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  • 301.
    Bylund, Kristoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Elnätsautomation i distibutionsnätet: Feldetektering och fjärrstyrning som metoder att förbättre leveranssäkerheten i elnätet2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Att öka leveranskvaliteten i sina elnät är något som varje nätbolag strävar mot. En metod att göra detta kan vara att utrusta nätstationer i mellanspänningsnätet med feldetektering och fjärrstyrning för snabbare felsökning och sektionering vid fel. I denna studie har dessa möjligheter utretts och även de potentiella vinsterna i kortare avbrottstider mätt i indikatorn SAIDI. Studien har resulterat i ett förslag för fortsatt investering i feldetektering och fjärrstyrning i Umeå Energis elnät. Den metod som använts är att beräkna SAIDI för det värsta felscenariot för varje matande linje som tittats på, både med och utan elnätsautomation. Det förslag som tagits fram har utgått ifrån de enskilda matningarna förutsättningar vad gäller kundantal, antal nätstationer och nättopologi och har sedan jämförts med två standardalternativ, med detektering i samtliga nätstationer samt detektering i mitten av linjen. Resultatet visar att det förslag som lämnats till Umeå Energi har potential att sänka det summerade SAIDI-värdet vid värsta felscenario från 37 minuter till 10 minuter i de matningar som undersökts. Detta till en kostnad av mindre än två miljoner kronor, eller en kostnad per potentiellt minskad SAIDI-minut på ca. 70 000 kr. Studien har tittat på 16 matande linjer med totalt ca. 17 000 kunder. 

  • 302.
    Byström, Johan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    En extra fasadskivas effekt på energiprestandan hos ett flerbostadshus: En kontroll av Boverkets krav för nära-nollenergibyggnader till 20212017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Increasing the energy efficiency of buildings and the introduction of more strict regulations are small but important steps towards a better climate. Today the housing and services sector stands for nearly 40 % of Sweden’s energy use. To push the development towards more energy efficient buildings in Europe, all the new buildings are required to be nearly zero-energy buildings by 2021.

    The purpose of this project was to evaluate whether the use of an additional facade board on an apartment building results in putting the energy performance within the current energy performance requirements, and also within the future requirements for nearly zero-energy buildings (NZEBs). The facade boards that were tested in this project are manufactured by Kingspan and Isover. The different boards were tested in thicknesses of 30 and 50 mm. The aim of the project was to calculate the building’s average heat transfer coefficient, specific energy use and primary energy number (PET) using COMSOL Multiphysics (CM) and IDA Indoor Climate and Energy (IDA ICE). The results were then about to be controlled against the current energy performance requirements together with the future requirements for NZEBs.

    The approach of this project consisted of the use of the softwares CM and IDA ICE. Because IDA ICE requires input of the thermal bridges of the building, CM was used to simulate these. This was done in order to achieve more reliable values than if an assumption was made or a standard value was used. A model of the building was then created in IDA ICE where its energy performance and average heat transfer coefficient were obtained from simulations over a normal year.

    The results obtained from the simulations in CM seemed credible as the use of the best facade board caused the values of the thermal bridges to end up at ”Good” according to IDA ICE’s built in scale. The simulations in IDA ICE showed that the specific energy use of the bulding without an additional facade board was 55,9 kWh/m2,year compared to Boverket’s current requirements at 80 kWh/m2,year. With the 50 mm Kingspan facade board, the board with the best result, the specific energy use was reduced to 53 kWh/m2,year, an improvement of 5,2 %. For the case without an additional facade board, the PET was 66,6 kWh/m2,year compared to the NZEBs requirements for 2018 at 85 kWh/m2,year together with the requirements for year 2021 at 65 kWh/m2,year. By using the 50 mm Kingspan facade board the PET was reduced to 63,3 kWh/m2,year, an improvement of 5,0 %. This resulted in putting the PET below the NZEB requirements for 2021. The facade board that resulted in the least energy savings, Isover P31 30 mm, had an improvement of 2,5 and 2,7 % for the specific energy use and the PET respectively. This facade board also resulted in putting the PET below the NZEB requirements for 2021.

    The most obvious conclusions that could be drawn from the simulations was that the specific energy use was below the current energy performance requirements with a great margin, both with and without an additional facadeboard. The PET was well below theNZEB requirements for 2018 and was also belowthe NZEB requirements for 2021 using any of the tested facade boards. The building’s average heat transfer coefficient was also well below both today’s energy performance requirements and the NZEB requirements for 2018 and 2021. A use of an additional facade board resulted in an energy saving of around 2,5 and 5 % in the worst and the best case, respectively. Due to the neglect of the ring wall under the bulding, the energy performance is most probably slightly high. However, this is not of utmost relevance since the company normally does not use this kind of solution for their standard buildings. Other uncertainties about the choice of airflows in property spaces may have influenced the results in the other direction. If there are any other obvious energy saving measures than using an additional facade board, these should be taken into account primarily as a facade board can only reduce the energy use marginally.

  • 303.
    Byström, Jonas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Verifiering av en kontorsbyggnads energianvändning2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis was commissioned by the department Fastighet (Real estate) at Umeå municipality in the spring of 2016. Since Fastighet represents Umeå municipality as landlords they are obliged by the Swedish law (2006:985) energy certification of buildings to declare a building’s energy use within two years after the building started operating.

    In this thesis an investigation was made regarding the energy use of an office building named Kuben, located at the city hall area in Umeå, Sweden. The purpose of the project was to investigate whether the building met the demands regarding its energy use. In addition an analysis was made during the project to indicate the reasons for the discrepancies between the energy consumption for the simulation model in IDA ICE and the measured energy consumption of Kuben in the year of 2015.

    According to the energy balance calculation in IDA ICE, it was found that the building was expected to have a specific energy use (BSE) of 52 kWh/m2,year, while in reality the building had a measured BSE of 91,1 kWh/m2,year in the year of 2015. Therefore Kuben did not fulfill the main requirement of the Green Building which is 90 kWh/m2,year, but it did however fulfill the BBR requirement.

    The reason behind the large deviation in BSE is primarily due to the occupants having used significantly less electricity than expected, combined with a higher use of domestic hot water and higher indoor temperatures than expected. Another detection factor that has further increased the differences is the fact that the ventilation system has been switched on basically around the clock during the year of 2015. Something which is very common during the building’s first year of operation since the building is setting and the construction body is in a dry-phase and emissions are being vented.

    To be able to perform a follow-up on a building’s energy consumption, it is very important to have access to real data of the energy sources included in BSE, in order to really be able to verify whether the building meets the requirement or not. It is also an advantage if there is a possibility to have access to lots of sub-meters, since it makes it easier to determine and verify the causes that lead to deviation between the energy use for the simulation model and measured data.

    It is recommended that a follow-up regarding the buildings energy use should take place during the building’s second year of operation or later, since the first year contains more reasons that can cause deviation and that the BSE is higher than normal because of the complications.

  • 304.
    Byström, Stig
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Berglund, Stefan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kvalitetshöjning med avseende på projektledningsinnehållet i ingenjörs- och civilingenjörsutbildningar2013In: Utvecklingskonferensen för Sveriges ingenjörsutbildningar, 2013, p. 85-88Conference paper (Other academic)
    Abstract [sv]

    Hösten 2010 startade projektet ”Fortbildning av lärare i projektledning” med syftet att ytterligare förbättra kvalitén på ingenjörsutbildningar genom ett tydligare projektledningsinnehåll. Projektet bedrivs vid Institutionen för tillämpad fysik och elektronik (TFE) och strategiska utvecklingsmedel erhålls frånTeknisk-naturvetenskaplig fakultet, Umeå universitet. Vi har utvecklat ett kostnadseffektivt och självbärande koncept där nästan halva kompetensutvecklingstiden betalas genom att deltagaren utför handledning och återkoppling till studenter i en projektledningskurs. Övrig kompetensutvecklingstid i konceptet finansieras av deltagares egna enheter. Projektet pågår fram till juni 2014, hittills har 15 deltagare fortbildats.

  • 305.
    Bäck, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Back-end development of mobile application for the collection of dietary data2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Smartphones are used by incredibly many people, and in 2011 there where a total of 491.4 million units soled worldwide. This makes it a relevant technique for performing dietary studies when the test patients are on the move. This thesis shows how to create a back end environment for an Android application with existing techniques linked together, using MSSQL database, Visual Studio Web Service, web pages and C# classes and ASP.NET security. The back end development is used in a dietary study on Gothenburg University, butcould be applied on many similar back end projects using databases and server development.Techniques used in this thesis are: REST (Representational State Transfer) -client implementation and development inside the Android application, using HTTP methods to set and get information from the server and database, and JSON-format to read and transferinformation in an easy and understandable way, both from the Android application and from the database. FileMaker is also used in this project as a third part programme tovisualise the information in the database.

