441 research outputs found
50-year return-period wet-snow load estimation based on weather station data for overhead line design in France
No full textHistorically, as far as wet-snow loads were concerned, overhead line design
was often based on experience or long-term applications with positive results.
New standard like CENELEC EN 50341-1 (2012) take into account characteristic
loads, i.e. 50-year return-period loads, for the overhead line design. This article proposes a method to estimate characteristic wet-snow
loads based on meteorological data recorded at weather stations. The model
used to calculate those loads is mainly inspired by a recent article written
by Nygaard et al. (2013a) in which a new parameterization is proposed for
the classical cylindrical wet-snow accretion model, as described in ISO 12494 standard (2001), annex C.
After a complete description of the model and its parameterization adapted
to French wet-snow events, the statistical issues are examined. Then, the
model is used with the meteorological data of 87 weather stations in order
to calculate wet-snow loads whose relevance has been positively tested
according to real damages recorded in a complete wet-snow event database.
At last, the characteristic loads of those 87 stations have been determined
according to all the loads generated by the model and processed by a peak-over-threshold (POT) method.
A practical method to determine the 90% confidence intervals of those
characteristic values is given. As it is demonstrated that there is only one
value of the ice class (IC) masses proposed by ISO 12494 in each confidence
interval, characteristic loads can be easily expressed in terms of ICs.
That method shows that ICs ranging from R1 (0.5 kg m−1) to R5
(5 kg m−1) could be used for overhead line design in France
Kan selskaper profittere på å endre navn? En event-studie av annonseringseffekten ved kosmetiske navneendringer hos norske børsnoterte selskaper
No full textMaster i økonomi og administrasjonI denne avhandlingen gjennomføres en event-studie for å undersøke annonseringseffekter ved kosmetiske navneendringer for norske børsnoterte selskaper. Analysen er basert på 61 selskaper i perioden 1998 til 2015. Vårt signifikante resultat viser at annonsering av en kosmetisk navneendring kan gi en positiv CAAR. En kosmetisk navneendring vil anses som ny informasjon i markedet, og i gjennomsnitt verdsettes slike endringer positivt på kort sikt.
Vi undersøkte deretter hvilke kontrollvariabler som kunne forklare den positive CAAR-verdien. Ved å benytte en kryss-seksjonsregresjon fant vi signifikante resultater for at selskaper med høy markedsverdi vil ha en lavere CAAR sammenlignet med mindre selskaper. Videre fant vi signifikante resultater for at radikale navneendringer kan gi en negativ CAAR, mens selskaper som forkorter eller fjerner deler av navnet kan oppleve en forsterket positiv CAAR.In this thesis we conduct an event study to investigate announcement effects regarding cosmetic name changes for Norwegian listed companies. Our analysis is based on 61 companies during the period 1998 to 2015. Our significant result shows that the announcement of a cosmetic name change can have a positive CAAR. A cosmetic name change will be considered as new information in the market, and are on average positively valued in the short term.
Further, we then examined certain control variables that could explain the positive CAAR-value. By conducting a cross-sectional regression, we found significant evidence that companies with a greater market capitalization will have a lower positive CAAR compared to smaller companies. Furthermore, we found significant results for radical name changes, which indicated a negative CAAR. We also found significant results suggesting that companies that shorten or remove a part of their name can expect an enhanced positive CAAR
Kan selskaper profittere på å endre navn? En event-studie av annonseringseffekten ved kosmetiske navneendringer hos norske børsnoterte selskaper
No full textI denne avhandlingen gjennomføres en event-studie for å undersøke annonseringseffekter ved kosmetiske navneendringer for norske børsnoterte selskaper. Analysen er basert på 61 selskaper i perioden 1998 til 2015. Vårt signifikante resultat viser at annonsering av en kosmetisk navneendring kan gi en positiv CAAR. En kosmetisk navneendring vil anses som ny informasjon i markedet, og i gjennomsnitt verdsettes slike endringer positivt på kort sikt.
