du.sePublications
Change search
Refine search result
45678910 301 - 350 of 1341
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 301.
    Forsell, Fredrik
    Dalarna University, School of Technology and Business Studies, Graphic Arts Technology.
    Acceptabel och effektiv färgreducering i tryck: Utvärdering av färgreduceringsresultat från Alwan CMYK Optimizer ECO2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Tryckeribranschen är en ekonomiskt pressad bransch som söker nya besparingsmetoder. En av metoderna är att minska insatsvaran tryckfärg med färgreduceringsprogramvara.

    Rapporten undersöker möjligheterna med färgreduceringssystem. Detta genom att studera hur man använder sig av färgreducering och hur det påverkar trycket.

    Studien avser besvara:

    • Hur stor färgminskning kan man använda sig av utan negativa konsekvenser på bildkvalitén?

    • Hur går man tillväga för att skapa den färgminskningen?

    • Överensstämmer total färgförändring och visuell bedömning av tryck?

    För att få svar på dessa frågor togs en testform fram med nödvändiga bilder och färgfält som sedan genomgick en rad färgreduktioner. Testformen utvärderades digitalt med avseende på TAC och total färgförändring. Därefter trycktes testformen och utvärderades visuellt av en testgrupp och uppmättes för att visa färgförändring efter tryck.

    Resultatet av undersökningen visar att det går att färgreducera tryck utan avsevärda negativa konsekvenser på bildkvalitén. En reducering från 300 % TAC till en TAC mellan 240 % och 210 % är fullt möjlig för att få en besparing och vara inom standard för total färgförändring. Detta går att göra väldigt lätt med en programvara som Alwan CMYK Optimizer ECO, med enbart förvalda inställningar och en inställd Total Ink Limit mellan 240 % och 210 %. Resultatet visade även en stark korrelation mellan den visuella bedömningen och den totala färgförändring, som tyder att både metoder är lämpliga för bedömning av tryck.

  • 302.
    Fransson, Jessica
    et al.
    Dalarna University, School of Technology and Business Studies, Graphic Arts Technology.
    Funke, Linnea
    Dalarna University, School of Technology and Business Studies, Graphic Arts Technology.
    Manlig eller kvinnligförfattare?: En analys av pocketböckersomslagsdesign utifrån ett genusperspektiv.2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Books are, despite a decline in interest, still an important part of our culturalsociety. It is not unusual for a book’s cover to adapt to its target audience butthe question stands whether the gender of the author functions as a part of thedesign equation as well.The purpose of this study was to through a visual analysis of paperback bookcovers map out differences found between male and female writers’ bookcovers.This study is based on a visual content analysis were 200 paperback coverswere analysed, 100 from Swedish authors and 100 from English authors. Thesewere then evenly divided between the genders. The analysis reflects over themotifs on the covers as well as the dominant colour, font families and fontcolours.The results from the analysis indicate that female authors generally got a morefeminine appearance on their covers, and that covers by Swedish female authorsshowed most signs of a feminine design. Alas, it is impossible to rule out genreas an important influence regarding the books’ cover design. However, as it washard to pinpoint the genre of many of the books analysed it was difficult tomake a distinct connection between genres and books’ cover design.

  • 303.
    Franzon, Joffe
    Dalarna University, School of Technology and Business Studies, Construction.
    Hur en armerad betongbalk dimensioneras för hål i livet2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the design stage, conflicts between installations and bodies often arise. In multi-story

    buildings huge profits can be made from being able to make holes in concrete beams in

    order to carry an installation through the beam. But the knowledge of how the beam is to

    be dimensioned for larger holes is not generally known.

    Two concrete manuals with different calculation methods have therefore been analyzed to

    evaluate which of these could be the basis for a calculation template. The prerequisites

    were defined as beams without prestressed concrete, with rectangular cross-sections and

    square or rectangular holes.

    The Mathcad calculation program was used to make two calculation templates for the

    Swedish and Norwegian methods. As a calculation example, dimensions and loads were

    used from an experimental study in Egypt 2005. In that study, the beam was exposed to

    loads that brought it to failure. Their theoretical failure capacity was in line with the

    practical values.

    A comparison of the amount of reinforcement and execution was made between the three

    different models. It turned out that the Norwegian model was the most similar to the

    Egyptian. The reinforcement of the Norwegian model was the most similar to that of the

    Egyptian model, but the amount of reinforcement was slightly less.

    The Swedish model was not considered reliable for design purposes. As the Norwegian

    model had a little less reinforcement, it was considered necessary to add a safety factor or

    perform a load capacity test in order to ensure the beam’s capacity.

  • 304.
    Fredin, Andreas
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Snöborgs, Oscar
    Dalarna University, School of Technology and Business Studies, Construction.
    Energimässig och kostnadsmässig jämförelse av FTX och FX system i landet: Jämförelse av två alternativa renoverings lösningar för värmeåtervinning i flerbostadshus2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report includes an energy- and geographical comparison between two alternative renovation solutions for heat recovery in apartment buildings. The survey includes a typical apartment building that is representative of the ‘Miljon Program’, and was carried out because of the ongoing debate about which system works best for the renovation of apartment buildings. The project work was carried out with simulations through an Excel-based program called TMF Energy 2.2 developed by SP, Sweden’s Technical Research Institute.

    he purpose of this project was to develop two geographical representations of Sweden that would show where in the country the two different ventilation and heat recovery systems worked most efficiently regarding primary energy and energy costs for heating.

    The results showed that there was no threshold, boundary of grey area in the country, one of the systems was more efficient in terms of primary energy use and the other system was more energy cost efficient.

    The discussion section of this report includes a variety of topics such as primary energy factors, how to manage requirements, why airtightness affects the systems differently and energy costs for district heating.