  • 306.
    Bäck, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Back-end development of mobile application for the collection of dietary data2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Smartphones are used by incredibly many people, and in 2011 there where a total of 491.4million units soled worldwide. Smartphones are known as advanced phones, or personal digital assistants (PDAs). This makes a relevant technique for performing dietary studies when the test patients are on the move. This thesis shows how to create a back end environment for an Android application with existing techniques linked together, using MSSQL database, Visual Studio Web Service, web pages and C# classes and ASP.NET security.The back end development is used in a dietary study on Gothenburg University, but could be applied on many similar back end projects using databases and server development.Techniques used in this thesis are: REST (Representational State Transfer) -clientimplementation and development inside the Android application, using HTTP methods toset and get information from the server and database, and JSON-format to read and transfer information in an easy and understandable way, both from the Android application and from the database. FileMaker is also used in this project as a third part programme to visualise the information in the database.

  • 307.
    Bäcklund, Johannes
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energieffektivisering av fjärrvärme- och fjärrkylanätet på campus i Umeå: Energy efficiency of the district heating and cooling systems on campus in Umeå2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete utfördes på uppdrag av Akademiska Hus som äger och förvaltar fastigheterna på campus i Umeå. Projektet bestod av att utifrån en övergripande bild på det interna fjärrvärme- och fjärrkylanätet på campus, ta fram alternativa utformningar på systemet i syfte om att göra det mer energieffektivt.

    Systemets interna fjärrvärme- och fjärrkylanät VP100 och KB100 växlar över värme och kyla från Umeå Energi som sedan distribueras vidare till fjärrvärme- och fjärrkylacentraler på campus. Några av centralerna har egenproduktion där returledningen från KB100 går till en värmepump som producerar både värme och kyla. Producerad värme används till att förvärma returledningen från uppvärmningssystemen från de byggnader som hör till respektive central. När behovet av värme är tillräckligt stort är systemet, tack vare värmepumparna, självförsörjande gällande kyla. Produktion sker alltså endast under de perioder då det finns behov i uppvärmningssystemen. Det leder till att systemet tvingas köpa både värme och kyla samtidigt under sommaren då behovet av kyla i stort sett är konstant under året.

    Två alternativa utformningar till det befintliga systemet har undersökts. Det första fallet har som syfte att reducera värmeförlusterna i VP100. Det andra fallet byggdes vidare på det första fallet med syftet att utvidga arbetsområdet för värme- och kylproduktionen i värmepumparna.

    Resultatet visar att det finns potential att mer än halvera värmeförlusterna i det befintliga VP100 och att produktionen av värme och kyla skulle kunna öka med 10 % respektive 6 %. Totalt skulle systemet kunna spara drygt 1,3 miljoner kWh per år genom en kombination av de två alternativa utformningarna. För att däremot få energibalans i systemet där det aldrig behöver köpas både värme och kyla samtidigt bör andra effektiviseringsåtgärder övervägas. 

  • 308.
    Bäcklund, Tomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Development and validation of a system for clinical assessment of gait cycle parameter in patients with idiopathic normal pressure hydocephalus2013Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A number of parameters have been identified as characteristic of the walking pattern in patients with INPH. Most of these have been identified through qualitative surveys and manually conducted test batteries. In order to obtain quantitative, standardized and objective measures, which enable studies based on larger patient populations and comparable results, there is a need for a user-friendly system that can measure specific key parameters over time in a reliable manner in everyday clinical work. Step height, width and the variability in the gait cycle are such parameters which are interesting research areas for this group of patient.

    Problems with balance and gait are very common in other patient groups as well, particularly in neurological diseases such as Parkinson's disease, multiple sclerosis and stroke.

    This is the reason that the development of this gait analyzer is performed. Giving access to a simple and objective method for estimating gait and balance ability in clinical routine investigations would increase the ability to provide the right kind of treatment, confirm treatment results, and conducting larger research studies. Therefore, this equipment can contribute to the assessment of diseases which contain impaired gait. As a first test of the usability and for the validation of accuracy and repeatability of the equipment a group of healthy volunteers was used. Results from tests on healthy subjects show god repeatability between measurements, for step width at normal gait the difference was -0,2 ±0,34 cm (mean, ±SD) and step height 0,69 ±3,34 cm. The stride time variability in the healthy group where very small 0,00048 ±0,00028 s2 with a difference between test of 0,000019 ±0,00038 s2. Three pilot patients have been tested where we have clearly seen indications of increased stride time variability and reduced step height.

  • 309.
    Bäcklund, Tomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Konstruktion av tryckförstärkare2013Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 310.
    Bäckström, Johan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Optimerad värmeleverans från Hedensbyverket2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Skellefteå Kraft AB has currently problems with the central district heating network in Skellefteå concerning low pressure difference between the delivering, hot, and returning, cold, pipeline. Cause of this low so called differential pressure, the customers heating requirements in these areas is not fulfilled in a satisfying way. The intent of this project has been, with the use of simulations, to clarify if a solution can be possible by connecting an increasing pressure pump to the district heating network. A pumpstation will be placed in such a way that it improves the ability to control the pressurization of the district heating pipelines and also makes it possible to distribute more heat from Hedensbyn, where the main production of district heat in Skellefteå takes place. Determine if the increase in pressure may result in an increase in electricity production, by lowering the temperature of the outgoing water.

    The result is this project shows that placing a pumpstation at Moröskolan is the most advantageous position. An increasing pressure pump at Moröskolan in Skellefteå would create more favourable conditions in order to control the pressure in the district heating network and maintain a minimum differential pressure. The simulations made shows that with a pumpstation, it is possible to distribute up to 20 MW more heat from the Hedensbyn. A pressure increase in the district heating network would currently allow for an increase in electricity distribution of approximately 4-5,5 GWh/year. Based on these results, the project concerning the pump is planned to begin during spring 2011.

  • 311.
    Bäckström, John
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Intellus360 Push -Mobilitet där det behövs2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Intellus AB has a large need to inform users when their monitoring software finds erroneous behavior in the monitored processes. To provide such service to the users, an application for mobile devices has been developed during the course of this project. High demands have been that the application must be available on both iOS-devices and Android operated devices. The primary priority in the actual implementation has been to notify the devices as fast as possible when an alert has occurred. Other high priorities has been to make the user experience as pleasant as possible with easy navigated applications and stability, the applications are not allowed to crash when used by a user. During development concepts like APNs- and C2DM-messages, XML document and HTTP requests has been evaluated.The result from the project involves two applications, one for iOS devices and one for Android devices, and a server environment to handle messages. The both applications have the same functionality where a message is pushed with Apples APN-framework and Google’s C2DM-framework to the devices. When the user sees the message and chooses to investigate more, all the data about the message is downloaded with an HTTP request as an XML document.In the end of the report future work is discussed and an example from the discussion is that it would be good to implement a search functionality to let the user search for specific messages on the server.

  • 312.
    Bäckström, Lars
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Guilloux, Tom
    Fusing Kite and Tether into one Unit2017In: Airborne Wind Energy Conference 2017: Book of Abstracts / [ed] Moritz Diehl, Rachel Leuthold, Roland Schmehl, Freiburg, Germany: Albert-Ludwigs-Universität Freiburg; Delft University of Technology , 2017, p. 40-41Conference paper (Refereed)
  • 313.
    Bäckström, Marcus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pneumatisk Dragprovmaskin: För uppmätning av separationskrafter för skogsplantor från deras kassetter i samband med plantering vid olika förhållanden.2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Bracke Forest AB tillverkar maskinella planteringsaggregat som utvecklas för en modernare och en mer noggrann skogsplantering. Deras planteringsaggregat har ett begränsat antal platser i hållaren som lagrar plantorna innan de sätts i marken. Aggregatet laddas med nya plantor manuellt av skogsmaskinens operatör, där en planta flyttas från dess kassett till hållaren. En process som Bracke Forest AB planerar att förändra på nästa generations planteringsmaskiner.

    Syftet med detta examensarbete är att ta reda på vilka krafter som uppstår vid lyft av planta från dess kassett, vilket ska ligga som underlag vid utvecklingen. I detta examensarbete testas olika kassetter där snabba och långsamma hastigheter jämförs vid blöta och återbevattnade förhållanden, för att ta reda på vilken kassett som lämpar sig bäst för automatisk hantering. Examensarbetet begränsas till gran och tall där de tre kassetterna Hiko, Jackpot och Starpot från respektive skogsbolag analyseras.

