Search results for "Matematikk"

Modelling Demagnetized Permanent Magnet Synchronous Generators using Permeance Network Model with Variable Flux Sources

2019

The partial demagnetization in a four-pole 1.5 kW surface mounted permanent-magnet synchronous-generator was modeled by permeance network model (PNM). The results were compared to a 2-D time-stepping finite element analysis (FEA). Both models where simulated in scenarios where one of the magnets where 20 % and 100 % demagntized and when none of the magnets where demagnetised. The results showed that the proposed PNM with variable magnetic flux sources matched the results of the FEA. The proposed method only need to invers the permeance matrix once before the time simulation, while the traditinal PNM need to invers it in every time step. This make the proposed model less computationally heav…

Solution properties of the incompressible Euler system with rough path advection

2021

The present paper aims to establish the local well-posedness of Euler's fluid equations on geometric rough paths. In particular, we consider the Euler equations for the incompressible flow of an ideal fluid whose Lagrangian transport velocity possesses an additional rough-in-time, divergence-free vector field. In recent work, we have demonstrated that this system can be derived from Clebsch and Hamilton-Pontryagin variational principles that possess a perturbative geometric rough path Lie-advection constraint. In this paper, we prove the local well-posedness of the system in $L^2$-Sobolev spaces $H^m$ with integer regularity $m\ge \lfloor d/2\rfloor+2$ and establish a Beale-Kato-Majda (BKM)…

Applying Artificial Intelligence Methods to Detect and Classify Fish Calls from the Northern Gulf of Mexico

2021

Passive acoustic monitoring is a method that is commonly used to collect long-term data on soniferous animal presence and abundance. However, these large datasets require substantial effort for manual analysis

The genetic legacy of extreme exploitation in a polar vertebrate

2020

Understanding the effects of human exploitation on the genetic composition of wild populations is important for predicting species persistence and adaptive potential. We therefore investigated the genetic legacy of large-scale commercial harvesting by reconstructing, on a global scale, the recent demographic history of the Antarctic fur seal (Arctocephalus gazella), a species that was hunted to the brink of extinction by 18th and 19th century sealers. Molecular genetic data from over 2,000 individuals sampled from all eight major breeding locations across the species’ circumpolar geographic distribution, show that at least four relict populations around Antarctica survived commercial huntin…

Imaginary Dialogues – In-service Teachers’ Steps Towards Mathematical Argumentation in Classroom Discourse

2018

The purpose of this qualitative study was to explore in-service teachers’ first experiences with imaginary dialogues – a form of mathematical writing where students are introduced to a written and unfinished dialogue between two imaginary persons discussing a mathematical problem. Students are supposed to continue working with the problem and to complete the initial dialogue between these persons. In-service teachers were enrolled in a continuing university education mathematics course. They were given the task to try out imaginary dialogues in their classes from grades 4 to 10. Based on in-service teachers’ responses in open-ended self-evaluation forms, the study examined how the in-servic…

Engaging Mathematical Reasoning-and-Proving: A Task, a Method, and a Taxonomy

2019

This article is the second paper in a series of papers on studies focusing on teaching mathematical reasoning-and-proving in elementary mathematics classroom. Participants are in-service teachers enrolled in a continuing university education program in mathematics. Results from the first paper suggested the method of imaginary dialogues to have the potential to support in-service teachers in engaging their students in mathematical reasoning-and-proving, and Balacheff’s taxonomy of proofs to support in-service teachers in identifying students’ argumentation. This study is on the following years’ in-service teachers in the program. It examines their perceptions of the usefulness of two consti…

Using Audio-Logs for Analyzing the Development of a Common Operational Picture in Multi-agency Emergency Response

2020

Multi-agency emergency response requires effective communication and collaboration for building and maintaining a common operational picture. Full-scale exercises are shown to be effective for learning, and for training the collaborative skills needed. This paper presents a methodology for analysis of real-time communication for building the common operational picture, using audio-logs. The analysis of the audio-logs provides insights for both practitioners and researchers in the emergency management domain concerning the dynamics of inter-agency collaboration and information exchanges when responding to emergencies. Coding and categorizing of audio-log-based information exchanges among mul…

A Conclusive Analysis of the Finite-Time Behavior of the Discretized Pursuit Learning Automaton

2019

Author's accepted version (post-print). © 20XX IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Available from 20/03/2021. This paper deals with the finite-time analysis (FTA) of learning automata (LA), which is a topic for which very little work has been reported in the literature. This is as opposed to the asymptotic steady-state analysis for which there are, probabl…

Short form of revised two-factor study process questionnaire: Development, validation, and cross-validation in two European countries

2022

A diversity of patterns: 10-year trajectories of men and women diagnosed with psychosis for the first time. A time-geographic approach

2020

People with severe mental illness face a different interventional landscape compared to some decades ago, when mental hospitals were dominant, in Sweden as well as in the rest of the Western world. The aim of the research reported in this article was to follow men and women diagnosed with psychosis for the first time over a 10-year period, and to explore what interventions they experienced. The interventions, here defined as "spheres", were either community-based or institutional. A third sphere represents no interventions. Based on data from registers and using a time-geographic approach, the individuals were visualised as 10-year trajectories where their transitions between the different …