Det finns kunskapsluckor att fylla när det gäller mikroplaster från vindkraftsblad. Denna studie bidrar med ökad kunskap om mikroplaster från erosionsskador på vindkraftsblad. Metoden som använts består av datainsamling från bladreparationer och manuell granskning av bladskador via plattformen IRIS från Clobotics. Resultatet visar att vindparken Mörtjärnberget (MTB) eroderar i snitt cirka fem gram mikroplaster per turbin per år eller cirka 1,8 kilo för hela parken per år och totalt cirka 14 kilo sedan etableringen. Skadeläget för Mörttjärnberget visar på att det finns erosionsskador på alla turbiner. Kemikalierna som sprids och påverkar miljön finns i coatingen (topplacken) det handlar om methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate och bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate. Dessa kemikalier är väldigt skadliga för vattenlevande organismer med långvarig effekt. Totalt har parken på MTB släppt ut 4,56 kilogram coating som innehåller de miljöfarliga ämnena. En slutsats från denna rapport är att utsläppen av mikroplaster från Mörtjärnberget i form av erosionsskador är lägre än vad flera tillverkare och vinkraftsägare uppger. En annan slutsats är att om mikroplaster släpps ut vid reparationen av erosionsskador i form av slipdamm så kan dammet spridas i den lokala miljön. Den högsta koncentrationen vid markytan beräknas vara efter 300 meter respektive 500 meter i vindens riktning med en vindhastighet på en meter per sekund beroende på atmosfärisk stabilitet. Mikroplasterna från reparation av erosionsskador kan hamna i avrinningsområden med en ekologisk status som kan försämras av mikroplaster. / There are knowledge gaps to be filled regarding microplastics from windturbine blades, this study contributes with increased knowledge about microplastics from erosion damage. The method used consists of data collection from blade repairs and manual review of blade damage via the IRIS platform from Clobotics. The results show that the Mörtjärnberget wind farm erodes an average of about five grams of microplastics per turbine per year or about 1.8 kilograms for the entire park per year and a total of about 14 kilograms since it was built. The damage situation for Mörttjärnberget shows that erosion damage is present on all turbines and all turbines have at least one more serious erosion damage that reach the layer filler. The chemicals that spread and affect the environment are found in the coating (topcoat), it is about methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate and bis (1,2,2,6,6-pentamethyl-4- piperidyl) sebacate. These chemicals are very harmful to aquatic organisms with long-term effects. In total, the park at MTB has released 4.56 kilograms of coating that contains environmentally hazardous substances. One conclusion from this report is that the emissions of microplastics from the Mörtjärnberget in the form of erosion damage are lower than what several manufacturers and what is said in the media. Another conclusion is that if microplastics are released during the repair of erosion damage in the form of grinding dust, the dust can be spread in the local environment. The highest concentration at the ground surface should be after 300 meters and 500 meters respectively in the direction of the wind with a wind speed of one meter per second depending on atmospheric stability. The microplastics from the repair of erosion damage can end up in watersheds with an ecological status that canbe degraded by microplastics. / <p>2023-11-03</p>

No description available.

No description available.