    The conclusions that were drawn from the results includes that the FTX-system is the most primary energy efficient and that the FX-system is the most energy cost efficient. There was no boundary or grey area in the country for the chosen building, and the FTX-system is affected more by varying airtightness than the FX-system.

  • 305. Freitas, Iuri
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Green building rating systems in Swedish market: A comparative analysis between LEED, BREEAM SE, GreenBuilding and Miljöbyggnad2018In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 153, p. 402-407Article in journal (Refereed)
    Abstract [en]

    In Sweden, there are four most commonly used green building rating systems, which are LEED, BREEAM SE, GreenBuilding and Miljöbyggnad. In this study, each of them is analyzed under the aspects of certification process, implementation cost, educational needs and the variety of categories. SWOT method is further applied to extract the strengths, weaknesses, opportunities and threats of each of the rating system in a direct and indirect manner, making it clearer to choose among various options when considering the individual needs of each project in practice. 

  • 306.
    Frid, Mikael
    Dalarna University, School of Technology and Business Studies, Construction.
    Solcellsdrivet FTX-system för miljonprogramshus: Tjärna Ängar, Borlänge2013Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The project is a feasibility study of including the installation of solar cells and an FTX ventilation system in the renovation of a Swedish million program multi-family ouse. The question concerns whether the energy production of the PV system can match with the energy consumption of the FTX-system. Input data was obtained from:

    • Databases, literature and interviews.
    • Simulations of photovoltaics modules in the computer program PVSYST
    • Modulation of the vents in the computer program MagiCAD

    The aim was primarily to investigate whether it was possible to get a theoretical working system. The economy of the project should also be investigated depending on the results.

    The study showed that it should be theoretically possible to install photovoltaics for electricity generation that is able to cover the FTX system's electricity needs on a yearly basis. The photovoltaics are also expected to produce enough electricity for some other equipment that requires electricity for much of the year. It was also found that it should be possible to get the photovoltaics modules economically viable if a pay-back time of 14 years was used. The method used for these results is thoroughly described and with small changes applicable to a large number of buildings in the Swedish building stock.

    An important conclusion from the project is that if property owner can see 14 years into the future with an investment in solar energy, there is much to be gained. There are already skills, available technologies and products available in order to recover a large portion of the properties' electricity needs through solar energy.

  • 307.
    Frota de Albuquerque Landi, Fabiana
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energy Performance Contracting in Swedish scenario: a case study with Morastrand AB2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Renovation of the existing buildings in Sweden represents a great potential to achieve the

    energy efficiency and carbon emission targets set by the European Union and the Swedish

    government. The Energy Performance Contracting (EPC) is regarded as an efficient way

    to manage and to outsource the risks of energy efficiency (EE) measures.

    The thesis aims to identify the theoretical framework of EPC in the Swedish scenario and,

    through a real case, develop a model that relates EE measures and its results considering

    the capital investment versus running costs of renovation projects.

    The work is based on the incorporation with the Morastrand AB. The research expects to

    assess EPC processes and measures as in Energy Service Companies (ESCO) and

    consequently help in the decision making and the management of the projects.

    The thesis is composed of two parts. The first part identifies the theoretical framework of

    energy contract models focusing on the EPC, while a case study with Morastrand AB is

    subsequently presented. It is suggested one approach for the preliminary comparison of

    different renovation measures in EE projects, corresponding to the first step of the

    planning phase of an EPC.

    General recommendations and sensitive factors were identified and can assist Morastrand

    AB to effectively implement EE projects in the future. For orienting investments, the

    Lifecycle Cost Analysis (LCCA) is a method to study solutions under economic aspects

    and further it can be extended to the complete Lifecycle Assessment of the upcoming

    projects.

    The theoretical framework of the EPC is composed by identifying the projects, performing

    the technical analysis, determinizing the potential in energy savings, deepening the

    analysis with auditions, tendering the project, designing and executing the project,

    commissioning, operating and supporting the systems with constant monitoring and

    maintenance.

    The biggest challenge for the EPC in Sweden is the relation between the ESCOs and their

    clients. The figure of the facilitator could improve the results and balance the knowledge

    gap between the parts.

    The actors of these projects are the ESCO, the client, the facilitator and the financing part.

    In Sweden, very frequently the client finances the operation. There are a few models of

    contracting, and the most popular are guaranteed savings and shared savings.

    The thesis performed the LCCA of three options for window replacement in a building at

    the end of its lifespan. The results show that the trends in prices and interest rates are

    sensitive factors. In this case, the projects with higher initial investments were more

    profitable. Those solutions can shield the company against energy prices escalates and

    contribute to the green policies.

  • 308.
    Fröberg, Elise
    Dalarna University, School of Humanities and Media Studies, Moving Image Production.
    Gatsby – en scenograferad karaktär2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med den här uppsatsen är att undersöka scenografin i filmen The Great Gatsby för att se hur

    den används som ett karaktärsbyggande verktyg. Som grund för uppsatsen ligger även boken med

    samma titel och dess miljöbeskrivningar för att undersöka hur de har fungerat som utgångspunkt i

    skapandet av den filmiska karaktären Gatsby. Ett stöd för analysen har varit symboltolkning

    eftersom symboler är ett återkommande hjälpmedel för karaktärisering i både bok och film.

    Resultatet visar att scenografin används på flera olika sätt för att förtydliga och berätta om Gatsbys

    karaktär. Bland annat speglar scenografin Gatsbys känsloliv, mysteriet kring Gatsby och hans

    förhållande till sin egen karaktär. Rekvisita används ofta som karaktärsbyggande symboler. Det

    görs dessutom tydliga skillnader i scenografin för att visa på olika teman och vändningar i filmen.

