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286 Uppsatser om Thermal radiation - Sida 6 av 20
Fördelar och nackdelar med vismutskydd över bröst vid datortomografiundersökning : En litteraturstudie
Sammanfattning Bakgrund Stråldosen vid en datortomografiundersökning (CT-undersökning) kan vara 100 gånger större än vid en konventionell röntgenundersökning [1]. På 10 år har antalet CT-undersökningar nästan fördubblats [2], vilket också innebär att stråldosen till patienterna ökar [1]. Bröstkörtlarna är ett av de mest strålkänsliga organen och är därför viktiga att skydda [3, 4]. Material som dämpar röntgenstrålning kraftigt och som lämpar sig för strålskydd är t.ex. bly och vismut [5].
137Cesium i myrsamhällen i Gävleborgs län 24 årefter Tjernobylolyckan
24 years have passed since the Chernobyl accident when radionuclides were spread over largeareas of Europe, including the Scandinavian countries. Today, measurable activities of 137Csare still observed in many Swedish ecosystems.Ants (belonging to the order Hymenoptera) are social insects which collect organic materialfrom a large area around their nests. This study focuses on the 137Cs activity in ant nests andthe cesium accumulation in these nests. The aims were (1) to estimate the 137Cs fall-out in1986, (2) estimate the radiation exposure of ants and (3) find how 137Cs is distributed in an anthill. Seven ant hills (occupied by the species Formica polyctena) were studied near the villageof Hille, situated north of the city of Gävle in central Sweden.
Termisk hantering av litium-jon- batterier i elektriska drivsystem
The automotive market is currently undergoing a historical change where stricter emission legislations and ever increasing fuel costs have intensified the search for effective alternatives to the conventional internal combustion engine, which has resulted in a substantial trend towards electrification of powertrains. Storage of electrical energy is the fundamental component in this technology where the lithium-ion batteries are currently considered as the most appropriate solution. Lithium-ion batteries, however, as other types of batteries, can only be used efficiently and durably within a specific temperature range.This Master thesis has been carried out in collaboration with Electroengine in Sweden AB, situated in Uppsala, which has an ongoing project regarding development of a modular battery system for electric powertrains. The project is at a stage where an initial prototype has been developed which provides the foundation for this thesis. The study has addressed the battery system performance from a thermal perspective, in order to validate the ability of the system to create a thermally serviceable environment for the lithium-ion battery cells.
Skapandet av ett byggnadsfysikaliskt detaljbibliotek åt byggnadskonstruktörer : fokus på fukt- och värmetillstånd i köldbryggor
Det konstrueras i stor utsträckning bristfälliga detaljlösningar på byggnader i dagsläget. Den bärande stommen i konstruktionen prioriteras ofta medan det inte ägnas lika mycket fokus åt att tillgodose de byggnadsfysiska aspekterna. Anledningen till de bristfälliga detaljerna är även att den som utför arbetet saknar rätt kunskap och tid. För att skapa en förbättring behövs ett hjälpmedel!Kunskap och erfarenhet om hur bra detaljer skapas finns redan i företag, svårigheten är dock att sprida kunskapen till de som är i behov av den.Målet med denna rapport är att skapa en metodik som blir startskottet för ett omfattande arbete kring framtagandet av ett detaljbibliotek, vars syfte är att sprida byggnadsfysiska kunskaper inom företaget och inspirera konstruktörer till att konstruera bra detaljlösningar. Biblioteket ska innehålla byggnadsfysiskt utredda detaljlösningar som analyserats enligt den utarbetade metodiken.
Torrefaction of biomass : a comparative and kinetic study of thermal decomposition for Norway spruce stump, poplar and fuel tree chips
Stump biomass is energy rich and stump harvesting for use as fuel become more and more
interesting in Sweden. Swedish Forest Agency (2009) has estimated that stump harvesting in
Sweden would respond to an annual energy supply of 57 TWh/year. However, stump has not
been recognized as a bioenergy resource in Sweden. Suitable methods for pre-treatment of
stump are probably of great importance to make it accepted as fuel. It is therefore rewarding
to carry out an investigation in this area for stump.
This report represents results from a diploma project, which was aimed to develop a fixed bed
reactor for experimental study of biomass torrefaction, followed by TG analysis and kinetic
modelling employing Ozawa method and different kinetic models including one-step and
three-pseudo-component models.
Konstruktion av värmespridare med grafit för flygelektronik
This master thesis was carried out for Saab Avitronics, a business unit of Saab ABactive in electronic systems for military aircrafts. Reliability and weight are of crucialimportance in this environment. To improve reliability and lower the weight graphitemay be used for electronics cooling. Graphite is an anisotropic material and hasthereof high thermal conductivity in two directions (in-plane) and a relatively lowconductivity in the third direction (through thickness).The purpose of this thesis was to investigate if graphite is an adequate thermalconductor to use in PCB carriers. The carriers support and cool the PCB by divertingthe heat dissipation from the PCB components to the edge.