    En egenkonstruerad pneumatisk dragprovmaskin tillverkas och med hjälp av en analog tryckgivare registreras tryckskillnaden via ett styrkort, Arduino Mega 2560. Tryckskillnaden beräknas om till kraft och ett resultat i form av tabeller och diagram tas fram. För att kontrollera att den egenkonstruerade dragprovmaskinen redovisar relevanta resultat används en befintlig dragprovmaskin som referens. Detta examensarbete berör pneumatik, 3D-konstruktion i Solidworks, elektronik, Arduino programmering, tillverkning och grafisk analys av analog signaldata.

    Resultatet från dragproven visar att Starpot kassetten kräver minst medelkraft för lyft av en planta från dess kassett. På grund av att rötterna för både Starpot och Jackpot kunde fastna i kassetten och gå av vid dragningarna är rekommendationen att använda Hiko-kassetten, då dess plantor kan dras vid olika hastigheter utan att rotdelning uppstod.

  • 314.
    Bäckström, Simon
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Dagsljusinsläpp genom fasad: Undersökning av fönsterlösning med reflekterande ljushylla2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Buildings are constantly developing and becoming more energy efficient. This progress is partly down to building regulations forcing constructions to be better insulated, but also by using more energy efficient materials. In modern energy efficient buildings the windows are a great cause for concern. They contributes to heat loss, and if not shaded in a good way they can increase the needs for additional cooling during summer. Well planned property fenestrations can decrease the window area and thereby minimizing energy loss through windows.

     

    In the project Kub och Länk in Umeå, Link arkitekture has created a fenestration solution with a light shelf. The purpose of the light shelf is to help increase daylight transport further in to the building. This report investigates the window positioning and analyses the benefits of the light shelf.

     

    Velux daylight visualizer is used to analyze the building through computer analysis. Simulations were made in both clear and overcast skies analyzing, luminance, illuminance and daylight factor.

     

    The analyses of the daylight factor showed that the original solution was good enough to reach the gold level of Miljöbyggnad. Further simulations of the different fenestrations showed that this was not likely a result of the light shelf itself. In fact, most result indicated that the light shelf was shading the room more than lighting it and therefore created less use of the window area than regular window solutions.

  • 315.
    Bäckström, Tove
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Large digital screen as a corporate communication channel: Enhancing the dissemination of information, administration and interaction2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Public areas are more and more equipped with digital screens that are used to inform or promote a particular product. This is a way to communicate with the people on that area. The idea is to get people's attention, make them read and take in information and possibly buy the product that is marketed. This type of digital display is called digital signage and can also be used as an information channel of a company where information directed to employees and visitors is displayed. CGI Östersund has a screen placed in their office that works as such an information channel.

    This thesis is about investigating and analyzing the current presentation and creating a new solution with a custom interface that will be more effective and engage more people.

    The new solution is interactive and clickable with the help of a mouse. A user study has been done using a Kinect sensor to see how many people are watching the screen, how long they look at the screen and from what distance. This data was also supplemented by a survey sent to the employees at CGI Östersund. The result of the user study shows that there was no significant difference between the previous solution and the new one. This may be due to two main reasons: the lack of time in which the experiment was performed and the location of the digital screen that is not currently optimal.

  • 316.
    Bäfver, Linda
    et al.
    Pöyry SwedPower.
    Renström, Caroline
    Pöyry SwedPower.
    Fahlström, Johan
    Ragn-Sells.
    Enfält, Patrik
    EasyMining Sweden.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Holmén, Erik
    ENA Energi.
    Slambränsleblandningar: Förbränning och fosforutvinning2013Report (Other academic)
    Abstract [en]

    For sustainable phosphorus recycling, the phosphorus in sewage sludge needs to be recovered, as it is a major phosphorus-source. However, all sludge is not suitable for direct recycling on agricultural land, e.g. when the content of heavy metals is too high. To achieve an increased recycling of phosphorus from sewage sludge there is a need of research and development of alternative methods to return the phosphorus from sewage sludge to agricultural land.

    The aim of the project is to show that sewage sludge can be co-combusted with demolition wood in existing boilers, and that the ash can be processed for extraction of phosphorus, together with valuable by-products from the process. Further effects of the project will be the development of new knowledge about combustion with a high sludge to demolition wood ratio in a grate boiler (up to 45 % sludge with respect to wet mixture), which has not been studied in full-scale combustion earlier. The project's goal is to demonstrate mixing and combustion of fuel mixtures of sludge and demolition wood, and subsequent extraction of phosphorus from ash. The target groups for this work are energy companies, suppliers of grate boilers, municipalities, wastewater treatment plants and authorities.

    The project involves the mixing of sewage sludge and demolition wood, combustion-tests of the fuel mixtures and laboratory experiments on bottom ash and fly ash for phosphorus extraction using EasyMining Sweden's method for phosphorus extraction from ash. Extensive analyses have been carried out on fuel, bottom ash and fly ash, as well as thermodynamic equilibrium calculations on the formed compounds containing phosphorus.

    The experience of preparing sludge fuel mixtures shows that the mixtures should be prepared in the near future to when they are to be combusted, to avoid a composting process in the fuel. The project shows that it is possible to combust sludge fuel mixtures with an admixture of up to 45 % sludge relative wet fuel, in an existing grate boiler during one day. However, to combust sludge fuel mixtures over a longer period of time and at a higher load, modifications of the de-ashing system and the flue gas cleaning system are needed. The results indicate a reduced tendency of slagging on the fuel bed at the combustion of sludge mixtures. The analyses of the fly ash showed a trend towards less corrosive ash at combustion of sludge mixtures. The phosphorus content in the ash in this work was 3-4 %. For process economics and from the phosphorus extraction point, as high phosphorus content as possible in the ash is preferable. Higher phosphorus content can be accomplished by mixing sludge with a fuel with lower ash content than demolition wood, co-combustion with a fuel with higher phosphorus content than demolition wood, or by increasing the percentage of sewage sludge in the fuel mixture. Still, a higher proportion of sludge in the mixture would require a higher dry matter content of the sludge in order to get proper combustion conditions. It is primarily bottom ash that is suitable for phosphorus extraction using Easy Mining Sweden's method. If fly ash are to be used for phosphorus extraction, an optimization of the dissolution conditions is required, which was not included in this project. In this project, phosphorus is extracted as ammonium phosphate. The purity of ammonium phosphate is very high, which means that unwanted substances and heavy metals in sewage sludge will not be returned to contaminate fields.

  • 317.
    Bååth, Johanna
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Evaluating University course search: - development of a new user-centred interface concept2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Findwise is a Europe-wide producer of search solutions. One of their search solutions included a university course search interface, which needed revision due to a loss of coherence in the structure. This had negative impact on the simplicity and usability. The thesis describes a process for improving the interface design and user-friendliness of the course search. The search interface previously developed by Findwise have been studied and evaluated in order to develop and bring forward a proposal for a new interface design mock-up. In addition to this, two areas have been explored in more detail; search engines and Human computer interaction methods.

    The resulting proposal consist of usable methods for structuring course search interfaces, creating a more intuitive new design.

  • 318.
    Cabral, Regis
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    QoE: Quality of Experience: a conceptual essay2007In: Integration and Innovation Orient to E-Society, Vol 2: Seventh IFIP International Conference on e-Business, e-Services, and e-Society (13E2007), October 10–12, Wuhan, China / [ed] Weijun Wang, Yanhui Li, Zhao Duan et al, New York: Springer-Verlag New York, 2007, Vol. 252, p. 193-199Conference paper (Refereed)
    Abstract [en]

    The ICT industry and services are on the verge of substituting quality of service and utility functions; with quality of experience, QoE. While intuitive, QoE, has eluded the research community. QoE takes into account what the user is experiencing with new products and services. Once this information is collected, it becomes an input in the development of the new product or new service. But how does one measure directly quality of experience? In this conceptual paper, I discuss from an ICT perspective, the utility function and quality of service, QoS. I also present how active interested the industry is in QoE. I concluded with some key points that may serve as a guideline in the process of constructing the QoE function.