  • 309.
    Garmo, Erik
    Dalarna University, School of Technology and Business Studies, Graphic Arts Technology.
    Är utseendet viktigt?: En tentativ jämförelse mellan lekmäns ochformgivares uppfattningar avmusikaffischer2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis was to examine if there are similarities and differences between educated graphic designer’s and laymen’s opinions when viewing design work.Semi-structured interviews were conducted with three graphic designers and three laymen. The interviews focused on three defined categories regarding the design of five music posters. The three categories were opinions about the posters’ quality of information, aesthetics and craftsmanship.Individual preferences seemed to affect opinions of the posters more than education and experience in graphic design. Designers sometimes experienced the information as clear, while the laymen did not. Designers also noticed more small details compared to the laymen. The laymen seldom noticed typographic errors.A poster could be too advanced for a layman, it could also be too ugly for a graphic designer. There was a middle ground where both groups thought the information to be clear and the poster to be aesthetically pleasing. The laymen more often considered clear information to be more important than good aesthetics.To conduct target group analyses seems to be the most important conclusion from this thesis since the designer’s opinions on what was considered clear and informative did not always correlate with the view of the laymen. With such analyses the graphic design can be more purposeful and probably produce a better result.

  • 310.
    Garnegård, Agnes
    Dalarna University, School of Humanities and Media Studies, Sound and Music Production.
    Utbildningsmedier i undervisningen: En studie av medieanvändning och lärande2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I denna uppsats har jag undersökt vilka utbildningsmedier som används på några skolor

    i utvalda kommuner i Dalarnas län: Älvdalen, Orsa, Mora och Falun, samt vilken

    påverkan dessa medier kan ha på elevernas inlärning. Uppsatsens övergripande syfte är

    att bidra med kunskap om hur utbildningsmedier kan användas i undervisningen i

    grundskolan samt hur elevers lärande kan påverkas av medier med audiovisuell

    information. Denna uppsats har följande forskningsfrågor: Hur vanligt är det att olika

    utbildningsmedier används i undervisningen och vilka typer av medier är vanligast?

    Vilken effekt kan utbildningsmedier ha på elevernas inlärningsförmåga? Och hur kan

    mediepedagogik vara ett redskap i undervisningen? Uppsatsens frågeställningar

    besvaras genom kvantitativa metoder i form av en enkät och ett experiment.

    Enkätundersökningen visa att medier ofta används som komplettering till undervisning

    på dessa utvalda skolor och de medier som används mest är video/film, bild/foto och

    internet. Experimentets resultat tyder på att det finns elever som troligtvis lär sig bättre

    genom att använda medier. Detta visades då experimentgrupperna som under en lektion

    fick titta på en video visade större inlärning än kontrollgrupperna som endast lyssnade

    på en föreläsning utan stöd av några utbildningsmedier.

  • 311.
    Gasso, Edwini
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    A Comparison Between Structural Equations and Predictive Modelling Approaches for Estimation of Causal Effects for Hospital Outlier on Patient Outcomes: The Case of Patient Care Units in Dalarna Region, Sweden2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Many studies have been done on the identification of the causal effect of a treatment (or intervention) but still the field of causal effect identification is highly debated in many disciplines e.g. data science, econometrics, biostatistics etc. This study examined the theoretical motivation of predictive modelling approach to estimate and check the sensitivity analysis for causal effects by using structural equations modelling framework with application of real data from Landstinget Dalarna. In this study, the link between causal inference using structural equations modelling approach of Heckman's two-step estimation framework and predictive modeling approach has been established. Furthermore, two different simulation studies under linearity and nonlinearity assumptions were conducted to see the finite sample properties of the predictive modelling approaches such as Support Vector Machine, Random Forest, Gaussian boosted regression trees and Bayesian additive regression trees. Finally, the predictive modelling approaches were used to estimate the treatment effects on patient outcomes in terms of length of stay, unplanned readmission and mortality within 30 days after discharge. The results were also compared with the traditional approaches: propensity score matching, propensity weighting and two-step estimation method. This study used two types of estimates, average treatment effects and treatment on treated. The estimates and their standard errors were calculated for the real data from Landstinget Dalarna. The study found that, non-outlying patients are staying in the hospital for longer periods of time (in days) compared to outlying patients though the reasons that make long of stay remained unknown. For readmission and mortality, the results varied a lot between the alternative models, and we can therefore not conclude that non-outlying patients have higher mortality and readmission rates compared to outlying.

  • 312.
    Gasti, Maria
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Techno-economic Appraisal of Concentrating Solar Power Systems (CSP)2013Independent thesis Advanced level (degree of Master (One Year)), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    The diffusion of Concentrating Solar Power Systems (CSP) systems is currently taking place at a much slower pace than photovoltaic (PV) power systems. This is mainly because of the higher present cost of the solar thermal power plants, but also for the time that is needed in order to build them. Though economic attractiveness of different Concentrating technologies varies, still PV power dominates the market. The price of CSP is expected to drop significantly in the near future and wide spread installation of them will follow. The main aim of this project is the creation of different relevant case studies on solar thermal power generation and a comparison betwwen them. The purpose of this detailed comparison is the techno-economic appraisal of a number of CSP systems and the understanding of their behaviour under various boundary conditions. The CSP technologies which will be examined are the Parabolic Trough, the Molten Salt Power Tower, the Linear Fresnel Mirrors and the Dish Stirling. These systems will be appropriatly sized and simulated. All of the simulations aim in the optimization of the particular system. This includes two main issues. The first is the achievement of the lowest possible levelized cost of electricity and the second is the maximization of the annual energy output (kWh). The project also aims in the specification of these factors which affect more the results and more specifically, in what they contribute to the cost reduction or the power generation. Also, photovoltaic systems will be simulated under same boundary conditions to facolitate a comparison between the PV and the CSP systems. Last but not leats, there will be a determination of the system which performs better in each case study.