This dissertation presents measurements of the far-field noise associated with the interaction of grid-generated turbulence with a series of airfoils of various chord lengths, thicknesses, and camber. The radiated noise was measured for a number of angles of attack for each airfoil to determine the effects of angle of attack on the leading edge noise. Measurements are compared with numerous theories to determine the mechanism driving the production of leading edge noise. Calculations were also made using a boundary element method to determine the effects of airfoil shape on the unsteady loading spectrum on the different airfoils to attempt to explain the far-field noise. Measurements of the unsteady surface pressure on a single airfoil were made for a number of angles of attack to determine the effects of wind tunnel interference corrections on the unsteady surface pressure. These measurements were compared with those of Mish (2003) to determine the effects of the interference correction. An attempt was also made to correlate the unsteady loading on the airfoil with the far-field noise. The airfoils studied were a 0.203-m chord NACA 0012, a 0.61-m chord NACA 0015, a 0.914-m chord NACA 0012, a 0.914-m chord DU96, and a 0.914-m chord S831. All airfoils spanned the entire 1.83-m height of the test section. Measurements were made using the Virginia Tech Stability Wind Tunnel in its acoustic configuration with an anechoic test section with side walls made of stretched Kevlar fabric to reduce aerodynamic interference. Measurements were made in grid-generated turbulence with an integral length scale of 8.2-cm and a turbulence intensity of 3.9%. Far-field noise measurements were made at Mach numbers of 0.087 and 0.117 with various configurations of up to 4 Bruel and Kjaer microphones mounted at an observer angle of 90° measured from the wind tunnel axis. Unsteady surface pressure measurements were made on the NACA 0015 airfoil immersed in the same grid generated turbulence used in the far-field noise study. An array of microphones mounted subsurface along the airfoil chord and a spanwise row was used to measure the unsteady surface pressure. These measurements were made at angles of attack from 0 through 16° in 2° increments. Far-field noise measurements of the leading edge noise show a consistent angle of attack effect. The radiated noise increases as the angle of attack is increased over the frequency range. These effects are small for large integral scale to airfoil chord ratios. The larger airfoils have been shown to generate significantly less leading edge noise at high frequencies, but this effect does not appear to be solely dependent upon the leading edge radius. The leading edge noise can be predicted with accuracy using the method of Glegg et al. (2008). Unsteady surface pressure measurements have been shown to be largely independent of the wind tunnel interference correction as shown by comparison with Mish (2008). The same low frequency reduction described by Mish was seen for an interference correction that was nearly 30% larger. The unsteady sectional lift spectra have been shown to be related to the far-field noise spectra by a factor close to the dipole efficiency factor; however, no correlation could be found between the instantaneous unsteady surface pressure and the radiated noise. The spanwise averaged unsteady pressure difference spectra have been shown to be related to the far-field noise spectra by the dipole efficiency factor. / Ph. D.

The interaction of an unsteady wake with a solid body can induce sizable loading of the structure, which has many detrimental side effects in both the structural and acoustic senses. These interactions are ubiquitous in nature and engineering. A flow control technique is sought to mitigate this interaction, thereby decreasing the level of structural vibration. This thesis investigates the effectiveness of steady leading-edge blowing (LEB) flow control for modifying the vortex induced vibrations on an airfoil in the wake of a circular cylinder. The airfoil was allowed to oscillate perpendicular to the fluid flow direction in response to the impinging Von-Karman vortex street. The flow field and airfoil vibrations were simultaneously captured using Digital Particle Image Velocimetry (DPIV) and accelerometer measurements in a time-resolved sense. The results indicate that LEB can significantly reduce the degree of unsteady loading due to the blade vortex interaction (BVI). In some cases, the LEB jet appears to break the coherency of a vortex incident on the airfoil, and in other cases the jet increase the mean stand-off distance of the vortex as it convects over the airfoil surface. It was also found that, for large circular cylinders, if the airfoil is within the mean closure point of the circular cylinder wake, the LEB can increase the level of BVI. The Proper Orthogonal Decomposition (POD) was also used to analyze the DPIV data. POD is mathematically superior for reducing a data rich field into fundamental modes; a suitable basis function for the reduction is chosen mathematically and it is not left to the researcher to pick the basis function. A comparison of the energy in these modes is useful in ascertaining the dynamics of the BVI. For one of the two cases examined with POD, it was found for no LEB the fundamental (i.e. most energetic) mode is given by the vortex shedding of the circular cylinder upstream. The addition of LEB reduces the energy contained in this fundamental mode. Thus the LEB jet has the effect of reducing the flow field coherency; the structure of the large vortices is broken up into smaller vortices. For the other case, the LEB jet has the opposite effect: the jet has the ability to organize the circular cylinder wake into coherent structures. This acts to increase the coherency of the circular cylinder wake and increases the level of BVI. / Master of Science

