Search results for "Mathematical Modelling"

River water quality modelling: a parsimonious model approach

2009

Biological Nutrient Removal Model No. 2 (BNRM2): a general model for wastewater treatment plants

2013

This paper presents the plant-wide model Biological Nutrient Removal Model No. 2 (BNRM2). Since nitrite was not considered in the BNRM1, and this previous model also failed to accurately simulate the anaerobic digestion because precipitation processes were not considered, an extension of BNRM1 has been developed. This extension comprises all the components and processes required to simulate nitrogen removal via nitrite and the formation of the solids most likely to precipitate in anaerobic digesters. The solids considered in BNRM2 are: struvite, amorphous calcium phosphate, hidroxyapatite, newberite, vivianite, strengite, variscite, and calcium carbonate. With regard to nitrogen removal via…

Linear stability analysis of gas-fluidized beds for the prediction of incipient bubbling conditions

2010

Abstract This work focuses on the development of a novel linear stability criterion for the state of homogeneous fluidization regime, based on a new mathematical model for gas-fluidized beds. The model is developed starting from the well-known particle bed model. A mono-dimensional momentum balance is derived leading to a set of equations which explicitly include voidage-gradient dependent terms (elastic force) for both solid and fluid phases. A fully predictive criterion for the stability of homogeneous fluidization state is here proposed, based on the well-known Wallis’ linear stability analysis. The criterion requires the choice of an appropriate averaging distance, which in the present …

MAD+. Introducing Misconceptions in the Temporal Analysis of the Mathematical Modelling Process of a Fermi Problem

2021

This work describes how the combination of the mistakes committed by a group of pre-service teachers when solving a Fermi problem, with the representation of the temporal analysis of their resolutions, can offer more in-depth information about their conceptual misconceptions regarding mathematical and modelling concepts. The combined representation allows knowing when mistakes occur and provides a powerful tool for instructors to adapt the teaching–learning processes of mathematics at all levels of education. Our study is based on a recent categorisation of students’ mistakes, together with the creation of a new representation tool, called MAD+, that can combine all this information. The ma…

Greenhouse Gas Emission Reduction Due to Improvement of Biodegradable Waste Management System

2014

Abstract To reduce emissions of greenhouse gas (GHG) from landfills, the European Union (EU) Landfill Directive 1999/31/EC requires that there be a progressive decrease in the municipal biodegradable waste disposal. The main problem of waste management (WM) in Latvia is its heavy dependence on the waste disposal at landfills. The poorly developed system for the sorted municipal waste collection and the promotion of landfilling as a major treatment option led to the disposal of 84% of the total collected municipal waste in 2012, with a high biodegradable fraction. In Latvia, the volume of emissions due to activities of the WM branch was 5.23% (632.6 CO2 eq.) of the total GHG emissions produc…

A mathematical model for wastewater modification processes assessment in a stabilization reservoir

2012

The paper presents a mathematical model for the simulation of the ecological status of a wastewater stabilization reservoir (WSR). WSRs are hypertrophic aquatic systems devoted to storage of water resources in warm countries where shortage conditions have quite often to be faced. Several factors that affect the stabilization reservoir effluent quality were taken into account: hydraulics and hydrology, solar radiation, atmospheric reaeration, algae, zooplankton, organic matter, pathogen bacteria, and sediment-water interaction. The model quantifies the specific influence of each factor on effluent quality, evaluating the correlation between the different considered factors. State variables i…

Modelling Keloids Dynamics: A Brief Review and New Mathematical Perspectives

2022

The keloids are fibroproliferative disorders described by an excessive growth of fibrotic tissue, which also invades adjacent areas (beyond the original wound borders). Since these disorders are specific to humans (no other animal species naturally develop keloid-like tissue), the experimental in vivo/in vitro research has not lead to significant advances in this field. One possible approach could be to combine in vitro human models with calibrated in silico mathematical approaches (i.e., models and simulations) to generate new testable biological hypotheses related to biological mechanisms and improved treatments. Since these combined approaches do not really exist for keloid disorders, in…

Wastewater modification processes in a stabilization reservoir: a new mathematical model

2018

The paper presents a mathematical model for the simulation of the ecology of a wastewater stabilization reservoir (WSR). WSRs are hypertrophic aquatic systems devoted to water storage in warm countries where shortage conditions are often encountered. Several factors that affect the stabilization reservoir’s effluent quality were taken into account: hydraulics and hydrology, solar radiation, reaeration, algae, zooplankton, organic matter, pathogens, and sediment-water interactions. The model quantifies the specific influence of each factor on effluent quality, and evaluating the correlation between the different factors. State variables included in the model were: algae, dissolved oxygen, or…

Analytical and quasi-analytical solutions of direct problems in eddy current testing

2014

Elektroniskā versija nesatur pielikumus

Mathematical Models and their Solutions for Domains of Compex Form

2014

Promocijas darbā tiek apskatīti dažādi oriģināli modeļi un to risinājumi sarežģītas formas apgabaliem. Intensīvās tērauda rūdīšanas procesi sistēmām ar ribām tiek aprakstīti ar 3D hiperbolisko, kā arī ar klasisko siltuma vadīšanas vienādojumu. Precīzā atrisinājuma iegūšanai izmantota Grīna funkciju metode un tās vispārinājums. Modernajos datoros sastopamajām sistēmām ar dubulsieniņu un dubultribu dota stacionārā un nestacionārā siltumvadīšanas problēma 2D gadījumā. Tās risinājums tiek iegūts ar konservatīvās viduvēšanas metodi, galīgo diferenču metodi un tās modifikāciju robežnosacījumiem. Piedāvāts jauns matemātiskais modelis vītola flautai, problēmas formulējumā izmantojot 1D lineāru viļņ…