  • 313.
    Gerardi, Marcelin
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Namsrai, Miki
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    A software system for variables comparison of a paper machine for improved performance2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today paper is to find everywhere, and the production factories always need to increase the

    productivity if they want to stay competitive. Stora Enso Kvarnsveden has one of the biggest

    magazine paper machines in the world, which produces around 1900 meters of paper per

    minute. The production process is highly automatized, which reduces the number of operators

    that work on the machine. Still, process variations can cause brakes in the paper web and lead

    to loss of income, energy and paper production. It may also have a direct impact on the paper

    quality. This report is focusing the following question:

    How to keep the Paper Machine production process under controlled conditions?

    To make a data analysis fully relevant, we need to use the most important variables of the

    machine. By analyzing these data some unexpected behavior and variation of process values

    can be pointed out. The analyzing tool needs to be fast and portable, and therefore a software

    system has been developed. By comparing process data with reference data this software can

    make a powerful analysis.

    The created software is intended to be used either by operators or engineers. The most

    important results are collected in a file. In this text file, the comparison function gives the

    results which are stored in a CSV-format. Furthermore, an auto-update function allows the

    users to run it automatically. Graphical presentations are supporting the interpretation of the

    results.

  • 314.
    Gesar, Daniel
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Hansson, Erik
    Dalarna University, School of Technology and Business Studies, Construction.
    Uppvärmningslösningars klimat- och resurspåverkan i Dalarna: Jämförelse mellan fjärrvärme och andra uppvärmningslösningars klimat- och resurspåverkan beroende på renoveringsstrategi och geografisk placering i Dalarna2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För att nyttja jordens resurser på bästa sätt är det viktigt att använda rätt energityp till dess mest effektiva ändamål. Att energieffektivisera och minska utsläppen av växthusgaser är något som har fått mycket uppmärksamhet under 2000-talet och är fortsatt en högt prioriterad fråga i dagens samhälle.

    Detta examensarbete syftar till att jämföra byggnaders klimat- och resurspåverkan inom Dalarnas fjärrvärmenät. Genom olika renoveringssenarier påverkas en byggnads primärenergianvändning och utsläpp av koldioxid olika beroende på vart i Dalarna den är placerad. I arbetet ingår även en jämförelse av vanliga värmesystem jämfört med Dalarnas kommuners fjärrvärmesystem. Vid jämförelserna användes data från en byggnadssimulering för att simulera olika förhållanden i byggnaden. Beräkningar och jämförelser av resultaten belyser vilka faktorer som har stor inverkan på energianvändning, utsläpp samt vilka åtgärder som ger den bästa förändringen.

    Resultaten visar att variationen är stor mellan fjärrvärmesystemen i Dalarnas kommuner och de olika värmesystemen, där kommunernas bränslemix har en stor inverkan på resultatet. Bränslen med höga primärenergifaktorer leder till en stor ökning av primärenergianvändningen. Eftersom el har en hög primärenergifaktor är det viktigt att minimera elanvändningen. Renoveringsresultaten tyder på att en sänkning av inomhustemperaturen ger den största förändringen i primärenergianvändning och koldioxidutsläpp. Att installera en frånluftsvärmepump till fjärrvärmesystemet är överlag sämre ur miljösynpunkt. Att byta till en oljepanna är mycket dåligt i samtliga kommuner medan en pelletspanna kan minska koldioxidutsläppen i stora kommuner.

  • 315.
    Ghaghazanian, Arash
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    System Integration of PV/T Collectors in Solar Cooling Systems2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The demand for cooling and air-conditioning of building is increasingly ever growing. This increase is mostly due to population and economic growth in developing countries, and also desire for a higher quality of thermal comfort. Increase in the use of conventional cooling systems results in larger carbon footprint and more greenhouse gases considering their higher electricity consumption, and it occasionally creates peaks in electricity demand from power supply grid. Solar energy as a renewable energy source is an alternative to drive the cooling machines since the cooling load is generally high when solar radiation is high.

    This thesis examines the performance of PV/T solar collector manufactured by Solarus company in a solar cooling system for an office building in Dubai, New Delhi, Los Angeles and Cape Town. The study is carried out by analyzing climate data and the requirements for thermal comfort in office buildings. Cooling systems strongly depend on weather conditions and local climate. Cooling load of buildings depend on many parameters such as ambient temperature, indoor comfort temperature, solar gain to the building and internal gains including; number of occupant and electrical devices.

    The simulations were carried out by selecting a suitable thermally driven chiller and modeling it with PV/T solar collector in Polysun software. Fractional primary energy saving and solar fraction were introduced as key figures of the project to evaluate the performance of cooling system. Several parametric studies and simulations were determined according to PV/T aperture area and hot water storage tank volume.

    The fractional primary energy saving analysis revealed that thermally driven chillers, particularly adsorption chillers are not suitable to be utilizing in small size of solar cooling systems in hot and tropic climates such as Dubai and New Delhi. Adsorption chillers require more thermal energy to meet the cooling load in hot and dry climates. The adsorption chillers operate in their full capacity and in higher coefficient of performance when they run in a moderate climate since they can properly reject the exhaust heat. The simulation results also indicated that PV/T solar collector have higher efficiency in warmer climates, however it requires a larger size of PV/T collectors to supply the thermally driven chillers for providing cooling in hot climates. Therefore using an electrical chiller as backup gives much better results in terms of primary energy savings, since PV/T electrical production also can be used for backup electrical chiller in a net metering mechanism.

  • 316. Giannantoni, Corrado
    et al.
    Cialani, Catia
    University of Florida.
    Mansueti, Alberto
    “G. D’Annunzio” University, Pescara.
    Analysis of investments based on the trilateral externality approach (firm, citizen, state)2002In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 2, no 1-2, p. 27-38Article in journal (Refereed)
    Abstract [en]

    The Trilateral Externality Approach takes its origin from a several year integration activity of various evaluation methodologies (Energetic, Exergetic, Emergetic, Economic, etc.) and aims at giving a rigorous synthesis of such an integration process in the context of Neo-Classical Economics through the fundamental category of externality, in its extensive and intensive meaning.

