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326 Uppsatser om Experiments - Sida 4 av 22

Flödesmätning i vattenkraftverk : Studie av alternativa mätmetoder

Flow measurement is one of the greatest challenges in order to calculate efficiency in hydropower. Most hydropower plants in Sweden use differential pressure methods for flow measurement. These methods are dependent on constant conditions in the waterways. A change in these conditions, like turbine improvements, prevents differential pressure methods to verify efficiency improvements. Since efficiency improvements can?t be verified by one measurement system, another method, which isn?t affected by changing conditions, can be used.

Uppfattningar om laborationens betydelse för utvecklandet av förståelsen i naturvetenskapliga ämnen

SammanfattningLaborationer i naturvetenskapliga ämnen är en naturlig del av undervisningen. Syftet med den här uppsatsen är att ta reda på om man tar bort en möjlighet till inlärning och förståelse för eleverna om laborationer inte används i undervisningen. Vidare ville jag undersöka om lärare och elever anser att laborationer utvecklar förståelsen av naturvetenskap, dessutom om eleverna förstår syftena med laborationerna.Undersökningen utfördes genom att kvalitativa intervjuer gjordes med fyra lärare och sex elever i en gymnasieskola. Resultatet visar att lärarna har olika åsikter om laborationens betydelse för förståelsen av ämnet. Däremot anser eleverna att laborationer utvecklar deras förståelse för naturkunskap.

Söktjänster för akademiskt bruk: En utvärdering av Google och Argos med frågor från en akademisk ämnesdisciplin

The purpose of this MSc thesis is to examine the retrieval effectiveness of two Web search engines with queries from the academic discipline of Classical Studies. The two search engines are chosen to represent two different types Google as a broad general search engine and Argos as a specialised search engine for the subject of Classical Studies. The search engines are compared for precision among the first twenty results returned for thirty queries. In order to avoid bias in the study, the queries are based on real users' information needs. Due to the subjective character of the concept of relevance, the study is performed with five different Experiments with five different definitions of relevance.

Kemin bakom framtidens avgasrening : En studie av ureasönderfall under kvävgasatmosfär

The purpose of this work was to provide a better understanding of urea?s decomposition and byproduct formation in an SCR system on heavy trucks. In my experimental setup with TGA-DSC-FTIR (a combination of two thermal analysis methods and a method for gas phase detection), an FTIR method for urea in the gas phase was developed for the qualitative and quantitative determination of urea and its decomposition products. Chemicals such as urea, biuret, cyanuric acid and melamine of p.a. quality were used in this method development. Beforehand, there was no FTIR method available to detect these substances; hence, the aim of this work was to develop an FTIR method to understand the degradation chain of urea. The combination of TGA and DSC was used for analysis of different samples, where urea, biuret, cyanuric acid and melamine in varying amounts have been weighted in for various Experiments in order to study the temperature at which a phase transition or reaction occurs, i.e.

Utdragshållfasthet av inlimmade skruvar i limträ

In this thesis tests has been performed on the pull strength of screws glued into glulam beams.The experiment is based on the already approved method whereby the diameter of the drilled holes is the same as the screw outer diameter of 1 mm or bigger. The screws strength class shall not be less than 4.6 (EN ISO 898-1:1999, 1999).The difference in the Experiments that were performed where that the drilled diameter were 1 mm smaller than the outer diameter of the screw so that the screw thread was worked into the wood.In the tests the gluing where made on M8 glulam beams. The screws where drilled at and angel of 90°tangental to the fiber direction with a diameter of 7 mm. The gluing of the screws where made in three different depths and where later exposed to pulling forces. The results showed both pulling breaks and screw breaks when they reached their maximum capacity.

Anlockning och gnag av snytbaggar (Hylobius sp.) : effekt av plantstorlek och behandling med metyljasmonat

Two field Experiments were conducted in central Sweden in order to: 1) Determine a relationship between the number of approaching pine weevils (Hylobius sp.) and the number of attacks by pine weevils, in relation to the size of seedlings of Scots pine (Pinus sylvestris). 2) Determine if application of methyljasmonate (MJ) on seedlings of Scots pine will result in higher resistance towards attacks by pine weevils and/or have any effect on the number of approaching pine weevils. The field Experiments were designed with two separate parts in close vicinity on the same clear cuttings: a) pitfall traps placed in patches of scarified soil that caught approaching pine weevils at 2.5 cm from the bait, which consisted of different sized seedlings of Scots pine some of which were subjected to application of MJ and b) the same type of seedlings planted out in patches of scarified soil. The first field experiment was conducted on a 1-year old clear cutting outside Uppsala in east central Sweden and the trapping part of the experiment consisted of 8 blocks with 6 treatments: 1) control, 2) small over-wintered seedling, 3) medium sized seedling, 4) medium sized seedling treated with 0.5 ml 100 mmol MJ 4 days prior to start of experiment, 5) large seedling, 6) vial with 9.5 ml of ?-pinene. The trapping experiment lasted for 6 weeks in the early summer.

Studie utav ett larmsystem ur ett signalteoretiskt perspektiv : Study of a detector by a signal detection theory

In present-day situation many libraries use detectors so that they can be able to prevent attempts too take out books without registering them. The university library in Jonkoping is one of the libraries that have such a detector. But unfortunately it doesn?t always work correct and can also react on other things a part from books. This is a big problem since the library staff don?t have time to check all signals that comes from detector.

