Today most ice rinks in Sweden use secondary refrigeration systems with a solution of calcium chloride and water as secondary refrigerant. Due to the large amount of energy such a system uses more efficient systems would be desired.An earlier study concluded in the possibilities of using carbon dioxide as secondary refrigerant with copper tubes as the loops in the ice rink. Since then 3 ice rink refrigeration systems has been built with carbon dioxide in copper tubes. Excluding the ones being direct involved in those projects there is still very little knowledge about how these system works. This study has been made primarily with the aim of adding to the knowledge concerning availability and cost and secondary to look at possibilities for improvement.A comparison between systems with carbon dioxide, calcium chloride respective ammonium solved in water has been made by using Decision Matrix.

In coastal wetlands carbon/organic matter can be stored for long periods of time thanks to, among other things, the presence of water which slows down the decomposition. Because of this, restauration and management of such habitats have the potential to decrease the emission of greenhouse gasses and help mitigate climate. Internationally these environments are called ?blue carbon? ecosystems. In Sweden, alder (Alnus glutinosa and Alnus incanata) covered wetlands along the coast is a nature type that potentially could function as a ?blue carbon? habitat.

Environmental destruction is a growing problem in our world. Almost every day there are new reports concerning that we have to do something about the greenhouse gasses. Simultaneously is the human constantly more eager to have a life with higher standards and therefore uses more energy. The environment is a question that is highly up-to-date and more people try to find solutions on how to save our planet. One way to decrease the energy demand is to build passive houses, where the houses don?t have any active heating.

The harbour in Arvika is closed down and the industry that has been established in the area is now beeing wound up. A deepened comprehensive plan for the area is under progress in the municipality. The intentions are for instance that the harbour should be integrated with the city and that Arvika is facing a lake should be more apparent from the city center. The harbour should also contribute to a more attractive city. These intentions have hence been the starting point of my undergraduate theses, which has resulted in a proposal on how to develop the harbour. During the process I have analysed the city image, how the area is used today and the public places in the city centre.

The purpose of the house which is the basis of this report is to be able present itself on the market as a relatively cheap and at the same time a climate friendly choice. The house is supposed to be able to be built anywhere in Sweden and the rest of Scandinavia in a short period of time. This puts demand on what kind of heating system the house can have, since not all places have the geographic advantage of being able to use geothermal or district heating. Therefore the heating system choices will only include those that are not limited by their geographic location. The house will be built in modules which only require the groundwork to be done before the house can be erected. In this report "System solutions for plus or passive-housing" a comprehensive literature search has been conducted as well as a number of calculations.

Syftet med studien är att undersöka varsels effekter för företags effektivitet och produktivitet under lågkonjunktur. Vår studie bygger på intervjuer med både chefer och anställda från företaget Water Jet Sweden AB. Studiens resultat är att personal påverkas av företags beslut om varsel om uppsägning genom att arbeta mindre effektivt. Detta är så för att varslet sänker arbetsmotivationen och tryggheten vilket gör att personalen underpresterar, detta påverkar hela företaget negativt..

Transformation of inorganic mercury (Hg) to methyl mercury (MeHg) is a biotic process that is proposed to be conducted primarily by sulphate reducing bacteria (SRB). The formation of MeHg is of great interest because it is the mercury species that biomagnifies to the greatest extent in the aquatic food webs; about 90 % of all Hg in fish is MeHg. Our understanding of factors involved in the production of MeHg is very important for making a reliable risk assessment. The purposes of this study were to investigate the different factors that control the solubility of Hg and the production of MeHg in a contaminated lake sediment. The lake Ala-Lombolo, Kiruna municipality, is well-known to be contaminated by mercury from different sources. Sediment cores were sampled at three different locations (N, SW and SE) in the lake and divided in three different layers; 0-5, 5-10 and 10-15 cm.

Aquaponics is a food production system consisting of a consecutive cultivation of plants and aquatic animals, fish or shellfish, in recirculating water. The plants feed on the nutritious effluents from the fish tank and bacteria converts ammonia from the fish tank into nitrate that is absorbed by the plants. The plants receive nutrition and the fish gain purified water. The environmental impact of the production of fish meal and fish oil used in conventional fish feed includes a large consumption of fossil fuels with subsequent carbon dioxide emission. The aquaponic system can be made environmentally sustainable and self-supporting if supplemented with a vermicompost/vermiculture for the production of worm protein as a fish feed. Vegetable waste from the hydroponic part of the system can be reused as worm feed in the compost and the protein rich worms can be harvested, dried and grinded and brought back to the aquaculture as fish feed. As a first step in this direction, I have investigated the effect of recycling of vegetable waste in vermicomposts on the growth and number of earthworms (this was evaluated after harvesting). The hypotheses were that earthworms can be cultivated in the vegetable waste and that by adding manure to the vermicompost it is possible to obtain a nutrient content adequate to support a continuous worm harvest, in other words create a vermiculture. Eisenia fetida and Dendrobaena veneta were grown in 20 L bins containing peat mixed with either poultry or cattle manure. The proportions were 70% peat and 30 % manure. Discarded plant parts from lettuce cultivation was added to the vermicomposts (35 g per week) and water was supplied with 0.8 L per week.