    After having shown the different (but complementary) perspectives of elaborating a unifying concept of externality (bottom-up and top-down approaches), the paper presents a limited set of synthetic Indicators for possible strategies of investment (at a regional and national level). An example of application devoted to Hydrogen technologies will show how renewable (or “equipollent”) Sources are already widely “competitive” with respect to fossil fuel technologies, obviously if analyzed in the light of such a general evaluation approach, which involves a unique trilateral relationship between firm, citizen and state.

    In this context it will be thus much easier to show why the so-called “incentives” (in their several different possible forms) are nothing but a “remuneration” of positive externalities that a firm produces in favor of the collectivity, whereas the state recuperates such “incentives” because of a consequential increase in economic activities induced by those primary externalities, in a non-zero sum global process.

  • 317. Giglio, Alessandra
    Wordpress: uno strumento online per la gestione della didattica?2014In: TD Tecnologie Didattiche, ISSN 2499-4324, Vol. 22, no 2, p. 114-118Article in journal (Refereed)
  • 318.
    Gilén, Karolina
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Haglund, Arvid
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Sammankoppling av fjärrvärmenät: Transiteringsledning mellan Borlänge, Ornäs och Torsång2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Borlänge Energi, BE, owns small district heating, DH, networks in Ornäs and Torsång outside Borlänge, these have high operating costs that are not weighed up by the revenue they make, due to this BE makes a yearly loss on them. Because of this BE wants to connect the small DH networks with the main DH network in Borlänge where the production costs are lower. The technical and economical prerequisites for a connection have therefore been studied.

    Previous literature has been studied regarding economic parameters for connection of DH networks. Unfortunately, the type of connection that is studied in this report has not been found. The studied literature covers expansion of DH network and connection of larger DH networks, and in most cases, the connecting networks have different owners.

    Three possible routes were chosen for the connection with Borlänges DH. The current load for Ornäs and Torsång as well as possible new customers was calculated and used to dimension the pipes and calculate the costs for three different scenarios with different loads. Thereafter the costs and incomes from a connection has been calculated, and then used in BEs capital budget where the pay-off time was calculated based on the discounting method. The capital budgets showed that all the routes except one in the base case were profitable within the time frame of 30 years that was set by BE for investments in DH. Sensitivity analyses were made for pay-off time, construction costs and pipe dimension, which showed that the pay-off time is affected by several factors. But was mostly affected if production costs increase or if pipes are dimensioned for a much larger load than what actually is connected in the end. The number of new customers is therefor important to ensure before building the interconnecting pipe. Pipe dimension was affected most by the load as the transition losses are relatively small, and the building costs were affected most by the cost of the DH pipes since they constitute a large part of those costs.

    Besides from the technical and economical results it has been shown that each and all of the routes have its own prerequisites, where each route has its own pros and cons. All-in-all one route has been chosen as more suitable than the other two, as it besides one of the shortest pay off times also include possibilities to connect new customers along the route.

    As district heating is dependent on local conditions, in regard to both the technical aspects and the soil composition, the report includes several simplifications and assumptions, which have been made based on local conditions and experience. It is necessary to take this into consideration before attempting to apply the findings of this report in other places than Borlänge.

  • 319.
    Goldheim Jämthagen, Fredrik
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Reyier, Marcus
    Dalarna University, School of Technology and Business Studies, Construction.
    Behovsstyrning av ett småhus: Behovsstyrning av värme, ventilation, belysning och dess påverkan på energianvändningen i ett småhus2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    All people use some kind of energy to live. A disadvantage of this is that it has a

    impact on the climate, because energy consumption is greater than the Earth is

    capable of. Sweden has set a goal that energy use should be 20% more

    effective by year 2020. Boverket’s building rules have several instruments where

    energy use is greatly affected. Among other things, the energy performance is

    measured in primary energy. BBR provides guidelines for air turnover and flows.

    These affect the use of heating energy in a building. The rules makes a

    possibility of reducing flow and turnover when no need exists. In order to effect

    the use of energy in a building, demand control of energy systems can be used.

    The indoor climate can then be affected depending on whether people are in the

    room or not. The purpose of the study is to investigate differences in purchased

    energy between demand controlled and no demand controlled indoor climate. In

    order to assume a single-family house, the study was based on Dalarnas villa. It

    is a modern two-story house with large windows. The house is built between

    Borlänge and Falun. Demand control of a single house is a relatively unexplored

    area. RISE performs a study at the time of writing. They investigate the

    possibility of demand control ventilation in homes. In order to enable efficient

    demand control, several sensors and set points are required, as well as a

    control system that enables communication between the sensors. The test

    object was used to calculate energy use with different grade of demand control.

    The calculations were performed in three different ways to verify the result.

    These three were: hand calculation, TMF energi 7.11 and IDA ICE. The different

    ways consider different parameters and data. With IDA ICE, a theoretical model

    was built and several simulations were performed. The results of the calculations

    differ relatively slight between the different calculations. What all the calculations

    indicate is that there is a possibility for reducing energy use with demand

    control. When lighting, heating and ventilation are controlled, a reduction of 26 %

    (exclude hot water and equipment electricity) in energy consumption can be

    achieved by using demand control. This is due to the fact that heat loss is

    effectively reduced with less airflow and lower indoor temperature when no

    person is present in the room. The possibility of demand control in this small

    house is seen to be good, but in order to have an efficient demand control, a

    well-adjusted control system is required.

