Search results for "Mathematical model"
showing 10 items of 346 documents
A method for modeling the battery state of charge in wireless sensor networks
2015
In this paper we propose a method for obtaining an analytic model of the battery State-of-Charge (SoC) in wireless sensor nodes. The objective is to find simple models that can be used to estimate accurately the real battery state and consequently the node lifetime. Running the model in the network nodes, we can provide the motes with the required information to implement applications that can be considered as battery-aware. The proposed methodology reduces the computational complexity of the model avoiding complicated electrochemical simulations and treating the battery as an unknown system with an output that can be predicted using simple mathematical models. At a first stage, during a se…
A hydrodynamic water quality model for propagation of pollutants in rivers.
2010
Numerical modelling can be a useful tool to assess a receiving water body's quality state. Indeed, the use of mathematical models in river water quality management has become a common practice to show the cause-effect relationship between emissions and water body quality and to design as well as assess the effectiveness of mitigation measures. In the present study, a hydrodynamic river water quality model is presented. The model consists of a quantity and a quality sub-model. The quantity sub-model is based on the Saint Venant equations. The solution of the Saint Venant equations is obtained by means of an explicit scheme based on space-time conservation. The method considers the unificatio…
A Mixture Modeling Approach to Estimate Vegetation Parameters for Heterogeneous Canopies in Remote Sensing
2000
In this article, we describe a reflectance model which parametrizes the reflectance of vegetation canopies from optical properties of leaves and soil, and dominant canopy structural parameters. The model assumes certain principles of geometric models, for example, that sensor integrates the radiance reflected from three components, plant, shaded soil, and illuminated soil. Its inversion provides compositional information of the ground surface that is linked with the interpretation of the linear spectral mixture modeling (LSMM). This model also offers the potential for retrieving other meaningful biophysical properties such as LAI. The model has been tested on simulated spectra of spectral m…
Numerical investigations of single mode gyrotron equation
2009
A stationary problem with the integral boundary condition arising in the mathematical modelling of a gyrotron is numerically investigated. The Chebyshev's polynomials of the second kind are used as the tool of calculations. The main result with physical meaning is the possibility to determine the maximal value of electrons efficiency. First published online: 14 Oct 2010
Mixed microalgae culture for ammonium removal in the absence of phosphorus: Effect of phosphorus supplementation and process modeling
2014
Microalgal growth and ammonium removal in a P-free medium have been studied in two batch photobioreactors seeded with a mixed microalgal culture and operated for 46 days. A significant amount of ammonium (106 mg NH4-Nl(-1)) was removed in a P-free medium, showing that microalgal growth and phosphorus uptake are independent processes. The ammonium removal rate decreased during the experiment, partly due to a decrease in the cellular phosphorus content. After a single phosphate addition in the medium of one of the reactors, intracellular phosphorus content of the corresponding microalgal culture rapidly increased, and so did the ammonium removal rate. These results show how the amount of phos…
Modelling of retention behaviour of solutes in micellar liquid chromatography
1997
In micellar liquid chromatography (MLC), the resolution for a given multi-component mixture can be optimized by changing several variables, such as the concentrations of surfactant and organic modifier, the pH and temperature. However, this advantage can only be fully exploited with the development of mathematical models that describe the retention and the separation mechanisms. Several reports have appeared recently on the possibilities of accurately predicting the solute retention in MLC. Although the retention and selectivity may strongly change with varying concentrations of surfactant, organic modifier and/or pH, the observed changes are very regular, and are well described by simple m…
A Control Problem for a Class of Epidemics
2003
We consider a mathematical model corresponding to a class of epidemics. Controlling an epidemic is usually difficult. To implement the control policy suggested by a mathematical analysis in the real world is never easy. However, suggestions can be given to the public authorities about the effects of a particular control policy, and in this sense analysis and simulation by mathematical models becomes a powerful tool.
A commentary on the Special Issue “Innovations in measuring and fostering mathematical modelling competencies”
2021
This is a commentary on the ESM 2021 Special Issue on Innovations in Measuring and Fostering Mathematical Modelling Competencies. We have grouped the ten studies into three themes: competencies, fostering, and measuring. The first theme and the papers therein provide a platform to discuss the cognitivist backgrounds to the different conceptualizations of mathematical modelling competencies, based on the modelling cycle. We suggest theoretical widening through a competence continuum and enriching of the modelling cycle with overarching, analytic dimensions for creativity, tool use, metacognition, and so forth. The second theme and the papers therein showcase innovative ideas on fostering an…
Solving a model for 1-D, three-phase flow vertical equilibrium processes in a homogeneous porous medium by means of a Weighted Essentially Non Oscill…
2013
Mathematical models of multi-phase flow are useful in some engineering applications like enhanced oil recovery, filtration of pollutants into subsurface, etc. In this work, we derive a mathematical model for the motion of one-dimensional three-phase flow in a porous medium under the condition of vertical equilibrium, which can be viewed as an extension of some two-phase flow models described in the literature. Our model involves a system of two partial differential equations in the form of viscous conservation laws, whose solutions may contain very sharp transitions. We show that a high-order/high resolution Weighted Essentially Non Oscillatory scheme is an appropriate tool to discretize th…
Theory of Heterogeneous Circuits With Stochastic Memristive Devices
2022
We introduce an approach based on the Chapman-Kolmogorov equation to model heterogeneous stochastic circuits, namely, the circuits combining binary or multi-state stochastic memristive devices and continuum reactive components (capacitors and/or inductors). Such circuits are described in terms of occupation probabilities of memristive states that are functions of reactive variables. As an illustrative example, the series circuit of a binary memristor and capacitor is considered in detail. Some analytical solutions are found. Our work offers a novel analytical/numerical tool for modeling complex stochastic networks, which may find a broad range of applications.