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Eftersom användningen av små UAV:s (Unmanned Aerial Vehicles) fortsätter att öka, harbullret från deras framdrivningssystem blivit ett ökande problem. Denna rapport är resultatetav ett masterprojekt med målet att utveckla en framdrivningsmetod med låga bullernivåerför små UAV:s.Projektet startade med en informationssökning där målet var att hitta information ombullerkällor i nuvarande system samt information om de fundamentala sätten på vilket luftflödekan skapas.När informationssökningen var färdig, genererades ett stort antal olika koncept. Konceptetsom författarna ansåg ha mest potential, var en propeller med en ny metod för passivkontroll av gränsskiktet. Konceptet har ett luftintag nära rotationscentrum. Efter att luftenhar kommit in i detta luftintag, leds den genom interna kanaler och accelereras radiellt utåtpå grund av centrifugalkraften. Luften sprutas sedan ut genom en slits nära framkantenpropellerbladets lågtryckssida. Denna ström av luft färdas över propellerbladet och sugsin genom en slits nära vingens bakkant. Därefter sprutas luften ut genom ett utlopp närapropellerbladets spets.Tanken är att den beskrivna metoden ska fördröja eller förhindra avlösning. Detta skullepotentiellt möjliggöra högre lyftkraft vid lägre rotationshastigheter, vilket därigenom potentielltsänker bullernivåerna. Förenklade modeller av det valda konceptet har utvecklats ochanalyserats med hjälp av CFD (Computational Fluid Dynamics) och jämförts med simuleringarav en referensmodell utan gränsskiktskontroll. Resultaten indikerar att flödet ikonceptmodellen strömmar genom kanalerna och över propellerbladet som det var tänkt.Lyftkraften och effektiviteten ökade med 4.3 % respektive 1.9 %, jämfört med referensmodellen,vid samma rotationshastighet. Den möjliga minskningen av rotationshastigheten pågrund av ökningen i lyftkraft resulterar i en minskning av bullernivån med 0.9 dB. Detbör noteras att resultaten från simuleringarna bör ses med försiktighet och att ytterligarearbete måste göras innan några definitiva slutsatser kan dras beträffande potentiella prestandaökningarav konceptet jämfört med en konventionell propeller. / As the use of small UAVs (Unmanned Aerial Vehicles) keeps increasing, the noise emittedfrom their propulsion systems have become an increasing issue. This report is the resultof a master thesis project with the aim of developing a propulsion method with low noiseemissions for small UAVs.The project started with a background study, where the aim was to find informationabout sources of noise in current systems and information about the fundamental ways inwhich air flow can be created.When the background study was finished, a large number of different concepts were generated.The concept that the authors considered having the most potential, was a propellerwith a new method for passive circulation control. The concept has an air intake close tothe rotational center. After air has entered this inlet it is led through internal channels andis accelerated radially outwards due to centrifugal forces. The air is then ejected through aslot close to the leading edge on the low pressure side on the propeller blade. This stream ofair travels over the propeller blade and is the sucked in through a slot close to the trailingedge. After this, the air is ejected through an outlet close to the propeller blades tip.The idea is that the method described should delay or prevent boundary layer separation.This would potentially allow for higher thrust at lower rotational speeds, thus potentiallylowering the noise emissions. Simplified models of the chosen concept have been developedand analyzed using CFD (Computational Fluid Dynamics) and compared to simulations ofa baseline model with no circulation control. The results indicate that the fluid flow in theconcept model flows through the channels and over the propeller blade, as intended. Thethrust and efficiency were increased by 4.3 % and 1.9 % respectively, compared to the baselinemodel, at the same rotational speed. The possible reduction of the rotational speed due tothe increase in thrust, results in a reduction of the noise level by 0.9 dB. It should be notedthat the results from the simulations should be viewed with caution and the that furtherwork needs to be done before any clear conclusions can be drawn regarding the potentialperformance increase of the concept compared to a conventional propeller.

The aim of this study was to identify differences in how the service respite care in ordinary housing is offered to people who are caring for or supporting relatives with dementia in nine municipalities in a region in southern Sweden. The study has focused on organizational factors that may affect the use of the service and the theoretical aspects of professional discretion and assessment principles in social work. To examine this, data was collected from a semi-structured survey (n = 59) directed to assistance officers and chief managers. Secondary quantitative data from a mapping of the nine municipalities support for people with dementia and their relatives was also included in the study. The methods used to analyse data were statistical analysis and quantitative content analysis. The span between equal and individual care have been studied to gain perspective on how local assistance officers and chief managers can adapt the availability and configuration of the service, in relation to the guidelines and the individual's needs. The results of the study show that there are differences in how municipalities offer respite care in ordinary housing for the informal carers and on what grounds they have access to it. There are also differences in the range of the service in some of the municipalities. Respondents estimate that they have wide professional discretion to adapt the service to individual needs, while they feel that the municipality's guidelines should be followed. Furthermore, the results show that use of the service is relatively low in the studied municipalities. To increase the use, respondents believe that security, confidence and trust are especially important in the relationship between the staff in home care services and the carers.