Purpose: The purpose of the thesis is to describe which foreign exchange risk techniques that are used by medium- and large-sized Swedish companies within the Jönköping region, and how they as well as a bank evaluate the techniques in the current recession. Background: The reason why companies decide to expand their operations abroad is to take advantage from imperfections in other national markets. The fluctuations in currencies and exchange rates can have a huge effect on a company’s cash flows when doing business abroad. Therefore, when companies manage their foreign exchange risk, they have to be familiar with all the methods and tools available in order to pick the ones that best suit their needs. Method: We sent out a questionnaire and got it answered by eight companies within the Jönköping region regarding their strategy when managing foreign exchange risk. We have also interviewed a financial adviser, working at Handelsbanken, regarding the techniques offered to companies. A “foreign currency table” located in Linköping, was also contacted. They are in charge of creating recommendations and products sold by Handelsbanken. Conclusion: Hedging is the most frequently used tool by the companies in our study. Leading and lagging strategies are used quite often, while swaps and invoice currency is used less frequently by them. Exposure netting and cash pooling does not seem to be used at all. We believe that companies generally should seek more information on new techniques introduced in the market and be open to new possibilities and solutions for managing currency risk. Most of the companies in our sample, according to us, are too comfortable in their choice of techniques. / Syfte: Syftet med denna uppsats är att beskriva vilka valutarisk tekniker som används av medelstora och stora företag inom Jönköpings området, samt hur dessa företag och en bank utvärderar teknikerna i den rådande lågkonjunkturen. Bakgrund: Anledningen till varför företag väljer att expandera utomlands är för att ta nytta av fördelar som uppstår i andra marknader. Fluktuationer i valutor och valutakurser kan ha stor effekt på företagens kassaflöden när handel utomlands utförs. När företag hanterar sin valutarisk måste de vara familjära med de olika metoder som finns tillgängliga, för att få reda på vilka av dessa som bäst tillgodoser deras behov. Metod: Åtta företag inom Jönköpings regionen, svarade på ett formulär, angående deras strategi när det kommer till hantering av valutarisk. Vi har även intervjuat en företags rådgivare på Handelsbanken, angående teknikerna som de erbjuder företagen. Valutabordet i Linköping har också blivit kontaktat. De har till uppgift att ta fram rekommendationer och produkter som säljs av Handelsbanken. Slutsats: Hedging är den teknik som används mest av företagen i vår undersökning. Leading och lagging används rätt så ofta, medan swaps och invoice currency används mer sällan av dem. Exposure netting och cash pooling tycks inte användas alls. Vi anser att företag generellt ska eftersöka mer information om nya tekniker som introduceras på marknaden samt vara öppna för nya möjligheter och lösningar till att hantera valutarisk. De flesta av de undersökta företagen anser vi i dagsläget är för bekväma i sina val av tekniker.

