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532 Uppsatser om Temperature thresholds - Sida 4 av 36
Sjöars känslighet för klimatförändringar ? vilka faktorer påverkar?
The Earths climate is changing at a higher rate, i.e between 1861 and 1994 the annual mean temperature in Scandinavia increased with 0,68º C and according to recent climate models the annual mean temperature is likely to rise with another 3º C during this century.A warmer climate in many ways is associated with changing conditions for lake ecosystems. An expected higher water temperature and a stronger summer stratification of the water column increases the risk of anoxic conditions at the lake bottom. Thus anoxic conditions are likely to cause a phosphate leakage from the sediment, i.e. a higher internal loading of phosphate.In this project, the extremely warm summer of 2002 has been used as an example for a possible scenario for a future climate. By comparing levels of phosphorus in the summer of 2002 with a ten-year median value, a phosphorus related sensitivity to climate change has been analyzed for 55 Swedish lakes.
Kirunametoden-Jämförelse emot en konventionell injusteringsmetod
AbstractWith increasing population and increasing demands for comfort and thus an increase in energy demand, it is necessary to examine various energy-efficiency measures. This work deals with the ability to control the flow through the heating system to achieve the desired comfort with as little energy as possibleA heating system contains of different parts, roughly speaking, you can divide it to three main components: Heat source, Distribution and Heat emitters. All components are working together to bring heat to the building. What is examined in this report are different ways of adjusting the flow and supply temperature and how it affects comfort and energy use in a building.At today ?s date the conventional method is to use a high flow through the heating system, which affects pressure drop and cooling of the fluid.
Utvärdering av befintliga passivhus : En byggnadsfysikalisk bedömning och mätningar om temperatur, och fukt analys på ytterväggarna
Energy price are on the way up to a high level that will not diminish in the future make us to focus more on the sustainable development for a better solution of residential houses. Passive house or low energy housing are one of the solution to make residential more environment friendly, in same time it´s a financial security using less energy, and saving money. The last 10 years in Germany and all around Europe the concept of passive house been developed, and people aim to know more about these concept that leading the market more attractive for passive houses. A passive house is a well designed building highly insulated and air tight with mechanical ventilated system for the whole building envelope that minimizes the use of energy for heating [1].The housing company Mimer has chosen to invest in low energy consumption in every new housing project. These future plan projects are decided to use less than 75 kwh per square meter annually in purchased energy [2].This thesis is about new constructed passive houses, and focuses on the evaluations of the temperature, and moisture condition for attic, external walls and joist.
DYNAMIKEN OCH EFFEKTEN AV MARINA V?RMEB?LJOR P? TROPISKA KORALLER (SCLERACTINIA)
Marine heatwaves (MHW) have become increasingly common in recent decades due to greenhouse gas emissions that have caused climate change. A marine heatwave is when the sea surface temperature rises, which damage many different ecosystems in the sea. One ecosystem that is sensitive to temperature changes is tropical coral reefs, which are at risk of bleaching during marine heatwaves. Coral bleaching is when its symbionts leave the coral and they lose their color, while also starving to death as they lose their food source. The purpose of this report was therefore to investigate what the connection between marine heatwaves and coral bleaching looks like, and to see if there are any geographical differences.
Skuggvävens effekt på fryslagrade täckrotsplantor av tall (Pinus sylvestris) i upptiningsstadiet :
This project was an assignment by Sveaskog and Svenska Skogsplantor. The purpose was to study the effect of protective fabric on the thawing stage of frozen pine seedlings. The function of the protective fabric is that it should protect the seedlings against strong sunlight and create an even temperature inside the boxes containing the seedlings. The result has shown that there was no statistically significant difference when the protective fabric was used or when it was not used, although this was probably due to the weather conditions. The study was carried out under cold and cloudy weather conditions and probably would have given other results if there had been more sunny days with a higher ambient temperature.
Högtempererat borrhålslager för fjärrvärme
The district heating load is seasonally dependent, with a low load during periods of high ambient temperature. Thermal energy storage (TES) has the potential to shift heating loads from winter to summer, thus reducing cost and environmental impact of District Heat production. In this study, a concept of high temperature borehole thermal energy storage (HT-BTES) together with a pellet heating plant for temperature boost, is presented and evaluated by its technical limitations, its ability to supply heat, its function within the district heating system, as well as its environmental impact and economic viability in Gothenburg, Sweden, a city with access to high quantities of waste heat.The concept has proven potentially environmentally friendly and potentially profitable if its design is balanced to achieve a good enough supply temperature from the HT-BTES. The size of the heat storage, the distance between boreholes and low borehole thermal resistance are key parameters to achieve high temperature. Profitability increases if a location with lower temperature demand, as well as risk of future shortage of supply, can be met.
