Papers by Keyword: Mathematical Model

Abstract: The intensity of neutralization of dangerous gases (chlorine, sulfur dioxide, hydrogen cyanide, phosgene, hydrochloric acid, ammonia) is researching during deposition with small-dispersion water. For this purpose, a mathematical model of neutralization of a dangerous gas, which is lighter than air, with fine water was modified for use in neutralizing a dangerous gas, which is heavy relative to air. The model takes into account the main parameters of sorption (environmental conditions, physical and chemical properties of the dangerous gas, parameters of the liquid flow supplied for deposition), which minimizes the forecasting time and is critical in the elimination of an accident with a release of dangerous gases. It was found that when dangerous gases are deposited in a finely dispersed water stream, the determining parameter is the Henry's constant of the dangerous gas, rather than the intensity of the fine water stream. It is confirmed that for dangerous gases that are poorly soluble in water (have small values of Henry's constant), it is necessary to add additives to the water stream that increase the chemical activity of the solution.

Abstract: The article deals with the creation of a mathematical model that can be applied in the testing of various materials. These are testing cases where the measurement and subsequent evaluation of the value of the coefficient of friction in various tribological measurements is considered. The mathematical model considers the static and dynamic coefficient of friction. It started with the creation of a simpler mathematical model, which was subsequently modified to a more sophisticated one, considering the real situation, which is closer to the real case. With the mathematical model created in this way, various simulations were performed and evaluated for cases of (constant) permanent load, but also repetitive (periodic) load. In another case, an improvement of the mathematical model was carried out, which represented the addition of an option that allows considering the degradation of the investigated material. Degradation of the material represents only part of the surface of the material, which during testing is exposed to contact with another material with a higher hardness than the tested material.

Abstract: Decarbonisation is instrumental in attaining sustainable mobility. To actualize the Ghana Nationally Determined Contribution (NDC) set emission reduction target of 15% relative to Business-As-Usual (BAU) scenario by 2030, sustainable transport actions should be encouraged. Thus, promoting the use of Liquified Petroleum Gas (LPG) and Compressed Natural Gas (CNG) in automobiles is very crucial to ensure efficient and green mobility. Nonetheless, existing policies in Ghana overlook autogas (LPG/CNG) as prospective decarbonizing solution in the transport sector. The study employed survey analysis and analytical modeling approach to elicit the benign effects of autogas in the transport sector using Accra as a case study. The ecological, economic and social dimensions of autogas were expatiated to extrapolate effective measures to facilitate their smooth implementation. Survey was carried out in the central business district of Accra to attain the percentage of autogas and gasoline used by taxis operators for the first time per author’s knowledge. A purposive sample of 500 taxi drivers was selected and data analysis was conducted using R statistical package. From the survey, 14% of taxis were powered with LPG whilst 86% were gasoline, however, the LPG-powered taxis were retrofitted gasoline engine vehicles. The analytical model was based on physics principles involving three resistance forces- aerodynamic, rolling resistance and inertia. CO₂ emission savings of 29% and 18.4% were elicited from the use of CNG and LPG relative to gasoline fuel at the end of the simulation using the ambient conditions in Accra. Thus, use of autogas will limit global warming impact and aid the country to fulfill its pledged emission target by 2030. The government is entreated to regulate autogas use in the transport sector and increase its patronage by promoting flexible policies like meager custom duty on imported CNG/LPG vehicles as well as tax credits.

Abstract: In recent years, particular attention has been paid to the use of renewable energy, particularly biomass, for reasons related to both climate change and waste management. Biogas is frequently used in low value-added applications such as heating and fuel in engines, while it can be reformed into hydrogen, through certain process such as the process of dry reforming, of partial oxidation, of bi-reforming, or even of tri-reforming. The literature has indicated that the tri-reforming process is better than other reforming processes. Biogas tri-reforming is a simultaneous combination of endothermic dry reforming and steam reforming with exothermic methane oxidation, carried out in a single reactor to produce syngas which is an important feedstock for chemical production and energy vectors. Second, the process of tri-reforming overcomes several weaknesses of each main reform process. This article presents a new mathematical model of tri-reforming which will further optimize this type of process. The developed mathematical model was validated with literature data. Thus, the literature data used are among others, the optimal feed ratio in the tri-reforming process, CH₄/CO₂/H₂O/O₂ = 1:0.291:0.576:0.088. For optimal temperature and pressure, the data used are 1223 K and 5 bar respectively. This mathematical model makes it possible to achieve high conversion of methane (CH₄) and carbon dioxide (CO₂) coupled with high selectivity in hydrogen. The conversion rate of methane (CH₄) can reach 99% and that of carbon dioxide (CO₂) can reach 97%. The model is adapted with a high hydrogen selectivity: 2.88.