<p><strong>Purpose: </strong>The purpose of the thesis is to describe which foreign exchange risk techniques that are used by medium- and large-sized Swedish companies within the Jönköping region, and how they as well as a bank evaluate the techniques in the current recession.</p><p><strong>Background: </strong>The reason why companies decide to expand their operations abroad is to take advantage from imperfections in other national markets. The fluctuations in currencies and exchange rates can have a huge effect on a company’s cash flows when doing business abroad. Therefore, when companies manage their foreign exchange risk, they have to be familiar with all the methods and tools available in order to pick the ones that best suit their needs.</p><p><strong>Method: </strong>We sent out a questionnaire and got it answered by eight companies within the Jönköping region regarding their strategy when managing foreign exchange risk. We have also interviewed a financial adviser, working at Handelsbanken, regarding the techniques offered to companies. A “foreign currency table” located in Linköping, was also contacted. They are in charge of creating recommendations and products sold by Handelsbanken. <strong></strong></p><p><strong>Conclusion: </strong>Hedging is the most frequently used tool by the companies in our study. Leading and lagging strategies are used quite often, while swaps and invoice currency is used less frequently by them. Exposure netting and cash pooling does not seem to be used at all. We believe that companies generally should seek more information on new techniques introduced in the market and be open to new possibilities and solutions for managing currency risk. Most of the companies in our sample, according to us, are too comfortable in their choice of techniques.<strong></strong></p> / <p><strong>Syfte: </strong>Syftet med denna uppsats är att beskriva vilka valutarisk tekniker som används av<strong> </strong>medelstora och stora företag inom Jönköpings området, samt hur dessa företag och en bank utvärderar teknikerna i den rådande lågkonjunkturen.</p><p><strong>Bakgrund: </strong>Anledningen till varför företag väljer att expandera utomlands är för att ta nytta av fördelar som uppstår i andra marknader. Fluktuationer i valutor och valutakurser kan ha stor effekt på företagens kassaflöden när handel utomlands utförs. När företag hanterar sin valutarisk måste de vara familjära med de olika metoder som finns tillgängliga, för att få reda på vilka av dessa som bäst tillgodoser deras behov.</p><p><strong>Metod: </strong>Åtta företag inom Jönköpings regionen, svarade på ett formulär, angående deras strategi när det kommer till hantering av valutarisk. Vi har även intervjuat en företags rådgivare på Handelsbanken, angående teknikerna som de erbjuder företagen. Valutabordet i Linköping har också blivit kontaktat. De har till uppgift att ta fram rekommendationer och produkter som säljs av Handelsbanken.<strong></strong></p><p><strong>Slutsats: </strong>Hedging är den teknik som används mest av företagen i vår undersökning. Leading och lagging används rätt så ofta, medan swaps och invoice currency används mer sällan av dem. Exposure netting och cash pooling tycks inte användas alls. Vi anser att företag generellt ska eftersöka mer information om nya tekniker som introduceras på marknaden samt vara öppna för nya möjligheter och lösningar till att hantera valutarisk. De flesta av de undersökta företagen anser vi i dagsläget är för bekväma i sina val av tekniker.</p>

In the military arena there is an increase in demand for Low Observable (LO) flight vehicles. This drive for low observability imposes limits on Leading Edge (LE) sweep angles and prohibits the use of a tailplane/fin resulting in unconventional configurations; a typical example of which are Unmanned Combat Aerial Vehicles (UCAVs). This class of aircraft poses stability and control problems due to the early onset of flow separation. The focus of this project is on the on the use of Tangential Leading Edge Blowing (TLEB) as a means of separation suppression on such vehicles. This project is unique in that the TLEB slot is positioned on the wing lower surface facing the oncoming freestream. Also, the model in this project is representative of the outboard panel of a UCAV wing, a geometry on which TLEB has not been explored in the past. A swept wing model (LE sweep = 47 degrees, AR = 3) was designed. The model has a TLEB nozzle with a slot on the lower surface at approx. 1% yawed chord that spans 0.58 m (approx. 70% LE length). Baseline wing characteristics were obtained with the full slot exposed. The wing showed a variation in pitch between CL = 0 and 0.6 which from oil flow visualisation is believed to be due to laminar separation. At CL = 0.6 there is a positive pitch break which flow visualisation suggests is due to the occurrence of a LE vortex. Sensitivity studies for slot configuration, Re number and transition fixing were carried out. The blowing rates 0.0025, 0.005, 0.025, 0.05 were tested for two slot lengths; one full span (0.58 m) and another third span positioned at the midpoint of the full slot. All blowing rates show some suppression of the LE vortex and therefore reduction in severity of the pitch break at CL = 0.6. High blowing rates produce a negative shift in CM, which CFD suggests is due to a large amount of suction produced on the lower wing surface adjacent to the slot exit. This means the available trim power is less than for the lower blowing rates. Wool tuft results for high blowing rates from the middle slot show an increase in streamwise flow at the TE suggesting TLEB is capable of improving the effectiveness of TE devices. The effectiveness of TLEB at low blowing rates has been shown to be high compared to that found in literature. A 1st order analysis of the impact of TLEB on a full scale system shows realistic options.

