Search results for "mathematical model."

Unsupervised quantitative methods to analyze student reasoning lines: Theoretical aspects and examples

2019

[This paper is part of the Focused Collection on Quantitative Methods in PER: A Critical Examination.] A relevant aim of research in education is to find and study the reasoning lines that students deploy when dealing with problematic situations. This can be done through an analysis of the answers students give to a questionnaire. In this paper, we discuss some methodological aspects involved in the quantitative analysis of a questionnaire by means of two different clustering methods, a hierarchical one and a nonhierarchical one. We start from the coding procedures needed to obtain analyzable data from the questionnaire and from a definition of a correlation coefficient suitable for measuri…

Next-to-leading order improved perturbative QCD + saturation + hydrodynamics model for A + A collisions

2014

We calculate initial conditions for the hydrodynamical evolution in ultrarelativistic heavy-ion collisions at the LHC and RHIC in an improved next-to-leading order perturbative QCD + saturation framework. Using viscous relativistic hydrodynamics, we show that we obtain a good simultaneous description of the centrality dependence of charged particle multiplicities, transverse momentum spectra and elliptic flow at the LHC and at RHIC. In particular, we discuss how the temperature dependence of the shear viscosity is constrained by these data.

Mathematical models on the way from superstring to photon

2002

Coloring Linear Algebra

2016

[EN] We present an example of how we can introduce basic concepts on Linear Algebra in a first course of an Engineering School. We use the RGB pattern color which allows us to decompose a color into three primary colors (namely, red, green, blue). By using this model we give a natural connexion between the additivity of the color decomposition and the notions on linear algebra (as vector space, linear combination and convex linear span of vectors). To visualize these connexions we use Geogebra.

Abscisic Acid Connects Phytohormone Signaling with RNA Metabolic Pathways and Promotes an Antiviral Response that Is Evaded by a Self-Controlled RNA …

2020

© 2020 The Authors.

Use of machine learning approaches to improve non-invasive skin melanoma diagnostic method in spectral range 450 - 950nm

2020

Non-invasive skin cancer diagnostic methods develop rapidly thanks to Deep Learning and Convolutional Neural Networks (CNN). Currently, two types of diagnostics are popular: (a) using single image taken under white illumination and (b) using multiple images taken in narrow spectral bands. The first method is easier to implement, but it is limited in accuracy. The second method is more sensitive, because it is possible to use illumination considering the absorption bands of the skin chromophores and the optical properties of the skin. Currently CNN use a single white light image, due to the availability of large datasets with lesion images. Since CNN processing and analysis requires a large …

Nuclear Magnetic Resonance with Fast Field-Cycling Setup: A Valid Tool for Soil Quality Investigation

2020

Nuclear magnetic resonance (NMR) techniques are largely employed in several fields. As an example, NMR spectroscopy is used to provide structural and conformational information on pure systems, while affording quantitative evaluation on the number of nuclei in a given chemical environment. When dealing with relaxation, NMR allows understanding of molecular dynamics, i.e., the time evolution of molecular motions. The analysis of relaxation times conducted on complex liquid–liquid and solid–liquid mixtures is directly related to the nature of the interactions among the components of the mixture. In the present review paper, the peculiarities of low resolution fast field-cycling (FFC) NMR rela…

On Aggregation of Risk Levels Using T-Conorms

2019

This paper deals with solutions for numeric evaluation of risks containing several different risk factors assessed by experts. The proposed methods can be used to assess the risks and obtain the risk scores in different industries, including financial industry, but they are also suitable for assessing risks in other areas, e.g. project management. While risk is usually considered as a function of probability and impact with strong quantitative background, there are many practical cases when only qualitative risk assessment based on expert opinions can be used. At the same time there are still requirements and needs for applying numerical values and mathematical models to such qualitative as…

A macro-modelling approach for the analysis of infilled frame structures considering the effects of openings and vertical loads

2015

During the last decades, several macro-models have been proposed for the modelling of the infill panels' contribution to the lateral strength of frames. Despite all this effort, a robust model, which takes into account the influence of the vertical load, is not yet available. Furthermore, the influence of the very common case of infill walls with openings, such as windows and doors, has been neglected in all the code provisions that have been published so far. In this paper, an updated macro-model, based on the equivalent pin-jointed diagonal compressive strut, is presented. The proposed macro-model is able to represent the stiffening effect of the infill panel with openings by taking into …

Computer networks stability independence of the queuing delays

2015

Communication in intelligent computer networks is an indispensible attribute of the dataflow quality in Web traffic. We propose a model that investigates intelligent computer networks stability while specifying its limits. Packet queuing delay affects the performance of the network, and especially its stability. If the network is presented as a dynamic system in block diagram form, we compute a transfer function and determine the quasi-polynomial system. The characteristic polynomial distribution of zeros of complex variable quasi-plane determines the boundaries of the network stability. The approach relies on estimation of the network system's transfer functions and its quasi-polynomial. C…