Rapporten innefattar en jämförande studie mellan olika typer av membran och beläggningar.Främst sker en jämförelse mellan materialens förmåga att andas. Vattentäthet testas på nyamaterial och efter olika sorters nötning så som martindale, flexing och tvätt för att få en ökadförståelse för materialen. Verktyget som används i studien för att mätaånggenomsläppligheten är hudmodellen. Resultatet presenteras med ett Ret-värde vilket är enförkortning på Evaporative resistance of a textile. Metoden används för att på ett bra sättsimulera hur huden svettas.Projektet har utförts på Swerea IVF som är ett forskningsinstitut beläget i Mölndal.Hudmodellen är en av de senaste stora investeringarna på Swereas textil och plast avdelning.Resultatet av studien visar att laminat andas bättre än beläggningar, dock har bärarmaterialetstor inverkan på resultaten.

The project is a thesis which intends to strengthen the form language and increase the user friendliness of an International Moth. This is a single handed dinghy with only one sail. It sails on two hydrofoils and receives a very high speed compared to its size, and are therefore often referred to as ?the Formula One on water ?. The result is a new concept where the aerodynamic forces have been used to stabilize the boat and relieve the hydrofoils.

Organisationer förändras ständigt och måste anpassa sig till sin omgivning. Orsakerna till förändringar beror delvis på organisationernas egna frivilliga beslut men även externa påtryckningar, till exempel på grund av lagar och direktiv. Hur anställda uppfattar och reagerar på förändringar påverkar hur effektivt förändringarna implementeras. Därför är det nödvändigt för företaget att göra vad de kan för att anställda ska acceptera förändringen.Denna studie undersöker hur anställda reagerar vid organisationsförändringar. Syftet är att redogöra för hur och varför anställda reagerar i olika typer av organisationsförändringar.

After the storm Gudrun in 2005, the Swedish Transport Administration started clear-cutting of railroad corridors to reduce the risk of trees falling down on the tracks. Simultaneously, train accidents with moose and roe deer have become more frequent and the costs for consequent delays and repairs of engines are of growing concern. There is reason to assume that tree-clearance of railroad corridors may have contributed to an increase in number of accidents with moose and roe deer because the cleared areas provide attractive forage and thus may attract wildlife. The objective of my study was to investigate how clearing of trees affected the number of accidents with moose and roe deer. I compared deer-train collision frequencies before and after clearance of the selected railroads and compared these with uncleared control railroads in a BACI (before-after control-impact) approach.

Det har gjorts mycket forskning på pedagogiska datorspel och hur de kan användas i undervisning.Den här studien har försökt sammanfatta och sammanställa detta till en modell för hur datorspelkan utforskas och analyseras anpassat till verksamheten. Syftet med studien är således: Attutmejsla ett ramverk för pedagoger för högre åldrar, som kan hjälpa till att avgöra hur bra olikadatorspel (underhållningsspel och pedagogiska spel) skulle kunna fungera i verksamheten.Två strategispel med inriktning mot historia har analyserats, Age of Empires 3 och MakingHistory: The Calm and the Storm. Spelen har spelats och sedan analyserats utifrån RETAINmodellen.De har därefters spelats av fyra elever som har observerats, vilket har gett insyn i vilkaaspekter som är viktiga att titta på som pedagog vid analys av datorspel.Resultatet mynnar ut i ett antal olika kategorier och frågor som kan hjälpa till vid analys av ettdatorspel som ev. kan användas i undervisning. Vad spelet har för fokus, lärande ellerunderhållning? Vad spelet har för relevans till undervisningen? Hur har det akademiska materialetinkorporerats i spelet? I vilken kontext ska spelet spelas? Hur ska man tillämpa de kunskaper somspelet ger? Kan spelet verka motiverande och hur mycket tid och resurser måste läggas på spelet isin helhet? Detta ramverk är förhoppningsvis så pass konkreta och lättförståeliga att de kananvändas av en pedagog i verksamhet för att avgöra hur bra ett datorspel kan inkorporeras i enverksamhet..

No previous studies have been conducted on elementary school in Sweden about children`s thoughts about the first animals on earth. The work takes up the children`s ideas of the first animals and the difference between girls and boys knowledge. The purpose of this work was to determine if student`s views are consistent with the science know today. In the interview, five girls and five boys participated. Mankind is asking where it all began, today we know that the first life arose for 4 billion years ago and it was from the water.

A secondary and a pioneer tree species can with advantage be included in a mixed stand to increase the use of sunlight. Nitrogen-fixing plants have been shown to increase the supply of nitrogen in the soil by, for example, litter fall. This deposition acts as a biological fertilization, which may be used by non-fixing plants. Alder is a nitrogen-fixing, pioneer tree species that loses its nitrogen-rich leaves late in the autumn. The aim of this study was to examine the effect on the total volume of production, when different proportions of nitrogen-fixing Alder were part of spruce stands.