The Higgs self-coupling has a vital role by giving a deeper understanding of the Higgs particle. Furthermore, the way it opens to physics beyond the SM, encourages us to do MC simulationstudies for varying λ_hhh . In this project, we investigate the effects of choosing different values for λ_hhh on the kinematics of all particles involved in the hh → τ τ τ τ decay channel and the resultsare compared with what we get from the SM prediction of λ_hhh .The data show that λ_hhh more close to the SM trilinear Higgs self-coupling results in generatingthe Higgs particles with the higher masses and higher momenta. On the other hand, for the moremassive Higgs bosons we have more energetic neutrinos in the final states which escape from thedetector without being detected.

Elektroninio verslo vadybos baigiamajame darbe „Internetinių įmonių žlugimo pamokos“ nagrinėjama problematika yra aktuali, nes atsižvelgiant į istorinę e. verslo raidą, matoma, kad nepaisant e. verslo plėtros didėjimo tendencijų, nemaža dalis jį vykdžiusių įmonių sužlugo. Todėl šiame kontekste darbo problema yra formuluojama klausimu: kokie veiksniai nulemia įmonės veiklos nesėkmę internete? Darbo tyrimo objektas yra veiklos internete nesėkmę lemiantys veiksniai. Tyrimo tikslas: atlikus teorinę nesėkmę internete lemiančių veiksnių analizę, parengti koncepcinį jų modelį, ir jį empiriškai patikrinti. Šiam tikslui pasiekti įgyvendinti tokie uždaviniai: 1. Apžvelgta e. verslo samprata ir plėtros tendencijos; 2. Išskirti autorių nagrinėti įmonių nesėkmę lemiantys veiksniai. 3. Pagal išskirtus veiksnius sudarytas e. verslo nesėkmę lemiančių veiksnių koncepcinis modelis. Jame atspindimi veiksniai yra šie: verslo modelio klaidingas pasirinkimas ir jų nederinimas, specifinių žinių trūkumas, vartotojo poreikio nevertinimas, lojalumo neugdymas ir neteisingas finansų valdymas. Apžvelgus teorinę literatūrą, nagrinėjančią šiuos veiksnius, modelis papildytas. 4. Koncepcinis veiksnių lemiančių įmonės nesėkmę internete modelis patikrintas empiriškai atlikus žvalgybinį Lietuvos rinkos tyrimą. 5. Atlikus žvalgybinį tyrimą ir patikrinus koncepcinį įmonės nesėkmę internete lemiančių veiksnių modelį Lietuvos rinkoje, paaiškėjo, kad veiksniai, išskiriami šią problematiką nagrinėjančioje... [toliau žr. visą tekstą] / The Final Master of Electronic Business Administration paper deals with the management problems. It is relevant because the usage of internet and IT is growing, and the development of electronic business is inevitable. The enterprise, starting internet business, does not know what exactly to do and what to avoid, in oder to prevent from failure; and the company has no instrument to avoid business failure. The research object is the factors leading to the failure of electronic enterprises. The research purpose is based on the theoretical factors underlying the failure of electronic enterprise: development of a conseptual model of factors leading to the failure of electronic enterprises and verification of it by an empirical research. To reach this goal the following procedures were carried out: 1. The theoretical aspects of the e. business and its future tendencies were analized 2. The factors leading to the failure of e. enterprises analised by different authors were identified. 3. Based on theoretical issues, a conceptual model of factors leading to the failure of electronic enterprises was designed. The main factors identified were: a wrong e. business model, using only one business model, a lack of specific knowledge, loyalty problems and a wrong financial management. After the analysis of literature, the model was further elaborated on. 4. The conceptual model of factors leading to the failure of electronic enterprises was verified in the Lithuanian market by a pilot... [to full text]