  • 319.
    Candefjord, Stefan
    et al.
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Nyberg, Morgan
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Jalkanen, Ville
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ramser, Kerstin
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Lindahl, Olof
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Combining fibre optic Raman spectroscopy and tactile resonance measurement for tissue characterization2010In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 21, no 125801, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Tissue characterization is fundamental for identification of pathological conditions. Raman spectroscopy (RS) and tactile resonance measurement (TRM) are two promising techniques that measure biochemical content and stiffness, respectively. They have potential to complement the golden standard-–histological analysis. By combining RS and TRM, complementary information about tissue content can be obtained and specific drawbacks can be avoided. The aim of this study was to develop a multivariate approach to compare RS and TRM information. The approach was evaluated on measurements at the same points on porcine abdominal tissue. The measurement points were divided into five groups by multivariate analysis of the RS data. A regression analysis was performed and receiver operating characteristic (ROC) curves were used to compare the RS and TRM data. TRM identified one group efficiently (area under ROC curve 0.99). The RS data showed that the proportion of saturated fat was high in this group. The regression analysis showed that stiffness was mainly determined by the amount of fat and its composition. We concluded that RS provided additional, important information for tissue identification that was not provided by TRM alone. The results are promising for development of a method combining RS and TRM for intraoperative tissue characterization.

  • 320.
    Candefjord, Stefan
    et al.
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Nyberg, Morgan
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Jalkanen, Ville
    Umeå University, Faculty of Science and Technology, Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics.
    Ramser, Kerstin
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Lindahl, Olof
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Evaluating the use of a Raman fiberoptic probe in conjunction with a resonance sensor for measuring porcine tissue in vitro2009In: IFMBE Proceedings of the World Congress on Medical Physics and Biomedical Engineering, Heidelberg: Springer , 2009, p. 414-417Conference paper (Refereed)
    Abstract [en]

    Prostate cancer is the most common form of cancer and is the third leading cause of cancer-related death in European men. There is a need for new methods that can accurately localize and diagnose prostate cancer. In this study a new approach is presented: a combination of resonance sensor technology and Raman spectroscopy. Both methods have shown promising results for prostate cancer detection in vitro. The aim of this study was to evaluate the combined information from measurements with a Raman fiberoptic probe and a resonance sensor system. Pork belly tissue was used as a model system. A three-dimensional translation table was equipped with an in-house developed software, allowing measurements to be performed at the same point using two separate instruments. The Raman data was analyzed using principal component analysis and hierarchical clustering analysis. The spectra were divided into 5 distinct groups. The mean stiffness of each group was calculated from the resonance sensor measurements. One of the groups differed significantly (p < 0.05) from the others. A regression analysis, with the stiffness parameter as response variable and the principal component scores of the Raman data as the predictor variables, explained 67% of the total variability. The use of a smaller resonance sensor tip would probably increase the degree of correlation. In conclusion, Raman spectroscopy provides additional discriminatory power to the resonance sensor.

  • 321.
    Candefjord, Stefan
    et al.
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Nyberg, Morgan
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Jalkanen, Ville
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Ramser, Kerstin
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Lindahl, Olof
    Dept. of Computer Science and Electrical Engineering, Luleå University of Technology.
    Kombinationsinstrument för detektering av prostatacancer: korrelation mellan resonanssensor och fiberoptisk Ramanprobe2009In: Medicinteknikdagarna 2009, Svensk förening för medicinsk teknik och fysik , 2009, p. 60-Conference paper (Refereed)
  • 322.
    Cao, Guoqing
    et al.
    Tianjin University.
    Tu, Guangbei
    Tianjin University.
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Study of optimum horizontal shading device dimensions for energy saving in residential buildings2006In: Taiyangneng Xuebao, Vol. 27, no 1, p. 96-100Article in journal (Refereed)
  • 323. Capablo, Joaquin
    et al.
    Arendt Jensen, Peter
    Hougaard Pedersen, Kim
    Hjuler, Klaus
    Nikolaisen, Lars
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Frandsen, Flemming
    Ash properties of alternative biomass2009In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, p. 1965-1976Article in journal (Refereed)
    Abstract [en]

    The ash behavior during suspension firing of 12 alternative solid biofuels, such as pectin waste, mash from a beer brewery, or waste from cigarette production have been studied and compared to wood and straw ash behavior. Laboratory suspension firing tests were performed on an entrained flow reactor and a swirl burner test rig, with special emphasis on the formation of fly ash and ash deposit. Thermodynamic equilibrium calculations were performed to support the interpretation of the experiments. To generalize the results of the combustion tests, the fuels are classified according to fuel ash analysis into three main groups depending upon their ash content of silica, alkali metal, and calcium and magnesium. To further detail the biomass classification, the relative molar ratio of Cl, S, and P to alkali were included. The study has led to knowledge on biomass fuel ash composition influence on ash transformation, ash deposit flux, and deposit chlorine content when biomass fuels are applied for suspension combustion.

  • 324.
    Carlborg, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Exposure studies of refractory materials for biomass gasification2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Gasification is a technology mostly used to convert fossil feedstock to syngas. Biomass could be used as a feedstock instead but that puts different demands on, among other things, the materials in these reactors.

    In this work, two candidate materials for the inner lining in biomass gasifiers (63 and 85 weight percent Al2O3) have been exposed to three synthetic ashes, K2CO3-CaCO3-SiO2, K2CO3-CaCO3 and K2CO3 at 1050°C in CO2 atmosphere for 7 days in a muffle furnace to reproduce analogous chemical attack that would occur in a real gasifier. Samples were investigated with SEM-EDX for morphological and compositional effects and with XRD for crystalline phases at chosen distances from the exposed surface.

    A heterogeneous melt that prevented deep penetration of alkali was produced when Si was present in the ash composition. In the absence of Si, it turned out that only K was affecting the materials. K attacked the matrix and transported into the material and attacking grains. For the material containing more alumina potassium was found in continuously decreasing amounts down to 7-8 mm from the exposed surface. The other material showed a distinct border between affected and pristine matrix about 5 mm from the exposed surface. The affected part seemed to have been filled out and signs of expansion could be seen. The XRD analysis of the pristine and exposed refractories revealed significant differences. In the exposed ceramics the new phases; Leucite, Kalsilite, Kaliophilite, K(2-x)Al(2-x)SixO4 and Wollastonite were observed.

  • 325.
    Carlborg, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Refractory corrosion in biomass gasification2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To stop the net emission of CO2 to the atmosphere, we need to reduce our dependency of fossil fuels. Although a switch to a bio-based feedstock hardly can replace the total amount of fossils used today, utilization of biomass does still have a role in a future in combination with other techniques. Valuable chemicals today derived from fossils can also be produced from biomass with similar or new technology. One such technique is the entrained flow gasification where biomass is converted into synthesis gas. This gas can then be used as a building stone to produce a wide range of chemicals.

    Slagging and corrosion problems are challenges presented by the ash forming elements in biomass during thermochemical energy conversion. The high temperature in the entrained flow process together with ash forming elements is creating a harsh environment for construction materials in the reactor. Severe corrosion and high wear rates of the lining material is a hurdle that has to be overcome to make the process more efficient.

    The objective of this work is to investigate the nature of the destructive interaction between ash forming elements and refractory materials to provide new knowledge necessary for optimal refractory choice in entrained flow gasification of woody biomass. This has been done by studying materials exposed to slags in both controlled laboratory environments and pilot scale trials. Morphology, elemental composition and distribution of refractories and slag were investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy. Crystalline phases were investigated with X-ray diffraction, and thermodynamic equilibrium calculations were done in efforts to explain and make predictions of the interaction between slag and refractory.

    Observations of slag infiltration and formation of new phases in porous materials indicate severe deterioration. The presence of Si in the materials is limiting intrusion by increasing the viscosity of infiltrated slag. This is however only a temporary delay of severe wear considering the large amount of slag that is expected to pass the refractory surface. Zircon (or zirconium) (element or mineral?) based material show promising properties when modeled with thermodynamic equilibrium, but disassembling of sintered material and dissociation of individual grains was seen after exposure to a Si- and Ca-rich slag. Fused cast materials have a minimal slag contact where the only interaction is on the immediate hot face. Dissolution was however observed when exposed to a silicate-based slag, as was the formation of NaAlO2 after contact with black liquor.

  • 326.
    Carlborg, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Landälv, Ingvar
    Characterization of spent spinel-based refractory lining from a 3 MW black liquor gasifierManuscript (preprint) (Other academic)
    Abstract [en]

    Black liquor gasification is dependent on minimizing heat loss to the surroundings and thus needs to be well insulated. In combination with the high temperature and basic black liquor, a very corrosive environment is created on the hot face of such a reactor. Therefore the wall system is required to be chemically and thermally stable at the same time as it has insulating properties. These cannot easily be combined in the same material and therefore layers with different properties can be used in combination. Penetration of species through the lining can lead to further reactions with other construction materials, less suited for chemical resistance, corrosion of the pressure shell is an example with catastrophic consequences. This paper investigates two castable and one fused cast spinel (MgAl2O4) refractory after about 1 600 hours, and one fused cast material used for 15 000 hours of operation in a 3 MWth black liquor gasifier. Infiltration of Na, followed by destruction of microstructure, and extensive formation of NaAlO2 was observed throughout the whole castable materials, while it was mainly restricted to the hot face of the fused cast materials. Formation of NaAlO2 leads to a volumetric expansion which eventually lead to an increased pressure on the steel shell. In addition, the expansion of the bricks can cause stress and by that spallation and material loss.