Predatorinducerad fekunditet hos Daphnia pulex vid simulerade årstidsbundna temperaturvariationer
Female growth, number of eggs and egg growth of Daphnia pulex were studied at four temperatures, 12, 16, 18 and 20°C. I hypothesized that female growth and number of eggs would be lower and the size of the eggs larger in the presence of a predator (kairomones) than in its absence. This effect was expected to be more evident at lower temperatures. I could not find any effect of kairomones on female growth, number of eggs or egg size, although there was a weak tendency for an effect on number of eggs. There was, however, an effect of temperature, regardless of predator treatment (i.
VRA-PROGRAMVARA MED TILLHÖRANDE STYRELEKTRONIK
This thesis has been done at the Unversity of Örebro for Örebro University Hospital (USÖ). In our work we have developed a product for hearing tests to determine hearing thresholds of small children. Our product contains software and a control surface for controlling two separate screens. One of the demands was that our software could handle big file libraries. Reliability and simplicity were essential for the user.In our work we have utilized programming of both microcontrollers and Windows software.
Morgondagens effektiva fjärrvärme : En beskrivande litteraturstudie
This report is made as a literature review, focusing on the work done to increase understanding of efficiency in the categories of substations and secondary heating systems, with respect to the deviation from the theoretically possible cooling off in the distribution network as well as the economic benefit that appear. The main purpose of a considerable part of the literature used in this report addresses the issue of identifying individual causes of reduced cooling in district heating systems. These literature resources have been compiled and summarized as part of the report.The technology of district heating is associated with benefits such as better use of the energy in a fuel. This is the case of cogeneration plants where serial generation of electricity and thermal energy increases efficiency compared with the parallel generation where heat is generated locally and electricity is generated centrally. Serial generation thus allows for lower primary energy demand.
Nya trädgårdsväxter för ett allt varmare Sverige
The aim with this work has been to examine the climate changes and what these has meant, and will mean during the present century, for plants that have not been hardy in Sweden. A lot of new species can probably be grown today in Sweden's most southern parts, due to an increase in the average annual temperature by 1?C. There is a need of information about these new species and their hardiness. The insufficient information about the subject has been the background to this work.
Fjärrvärmesystem
This is a report written for an examination project C-level, on the subject of energy. The examination project is a product of the FVB Sweden AB (district heating bureau). It started with a meeting with Stefan Jonsson FVB Sweden AB, were he explained the content of the project, and from this a presentation of the problem was made. The problem that needed to be solved was how they could control the valves in the system to provide heating to everyone in the system. The valves are often oversized so the pump in the heating plant would have to be enormous to be able to provide enough flow to be sufficient, if everyone in the system had there valves fully opened. I came up with two solutions to the problem, one was a wireless network that could keep track of the valves and the other solution was an extra sensor that was placed on the radiator.
Feldiagnos för RM12 baserad på identifierade modeller
The jetengines of today are growing in complexity. Reliability for aircraft engines are of extreme importance, mainly due to safety reasons but also economical ones. This master thesis deals with faultdiagnosis in the turbine section of RM12, the engine used in Saab/BAe's Gripen. Three different faults which can occur in the turbine section was studied. These faults are: clogged fuel nozzle, hole in outlet guide vane and sensor fault.
Energianvändning i serverhallar: energiflöden och kylning
This thesis examines different methods for the cooling of data centers. Several means of cooling with the refrigeration cycle have been studied, as well as the feasibility of using free cooling in different parts of Sweden. In addition, the possibilities of transferring excess heat to a nearby district heating system were investigated. It was found that in all investigated cases except two, the data center could be cooled solely with free cooling for at least 300 days a year when only the outside air temperature was considered as a constraining factor. The limit was then set to 20 °C.The vast majority of all district heating systems in Sweden get little to none of their heat from other excess heat sources.
FAKTORER BAKOM M?GELTILLV?XT P? N??S SLOTT
With climate change, the temperature and relative humidity in Sweden are increasing. The majority of historical environments lack protection against this increase, which also increases the risk of mold infestation in these environments. One of these environments is N??s Slott, in which several rooms have recurring mold growth on objects and furniture. By examining one of the rooms in the castle that is in the risk zone or has mold growth, factors behind the mold growth can be investigated in order to create a basis for future actions against mold.
Kalvhyddans utformning : påverkan på kalvens hälsa och komfort
This paper aims to, through a literature review, examine how to best design and adapt calf huts to meet the calf's physiological requirements and reduce the infection pressure for enteric and respiratory diseases. It illuminates how the calf relates to different temperatures and climate, which temperature control mechanisms it uses and its ability to perform these regulations, as well as providing a summary of the past decades´ research on the calf huts housing system. These two theory chapters, along with a concluding discussion, provide a better understanding of how to, especially in temperate climates, design the most suitable calf hut, which cater to the calf's both thermal comfort and physical health. The literature suggests that the calf's own temperature control works well to counteract the temperature outside the desired range, and that one of the most important factors rather is ventilation of a calf hut, which reduces moisture and pathogens. The conclusion of this paper is mainly that there is not an obvious way to place and construct a calf hutch and that most design principles contribute to both positive and negative effects simultaneously.