Vi undersøkte deretter hvilke kontrollvariabler som kunne forklare den positive CAAR-verdien. Ved å benytte en kryss-seksjonsregresjon fant vi signifikante resultater for at selskaper med høy markedsverdi vil ha en lavere CAAR sammenlignet med mindre selskaper. Videre fant vi signifikante resultater for at radikale navneendringer kan gi en negativ CAAR, mens selskaper som forkorter eller fjerner deler av navnet kan oppleve en forsterket positiv CAAR
Begrebet bæredygtighed og socialøkonomiske virksomheder
No full textSustainability is a concept which contain a great deal of different connotations, depending on in which context it is applied. A widely used definition is the one, from the report developed by the World Commission on Environment and Development: Our Common Future. In this report sustainability or sustainable development is defined as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”.This understanding of the sustainability concept, is indeed a very general definition and is often to be accused of being vague in its formulation of the concept, however it is still the most commonly used definition of sustainability. The definition from Our Common Future, will also serve as fundamental for my understanding of the concept of sustainability in this thesis, as the theories used to illustrate the concept of sustainability is based upon this definition.It is my attention, that this thesis could contribute to a clearer definition of what sustainability really means, throughout the use of the following theories. Poul Lübckes theory aims to provide a nuanced understanding of the concept of sustainability, by splitting the definition up into four categories, respectively named; species and substance-specific sustainability, ecological sustainability, economic sustainability and social sustainability. These four categories clarify, that even though they are based on the same basic structure, containing reproducibility, yield and optimization within the four systems in the described categories, it is simply not possible to include all aspects of the sustainability concept within one joined definition.Also applied in this thesis, is the theory of the Triple Bottom Line, as described by John Elkington, with the intend to describe how sustainability can be obtained in companies focusing on respectively: economic prosperity, environmental quality and social justice.These theories are then confronted with theories of social-economic enterprises, in an attempt to clarify whether or not the social-economic enterprises have a significant impact on the sustainability debate.It is my intention, that this thesis, will be able to contribute to a clarification of the concept of sustainability starting from an understanding of social-economic enterprises.Significant issues that can be made in relation to this thesis, is whether it is possible for one, to speak of sustainability within social-economic enterprises. Are these companies by virtue of the way they are driven, in itself sustainable? And which aspects of sustainability is implicit applied in companies of this kind. <br/
New variety of Peridinium gatunense Nygaard f. kinnereta Krachmalny (Dinophyta) from Lake Kinneret (Israel)
No full textПредставлено діагноз і опис нової форми Peridinium gatunense Nygaard f. kinneretа Krachmalny f. nov. із оз. Кіннерет. Від типової форми вона відрізняється будовою і розташуванням апікальних пластин і швів між ними (1’ – асиметрична, велика, її верхня частина зміщена в ліву сторону тіла; 3’ – клиновидна, витягнута; 4’ – майже прямокутна, її довжина більш як в два рази перевищує ширину; шви між 4’ і 7’’, 4’ и 1’ пластинами утворюють пряму лінію; шов між 1’ і 2’ пластинами значно меньший, ніж між 1’ і 4’, тому форма пластини 1’ наближається до трикутної). Зроблено порівняння P. gatunense f. kinneret зі зразками з інших місцезростань виду (прісні водойми Північної, Центральної, Південної Америки, Центральної Африки, Європи, Тасманії).Diagnosis and description of the new variety of Peridinium gatunense var. kinnereta Krachmalny var. nov. from the lake Kinneret (Israel) are given. This variety differs from the type one by the morphology and position of the apical plates and sutures between them (1’ – asymmetrical, large, its upper part is shifted to the left side of the body; 3’ – wedge, elongated; 4’ – almost rectangular, its length more than twice exceeds the width; sutures between 4’ and 7’’, 4’ and 1’ plates form an almost straight line; suture between 1’ and 2’ is considerably less than between1’ and 4’ plates, consequently the shape of the plate 1' is close to triangular). Comparison between P. gatunense var. kinnereta and the samples from the other regions where this species is recorded (fresh reservouars of the North, Central and South America, Central Africa, Europe and Tasmania) was carried out
An Innovative Mooring System for Floating Wind Turbines
No full textI dette prosjektet har det blitt undersøkt mulighetene for å kunne begrense maksimale laster i forankringslinene til flytende vindturbiner. De maksimale lastene vil kun inntre i situasjoner med ekstremvær, som ved 50- og 100-årsstorm.