  • 327.
    Carlborg, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kannabiran, Sankar
    Höganäs Bjuf AB.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Interaction between ash forming elements in woody biomass and two high alumina refractories part 1: effects on morphology and elemental distributionManuscript (preprint) (Other academic)
    Abstract [en]

    To gain more knowledge about possibly destructive effects of ash-forming elements in woody biomass on refractory materials in entrained flow gasification, an exposure study was performed on two high alumina refractories. The materials, a pre-fired castable consisting of about 63 weight-% Al2O3, and a phosphate bonded brick with 83 weight-% Al2O3 was exposed to synthetic ash mixtures at 1050°C and 1 atm CO2 for 7 days. This paper presents distribution of ash-forming elements and morphology of the samples microstructure, while identification and distribution of crystalline compounds is presented in a separate paper. In the samples, potassium (K) had infiltrated the materials and reacted with different components, while calcium (Ca) did not seem to have any direct effect during these conditions. The matrix of the castable absorbed much K, became clogged and produced a distinct border between reacted and unaffected matrix. The coarser matrix of the phosphate bonded brick retained much of its porosity and had ash transported further into the material without a clear distinction between reacted and unaffected matrix. Grains with >30 atomic-% Si, formed a layer enriched in K, with a thickness up to 40 µm and cracks propagating through it. Grains mainly consisting of Al2O3 seemed unaffected by the exposure. When the ash was rich in SiO2, a melt was produced that restricted the attack on the refractories to the surface and coarser pores.

  • 328.
    Carlborg, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kannabiran, Sankar
    Höganäs Bjuf AB.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Interaction between ash forming elements in woody biomass and two high alumina refractories part 2: transformation of crystalline compoundsManuscript (preprint) (Other academic)
    Abstract [en]

    Two high alumina refractories, one brick and one pre fired castable was exposed to pure K2CO3, K2CO3 + CaCO3, and K2CO3 + CaCO3 + SiO2 at 1050°C and a CO2 atmosphere. A stratified investigation of crystalline phases was made with polycrystalline x-ray diffraction, and thermodynamic equilibrium calculations were performed to explore possible formation paths. A monoclinic polymorph of KAlSiO4 was formed to a large extent in both materials exposed to pure K2CO3. Throughout the affected part of the castable and a small layer close to the surface of the brick, a solid solution between KAlO2 and KAlSiO4 formed, K1-xAl1-xSixO2, x = 0.19. The affected area of the castable had 30-50 %wt new phases and made a sharp transition to unaffected material. The concentration of new phases in the brick was decreasing at an even rate from about 40 to 15%wt throughout the whole material thickness of 14 mm. Exposure to K2CO3 and CaCO3 showed the same phases and behavior, but no Ca-bearing phases could be detected. The mixture containing K2CO3, CaCO3 and SiO2 did not penetrate far into the material but formed the same phases in the affected areas. Wollastonite (CaSiO3) formed in the slag on top of these materials. The major mechanism for formation of new phases is suggested to be the formation of an initial melt composed of K2O and SiO2. This liquid is then dissolving refractory components and forms a liquid in equilibrium with KAlSiO4 and K1-xAl1-xSixO2.

  • 329.
    Carlborg, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Weiland, Fredrik
    Ma, Charlie
    Backman, Rainer
    Landälv, Ingvar
    Wiinikka, Henrik
    Exposure of refractory materials during high-temperature gasification of a woody biomass and peat mixture2018In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 38, no 2, p. 777-787Article in journal (Refereed)
    Abstract [en]

    Finding resilient refractory materials for slagging gasification systems have the potential to reduce costs and improve the overall plant availability by extending the service life. In this study, different refractory materials were evaluated under slagging gasification conditions. Refractory probes were continuously exposed for up to 27 h in an atmospheric, oxygen blown, entrained flow gasifier fired with a mixture of bark and peat powder. Slag infiltration depth and microstructure were studied using SEM EDS. Crystalline phases were identified with powder XRD. Increased levels of Al, originating from refractory materials, were seen in all slags. The fused cast materials were least affected, even though dissolution and slag penetration could still be observed. Thermodynamic equilibrium calculations were done for mixtures of refractory and slag, from which phase assemblages were predicted and viscosities for the liquid parts were estimated.

  • 330.
    Carlborg, Ylva
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash transformation during combustion of phosphorus-rich industrial sludge: Investigation of phosphorus recovery potential, and effects on emissions and deposit formation 2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Effective use of resources is essential in the development towards a sustainable industry. Waste products, such as sludge from industrial waste water treatment, often contain valuable reserves of plant nutrients but this resource is nonetheless commonly disposed of as contaminated waste.  Approximately 1 500 ton phosphorus per year is added in biological waste water treatment at the Swedish pulp and paper industries and this non-renewable resource thereby ends up in their so called biosludge. The most common way to discard the sludge is by incineration. Besides the high levels of phosphorus, the biosludge usually contains high levels of moisture and ash forming elements, sulfur and chlorine, which makes it a rather problematic fuel.

    The aim with this study was to investigate different aspects on ash transformation chemistry during co-combustion of biosludge, from the pulp and paper mill SCA Packaging Obbola AB, with wood fuels and wheat straw. The phosphorus recovery potential, and the effects on deposit formation and emissions,  were examined by SEM-EDS- and XRD-analysis of ash from co-combustion experiments. The experimental results were complemented with theoretical analysis based on thermochemical equilibrium calculations.

    The biosludge from SCA Obbola contained high levels of Ca which had a large impact on the ash transformation reactions. Most of the phosphorus from the fuels stayed in the solid ash during combustion, and in all ash assortments, except for the pure wood fuel, it was primarily found in the crystalline structure whitlockite, Ca9(K,Mg,Fe)(PO4)7. Hydroxyapatite, Ca5(PO4)3OH, was identified in ash from combustion of the pure wood fuel and wheat straw, and in the mixture of biosludge and wood fuels with the lowest proportion of sludge. Of the two phosphorus compounds, hydroxyapatite is more difficult to break down. It is therefore promising from a phosphorus recovery perspective that whitlockite was the main phosphorus compound in most of the ash assortments. Some of the sulfur in the sludge reacted with Ca and formed solid CaSO4, which stayed in solid ash during combustion, while chlorine generally left the bottom ash by volatilization.

    K- and Si-rich agricultural residues, such as wheat straw, are associated with a number of ash-related problems, including deposit formation due to low ash-melting points. During co-combustion of biosludge and wheat straw, the melting tendencies of the wheat straw ash elements were examined. According to the thermochemical equilibrium calculations, the composition of the mixed fuels would result in a significantly higher initial slag formation temperature compared to the pure wheat straw. This trend was also observed in the experimental results. It is likely that the relatively high levels of Ca, Al and P in the sludge all contributed to reduced slag formation in the wheat straw ash, by formation of ash compounds with higher melting temperatures. The high calcium levels may however have reduced some of the positive effects of increased P and Al contents by these elements preferably reacting with Ca instead of capturing alkali in crystalline structures.

  • 331.
    Carleborg, Mattias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Elanvändning i skolkök2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 332.
    Carlqvist, Freddy
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Studie och analys av energieffektiviserande åtgärder på sjukhus i Västra Götalandsregionen2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Västfastigheter är en av Västsveriges största fastighetsförvaltare och förser Västra Götalandsregionen med lokaler samt fastighetsförvaltning. Västra Götalandsregionen har som långsiktigt miljömål att halvera sin energianvändning i egna lokaler till år 2030 jämfört med år 1995. Ett led i att nå detta mål har varit att genomföra energikartläggningar på sjukhusbyggnader för att lokalisera energieffektiviserande åtgärder som kan genomföras för att reducera energianvändningen. Beskrivning av de energieffektiviserande åtgärder som föreslagits samt beräknad kostnad och energibesparing för dessa har dokumenterats i en databas. Energibesparingen för de energieffektiviserande åtgärderna i databasen har bland annat beräknats med simuleringsprogrammet IDA ICE.