Mineraliska material som reaktiva filter för avskiljning av tungmetaller från dagvatten

Highly polluted urban storm water from e.g. highways can contain large amounts of heavy metals that may cause harm if they are discharged into recipients. To remove the heavy metals a possible low-cost method that does not require much maintenance, could be the use of reactive filters with filter materials consisting of industrial residues or other cheap mineral based materials. Dissolved metal ions are removed by reactive filters through the processes of ions binding to active sites on the surface of the filter materials, or by formation of insoluble precipitates.The ability of CaO-treated granulated blast-furnace slag, iron oxide coated sand, olivine and nepheline to remove seven heavy metals (Cr, Cd, Cu, Ni, Zn, Pb and Hg) from urban storm water was studied. Initially batch Experiments were performed where the effect of pH, dissolved organic carbon (DOC) and dissolved ions on the adsorption efficiency was studied.

Effects of biogas residues on respiration and denitrification in arable soil : evaluation of methods, microbial activity and agronomic implications

Agricultural soils constitute the base in human food production and soil content of organic matter and plant nutrients together with soil microbial activity are all important parameters for high crop yield of good quality. These parameters are dependant on proper fertilization.Anaerobic digestion of organic wastes for biogas production generates a liquid residue called biogas residue (BR). It contains organic material and plant nutrients which makes ita potential fertilizer for arable cropping. However, it also contains heavy metals and toxic organic compounds and it is therefore in need of evaluation before usage.Microbial tests were performed aiming to evaluate the agronomic traits of four different BR and to find a viable procedure for evaluating slurry fertilizers. Two Experiments where soil respiration and soil potential denitrification activity (PDA) was measured at fertilizer addition were performed.

Hantering av QoS i Distribuerade MPEG-videosystem

With the advance in computer and network technologies, multimedia systems and Internet applications are becoming more popular. As broadband network is prevailing, more clients are able to watch streaming videos or to play multimedia data over the Internet in real-time. Consequently, there is an increasing demand in the Internet for streaming video systems. As the run-time environment of such applications tends to be dynamic, it is imperative to handle transient overloads effectively. The goal of this work is to develop an algorithm that would provide a robust and controlled behavior of the video system so that important data is delivered on time to the video clients.

Gremmeniella abietina-epidemin 2001 : har skogen återhämtat sig?

The fungus Gremmeniella abietina causes damage to conifers that can lead to tree death. In 1999 and 2001 the pathogen caused severe attacks in Sweden, where about 500 000 ha of pine forest were affected. Trees of all ages were attacked, but mainly forests between 30-60 years that were ready for their first commercial thinning. After recommendations from the forest agency, sanitary fellings were made to trees that had more needle loss than 85%, a total of about 50 000 ha. Economic losses have been estimated to more than one billion SEK.

Försöksmetod för automatisering av kvalitetssäkring av SKB

Within all industries, there is a change in working time required; this also includes the construction sector. However, the way construction sectors are differentiated is by not having been given the opportunity to be practiced or tested.  The aim of this thesis that we have done in collaboration with the Concrete Industry was to investigate the possibility of developing an automated method for quality assurance of SKB at the site. The idea is to make the O-funnel to be more utilized and therefore ensuring that the appropriate concrete quality is provided which eventually would lead to a better development in the production process.The project has involved theoretical work and laboratory Experiments. The theoretical work gave us a good foundation at the beginning of the project. After gathering the information and material, the laboratory Experiments began by SCC in their laboratory in Hammarby. The collected data from the various laboratory tests formed the foundation for trying to relate measurements for consistency of SCC with each other and therefore find out how measurements from O-funnel varies with different concrete mixtures.

Plant defensive mechanisms against insect pests

This study has focused on testing the following two hypotheses:? Pest resistant plants have higher levels and/or several different kinds of secondary metabolites. ? Induced defensive systems in resistant plants are activated more rapidly than those of susceptible plants. As a background for the test of the hypotheses a short literature study was performed concerning plant defensive mechanisms in Arabidopsis thaliana.

Borrning och gängning av laxkilar till vågkraftverk med industrirobot

To make wave power more competitive on the market Uppsala University leads projects that examine how to accomplish better efficiency in the production. One of these projects is described in this report and examines whether it is possible to make the production of dovetails more efficient by using an industry robot of type ABB IRB6000 S3 M91. This project is using an already presented working method, from a previous project, which involves that the robot picks up the dovetail and moves against fixed cutting machines where the dovetail will be drilled, threaded and milled. Drilling and threading are the sub operations that will be examined in this project where Experiments are made with the presented working method and with equipment from Uppsala University.Experiments show whether it is possible to drill the holes in the dovetail within specifications by using the specific robot and the presented working method. The threading operation is examined theoretically if it is possible to accomplish by using the same working method.

Skogsbrandens påverkan på död ved :

Fire is an important ecological factor, but its consumption of coarse woody debris, CWD, has hardly received any attention. In this study, I investigate the consumption in relation to the time of initial flame exposure and propensity for continued combustion of standing CWD of pine (Pinus sylvestris). Two types of CWD were studied. Firstly, wood that had been dead for one to ten years. Secondly, wood that had been dead for several decades. In the burning Experiments, logs of approx.

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