En fallstudie om effektivisering av kosthanteringen inom Nybro kommun
In December 2008 the municipal council in Nybro, decided that the municipality shouldreduce the budget for food service. The budget should be reduced by 2 100 000 SEK.They decided that the children- and education committee, and the care committee would haveto lower their budget with 1 264 000 SEK respectively 636 000 SEK. The change have to bedone under two years, 60 % should be done under 2009 and 40 % under 2010.As a result of the decision, many kitchens have to become kitchens that only serve food, notcook it. This will result in preschool staff and nursing staff take over some of the tasks fromthe kitchen staff. The municipal council also decided that entrepreneurs could take over one(later two) cooking areas.A kitchen that serves food means that there isn?t any cooking involved.
Ekologisk slaktgrisproduktion i Sverige :
This literature review describes organic pig production in Sweden, its advantages and disadvantages, but also how its problems can be reduced or solved. Organic pigs have the possibility to a more natural behaviour than conventional pigs. With outdoor pigs comes problems, especially during wintertime, concerning water and feed supply, thermal environment and supervision. Parasites and leakage of plant nutrients are other difficulties that comes with outdoor pigs. All problems and difficulties can be reduced or put right through correct management.
Enstudie om lågtempererat värmesystem i vägg : -Fokus på inomhusklimatet och energianvändning
Today the human being see energy as a matter of course but the resources that is used for extract energy is today not enough for the world demand. Of all the energy that is used in Sweden today approximately 40 % goes to the building stock. This number will most likely increase if not necessary actions will be made on the already existing building stock since new houses constantly are built which will be added up on the already existing energy supply. This takes cause of action on the already existing building stocks, to fulfill the demands of the future use of energy that has been set by the authority. At the same time the thermal conditions cannot be influenced by the necessary changes that must be made.
Laborationsmätning av vindtäthetens betydelse för en väggs U-värde
To fulfill the climate target that EU and the Swedish government have decided to apply, it becomes increasingly important that the energy efficiency of existing buildings and making new buildings energy efficient as possible. Of Sweden?s total energy consumption in 2011 was 40% used by residential and service. Of the 40% of the energy consumption was 60% used for heating and domestic hot water. A report from year 2012 shows that one reason why the heating volume is so great could be due to underestimating on the energy consumption for the heating in the planning of the building.
Effektivisering vid bedömningsprocessen av indikatorn Dagsljus för miljöcertifieringsmetoden Miljöbyggnad : Ett förprojekteringsverktyg
Dagsljus i byggnader är viktigt för både den fysiska och psykiska hälsan. Dagsljusinsläpp i byggnader sker genom fönster, men fönster är även den byggnadskomponent som medför störst energiförluster i en byggnad. Därför finns det problem i att skapa en god balans mellan utformning, energieffektivisering och termisk komfort samtidigt som ett tillfredsställande dagsljus ska tillämpas i byggnader där människor vistas.Detta examensarbete som omfattar 15 hp syftar till att effektivisera samt förenkla bedömningen av ett tillfredsställande dagsljus, för att uppnå kraven i miljöcertifieringsmetoden Miljöbyggnad, där även intilliggande faktorer som energi och termiskt klimat studeras. Målet var att upprätta ett förprojekteringsverktyg för indikatorn Dagsljus som i framtiden kan användas av konsulter, arkitekter och andra inom byggbranschen när en byggnad ska miljöcertifieras enligt metoden Miljöbyggnad. För att skapa verktyget gjordes datamodeller av testrum med olika förutsättningar, där dagsljusfaktorn, DF, kontrollerades.
En förstudie för bioetanol produktion i Borås
AbstractThe purpose of project is to study the possibility for Borås Energy & Environment to build and run a commercial ethanol production facility in Borås. The project also studies the technology for the production of ethanol using renewable energy, e.g. lignocelluloses with focus on two processes, svag-syra hydrolyse and enzymatic hydrolyse. The technology of the process is based of hydrolysation of biomass (hemicelluloses and cellulose) to sugar and extract it to ethanol. These two techniques will compare with each other to determine which of them that it?s more suitable for ethanol production.
Klimat i miljökonsekvensbeskrivningar : hantering av klimatförändringar och extrema väderhändelser i MKB
There has always been global warming on earth and it is because of it that the earth is inhabitable. Without global warming the temperature on earth would be around -18 ° C instead of today's + 15 ° C. Global warming is generated by greenhouse gases like carbon dioxide and methane which trap long wave radiation in the earth's atmosphere. The problem today is that the global concentration of green house gases has significantly increased since the 1750's as a result of human activity. Today's values widely exceed the preindustrial values.
Grinda Wärdshus : Hållbara Isoleringsmöjligheter förVandrarhemmet på Grinda
pelago. There is an old inn that is located on the island that has become a very popular attraction in the last couple of years. The inn has both a well-known restaurant as well as conference facilities that are used by tourists as well as the people of Stockholm over the summer months. The inn was built 1908 and has since remained in the same condition.make islands in the archipelago more environmentally friendly and promote sustainability. One of their project islands is Grinda.
Brännkammare för träpulver : Teoretisk analys och praktisk försök
The thesis describes a completely new biofuel system to generate particle-free heat from combustion of ash-containing biofuel particles at high temperatures.The suggested system gives opportunities to introduce biofuels in new areas.Main components in the suggested system is a heat radiating combustion chamber intended for pulverized wood, combined with regenerators to extract heat from flue gases and simultaneously preheating the combustion air.The thesis contains a description of the suggested system, theoretical considerations, calculations regarding the combustion, and includes results from tests performed.The results from calculations and tests performed concludes that the system is workable and possible to apply..