    Syftet med detta examensarbete var dels att studera, strukturera och analysera det material som finns i databasen. Detta har gjorts genom att kategorisera de energieffektiviserande åtgärderna i databasen i tre huvudkategorier; driftoptimerande-, installationstekniska- samt byggnadstekniska åtgärder. Därefter har statistik för enskilda åtgärder tagits fram i form av medelvärde för respektive åtgärdskategori för att indikera vilka typer av enskilda åtgärder i databasen som ger den största energibesparingen samt är mest kostnadseffektiva. Resultatet från detta indikerar att de enskilda åtgärder i databasen som är av driftoptimerande karaktär är mest kostnadseffektiva, därefter följer installationstekniska åtgärder och sist åtgärder av byggnadsteknisk karaktär. För att även behandla de åtgärder som endast genomförs som åtgärder i åtgärdspaket, har kostnads- och energibesparingskurvor tagits fram för Skaraborgs Sjukhus Skövde (tidigare KSS - Kärnsjukhuset i Skövde). Resultatet indikerar att de åtgärder som förslagits för byggnad 4-6 samt 22-24 på KSS ger den största energibesparingen till lägst kostnad per sparad kilowattimme. Slutsatsen är att det är en god idé att ta fram liknande kurvor för de övriga sjukhusen, då dessa kurvor ger en indikation om vilka byggnader som bör prioriteras vid energieffektivisering.

    Syftet var även att undersöka hur en osäkerhet hos parametrar vid energibesparingsberäkningar påverkar resultatet samt undersöka interaktionseffekter för energieffektiviserande åtgärder. En modell av byggnad 16 på Södra Älvsbords Sjukhus i Borås har i detta examensarbete simulerats i IDA ICE för att undersöka inverkan av interaktionseffekter då flera energieffektiviserande åtgärder genomförs samtidigt. Resultaten indikerar att vid kombination av flera åtgärder uppstår i regel interaktionseffekter, vilket ligger i linje med andra studier. Vidare har det gjorts en känslighetsanalys, där det undersökts om osäkerhet hos köldbryggor, infiltration samt ventilationsflöde för en modell i IDA ICE påverkar den beräknade energibesparingen från energieffektiviserande åtgärder. Känslighetsanalysen visar att energibesparingen från energieffektiviserande åtgärder påverkas om det finns en osäkerhet i någon av de parametrar som justerats. Därmed är det viktigt att den modell som simuleras är rätt kalibrerad.

  • 333.
    Carls, Johan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    NGN – Nästa Generations Nätverk (Nätverks- och Riskanalys) för Piteå Kommun2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    My mission has been to technical documentation and identify Piteå Municipality's existing network infrastructure. Everything has been summarized in several different areas: Network Services, Network-related services, Technology, Management/Control and Security. A risk analysis has been developed where I have identified a total of 28 risks and deficiencies in the municipality's existing network infrastructure. 4 risks and deficiencies under Design, 9 risks and deficiencies under Security, 5 risks and deficiencies under Network related services, 2 risks and deficiencies under Network Services, 2 risks and deficiencies under Management/Control and 5 risks and deficiencies under Technology. All risks and deficiencies have been categorized in order of low, medium and high risks and deficiencies of varying action time (0-24 + months). This final report has been the basis for then developing a new future-proof network infrastructure using a Requirements and Vision for the Municipality of Piteå.

  • 334.
    Carmenholdt, Jens
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    ID06 och införandet av den elektroniska personalliggaren i byggbranschen2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report describes a projectasignment for the client, the construction company Nåiden Bygg. Economic crime in the form of undeclared work is a major problem in the construction industry. Measures carried out in the form of new rules from Skatteverket and development of a system called ID06. The project is about exploring the new law on electronic record keeping in the construction industry and the customized system ID06. The goal is to present the most important information and development opportunities in their chosen field. The report results in costs and the time required for Nåiden Byggs implementation, a manual for the implementation of the system around the staff register to contractors and builders, and to show different developments for the system. An effort to reduce economic crime in the construction industry is going in the right direction. It is important to continue to develop common rules and systems in order to create a healthy and legal construction industry.

  • 335. Carter, Ellison
    et al.
    Lam, Nicholas
    Chafe, Zoe
    Carvalho, Ricardo
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Shan, Ming
    Ackerly, John
    Lancey, Forrest
    Household energy transitions to address air pollution exposure, health, and climate burdens associated with solid fuel burning2018In: Household energy transitions to address air pollution exposure, health, and climate burdens associated with solid fuel burning, Philadelphia, 2018Conference paper (Refereed)
    Abstract [en]

    Residential space heating and cooking are critical household energy service needs worldwide. Household transitions to clean-burning fuels at population scales are needed that do not contribute to poor indoor and outdoor air quality and the potential associated exposure, health, and climate burdens. We propose to discuss and debate research, implementation needs, and advances related to use of solid fuel for meeting residential energy needs with an express focus on residential heating demand, which has been less studied than residential cooking.We aim to identify knowledge gaps in the field of household energy systems in resource-constrained communities, set research priorities to address these gaps, and highlight opportunities for interdisciplinary and transnational learning and collaboration. 

  • 336.
    Carvalho, Ricardo
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Danish Building Research Institute.
    Tarelho, Luís (Contributor)
    Jensen, Ole Michael (Contributor)
    Wood stove combustion air retrofits: A low cost way to increase energy savings in dwellings2018In: Energy and Buildings, Vol. 164, p. 140-152Article in journal (Refereed)
    Abstract [en]

    In Europe, wood-fired stoves remain as major renewable household heating and emission sources. This study focused on improving the performance of a wood stove (natural draft) traditionally used in Portugal by the adoption of alternative combustion air retrofits. Additionally, the performance of a new pellet stove (forced-air) was determined to investigate the highest achievable goal for solid-fuel stoves. In the wood stove, an outer chimney component was installed around the existing chimney to allow the vertical admission of outdoor air that was preheated before entering the combustion chamber. This measure increased the thermal efficiency of the wood stove from 62% to up to 79%. Another component was used to administrate secondary air to the wood stove reducing the carbon monoxide emissions by 39% to 2808 mg Nm−3. The two retrofits enhanced a more stable heat release from the wood stove, which reached a thermal efficiency 11% lower than that achieved by the pellet stove. This research suggests that retrofitting stoves with chimney components that allow the admission of combustion air can substantially increase energy savings in dwellings. Further efforts should focus on improving the interplay between the outdoor air and secondary air admission to achieve higher emission reductions at low-cost.

  • 337.
    Carvalho, Ricardo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lindgren, Robert
    García-Lopez, Natxo
    Nyberg, Gert
    Boman, Christoffer
    Household Bioenergy Transitions with Alternative Biomass Feedstocks and Technologies: An Integrated System to Mitigate Environmental Risks in Western Kenya2018In: Household Bioenergy Transitions with Alternative Biomass Feedstocks and Technologies: An Integrated System to Mitigate Environmental Risks in Western Kenya / [ed] École Polytechnique Fédérale de Lausanne, UNESCO, Lausanne, 2018Conference paper (Refereed)
    Abstract [en]

    In Kenya, over 50% of the total primary energy consumption is from traditional solid-fuel cooking, being this a major cause of deforestation and household air pollution (HAP). Western Kenya has an agricultural biofuel feedstock of over 1.9 million Mt, which could be processed to supply cookstoves with crop-residue pellets and improved wood fallows. The sociotechnical viability of two novel bioenergy value chains were analysed using the Long-Range Energy Alternatives Planning system. Three scenarios of transition to efficient cookstoves and decentralized biofuel and electricity production systems were tested. In the “Optimal scenario”, the current feedstock in the Kisumu and Siaya counties could satisfy over 80% of the cooking energy demand by 2030. Here, the net greenhouse gas emissions from charcoal production and HAP could be reduced by 87% to 12.6 thousand Mt CO2e. Further work should integrate socioeconomic indicators reflecting additional local/regional stakeholders´ collaboration channels (cost-effective) to support the bioenergy transitions. 