Abstract: The aim of this work is to develop a numerical model and perform numerical simulations of avalanche-like collapse of buildings and structures in case of fire and explosions, taking into account the peculiarities of soil performance and its properties. The LIRA-SAPR software is a promising tool for calculations and modelling.

Abstract: When predicting the service life of a material, it is important to take into account its mechanical characteristics. The authors have developed a mathematical model that describes the dependence of titanium alloy durability on cyclic loads. The research tool was the "Solution Search" add-in of the Microsoft Excel spreadsheet program. Regularities and dependencies have been established, which help to improve the understanding of damage mechanisms of titanium alloys. It is proved that the temperature of preliminary plastic deformation does not influence the durability of titanium alloy PT-3V. The developed model can be used to optimize loading regimes and improve the performance characteristics of titanium alloy building structures.

Abstract: The computational studies of a predictive mathematical model for the extraction of interstitial (ISF) for transdermal and non-invasive diagnosis using biodegradable and hollow microneedle patch is presented in this paper. Rapid Diagnostic Tests diagnosis, which is non-invasive, affordable, straightforward, and provides results promptly and reliably, has increased access to parasite-based analysis on a global scale. Microneedle arrays are a rapidly evolving and promising technology for transdermal interstitial fluid extraction, which is used for many clinical diagnostic procedures. Hence, a developed mathematical predictive model used to optimize the design of microneedle patch for transdermal ISF extraction and subsequent diagnosis using dissolvable microneedle arrays was applied in this study. The model's solutions were obtained using the Differential Transform Method. The numerical Runge-Kutta method of fourth order was used to validate it. An experimental test result was also used to further validate the analytical results in the absence of the extracted velocity parameter. And there was a good agreement among them. Influence of dissolution rate constant, microneedle height, diffusion coefficient, velocity of ISF, microneedle ISF drug load, and density of the microneedle; were investigated. Increase in diffusion coefficient and density led to an increase in concentration of ISF extracted over time, an increase in dissolution rate led to a decrease in concentration extracted, while decrease in drug load and height, led to increase in ISF concentration extracted. A negligible effect was observed by varying the velocity of ISF extracted. The approximate analytical approach utilized in the current work has given us a more precise strategy for creating a mathematical model that predicts how ISF will be extracted from skin for use in transdermal and non-invasive rapid diagnostic tests.

Abstract: The article analyzes the state of the global problem of the fuel and energy crisis and environmental pollution by the combustion products of hydrocarbon fuels of industrial and transport power plants. To ensure the energy security of the state, the Cabinet of Ministers of Ukraine developed and adopted the «Energy Strategy of Energy Saving of Ukraine for the period until 2030», which was updated in 2008, to protect the country from energy risks. In addition, the Cabinet of Ministers of Ukraine approved the «Concept of a targeted scientific and technical program for the development of the production and use of biological fuels». To increase the efficiency of using alternative motor fuels, as one of the aspects of solving the problem, an original method and results of calculating the thermophysical properties of a wide class of such motor fuels (hydrogen, natural gas, biogas, mine gas, coke, blast furnace and synthesis gas, etc.) are proposed. A description of the developed mathematical model for determining parameters of phase equilibria and thermophysical properties of dense molecular systems (dense gases and liquids) is given. Calculation procedures are based on the thermodynamic theory of disturbances without the involvement of empirical parameters. Features of the proposed method are: limitation of initial information, high accuracy, the possibility of application in any practically important ranges of states. Calculation errors are at the level of traditional experimental errors.

Abstract: The CNC milling process is one of the most valuable traditional machining processes for machining hardened material by using various coated end mill tools. The attention of the current study has been done on end milling of hardened AISI D2 tool steel which is a commonly used tool steel grade in a press machine. The material removal rate is an essential aspect of improving productivity and reducing lead time and production costs. MRR has been considered as a response in this experimental work. A number of experiments were conducted using the design of the experiment via response surface methodology (RSM). MRR was calculated for each machining performance. A mathematical model of MRR was found using response surface methodology.

Abstract: The research objective is to simplify the method for estimating the density of straight-run hydrotreated winter diesel fuel (HTDFWs). The density of straight-run hydrotreated winter diesel fuel is one of the quality indicators ultimately determining the density of winter diesel fuel and therefore, the quality of winter diesel fuel in terms of density. Problems: to describe the current methodology for estimating the HTDFWs’ density, isolate the cycles, and express the cycles by formulas. Research methods – analysis, synthesis, comparison, mathematical analysis. As a result, simplified density calculation with expressing cycles by formulas has been proposed. A mathematical model has been obtained to estimate the density of straight-run hydrotreated winter diesel fuel.