Oppgaven har tatt utgangspunkt i den halvt nedsenkbare vindturbinen OO Star Wind Floater, som er designet av Dr.techn. Olav Olsen AS. I 2013-2015 ble dette designet undersøkt i Norges Forskningsråds RENERGIX-program, hvor det blant annet ble gjort et parameterstudie for å undersøke belastningen på forankringssystemet. Her ble det blant annet studert ULS-tilfeller basert på 100-årsstorm.
Et utvalg av ULS-tilfellene fra RENERGIX-prosjektet har blitt brukt i denne oppgaven, som utgangspunkt for egne simuleringer av OO Star Wind Floater. Simuleringer har blitt utført med 3DFloat, som er et aero-hydro-servo-elastisk simuleringsverktøy. Ekstremværet har blitt modellert med blant annet turbulent vind og irregulære bølger ut ifra JONSWAP-spektrum. For to av de studerte ULS-tilfellene har den signifikante bølgehøyden blitt satt til 10.5 meter. Maksimal kraft i den mest utsatte forankringslinen har da blitt simulert til å være over 10 500 kN.
En ny komponent i 3DFloat, kalt Force Limiter, har blitt modellert av Professor Tor Anders Nygaard. Denne har til hensikt å begrense lastene i forankringslinene til en egendefinert verdi (fxmax). Simuleringer er utført med den nye komponenten implementert, og det er valgt å «kutte» kreftene i forankringslinene ved forskjellige verdier mellom 5 000 kN og 9 000 kN. Dette med mål om å finne slaglengder og slaghastigheter. Ved å begrense linekreftene til 7 000 kN vil slaglengden bli rundt 4.5 meter og slaghastighetene vil ligge under 2.5 m/s.
Det er funnet ut at teknologien for passive hivkompensatorer (PHC) kan være egnet for å redusere dynamiske laster i forankringslinene. Norske PHC-produsenter, som Cranemaster/Ernst-B. Johansen AS og Safelink AS, kan lage enheter for demping av dynamiske krefter av samme størrelsesorden som gjelder for forankringslinene i dette prosjektet. For å kunne designe enhetene slik at de passer formålet vil det kreves et mer grundig arbeid, med simuleringer av ekstremlastsituasjonen i PHC-produsentenes spesialutviklede dataprogrammer.This project investigates the possibilities of limiting the maximum loads in mooring lines for floating offshore wind turbines during extreme conditions. The maximum loads would only occur in situations of extreme weather, such as a 50- or 100-year storm.
The project is based on the semi-submersible wind turbine OO Star Wind Floater, which was designed by Dr.techn. Olav Olsen AS. In 2013-2015 the design was examined in the Research Council of Norway’s RENERGIX programme, where amongst others a parameter study was conducted to look at the loads on the mooring system. This included studying ULS cases in the event of a 100-year storm.
A selection of ULS cases from the RENERGIX project has been used in this project as a basis or simulations of the OO Star Wind Floater. Simulations have been conducted with 3DFloat, an aero-hydro-servo-elastic simulation tool. The extreme weather was modelled with amongst others turbulent winds and irregular waves based on the JONSWAP spectrum. For two of the ULS cases, the significant wave height was set to 10.5 metres. Maximum force in the most exposed mooring line was simulated to being above 10 500 kN.
A new component in 3DFloat called Force Limiter has been modelled by Professor Tor Anders Nygaard, with the purpose of limiting the loads in the mooring lines to a chosen value (fxmax). Simulations in this project are carried out with the new component implemented and it was decided to limit the forces in the mooring lines at different values between 5000 kN and 9000 kN. The aim of this was to identify stroke lengths and stroke velocities. For example, by limiting the line forces to 7000 kN the stroke length proved to be around 4.5 metres and the stroke velocity was below 2.5 metres per second.