  • 320.
    Graefenhain, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energy Yield Simulation Analysis of Bifacial PV Installations in the Nordic Climate2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Recently, commercial softwares for PV system simulation released bifacial extensions. While research laboratories have developed their own simulation tools, in both cases it is imperative to display their applicability, as well as continuously assess their accuracy and/or limitations in practice, i.e. for different bifacial PV systems and field conditions. This paper presents a design and energy yield simulation study of two bifacial PV systems installed and operating in Nordic climate conditions, i.e. in Vestby, Norway (

    System 1) and in Halmstad, Sweden (System 2). The aim of this study is:

    • • To validate and compare the accuracy of two bifacial PV simulation tools newly featured in the software platforms of PVsyst and Polysun respectively, against real-field energy yield data.

    Each investigated system is modeled and analyzed with both simulation tools, resulting in four individual case stu

    dies. Further details on the systems’ monitoring set-up, the data input, modeling steps, and the involved uncertainties are presented in this paper.

    The results of the four case studies show higher percent deviations (both monthly and hourly data) between simulated energy results and real energy results during winter periods compared to summer periods. System 1 had a lower bifacial gain (around 2%) than System 2 which ranges from 2% in summer periods to 25% during winter.

    The collected field data had too high of an uncertainty to determine whether the bifacial PV simulation extensions are accurate within a certain tolerance. The reason for higher simulation inaccuracy in the winter is due to: lower production, higher uncertainty in albedo, and more diffuse irradiation.

    It is recommended for the bifacial PV simulation extensions include options for considering a variable albedo. The bifacial gain in System 2 was higher in the winter because of the higher albedo value given whereas in System 1, the albedo value was kept constant. Further parametric studies should be conducted on the bifacial gain using vertical mounted bifacial PV modules oriented east and west for Nordic climate conditions.

  • 321.
    Granbom, Ylva
    Dalarna University, School of Technology and Business Studies, Material Science.
    Structure and mechanical properties of dual phase steels: An experimental and theoretical analysis2010Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The key to the understanding of the mechanical behavior of dual phase (DP) steels is to a large extent to be found in the microstructure. The microstructure is in its turn a result of the chemical composition and the process parameters during its production. In this thesis the connection between microstructure and mechanical properties is studied, with focus on the microstructure development during annealing in a continuous annealing line. In-line trials as well as the lab simulations have been carried out in order to investigate the impact of alloying elements and process parameters on the microstructure. Further, a dislocation model has been developed in order to analyze the work hardening behavior of DP steels during plastic deformation. From the in-line trials it was concluded that there is an inheritance from the hot rolling process both on the microstructure and properties of the cold rolled and annealed product. Despite large cold rolling reductions, recrystallization and phase transformations, the final dual phase steel is still effected by process parameters far back in the production chain, such as the coiling temperature following the hot rolling. Lab simulations showed that the microstructure and consequently the mechanical properties are impacted not only by the chemical composition of the steel but also by a large number of process parameters such as soaking temperature, cooling rate prior to quenching, quench and temper annealing temperature. Studying the behavior of DP steels under deformation it was observed that the plastic deformation proceeds inhomogeneously. This was taken into account when developing a dislocation model accurately describing the work hardening behavior for this type of steel. By fitting the dislocation model to experimental stress-strain data it is possible to obtain information about the material’s behavior, e.g. it was observed that only a fraction of the ferrite phase takes part in the initial plastic deformation, which explains the high initial deformation hardening rate in DP steels. Another finding was that the flow stress ferrite grain size sensitivity in DP steels is much larger than that in ferritic steels. Further, the deformation hardening part of the flow stress experiences a ferrite grain size dependence, which is in glaring contrast to that found for ferritic steels.

  • 322.
    Granbom, Ylva
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Ryde, Lena
    Jeppsson, Johan
    Simulation of the soaking and gas jet cooling in a continuous annealing line using dilatometry2010In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 81, no 2Article in journal (Refereed)
    Abstract [en]

    The present study concerns the simulation of a continuous annealing line (CAL), using dilatometry. Simulations of CAL have been performed on four commercial steel grades with different chemical compositions in order to investigate how the alloying elements C, Mn, Si and B affect the microstructure and hardness of dual phase (DP) and martensitic steels. Three annealing cycles corresponding to those used in a CAL have been applied. When annealing intercritically, as is the case in DP-steel production, the materials do not reach equilibrium during soaking. Mn and C increase the austenite content and consequently the hardness of the materials. Higher levels of Si (0.4?wt %) are required to retard the formation of new ferrite during cooling in the gas jet section, prior to quenching. B increases hardenability effectively when annealing in the austenite region but is not as efficient during intercritical annealing, which implies that boron restrains ferrite nucleation rather than impeding ferrite growth. Results from DICTRA calculations show that it is possible to simulate the phase transformations during soaking, gasjet cooling and quenching.

  • 323.
    Granfors Wikström, Gabriella
    Dalarna University, School of Education and Humanities, Educational Work.
    Implementering av ipad i förskolan: En enkätundersökning om pedagogers erfarenheter av barns utveckling genom införande av ipad i verksamheten - både för och nackdelar2012Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I denna undersökning är syftet att ta reda på hur ipad implementeras i förskolan. Med utgångspunkt i detta har jag lagt fokus på de verksamma pedagogernas uppfattning och vad ipad kan betyda gällande barns utveckling i förskolans verksamhet. Hur pedagogerna ser på ipaden som ett eventuellt utvecklande hjälpmedel är också grundläggande för denna studie. 

    Studiens teoretiska utgångspunkt är ett sociokulturellt perspektiv på lärande. 

    Denna undersökning grundar sig i första hand i en kvantitativ metod i form av enkäter, där 27 pedagoger på 6 olika förskolor har delat med sig utav sina tankar gällande ipad. Enkäten är konstruerad med både fasta och öppna svarsalternativ, vilket erbjudit empiriska data för tolkningsbar fördjupad information.