  • 338.
    Castelain, Mickaël
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Koutris, Efstratios
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Andersson, Magnus
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wiklund, Krister
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Björnham, Oscar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Schedin, Staffan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Axner, Ove
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Characterization of the Biomechanical Properties of T4 Pili Expressed by Streptococcus pneumoniae – A Comparison between Helix-like and Open Coil-like Pili2009In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 10, no 9-10, p. 1533-1540Article in journal (Refereed)
    Abstract [en]

    Bacterial adhesion organelles, known as fimbria or pili, are expressed by Gram–positive as well as Gram–negative bacteria families. These appendages play a key role in the first steps of the invasion and infection processes, and they therefore provide bacteria with pathogenic abilities. To improve the knowledge of pili-mediated bacterial adhesion to host cells and how these pili behave under the presence of an external force, we first characterize, using force measuring optical tweezers, open coil-like T4 pili expressed by Gram–positive Streptococcus pneumoniae with respect to their biomechanicalproperties. It is shown that their elongation behavior can be well described by the worm-like chain model and that they possess a large degree of flexibility. Their properties are then compared with those of helix-like pili expressed by Gram–negative uropathogenic Escherichia coli (UPEC), which have different pili architecture. The differences suggest that these two types of pili have distinctly dissimilar mechanisms to adhere and sustain external forces. Helix-like pili expressed by UPEC bacteria adhere to host cells by single adhesins located at the distal end of the pili while their helix-like structures act as shock absorbers to dampen the irregularly shear forces induced by urine flow and to increase the cooperativity of the pili ensemble. Open coil-like pili expressed by S. pneumoniae adhere to cells by a multitude of adhesins distributed along the pili. It is hypothesized that these two types of pili represent different strategies of adhering to host cells in the presence of external forces. When exposed to significant forces, bacteria expressing helix-like pili remain attached bydistributing the external force among a multitude of pili, whereas bacteria expressing open coil-like pili sustain large forces primarily by their multitude of binding adhesins.

  • 339. Castillo, Ismael
    et al.
    Vazquez, Carlos
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Fridman, Leonid
    Overhead Crane control through LQ Singular Surface Design MATLAB Toolbox2015In: 2015 AMERICAN CONTROL CONFERENCE (ACC), 2015, p. 5847-5852Conference paper (Refereed)
    Abstract [en]

    The experimental application of LQ Singular Optimal surface design methodology through a MATLAB Toolbox to an overhead crane is presented. Based on the properties of a given performance index, it is possible to apply all the cases of Higher-Order Sliding Mode Controllers, from conventional Sliding Mode Controller up to Higher-Order Sliding Mode Controller of order n, for a specified system. Moreover, it is illustrated how the MATLAB Toolbox can be a helpful tool to select a better performance option. The experimental results confirm the advantages of the proposed control design methodology.

  • 340.
    Cederquist, Joel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Från zinkfosfatering till silanbehandling: Potentiell kostnadsbesparing i förbehandlingen hos Ålö AB2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is to investigate if cost reductions can be accomplished by changing the pretreatment method from zinc-phosphating to silane at Ålö’s plant in Brännland.

    A survey has been conducted to identify economic benefits and drawbacks of the two techniques. The survey, facilitated by chemical supplier, Chemetall, is in the form of an application for calculation of process and chemical parameters for the current process so that comparative results can be presented for evaluation in the form of prospective savings per annum in the event of a change of pretreatment method.

    The zinc-phosphating technique is a conventional method, utilizing activation and crystallization steps, which, when correctly exercised, facilitates both good corrosion resistance and paint adhesion. Drawbacks of this method include high water and energy consumption, maintenance costs, and the generation of toxic waste that requires human handling and expensive disposal.

    Silane pretreatment is a comparatively new method used by Ålö’s facilities in the USA and China, as well as established international automotive manufacturers. This method of pretreatment has developed the quality and stability aspects considerably, has the advantages of lower water and energy consumption and a non-toxic waste generating process. It is considered capable of fully replacing zinc-phosphating without compromising corrosion resistance or paint adhesion characteristics.

    The most important conclusion from this thesis is that the silane pretreatment method is economically beneficial for Ålö at the current rate of production (21 333 front-loaders per annum), with an estimated cost reduction of 25 % or more than € 50 000 per annum. The results of this report also indicate a rise in economic benefits with silane pretreatment in the event of increased production rates.

    This shows that although the silane pretreatment method entails the possibility of substantial annual cost reduction, further investigation in this field is required.

  • 341. Challamel, Noel
    et al.
    Girhammar, Ulf Arne
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boundary-Layer Effect in Composite Beams with Interlayer Slip2011In: Journal of Aerospace Engineering, ISSN 0893-1321, E-ISSN 1943-5525, Vol. 24, no 2, p. 199-209Article in journal (Refereed)
    Abstract [en]

    An apparent analytical peculiarity or paradox in the bending behavior of elastic-composite beams with interlayer slip, sandwich beams, or other similar problems subjected to boundary moments exists. For a fully composite beam subjected to such end moments, the partial composite model will render a nonvanishing uniform value for the normal force in the individual subelement. This is from a formal mathematical point of view in apparent contradiction with the boundary conditions, in which the normal force in the individual subelement usually is assumed to vanish at the extremity of the beam. This mathematical paradox can be explained with the concept of boundary layer. The bending of the partially composite beam expressed in dimensionless form depends only on one structural parameter related to the stiffness of the connection between the two subelements. An asymptotic method is used to characterize the normal force and the bending moment in the individual subelement to this dimensionless connection parameter. The outer expansion that is valid away from the boundary and the inner expansion valid within the layer adjacent to the boundary (beam extremity) are analytically given. The inner and outer expansions are matched by using Prandtl's matching condition over a region located at the edge of the boundary layer. The thickness of the boundary layer is the inverse of the dimensionless connection parameter. Finite-element results confirm the analytical results and the sensitivity of the bending solution to the mesh density, especially in the edge zone with stress gradient. Finally, composite beams with interlayer slip can be treated in the same manner as nonlocal elastic beams. The fundamental differential equation appearing in the constitutive law associated with the partial-composite action in a nonlocal elasticity framework is discussed. Such an integral formulation of the constitutive equation encompassing the behavior of the whole of the beam allows the investigation of the mechanical problem with the boundary-element method.

  • 342. Challamel, Noel
    et al.
    Girhammar, Ulf Arne
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lateral-torsional buckling of vertically layered composite beams with interlayer slip under uniform moment2012In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 34, p. 505-513Article in journal (Refereed)
    Abstract [en]

    The lateral-torsional stability of vertically layered composite beams with interlayer slip is investigated in this paper, based on a variational approach. Vertically layered elements are typically used in timber engineering but also in case of laminated glass elements. Both across-longitudinal or vertical slip due to rotation and longitudinal or horizontal slip due to lateral deflection are discussed. The theoretical framework of the lateral-torsional buckling problem is given, and some engineering closed-form solutions are presented for partially composite beams under uniform bending moment. Simplified kinematical relationships neglecting the axial and vertical displacements of the sub-elements give unrealistic values for the lateral-torsional buckling moment. Refined kinematical assumptions remove this peculiarity and render sound buckling moment results. Inclusion of the horizontal and vertical slips significantly affect the lateral-torsional buckling moment of these vertically laminated elements. A single lateral-torsional buckling formulae is derived, depending on both the horizontal and the vertical connection parameters. (C) 2011 Elsevier Ltd. All rights reserved.

  • 343.
    Chen, Ailu
    et al.
    Nanyang Technological University.
    Cao, Qingliang
    Nanyang Technological University.
    Zhou, Jin
    Nanyang Technological University.
    Nazaroff, William
    University of California, Berkeley.
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Chang, Wei-Chung
    Nanyang Technological University.
    Indoor/outdoor pollutant relationships in an air-conditioned room during and after the 2013 haze in Singapore2014In: Indoor Air 2014, Hong Kong : exploring indoor air sciences for a sustainable built environment: proceedings of the 13th International Conference on Indoor Air Quality and Climate, July 7-July 12, 2014 / [ed] Yuguo Li and Xinyan Yang, 2014Conference paper (Other academic)
  • 344. Chen, Ailu
    et al.
    Cao, Qingliang
    Zhou, Jin
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Chang, Wei-Chung
    Nazaroff, William
    Indoor and outdoor particles in an air-conditioned building during and after the 2013 haze in Singapore2016In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 99, p. 73-81Article in journal (Refereed)
    Abstract [en]

    Particles released from biomass burning can contribute to severe air pollution. We monitored indoor and outdoor particles in a mechanically ventilated and air-conditioned building during and after the 2013 haze event in Singapore. Continuous monitoring of time-and size-resolved particles in the diameter range 0.01–10 μm was conducted for two weeks in each sampling campaign. During the haze event, the averaged size-resolved outdoor particle volume concentrations (dV/d(logDp)) for diameters larger than 0.3 μm were considerably higher than those during the post-haze days (9–185 μm3 cm−3versus 1–35 μm3 cm−3). However, the average number concentration of particles with diameters in the range 10–200 nm was substantially lower on the hazy days than on the post-haze days (11,400 to 14,300 particles cm−3 for hazy days, versus an average of 23,700 particles cm−3 on post-haze days). The building mechanical ventilation system, equipped with MERV 7 filters, attenuated the penetration and persistence of outdoor particles into the monitored building. Indoor particle concentrations, in the diameter ranges 0.3–1.0 μm and 1.0–2.5 μm, closely tracked the corresponding patterns of outdoor particle concentrations. For particles in the size range 0.01–1.0 μm, the size-resolved mean indoor/outdoor (I/O) ratios were in the range 0.12–0.65 with the highest mean I/O ratio at 0.3 μm (0.59 in AC on mode and 0.64 in AC off mode). The air conditioning and mechanical ventilation system with MERV 7 filters provided low single-pass removal efficiency (less than ∼ 30%) for particles with diameters of 0.01–1.0 μm. During the haze, for particles larger than ∼0.2 μm, lower I/O ratios and higher removal efficiencies occurred with the air conditioning operating as compared to with mechanical ventilation only. This observation suggests the possibility of particle loss to air conditioning system surfaces, possibly enhanced by thermophoretic or diffusiophoretic effects.

