scholarly journals Modeling of Hygro-Mechanical Behaviour through Raffia vinifera Fiber during the Water Diffusion Phenomenon

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Harrond Nimjieu Takoudjou ◽  
Nicodème R. Sikame Tagne ◽  
Peguy R. Nwagoum Tuwa ◽  
Médard Fogue ◽  
Ebenezer Njeugna
Keyword(s):  
Mathematical Model ◽  
Natural Fibers ◽  
Mathematical Expression ◽  
Water Diffusion ◽  
Integration Rule ◽  
Diffusion Phenomenon ◽  
Kinetics Of ◽  
Industrial Context ◽  
Fiber Radius ◽  
Model Expression

In an industrial context where the use of friendly materials is encouraged, natural fibers of vegetable origin become more solicited for the reinforcement of composite materials. This work deals with the modeling of the hygro-mechanical behavior through raffia vinifera fiber during the diffusion phenomenon. The modeling of water diffusion through the raffia vinifera fiber is described by Fick’s second law and taking into account the swelling phenomenon of the fiber. The equation obtained is solved numerically by the finite difference method, and the evolution of the fiber radius as a function of time is obtained. By applying the Leibniz integration rule, a mathematical expression to predict the evolution of this radius as a function of time is proposed. It is observed numerically and analytically an increase of the dimensionless fiber radius with time up to a critical value after what one observes the saturation. This model allowed us to propose a mathematical model describing the absorption kinetics of the raffia vinifera fiber through its absorption ratio. By comparing the results of this model with the experimental results from the literature, one observes a good agreement. Moreover, the induced stresses in the fiber during the water diffusion can also be estimated with the proposed mathematical model expression of fiber. These stresses increase with time and can reach between 5 and 7 GPa. The results of this work can be used to predict the behavior of the raffia vinifera fiber inside a composite material during its development.

SENSITIVITY ANALYSIS AND IDENTIFIABILITY OF A MATHEMATICAL MODEL OF A CHEMICAL REACTION

2021 ◽  
pp. 14-18
Author(s):  
Л.Ф. Сафиуллина
Keyword(s):  
Mathematical Model ◽  
Inverse Problem ◽  
Sensitivity Analysis ◽  
Chemical Reaction ◽  
Reaction Model ◽  
Numerical Calculations ◽  
Specific Reaction ◽  
Uniqueness Of The Solution ◽  
The Mathematical Model ◽  
Kinetics Of

В статье рассмотрен вопрос идентифицируемости математической модели кинетики химической реакции. В процессе решения обратной задачи по оценке параметров модели, характеризующих процесс, нередко возникает вопрос неединственности решения. На примере конкретной реакции продемонстрирована необходимость проводить анализ идентифицируемости модели перед проведением численных расчетов по определению параметров модели химической реакции. The identifiability of the mathematical model of the kinetics of a chemical reaction is investigated in the article. In the process of solving the inverse problem of estimating the parameters of the model, the question arises of the non-uniqueness of the solution. On the example of a specific reaction, the need to analyze the identifiability of the model before carrying out numerical calculations to determine the parameters of the reaction model was demonstrated.

Final products and kinetics of biochemical and chemical sulfide oxidation under microaerobic conditions

2018 ◽  
Vol 78 (9) ◽  
pp. 1916-1924 ◽  
Author(s):  
Lucie Pokorna-Krayzelova ◽  
Dana Vejmelková ◽  
Lara Selan ◽  
Pavel Jenicek ◽  
Eveline I. P. Volcke ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Oxidation Rate ◽  
Elemental Sulfur ◽  
Sulfide Oxidation ◽  
Cost Effective ◽  
Anaerobic Treatment ◽  
Batch Experiments ◽  
Cost Effective Method ◽  
Microaerobic Conditions ◽  
Kinetics Of

Abstract Hydrogen sulfide is a toxic and usually undesirable by-product of the anaerobic treatment of sulfate-containing wastewater. It can be removed through microaeration, a simple and cost-effective method involving the application of oxygen-limiting conditions (i.e., dissolved oxygen below 0.1 mg L−1). However, the exact transformation pathways of sulfide under microaerobic conditions are still unclear. In this paper, batch experiments were performed to study biochemical and chemical sulfide oxidation under microaerobic conditions. The biochemical experiments were conducted using a strain of Sulfuricurvum kujiense. Under microaerobic conditions, the biochemical sulfide oxidation rate (in mg S L−1 d−1) was approximately 2.5 times faster than the chemical sulfide oxidation rate. Elemental sulfur was the major end-product of both biochemical and chemical sulfide oxidation. During biochemical sulfide oxidation elemental sulfur was in the form of white flakes, while during chemical sulfide oxidation elemental sulfur created a white suspension. Moreover, a mathematical model describing biochemical and chemical sulfide oxidation was developed and calibrated by the experimental results.