The technology and functionality of passive heave compensators (PHC) could be suitable for reducing dynamic loads in the mooring lines. Norwegian PHC companies, such as Cranemaster/Ernst-B. Johansen AS and Safelink AS, could produce units for reducing dynamic loads in the same magnitude that applies to the mooring lines in this project. In order to design the PHC units to fit the purpose, more thorough analysis will be required, including the simulation of the extreme load case in the PHC companies’ specially developed computer programs.M-MP
Design of mooring line systems for floating wind turbines in intermediate water by optimization
No full textSom resultat av økt fokus på bærekraftige løsninger blir insentiver for innovasjon viktig. Flytende vindturbiner har et stort potensial for å bidra til reduksjon av \ce{CO2}-utslipp. Kostnadene for flytende vindturbiner er i dag høye. Det er kjent at dimensjonering og konseptutvalg for flytende vindturbiner på mellomdypt vann er komplisert. Ved redusert kjettinglengde må ofte kjettingdiameteren økes. Dette øker et allerede høyt kostnadsbilde for flytende vindturbiner. Optimering av variabler som inngår i kostnadene blir sett på som et interessant emne for kostnadsreduksjon.
Denne oppgaven studerer en optimeringsrutine som dimensjonerer et forankringssystem. Optimeringsrutinen er bygd i SIMA workbench og bruker en ekstern optimeringsalgoritme kalt NLPQLP. Algoritmen optimerer utvalgte variabler i lys av en kostnadsfunksjon for kjetting.
Modellen er Olav Olavsen sin OO-Star Wind Floater Semi 10MW. Til å starte med ble optimeringsrutinen bygd ved en fullstendig dynamisk modell, men siden krevende simuleringer brukte lang tid ble det gjort noen forenklinger. Modellen gikk fra å være en dynamisk modell til en kvasi-statisk modell. Turbinen ble fjernet og erstattet med et stivlegeme med masse-, treghet- og vindkraftkoeffisienter.
Modellen ble utsatt for bruddgrensetilstand (ULS) og utmattingsgrensetilstand (FLS). Det var tre tilfeller av ULS, hvor turbinen var parkert i to av dem. For FLS var det full produksjon i turbin ved samtlige 13 utvalgte tilfeller. Alle simuleringene ble gjennomført ved vanndyp på 130 meter.
En av restriksjonene i oppgaven var levetiden for linene. Utmattingsanalysen ble gjort ved et integrert utmattingsskadeberegningsprogram som gjør rainflow counting på en tidsserie og regner delskade med Miner-Palmgren.
Simuleringen av FLS-tilfellene viste høye krefter og akkumulert delskade på forankringsline 1 ved samtlige tilfeller. Levetiden for forankringsline 2, som var linen med nest kortest levetid, viste nesten 16 ganger høyere levetid enn forankringsline 1. Det ble derfor undersøkt hva dimensjonene ville bli dersom den akkumulerte delskaden på forankringsline 1 ble neglisjert. Resultatene viste en diameterreduksjon fra 266.73 millimeter til 155.68 millimeter, og linelengdereduksjon fra 703.04 meter til 689.8 meter.
Optimeringsrutinen undersøkte restriksjonene og viste til resultater som ble testet i etterkant utenom optimeringsrutinen. Resultatene viste at alle krav var overholdt ved begge tilfeller.Because of an increased focus on sustainable energy, incentives for innovations has become important. Floating wind turbines has a great potential in contributing as a tool to reach the goals to reduce CO2. Floating turbines has a high cost these days. It is known that the design and the repertoire of concepts for wind turbines in intermediate water depth is complicated. This raises the already high cost for floating wind turbines. The optimization of the different variables that attributed the cost is seen as an interesting topic when discussing how to reduce the costs of floating wind turbines.
