Search results for "Matematik"
showing 10 items of 727 documents
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,…
Spatial data of Ixodes ricinus instar abundance and nymph pathogen prevalence, Scandinavia, 2016-2017.
2020
ticks carry pathogens that can cause disease in both animals and humans, and there is a need to monitor the distribution and abundance of ticks and the pathogens they carry to pinpoint potential high risk areas for tick-borne disease transmission. In a joint Scandinavian study, we measured Ixodes ricinus instar abundance at 159 sites in southern Scandinavia in August-September, 2016, and collected 29,440 tick nymphs at 50 of these sites. We additionally measured abundance at 30 sites in August-September, 2017. We tested the 29,440 tick nymphs in pools of 10 in a Fluidigm real-time PCR chip to screen for 17 different tick-associated pathogens, 2 pathogen groups and 3 tick species. We present…
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 …
Downscaling and improving the wind forecasts from NWP for wind energy applications using support vector regression
2020
Abstract The stochastic nature of wind poses challenges in the large scale integration of wind energy with the grid. Wind characteristics at a site may significantly vary with time. which will be reflected on the wind power production. Understanding and managing such variations could be challenging for wind farm owners. energy traders and grid operators. In this work. we propose models based on support vector regression (SVR) to downscale the speed and direction of wind at a specific site using both historical observed measurements and numerical weather predictions (NWP). Several meteorological variables. considered to have potential influence on the wind. were used in the feature selection…
"Alt rett i medikamentregning" : rapport fra en undersøkelse om regneferdigheter og undervisning i medikamentregning utført studieår 2007/2008 ved UIA
2009
Studiedirektøren ved Universitetet i Agder (UiA) bevilget i juni 2007 midler til et samarbeidsprosjekt mellom Fakultet for helse- og idrettsfag og Fakultet for teknologi og realfag. Samarbeidsprosjektet hadde til hensikt å se på muligheter for å redusere antall stryk ved eksamen i medikamentregning. Det blir tatt opp ca 240 studenter i bachelorprogrammet i sykepleie ved UiA og undervisningen foregår på to virksomhetssteder: Arendal og Kristiansand. Strykprosenten har stor sett variert mellom 30 – 60 %. I prosjektet har Judith Narvestad Tollisen og Arne Leland (Fakultet for helse- og idrettsfag) samarbeidet med følgende på Fakultet for teknologi og realfag: Mastergradstudent Leif Johannes Om…
Observation of intrinsically bright terrestrial gamma ray flashes from the Mediterranean basin
2015
Abstract We present three terrestrial gamma ray flashes (TGFs) observed over the Mediterranean basin by the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) satellite. Since the occurrence of these events in the Mediterranean region is quite rare, the characterization of the events was optimized by combining different approaches in order to better define the cloud of origin. The TGFs on 7 November 2004 and 16 October 2006 came from clouds with cloud top higher than 10–12 km where often a strong penetration into the stratosphere is found. This kind of cloud is usually associated with heavy precipitation and intense lightning activity. Nevertheless, the analysis of the cloud type…
Characterization and Evaluation of Hydrothermal Liquefaction Char from Alkali Lignin in Subcritical Temperatures.
2021
An evaluation of hydrothermal liquefaction (HTL) char is investigated in this work. Morphological studies, N2 adsorption behavior, FTIR analysis, thermal behavior, and elemental composition are studied. The HTL char yield showed an increase with higher operating temperatures. It increased from 11.02% to 33% when the temperature increased from 573 K to 623 K. At lower temperatures, the residence time showed an impact on the yield, while close to the critical point, residence time became less impactful. Elemental analysis showed that both higher operating temperatures and longer residence times increased the nitrogen content of the chars from 0.32% to 0.51%. FTIR analysis suggested the char b…
Review of the Hydrogen Evolution Reaction—A Basic Approach
2021
An increasing emphasis on energy storage has resulted in a surge of R&D efforts into producing catalyst materials for the hydrogen evolution reaction (HER) with emphasis on decreasing the usage of platinum group metals (PGMs). Alkaline water electrolysis holds promise for satisfying future energy storage demands, however the intrinsic potential of this technology is impeded by sluggish reaction kinetics. Here, we summarize the latest efforts within alkaline HER electrocatalyst design, where these efforts are divided between three catalyst design strategies inspired by the three prevailing theories describing the pH-dependence of the HER activity. Modifying the electronic structure of a …
The Hierarchical Continuous Pursuit Learning Automation: A Novel Scheme for Environments With Large Numbers of Actions.
2019
Although the field of learning automata (LA) has made significant progress in the past four decades, the LA-based methods to tackle problems involving environments with a large number of actions is, in reality, relatively unresolved. The extension of the traditional LA to problems within this domain cannot be easily established when the number of actions is very large. This is because the dimensionality of the action probability vector is correspondingly large, and so, most components of the vector will soon have values that are smaller than the machine accuracy permits, implying that they will never be chosen . This paper presents a solution that extends the continuous pursuit paradigm to …
Public Procurement of Information Systems – A Dialectical Analysis
2015
The paper III and IV are excluded from the dissertation with respect to copyright. In this thesis I identify dialectics in public procurement of Information Systems (IS), and for some of the dialectics I identify synthesis. My study is based on a research gap, revealed through a literature review that I conducted. Public procurement in general and public procurement of IS in particular has been a neglected field of study. This is surprising, given the fact that public procurement account for a high proportion of the gross domestic product in the western world, and that procurement of IS especially is a highly complex task. My literature review identified a lack of research on the challenges…