CH4 Direct Reduction of In-Flight Fe3O4 Concentrate Particles

2018 ◽  
Vol 14 (1) ◽  
Author(s):  
Bahador Abolpour ◽  
M. Mehdi Afsahi ◽  
Ataallah Soltani Goharrizi
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Fine Particles ◽  
Direct Reduction ◽  
Constant Heat Flux ◽  
Constant Heat ◽  
Dynamic Motion ◽  
Magnetite Ore ◽  
Model Predictions ◽  
Kinetics Of

Abstract In this study, reduction of in-flight fine particles of magnetite ore concentrate by methane at a constant heat flux has been investigated both experimentally and numerically. A 3D turbulent mathematical model was developed to simulate the dynamic motion of these particles in a methane content reactor and experiments were conducted to evaluate the model. The kinetics of the reaction were obtained using an optimizing method as: [-Ln(1-X)]1/2.91 = 1.02 × 10−2dP−2.07CCH40.16exp(−1.78 × 105/RT)t. The model predictions were compared with the experimental data and the data had an excellent agreement.

scholarly journals Mathematical model for reliability indicators calculation of tethered UAV hybrid navigation system

2021 ◽  
Vol 2091 (1) ◽  
pp. 012033
Author(s):  
V M Vishnevsky ◽  
K A Vytovtov ◽  
E A Barabanova ◽  
V E Buzdin
Keyword(s):  
Mathematical Model ◽  
Navigation System ◽  
Analytical Method ◽  
Mathematical Expression ◽  
Equation System ◽  
Kolmogorov Equation ◽  
Reliability Indicators ◽  
Technical Vision ◽  
The Mathematical Model ◽  
First Time

Abstract The mathematical model for reliability indicators calculation of the hybrid navigation system containing microwave and technical vision subsystems is proposed in this paper for the first time. The proposed method is based on the translation matrix concept of solutions to the Kolmogorov equation system and it allows us to obtain the mathematical expression of availability factor, downtime ratio, and other reliability indicators. Also the presented approach allows finding the reliability indicators for the cases of jump change of transition intensities caused by external influences. Besides the analytical method can be used for investigation of hybrid navigation system transient mode functioning. The results of the numerical calculations clearly demonstrated correctness of the proposed approach.

scholarly journals METHODS OF CALCULATING THE PROBABLE NUMBER OF FIRE TO BE ELIMINATED BY THE GAS PROTECTION SERVICE

2021 ◽  
Author(s):  
Oleksandr Cherkashyn ◽  
◽  
Sergii Shcherbak ◽  
Keyword(s):  
Mathematical Model ◽  
Empirical Distribution ◽  
Mathematical Expression ◽  
Main Trend ◽  
Expected Number ◽  
Distribution Law ◽  
Probable Number ◽  
City District ◽  
Absolute Growth ◽  
Main Components

The main types of operational actions of fire and rescue units during firefighting and emergency response are presented. An analysis of fires that have occurred during the last five years, which have been extinguished by units of the State Emergency Service of Ukraine with the participation of units of the gas and smoke protection service. After analyzing the statistics of the number of fires and emergencies in the city (district) over the years, a mathematical model of the dynamics of the number of fires and other emergencies. The forecast of the expected number of their occurrence is determined and the volume of work of the gas and smoke protection service for the next year is estimated, as well as the sufficiency of forces and means is determined. The most effective way to identify the main trend in the number of emergencies is analytical alignment using a mathematical expression that most accurately describes the nature of the empirical distribution of their number over the analyzed period and with which you can make predictions. To do this, the necessary mathematical distribution law is selected in the scientific search. To determine the speed and intensity of the number of fires and other emergencies over time, the following indicators were used: absolute growth, growth rate. The calculation of these indicators is based on comparing the levels of a number of dynamics. Under the level of a series of dynamics is taken each individual numerical value of the indicator, which characterizes the magnitude of the phenomenon, its size and location in chronological order. Based on the described indicators, a method of calculating the probable number of fires in the current year, which will be eliminated by the gas and smoke protection service, is proposed. An example of calculation is given: its main components are described, which should be taken into account during the calculation. The process of change and development of the occurrence and spread of fires by constructing time or time series is studied. Recommendations for building a mathematical model of the dynamics of the number of fires and other emergencies are given, the forecast of the expected number of their occurrence is determined, the volume of work of fire and rescue units for the next year is estimated.

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