  • 345.
    Chen, J.C.
    et al.
    Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015-4791, USA.
    Grace, J.R.
    Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, Canada V6T 1Z4.
    Golriz, M.R.
    Umeå University, Faculty of Science and Technology, Applied Physics and Electronics.
    Heat transfer in fluidized beds: design methods2005In: Powder Technology, Vol. 150, p. 123-132Article in journal (Refereed)
    Abstract [en]

    Large-scale fluidized beds for commercial processes commonly require heat transfer surfaces. Design then demands that heat transfer coefficients be specified. Empirical correlations are unable to cover the wide range of variables and conditions encountered. Mechanistic models are more reliable, but must be chosen carefully. For bubbling beds, the packet model approach gives reasonable predictions for the convective component of transfer, but further work is required to provide reliable estimates of two required time constants, dependent on the hydrodynamics. For industrial-scale circulating beds, a mechanistic model that incorporates the key factors influencing heat transfer, assumes fully developed transfer, and utilizes results from large-scale units is recommended.

  • 346. Chen, Mengying
    et al.
    Shi, Xiaoyan
    Chen, Yinhua
    Cao, Zhaolan
    Cheng, Rui
    Xu, Yuxiang
    Liu, Li
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Xiaonan
    A prospective study of pain experience in a neonatal intensive care unit of China2012In: The Clinical Journal of Pain, ISSN 0749-8047, E-ISSN 1536-5409, Vol. 28, no 8, p. 700-704Article in journal (Refereed)
    Abstract [en]

    Objectives: To assess pain burden in neonates during their hospitalization in China and thus provide evidence for the necessity of neonatal pain management. Patients and Methods: The Neonatal Facial Coding System was used to evaluate pain in neonates. We prospectively collected data of all painful procedures performed on 108 neonates (term, 62; preterm, 46) recruited from admission to discharge in a neonatal intensive care unit of a university-affiliated hospital in China. Results: We found that during hospitalization each preterm and term neonate was exposed to a median of 100.0 (range, 11 to 544) and 56.5 (range, 12 to 249) painful procedures, respectively. Most of the painful procedures were performed within the first 3 days. Preterm neonates, especially those born at 28 and 29 weeks' gestational age, experienced more pain than those born at 30 weeks' gestation or later (P < 0.001). Among those painful procedures, tracheal aspiration was the most frequently performed on preterm neonates, and intravenous cannulation was the most common for term neonates. Moreover, tracheal intubations and femoral venous puncture were found to be the most painful. Notably, none of the painful procedures was accompanied by analgesia. Conclusions: Neonates, particularly preterm neonates, were exposed to numerous invasive painful procedures without appropriate analgesia in hospitals in China. The potential long-term impacts of poorly treated pain in neonates call for a change in pediatric practice in China and in countries with similar practices.

  • 347. Chen, Mengying
    et al.
    Xia, Dongqing
    Min, Cuiting
    Zhao, Xiaoke
    Chen, Yinhua
    Liu, Li
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Xiaonan
    Neonatal repetitive pain in rats leads to impaired spatial learning and dysregulated hypothalamic-pituitary-adrenal axis function in later life2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 39159Article in journal (Refereed)
    Abstract [en]

    Preterm birth is a major health issue. As part of their life-saving care, most preterm infants require hospitalization and are inevitably exposed to repetitive skin-breaking procedures. The long-term effects of neonatal repetitive pain on cognitive and emotional behaviors involving hypothalamic-pituitary-adrenal (HPA) axis function in young and adult rats are unknown. From P8 to P85, mechanical hypersensitivity of the bilateral hindpaws was observed in the Needle group (P < 0.001). Compared with the Tactile group, the Needle group took longer to find the platform on P30 than on P29 (P = 0.03), with a decreased number of original platform site crossings during the probe trial of the Morris water maze test (P = 0.026). Moreover, the Needle group spent more time and took longer distances in the central area than the Tactile group in the Open-field test, both in prepubertal and adult rats (P < 0.05). The HPA axis function in the Needle group differed from the Tactile group (P < 0.05), with decreased stress responsiveness in prepuberty and puberty (P < 0.05) and increased stress responsiveness in adulthood (P < 0.05). This study indicates that repetitive pain that occurs during a critical period may cause severe consequences, with behavioral and neuroendocrine disturbances developing through prepuberty to adult life.

  • 348.
    Cheng, Xiaogang
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. College of Telecommunications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing, China; School of Electrical Engineering and Computer Science, Royal Institute of Technology, Stockholm, Sweden.
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi'an, China.
    Liu, Guoqing
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Haibo
    A total bounded variation approach to low visibility estimation on expressways2018In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 2, article id 392Article in journal (Refereed)
    Abstract [en]

    Low visibility on expressways caused by heavy fog and haze is a main reason for traffic accidents. Real-time estimation of atmospheric visibility is an effective way to reduce traffic accident rates. With the development of computer technology, estimating atmospheric visibility via computer vision becomes a research focus. However, the estimation accuracy should be enhanced since fog and haze are complex and time-varying. In this paper, a total bounded variation (TBV) approach to estimate low visibility (less than 300 m) is introduced. Surveillance images of fog and haze are processed as blurred images (pseudo-blurred images), while the surveillance images at selected road points on sunny days are handled as clear images, when considering fog and haze as noise superimposed on the clear images. By combining image spectrum and TBV, the features of foggy and hazy images can be extracted. The extraction results are compared with features of images on sunny days. Firstly, the low visibility surveillance images can be filtered out according to spectrum features of foggy and hazy images. For foggy and hazy images with visibility less than 300 m, the high-frequency coefficient ratio of Fourier (discrete cosine) transform is less than 20%, while the low-frequency coefficient ratio is between 100% and 120%. Secondly, the relationship between TBV and real visibility is established based on machine learning and piecewise stationary time series analysis. The established piecewise function can be used for visibility estimation. Finally, the visibility estimation approach proposed is validated based on real surveillance video data. The validation results are compared with the results of image contrast model. Besides, the big video data are collected from the Tongqi expressway, Jiangsu, China. A total of 1,782,000 frames were used and the relative errors of the approach proposed are less than 10%.

  • 349.
    Cheng, Xiaogang
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Nanjing Univ Posts & Telecommun, Coll Telecommun & Informat Engn, Nanjing, Jiangsu, Peoples R China; Royal Inst Technol, Sch Comp Sci & Commun, Stockholm, Sweden.
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Liu, Guoqing
    Olofsson, Thomas
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Haibo
    A variational approach to atmospheric visibility estimation in the weather of fog and haze2018In: Sustainable cities and society, ISSN 2210-6707, Vol. 39, p. 215-224Article in journal (Refereed)
    Abstract [en]

    Real-time atmospheric visibility estimation in foggy and hazy weather plays a crucial role in ensuring traffic safety. Overcoming the inherent drawbacks with traditional optical estimation methods, like limited sampling volume and high cost, vision-based approaches have received much more attention in recent research on atmospheric visibility estimation. Based on the classical Koschmieder's formula, atmospheric visibility estimation is carried out by extracting an inherent extinction coefficient. In this paper we present a variational framework to handle the nature of time-varying extinction coefficient and develop a novel algorithm of extracting the extinction coefficient through a piecewise functional fitting of observed luminance curves. The developed algorithm is validated and evaluated with a big database of road traffic video from Tongqi expressway (in China). The test results are very encouraging and show that the proposed algorithm could achieve an estimation error rate of 10%. More significantly, it is the first time that the effectiveness of Koschmieder's formula in atmospheric visibility estimation was validated with a big dataset, which contains more than two million luminance curves extracted from real-world traffic video surveillance data.

  • 350. Cheng, Xiaogang
    et al.
    Yang, Bin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Liu, Guoqing
    Olofsson, Thomas
    Li, Haibo
    Atmospheric visibility detection based on total variation and piecewise stationary time series for fog and haze weather2018In: Sustainable cities and society, ISSN 2210-6707Article in journal (Refereed)
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