This thesis studies a routine of optimization which designs a mooring line system. The routine of optimization is built with a SIMA workbench and uses an external algorithm of optimization called NLPQLP. The algorithm optimizes certain variables which contributes to the cost function for chains. The model is the OO-Star Wind Floater Semi 10MW made by Olav Olavsen. In the beginning, the routine of the optimization was built through a completely dynamic model. But because of some complexity and time-consuming simulations, there had to be made some simplifications. The model went from being a dynamic model to a quasistatic model. The turbine was removed and replaced by a rigid bode with mass-, inertia- and thrust force-coefficients.
The model was exposed to Ultimate Limit State (ULS) and Fatigue Limit State (FLS). There were three instances with ULS, where the turbine was parked in two of them. With the FLS, there were thirteen selected cases where the turbine produced completely in all of the instances. Every simulation was done with a water depth of 130 meters. One of the restrictions in this thesis is the lifetime of the lines. The fatigue analysis was done with an integrated fatigue damage software, that does rainflow counting in a timeline and calculates the partial damage with MinerPalmgren rule.
The simulation from the FLS-cases showed high forces and accumulated partial damage on anchoring-line 1 at every case. The lifetime on anchoring-line 2, which was the line with the second least lifetime, showed sixteen times higher lifetime than anchoring-line 1. Therefore, the dimension of what would happen if the accumulated partial damage on anchoring-line 1 was neglected was interesting to investigate. The results showed a diameter reduction from 266.73 millimeters to 155.68 millimeters and a line length-reduction from 703.04 meters to 689.8 meters. The routine of optimization investigated the restrictions and showed results which were tested afterwards without optimization. The results showed that every demand was adhered to both instances.M-MP
Carbon stock and geological development of a peatland in Karlshaugen nature reserve
No full textCarbon stocks of peatlands is of growing interest due to the ability to store large amounts of carbon. To provide data of this subject this master thesis presents results from a study of a peatland within a forest nature reserve outside of Oslo, Norway. First, peat volume was estimated using a combination of ground penetrating radar survey and GIS tools (EkkoPulse software, ArcMap and Excel). Second, sediment cores retrieved from the peat were analysed in the laboratory to analyse the bulk density and carbon content of the organic material and to calculate the carbon stock of the peatland. The data were also used to explain how this peatland has developed.
The volume of the total peatland analysed by the ground penetrating radar was calculated to be 6487 m3. Degree of decomposition, described by the von Post scale, shows similar trends for all four cores; it is low in the shallow peat and increases with depth where they stabilize at level 6-8. Using Loss On Ignition as total amount of organic material gave values well above 90%, except for the samples that visibly contain minerogenic material. These results were consistent with results from total carbon analysis using LECO Truspec instrument finding total carbon content of peat core MM1to be 47-55%. The total carbon content of the remaining three cores were determined by regression analysis to be 50-53% in core MM2, 5154% in core MM3 and 52-54% in core MM4. Carbon stocks in MM1 range from 2 kgC/m2 to 7 kgC/m2. The total amount of carbon stored in this peatland is calculated to be 278 ton. For the top meter the carbon stock is 41.1 kg/m2.