    Resultatet visade på att implementering av ipad i förskolan upplevs som positivt av pedagogerna. Deras utsagor handlade om att ipaden ofta betraktas som ett stimulerande verktyg som kunnat bidra till att påverka utvecklat lärande i exempelvis matematik, språk och naturorienterade ämnen. Enkätsvaren visade att verksamhet med ipad till övervägande del väckte barnens lust och intresse. Men det rådde delade meningar om ipadens fördelar och nackdelar. Bland annat ansåg pedagogerna att den inte fick ta överhanden från de övriga aktiviteterna i verksamheten, och det betonades att pedagogerna borde vara med och styra upp arbetet. Det förekom hos en del pedagoger även tankar kring faktorer som eventuella effekter av trådlöst nätverk och strålning vilket barnen kan utsättas för. Enkätstudien visade vidare på brister i kompetensutveckling i samband med införandet av ipaden. De pedagoger som ville ha mer kompetens önskande mer grundläggande insikter om hur ipaden kunde användas i verksamheten för att utveckla barns lärande. 

    Huvudsaklig slutsats från studien är att vid implementering av nya verktyg såsom ipad är kommuners satsning på kompetensutveckling en grundläggande faktor. Didaktiskt fördjupad kunskap behövs för att implementering utifrån en sociokulturell syn ska kunna äga rum. Men studien visar också på en positiv inställning och vilja hos pedagogerna. 

  • 324.
    Grehk, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Berger, Robert
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Investigation of the drying process of linseed oil using FTIR and ToF-SIMS2008In: Proceedings of the 17th International Vacuum Congress/13th International Conference on Surface Science/Internatinal Conference on Nanoscience and Technology, Stockholm, 2008, Vol. 100Conference paper (Refereed)
    Abstract [en]

    The drying process of linseed oil, oxidized at 80 oC, has been investigated with rheology measurements, Fourier transformation infrared spectroscopy (FTIR), and time of flight secondary ion mass spectrometry (ToF-SIMS). The drying process can be divided into three main steps: initiation, propagation and termination. ToF-SIMS spectra show that the oxidation is initiated at the linolenic (three double bonds) and linoleic fatty acids (two double bonds). ToF-SIMS spectra reveal peaks that can be assigned to ketones, alcohols and hydroperoxides. In this article it is shown that FTIR in combination with ToF-SIMS are well suited tools for investigations of various fatty acid components and reaction products of linseed oil.

  • 325.
    Grehk, Mikael
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Engkvist, Josefin
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Richter, Jan H
    Karlsson, Patrik G
    Sandell, Anders
    Initial stages of metal-organic chemical-vapor deposition of ZrO2 on a FeCrAl alloy2007In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, no 6, p. 875-879Article in journal (Refereed)
    Abstract [en]

    The initial stages of metal-organic chemical-vapor deposition of ZrO2 on a model FeCrAl alloy was investigated using synchrotron radiation photoelectron spectroscopy, X-ray absorption spectroscopy, scanning Auger microprobe, and time of flight secondary mass spectrometry. The coatings were grown in ultra-high vacuum at 400 °C and 800 °C using the single source precursor zirconium tetra-tert-butoxide. At 400 °C the coatings mainly consist of tetragonal ZrO2 and at 800 °C amixed ZrO2/Al2O3 layer is formed. The Almetal diffuses from the FeCrAl bulk to themetal/coating interface at 400 °C and to the surface of the coating at 800 °C. The result indicates that the reactionmechanism of the growth process is different at the two investigated temperatures.

  • 326.
    Gromark, Sten
    et al.
    Chalmers Tekniska Högskola.
    Malmqvist, Inga
    Chalmers Tekniska Högskola.
    Fröst, Peter
    Chalmers Tekniska Högskola.
    Nylander, Ola
    Chalmers tekniska Högskola.
    Wijk, Helle
    Elf, Marie
    Dalarna University, School of Education, Health and Social Studies, Caring Science/Nursing.
    Thörn, Catharina
    Göteborgs Universitet.
    SRE-AIDAH: Integrative ways of residing health and quality of residence2015In: ARCH 14: International Conference on Research on Health Care Architecture - Conference Proceedings / [ed] Ira Verma, Laura Nenonen, Helsinki, 2015Conference paper (Refereed)
    Abstract [en]

    Healthcare architecture has grown rapidly in recent years. However, there are still many questions remaining. The commission, therefore, is to share the existing research knowledge and latest results and to carry out research projects focusing more specifically on the health care situation in a variety of contexts. The ARCH14 conference was the third conference in the series of ARCH conferences on Research on Health Care Architecture initiated by Chalmers University. It was realized in collaboration with the Nordic Research Network for Healthcare Architecture .It was a joint event between Aalto University, Finnish Institute of Occupational Health (FIOH) and National Institute of Health and Welfare (THL International).The conference gathered together more than 70 researchers and practitioners from across disciplines and countries to discuss the current themes.

  • 327.
    Grälls, Gustav
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Kemell, Tim
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Energieffektivisering av glödskalsspolning: Utredning av högtryckssystem för glödskalsspolning, med avseende på energieffektiviserande förbättringar och förslag till åtgärder.2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The hot rolling mill at SSAB in Borlänge uses large amounts of electricity every year. The work of systematically reducing energy usage is an ongoing process, both for the sake of the environment but also for increasing profit in the production. The high pressure system for descaling uses 20 GWh of electricity every year. This is about 10 % of the hot rolling mills total electricity usage. The steel slabs are heated before being rolled. This causes iron and oxygen to react with each other and form a scale. This scale is not desired in steel production which is why several methods to remove it have been developed. The method being used at SSAB is high pressure water descaling.

    Large volumes of water are being pressurized and sprayed through nozzles in thin triangle-like jets against the steel. To remove the scale a certain amount of energy is required. It can be calculated by using impingement pressure as a function of specific water rate (amount of water per square meter). This thesis is based on the assumption that the energy usage in the total system can be reduced without reducing the amount of energy that strikes the steel surface. The total efficiency of the system is today 39 %.

