collecting System in Pneumatic Tools and Machines

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1592
Author(s):  
Dominik Gryboś ◽  
Jacek S. Leszczyński ◽  
Dorota Czopek ◽  
Jerzy Wiciak
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Noise Reduction ◽  
Sound Pressure ◽  
Acoustic Pressure ◽  
Pressure Level ◽  
Computational Results ◽  
Noise Measurements ◽  
Exhaust Noise ◽  
Collecting System

In this paper, we demonstrate how to reduce the noise level of expanded air from pneumatic tools. Instead of a muffler, we propose the expanded collecting system, where the air expands through the pneumatic tube and expansion collector. We have elaborated a mathematical model which illustrates the dynamics of the air flow, as well as the acoustic pressure at the end of the tube. The computational results were compared with experimental data to check the air dynamics and sound pressure. Moreover, the study presents the methodology of noise measurement generated in a pneumatic screwdriver in a quiet back room and on a window-fitting stand in a production hall. In addition, we have performed noise measurements for the pneumatic screwdriver and the pneumatic screwdriver on an industrial scale. These measurements prove the noise reduction of the pneumatic tools when the expanded collecting system is used. When the expanded collecting system was applied to the screwdriver, the measured Sound Pressure Level (SPL) decreased from 87 to 80 dB(A).

Modal Analysis of the Axial Compressor Blade: Advanced Time-Dependent Electronic Interferometry and Finite Element Method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mykhaylo Tkach ◽  
Serhii Morhun ◽  
Yuri Zolotoy ◽  
Irina Zhuk
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Element ◽  
High Reliability ◽  
Axial Compressor ◽  
Time Dependent ◽  
Experimental Setup ◽  
Vibration Modes ◽  
Compressor Blades ◽  
Isoparametric Finite Element

AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.

scholarly journals Modelling time efficiency of cobot-supported kit preparation

2019 ◽  
Vol 106 (5-6) ◽  
pp. 2227-2241 ◽  
Author(s):  
Patrik Fager ◽  
Martina Calzavara ◽  
Fabio Sgarbossa
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Cycle Time ◽  
Laboratory Experiments ◽  
Spare Parts ◽  
Batch Preparation ◽  
Assembly Quality ◽  
Numerical Example ◽  
Business To Business ◽  
Support Time

AbstractKitting – meaning to supply assembly with components in presorted kits – is widely seen as beneficial for assembly quality and efficiency when there is a multitude of component variants. However, the process by which kits are prepared – the kit preparation – is labour-intensive, and kit errors are problematic at assembly processes. The use of robotics to support kit preparation has received some attention by researchers, but literature is lacking with respect to how collaborative robots – cobots – can support kit preparation activities. The purpose of this paper is to identify the potential of a cobot to support time-efficient batch preparation of kits. To address the purpose, the paper presents a mathematical model for estimation of the cycle time associated with cobot-supported kit preparation. The model is applied in a numerical example with experimental data from laboratory experiments, and cobot-supported kit preparation is compared with manual kit preparation. The findings suggest that cobot-supported kit preparation is beneficial with diverse kits and smaller components quantities per SKU (Stock Keeping Unit) and provides less variability of the outcome, when compared to manual kit preparation. The paper reveals several insights about cobot-supported kit preparation that can be valuable for both academics and practitioners. The model developed can be used by practitioners to assess the potential of cobots to support kit-batch preparation in association with assembly, spare parts, repair and maintenance, or business to business industry.

Mathematical Model of the Sintering Process of Iron-Copper Bearings

2007 ◽  
Vol 23 ◽  
pp. 119-122
Author(s):  
Cristina Teișanu ◽  
Stefan Gheorghe ◽  
Ion Ciupitu
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Mathematical Model ◽  
Regression Analysis ◽  
Function Optimization ◽  
Chemical Compositions ◽  
Sintering Process ◽  
Molybdenum Disulphide ◽  
Iron Copper ◽  
Antifriction Properties

The most important features of the self-lubricating bearings are the antifriction properties such as friction coefficient and wear resistence and some mechanical properties such as hardness, tensile strength and radial crushing strength. In order to improve these properties new antifriction materials based on iron-copper powders with several additional components (tin, lead and molybdenum disulphide) have been developed by PM techniques. To find the optimal relationship between chemical compositions, antifriction and mechanical properties, in this paper a mathematical model of the sintering process is developed, which highlighted the accordance of the model with data by regression analysis. For the statistical processing of the experimental data the VH5 hardness values of the studied materials were considered. The development of mathematical model includes the enunciation of the model, the establishment of the performance function (optimization) and the establishment of the model equations and verifying. The accordance of the model with experimental data has been highlighted by regression analysis

Control and measuring modernization systems of the “Soil Channel” stand and the development of a wheel motion mathematical model in stand conditions

Trudy NAMI ◽  
2021 ◽  
pp. 25-34
Author(s):  
B. B. Kositsyn ◽  
Kh. Chzhen ◽  
R. L. Gazizullin
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Thrust Force ◽  
Bench Test ◽  
Large Set ◽  
Virtual Experiments ◽  
Automatic Mode ◽  
Wheel Rolling ◽  
Adaptive Laws ◽  
Stand Conditions

Introduction (problem statement and relevance). A promising direction for reducing a vehicle moving energy is the application of adaptive laws for controlling the power supplied to the propeller based on neural networks. To create a training array of the latter, a large set of experimental data is required, the collection of which, as a rule, is carried out by using research stands, such as the “Soil Channel”. But the fi eld studies require a lot of resources.The purpose of the study was to create a wheel rolling mathematical model in the conditions of the stand, with the help of which it would be possible to organize the collection of needed statistical data on the wheel rolling modes by calculation them in an automatic mode.Methodology and research methods. The paper describes the “Soil Channel” bench test, held by the Department of “Multipurpose tracked vehicles and mobile robots” of Bauman Moscow State Technical University. A list of the control and measuring systems components used in the process of its modernization in order to automate the collection of experimental data was considered. The “Soil Channel” stand mathematical model was presented which was based on the use of experimentally obtained dependences of the specifi c longitudinal thrust force on sliding and the specifi c longitudinal thrust force on the specifi c circumferential force.Scientifi c novelty and results. The developed mathematical model has been verifi ed on the basis of the data obtained in the course of fi eld studies. Conclusions were made about the suitability of the developed mathematical model of wheel motion under the stand conditions for conducting virtual experiments.Practical signifi cance. The data obtained by applying the developed mathematical model can be used to create a training array of a neural network to provide the implementation of adaptive laws for controlling the power supplied to the propeller.

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