The hypothesis for the formation of this peatland being a depression in bedrock filled with water to form a pond, later filled with sediments and organic material was supported by the shape of the peat basin illustrated in the GPR survey, and the fine minerogenic material in the bottom part of peat core MM1. Further field observations support peatland boundary is changing, and it can be predicted that the rise in temperature and changes in precipitation might cause degradation of organic material in the peatland. This process may be part of a positive feedback loop with climate change
Visionens mørkerøde frugt : Det imaginære i Stagnelius’ lyrik
No full textMads Nygaard Folkmann, Visionens mørkerøde frugt. Det imaginære i Stagnelius’ lyrik. (The Dark Red Fruit of Vision. The Imaginary in the Lyrical Poetry of Stagnelius.) The aim of the article is to read the lyrical poetry of the Swedish Romantic author Erik Johan Stagnelius (1793–1823) in light of the concept of imagination dominant within European Romanticism. While more readily debated in England and Germany at the time, the concept appears in Sweden as well, namely, in the aesthetic journal Phosphoros. While Stagnelius doesn’t participate in the discussions of his time, his work (especially the lyrical poetry) displays an imaginary or phantasmagoric world of its own. To understand the ways and functions of this imaginary, the article argues that it is necessary to examine Stagnelius’ work as an expression of a poetic imagination, that is, how the imaginary world is created as and through poetic devices. The article states three related concepts in order to analyze the poetic imagination in Stagnelius’s work, namely, internalization, unrealization, and transfiguration. The processes of internalization and unrealization should be understood as altering a relation to meaning through being formulated according to the premises of the speaking subject and placed in a productive distance to reality. The thesis proposes that Stagnelius, through the processes of internalization and unrealization, seeks a transfiguration of the given. In the texts of Stagnelius, this is often expressed through the discourse of religious salvation. Crucial, however, to the article’s understanding of the poetic imagination, is that transfiguration paradoxically becomes ‘real’ by remaining inside the space of the lyrical text. Paradigmatic for this structure of literary inversion is the famous poem “Endymion” (after 1821), in which the dreams of transcendence are ‘only a dream’, but where transcendence at the same time has a reality of its own within the immanent space of dream. In analyzing a series of poems, the article seeks to broaden the understanding of the concepts internalization, unrealization, and transfiguration. For example, in a reading of “Afsked till Lifvet” (“Parting from Life”, after 1818) it is shown how internalization doesn’t function as a principle of absolute self-knowledge but as the subject’s meeting with its own fractures and boundaries. Further, unrealization is discussed in the figure of ‘Amanda’, which plays a dominant role in a series of poems. Whereas in older scholarship ‘Amanda’ forms the basis for various kinds of biographical speculation, which in itself is problematic as very little is known about Stagnelius’ life, the article reads Amanda as a point of textual construction where meaning takes the form of an unrealizing textual presence based on a process of negation (in sympathy with the Sartrean notion of the imaginary’s capacity of pure negation). Finally, the principle of transfiguration is discussed in light of one of Stagnelius’ few theoretical prose fragments and through a reading of the enigmatic untitled and unfinished poem “Se blomman! På smaragdegrunden” (“See the Flower! On the Emerald Ground”, 1821–23). In conclusion, the article claims an inversion of transfiguration within the limits of poetic language whereby Stagnelius finds his specificity as a Romantic author: the lyrical text at one and the same time points to an explanatory ground (“förklaringsgrund”) beyond itself, thus suggesting a dimension of transfiguration, and states this kind of ’pointing beyond’ as solely a matter of the density of poetic language. Thus the title of the article: the vision can be retained within the figure of a mysterious dark red fruit, which points to a new way of understanding that is not yet part of given, known reality
Consistent effects of a major QTL for thermal resistance in field-released Drosophila melanogaster
No full textMolecular genetic markers can be used to identify quantitative trait loci (QTL) for thermal resistance and this has allowed characterization of a major QTL for knockdown resistance to high temperature in Drosophila melanogaster. The QTL showed trade-off associations with cold resistance under laboratory conditions. However, assays of thermal tolerance conducted in the laboratory may not necessarily reflect performance at varying temperatures in the field. Here we tested if lines with different genotypes in this QTL show different thermal performance under high and low temperatures in the field using a release recapture assay. We found that lines carrying the QTL genotype for high thermal tolerance were significantly better at locating resources in the field releases under hot temperatures while the QTL line carrying the contrasting genotype were superior at cold temperatures. Further, we studied copulatory success between the different QTL genotypes at different temperatures. We found higher copulatory success in males of the high tolerance QTL genotype under hot temperature conditions, while there was no difference in females at cold temperatures. The results allow relating components of field fitness at different environmental temperatures with genotypic variation in a QTL for thermal tolerance.Fil: Loeschcke, Volker. University Aarhus; DinamarcaFil: Kristensen, Torsten Nygaard. University Aarhus; DinamarcaFil: Norry, Fabian Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin
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