Search results for "VDP::Matematikk og naturvitenskap: 400::Matematikk: 410"
showing 10 items of 136 documents
Mathematical Modeling and Parameters Estimation of Car Crash Using Eigensystem Realization Algorithm and Curve-Fitting Approaches
2013
Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://dx.doi.org/10.1155/2013/262196 Open Access An eigensystem realization algorithm (ERA) approach for estimating the structural system matrices is proposed in this paper using the measurements of acceleration data available from the real crash test. A mathematical model that represents the real vehicle frontal crash scenario is presented. The model's structure is a double-spring-mass-damper system, whereby the front mass represents the vehicle-chassis and the rear mass represents the passenger compartment. The physical parameters of the model are estimated using cu…
Rough linear PDE's with discontinuous coefficients - existence of solutions via regularization by fractional Brownian motion
2020
We consider two related linear PDE's perturbed by a fractional Brownian motion. We allow the drift to be discontinuous, in which case the corresponding deterministic equation is ill-posed. However, the noise will be shown to have a regularizing effect on the equations in the sense that we can prove existence of solutions for almost all paths of the fractional Brownian motion.
Random dynamical system generated by the 3D Navier-Stokes equation with rough transport noise
2022
We consider the Navier-Stokes system in three dimensions perturbed by a transport noise which is sufficiently smooth in space and rough in time. The existence of a weak solution was proved recently, however, as in the deterministic setting the question of uniqueness remains a major open problem. An important feature of systems with uniqueness is the semigroup property satisfied by their solutions. Without uniqueness, this property cannot hold generally. We select a system of solutions satisfying the semigroup property with appropriately shifted rough path. In addition, the selected solutions respect the well accepted admissibility criterium for physical solutions, namely, maximization of th…
Girsanov Theorem for Multifractional Brownian Processes
2017
In this article we will present a new perspective on the variable order fractional calculus, which allows for differentiation and integration to a variable order, i.e. one differentiates (or integrates) a function along the path of a regularity function. The concept of multifractional calculus has been a scarcely studied topic within the field of functional analysis in the last 20 years. We develop a multifractional derivative operator which acts as the inverse of the multifractional integral operator. This is done by solving the Abel integral equation generalized to a multifractional order. With this new multifractional derivative operator, we are able to analyze a variety of new problems,…
Investigating Some Construct Validity Threats to TALIS 2018 Teacher Job Satisfaction Scale: Implications for Social Science Researchers and Practitio…
2020
The credibility of findings ensuing from cross-sectional survey research depends largely on the validity and reliability of the research instruments. Critical attention to the quality of such instruments will ensure logical and valid results. The purpose of this article is to provide evidence for two methodological issues observed that are potential threats to construct validity of widely used Teaching and Learning International Survey (TALIS) 2018 data on teacher job satisfaction scale (TJSS). The first issue concerns reverse recoding of some items necessary to obtain a coherence covariance between these items and other items on the same subscale. The second issue concerns the addition of …
Distributed Consensus for Discrete-Time Directed Networks of Multiagents with Time-Delays and Random Communication Links
2013
Published version of an article in the journal: Abstract and Applied Analysis. Also available from the publisher at: http://dx.doi.org/10.1155/2013/158731 Open Access This paper is concerned with the leader-following consensus problem in mean-square for a class of discrete-time multiagent systems. The multiagent systems under consideration are the directed and contain arbitrary discrete time-delays. The communication links are assumed to be time-varying and stochastic. It is also assumed that some agents in the network are well informed and act as leaders, and the others are followers. By introducing novel Lyapunov functionals and employing some new analytical techniques, sufficient conditi…
On Steady Solutions of a generalized Whitham equation
2021
Paid open access
Analysis of relations between attitude towards mathematics, prior knowledge, self-efficacy, expected and actual grades in mathematics
2022
The purpose of this study is to analyse relations between students’ attitude towards mathematics, prior knowledge, self-efficacy, expected grades, and performance in mathematics among 115 firstyear engineering students. We combine two statistical techniques to analyse the data we generated by questionnaires and two tests. First, item-level modeling, in terms of confirmatory factor analysis, which we use to compute the factor scores of construct-validated measures, and to control for measurement errors. Second, composite modeling, in terms of path analysis, which we use to test the research hypotheses. The findings show that both self-efficacy and expected grades have substantial effects on …
“The joy that engineers and mathematicians have come together.” Richard von Mises’ foundation of ZAMM, and its “Tasks and Goals” (1920/21)
2020
An exploration of how social science students utilise an opportunity to learn about simulation-based research methods : A design-based study
2021
Paper I, Paper III and Paper IV is excluded from the dissertation with respect to copyright. Paper III and Paper IV is not published yet. At the core of this thesis lies an exploration of how social science students utilise an opportunity to learn about Modeling and Simulation (M&S)-based research methods. The study is framed within the Cultural Historical Activity Theory (CHAT). The thesis also utilises local theories such as the community of practice theory, the theory of objectification, and the theory of semiotic representation, and these are used to analyse, interpret and discuss the data generated in the study. During the analysis, boundary-crossing, boundary objects, tension and cont…