Search results for ":MATHEMATICS [Research Subject Categories]"
showing 10 items of 472 documents
Preliminary photochemical studies of fluorene in various aqueous media
2014
- The current study investigates the direct photochemical degradation of aqueous fluorene with the aid of a 125W polychromatic medium, pressure Hg lamp. The purpose was to test the effectiveness of the lamp in irradiation using fluorene spiked solution as substrate. A 700 ml volume of fluorene solution of 0.002 mg/l was irradiated batch-wise at 1, 3, 6, 12, 18, 24 and 48 h. The amount of fluorene removal was studied for fluorene solutions prepared from , neutral (distilled water), acidic (by adjusting pH with hydrochloric acid, HCl), basic (by adjusting pH with sodium hydroxide, NaOH) and saline (addition of sodium chloride, NaCl) solutions and there was 95.95, 92.35, 96.65 and 97.15 % remo…
From clear lakes to murky waters – tracing the functional response of high-latitude lake communities to concurrent ‘greening’ and ‘browning’
2019
Climate change and the intensification of land use practices are causing widespread eutrophication of subarctic lakes. The implications of this rapid change for lake ecosystem function remain poorly understood. To assess how freshwater communities respond to such profound changes in their habitat and resource availability, we conducted a space-for-time analysis of food-web structure in 30 lakes situated across a temperature-productivity gradient equivalent to the predicted future climate of subarctic Europe (temperature +3 degrees C, precipitation +30% and nutrient +45 mu g L-1 total phosphorus). Along this gradient, we observed an increase in the assimilation of pelagic-derived carbon from…
Konkretiseringsmateriell i arbeid med brøk
2016
Fractions are a complex concept, and many students struggle in their first approach with it. In this study I have considered how 8th grade students used concrete materials in relation to their work with fractions, in light of the socio-cultural perspective of learning. This study was based on this research question: How do students in 8th grade perceive the concept of fraction through the use of concrete materials when solving tasks? To answer this research question, the use of concrete materials was considered with respect to how this contributed to the students' perception of the different aspects related to fractions: fraction as a part of a whole, fraction as measurement, fraction as di…
Networking logistic neurons can yield chaotic and pattern recognition properties
2011
Accepted version of an article the book: 2011 IEEE International Conference on Computational Intelligence for Measurement Systems and Applications (CIMSA) Proceedings. Published version available from IEEE: http://dx.doi.org/10.1109/CIMSA.2011.6059914 Over the last few years, the field of Chaotic Neural Networks (CNNs) has been extensively studied because of their potential applications in the understanding/recognition of patterns and images, their associative memory properties, their relationship to complex dynamic system control, and their capabilities in the modeling and analysis of other measurement systems. However, the results concerning CNNs which can demonstrate chaos, quasi-chaos, …
Semi-decentralized strategies in structural vibration control
2011
Published version of an article published in the journal: Modeling, Identification and Control. Also available from the publisher at: http://dx.doi.org/10.4173/mic.2011.2.2 In this work, the main ideas involved in the design of overlapping and multi-overlapping controllers via the Inclusion Principle are discussed and illustrated in the context of the Structural Vibration Control of tall buildings under seismic excitation. A detailed theoretical background on the Inclusion Principle and the design of overlapping controllers is provided. Overlapping and multi-overlapping LQR controllers are designed for a simplied five-story building model. Numerical simulations are conducted to asses the pe…
Critical alignment in inquiry-based practice in developing mathematics teaching
2013
Published version of an article in the journal: Educational Studies in Mathematics. Also available from the publisher at: http://dx.doi.org/10.1007/s10649-013-9489-z This paper reports a case study from a mathematics teaching developmental research project. The theoretical foundation for the research comprises communities of inquiry and critical alignment, with which the developmental methodology has a particular synergy. This synergy is the main focus of the paper. The paper elaborates theoretical and methodological antecedents of the project and traces these through a case study of developments in the practices of one upper secondary school team and a group of university didacticians (mat…
Observation of light-by-light scattering in ultraperipheral Pb+Pb collisions with the ATLAS detector
2019
This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at √sNN=5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb−1, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy EγT>3 GeV and pseudorapidity |ηγ|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events…
Analysis of the use of a workflow engine for OTRUM system software
2007
Masteroppgave i informasjons- og kommunikasjonsteknologi 2007 – Høgskolen i Agder, Grimstad Workflow engines are attracting more and more attention. Applications based on workflow engine technology are currently developed and deployed by many companies, such as OTRUM Company. In this project, we focus on the analysis and development of an efficient workflow engine for interactive TV. The research project will realize workflow engine solutions based on three choices including commercial workflow engine, open source workflow engine, and a workflow engine implemented from scratch. In this project, we go through all mentioned solutions. In the literature, many proposed workflow engines are invo…
Viscous dissipation and thermoconvective instabilities in a horizontal porous channel heated from below
2010
Accepted version of av article from the journal: International Journal of Thermal Sciences. Published version available on Science Direct: http://dx.doi.org/10.1016/j.ijthermalsci.2009.10.010 A linear stability analysis of the basic uniform flow in a horizontal porous channel with a rectangular cross section is carried out. The thermal boundary conditions at the impermeable channel walls are: uniform incoming heat flux at the bottom wall, uniform temperature at the top wall, adiabatic lateral walls. Thermoconvective instabilities are caused by the incoming heat flux at the bottom wall and by the internal viscous heating. Linear stability against transverse or longitudinal roll disturbances …
Observer-Based Robust Control for Spacecraft Rendezvous with Thrust Saturation
2014
Published version of an article in the journal: Abstract and Applied Analysis. Also available from the publisher at: http://dx.doi.org/10.1155/2014/710850 Open Access This paper proposes an observer-based robust guaranteed cost control method for thrust-limited rendezvous in near-circular orbits. Treating the noncircularity of the target orbit as a parametric uncertainty, a linearized motion model derived from the two-body problem is adopted as the controlled plant. Based on this model, a robust guaranteed cost observer-controller is synthesized with a less conservative saturation control law, and sufficient condition for the existence of this observer-based rendezvous controller is derived…