5 resultados para eddy-current
em Dalarna University College Electronic Archive
Resumo:
The report examines the factors which may be a contributing cause to the problems that are present when ferritic stainless steel are eddy current tested in a warm condition. The work is carried out at Fagersta Stainless AB in Fagersta which manufactures stainless steel wire. In the rolling mill there is an eddy current equipment for detection of surface defects on the wire. The ferritic stainless steels cause a noise when testing and this noise complicates the detection of defects.Because of this, a study was made of how the noise related to factors such as steel grade, temperature, size and velocity. By observing the signal and with the possibilities to change the equipment settings the capability to let a signal filter reduce the noise level were evaluated. Theories about the material's physical properties have also been included, mainly the magnetic properties, electrical conductivity and the material's tendency to oxidize.Results from the tests show that a number of factors do not affect the inductive test significantly and to use a filter to reduce the noise level does not seem to be a viable option. The level of noise does not relate to the presence of superficial particles in form of oxides.The ferritic stainless steels showed some difference in noise level. Which noise level there was did match well with the steels probability for a precipitation of a second phase, and precipitation of austenite may in this case contribute to noise when using an eddy current instrument.The noise is probably due to some physical material property that varies within the thread.
Resumo:
Going from having bought the most essential at the small shops close to home, better communications and an increasingly consumption oriented lifestyle has created a change in shopping behavior and has led to phenomenon such as shopping centres and more. These are constantly being built in Sweden: in the cities, outside the cities and more recently even in small cities -small cities as for one reason or another have access to a larger customer base which can have businesses to flourish economically. During the first decade of the 21st century, shopping centres have been established along the Swedish/Norwegian border. Since the Norwegian Krone is much stronger than the Swedish Krona Norwegians save a great deal of money on going to Sweden to shop. During the shopping trips to Sweden, it is mostly alcohol, meat, tobacco and candy that are being bought. However, other products such as clothing, technology, household appliances and more are also being purchased, all to save money on the trip. Together these cross border shoppers spent 11, 6 billion in Sweden during the year of 2010. This gives an average spending of approximately 10 900 SEK per cross border shopper on annual basis. Nordby, Töcksfors and Charlottenberg (small cities located in southwestern Sweden) are places characterized by Norwegian cross border shopping. Together, they generate billions every year and this only seems to increase. These places are relatively small in size but have prominent attributes such as proximity to the Norwegian border. Apart from these resorts and shopping centres, there are few or none similar places near the Norwegian border in the rest of Sweden. However, a place which is geographically well located and has a relatively large Norwegian and Swedish customer base is the ski resort of Sälen in west central of Sweden. Sälen is a village located near the Norwegian border, although fairly sparsely populated. The destination has annually about one million official guest nights, based on the 414 000 visitors who stay an average of about 4, 5 days. Per visit, these tourists individually spend an average of 862 SEK on shopping at the destination. The expenditure of the mountain tourists together with the Norwegian border shoppers makes it very interesting to explore the opportunities for shopping development in terms of a shopping centre in the region of Sälen.
Resumo:
Objective: For the evaluation of the energetic performance of combined renewable heating systems that supply space heat and domestic hot water for single family houses, dynamic behaviour, component interactions, and control of the system play a crucial role and should be included in test methods. Methods: New dynamic whole system test methods were developed based on “hardware in the loop” concepts. Three similar approaches are described and their differences are discussed. The methods were applied for testing solar thermal systems in combination with fossil fuel boilers (heating oil and natural gas), biomass boilers, and/or heat pumps. Results: All three methods were able to show the performance of combined heating systems under transient operating conditions. The methods often detected unexpected behaviour of the tested system that cannot be detected based on steady state performance tests that are usually applied to single components. Conclusion: Further work will be needed to harmonize the different test methods in order to reach comparable results between the different laboratories. Practice implications: A harmonized approach for whole system tests may lead to new test standards and improve the accuracy of performance prediction as well as reduce the need for field tests.
Resumo:
The Swedish upper secondary school has made a transition from a school for the elite to be a school for everybody. When almost every youth nowadays chooses to continue studying, for some of them this is not what they want to do most of all. However, as there in practice is no choice, there come up problems and many upper secondary school teachers experience a growing frustration. We will here discuss some aspects of the following questions: - How do upper secondary schoolteachers handle their working-conditions in a new situation? - What possible consequences do this have on teacher education?