    A big contribution to the low efficiency is that all pumps are running on constant rotational speed. They need a minimal flow of water through them for cooling. This minimal flow is according to the manufacturer supposed to be 12 m3/h, but in reality they run at 30 m3/h. This is because of wear in the relief valves that are supposed to reduce the drainage flow. The relief valves are also designed to close the minimal flow to drain during descaling. This is not working as it should and water is flowing to drain during descaling. This result in the yearly energy usage increasing with 3 GWh. Additionally, because of the increased flow to the drain, energy usage is increased by around 6 %. The accumulators being used, four in total at 7 m3 each, are not used in an optimal way. Some observations have been done and at those times the tanks have been filled with about 50 % water. An accumulator should, according to theory, be empty when reaching lowest allowed system pressure. As being used today only a few percent of the tanks water volume can be used.

    A suggestion of bigger change that has been developed is to change pumps and to install bigger accumulators at the furnace and roughing descaler. This would then be made into a separate system, separated from the finishing descaler. An advantage with separate systems is that the parts can be dimensioned for different pressures. This could be especially interesting if piston pumps are installed in the accumulator system.

  • 328. Gu, Yaxiu
    et al.
    Zhang, Xingxing
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Han, Mengjie
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Chen, Xiangjie
    Yuan, Yanping
    Techno-economic analysis of a solar photovoltaic/thermal (PV/T) concentrator for building application in Sweden using Monte Carlo method2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 165, p. 8-24Article in journal (Refereed)
    Abstract [en]

    The solar energy share in Sweden will grow up significantly in next a few decades. Such transition offers not only great opportunity but also uncertainties for the emerging solar photovoltaic/thermal (PV/T) technologies. This paper therefore aims to conduct a techno-economic evaluation of a reference solar PV/T concentrator in Sweden for building application. An analytical model is developed based on the combinations of Monte Carlo simulation techniques and multi energy-balance/financial equations, which takes into account of the integrated uncertainties and risks of various variables. In the model, 11 essential input variables, i.e. average daily solar irradiance, electrical/thermal efficiency, prices of electricity/heating, operation & management (OM) cost, PV/T capital cost, debt to equity ratio, interest rate, discount rate, and inflation rate, are considered, while the economic evaluation metrics, such as levelized cost of energy (LCOE), net present value (NPV), and payback period (PP), are primarily assessed. According to the analytical results, the mean values of LCOE, NPV and PP of the reference PV/T connector are observed at 1.27 SEK/kW h (0.127 €/kW h), 18,812.55 SEK (1881.255 €) and 10 years during its 25 years lifespan, given the project size at 10.37 m2 and capital cost at 4482–5378 SEK/m2 (448.2–537.8 €/m2). The positive NPV indicates that the investment on the selected PV/T concentrator will be profitable as the projected earnings exceeds the anticipated costs, depending on the NPV decision rule. The sensitivity analysis and the parametric study illustrate that the economic performance of the reference PV/T concentrator in Sweden is mostly proportional to solar irradiance, debt to equity ratio and heating price, but disproportionate to capital cost and discount rate. Together with additional market analysis of PV/T technologies in Sweden, it is expected that this paper could clarify the economic situation of PV/T technologies in Sweden and provide a useful model for their further investment decisions, in order to achieve sustainable and low-carbon economics, with an expanded quantitative discussion of the real economic or policy scenarios that may lead to those outcomes.

  • 329.
    Gunnars, Malin
    Dalarna University, School of Technology and Business Studies, Construction.
    Byggsats till attefallshus av sandwichkonstruktioner: Hur en byggsats planeras och kan sammanfogas2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sandwichkonstruktioner används för att tillverka många olika produkter och konstruktionerna har hög hållfasthet och låg vikt. Företaget Dala Laminat tillverkar och säljer sådana konstruktioner. Nu vill de bredda sin marknad och börja tillverka hus. De har tagit fram konstruktioner till en 1,5-plansvilla och vill testa dessa i ett attefallshus. I detta examensarbete ska en ritningssats till attefallshuset tas fram. Syftet med arbetet är att se till att kundens önskemål i möjligaste mån uppfylls och att tillämpliga lagkrav och bestämmelser följs för attefallshuset samt att ta fram ritningar. Handlingarna ska kunna användas direkt i Dala Laminats fabriker för att tillverka de element som behövs för att bygga huset. Det finns lagar och regler som gäller för attefallshus, dessa handlar bland annat om måttbestämmelser kopplade till borttaget krav av bygglov. Det finns även bestämmelser vad gäller installationer i ett hus som måste följas. Arbetet gjordes som en fallstudie. Det var viktigt att Dala Laminat hela tiden granskades och sågs mer som en beställare än som en källa. Referenser vad gäller husbyggsatser och sammanfogningsmetoder presenterades och granskades. Även Dala Laminats konstruktioner och företagets produktionsförutsättningar presenterades. Därefter förde slutkunden fram sina önskemål om attefallshusets utformning och funktioner. Baserat på dessa förutsättningar och krav togs kompletta ritningar över attefallshuset fram. Eftersom attefallshuset ännu inte är byggt är det svårt att veta hur det kommer att fungera i praktiken även om alla regler och bestämmelser har följts. Sammanfogningarna valdes att göras som förslag i och med den låga erfarenheten av materialet. Sandwichkonstruktioner är ett komplicerat material att räkna på i teorin. Dock är det ett enkelt material i praktiken vad gäller att tillverka och hantera. En felkälla i arbetet är de tolkningar som gjorts vid granskningen av arbetets referenser. Metoden för hur byggsatsen har gjorts kan tillämpas för många olika slags byggsatser. Eftersom inga tidigare studier i ämnet påträffades kommer arbetet att bidra med kunskap i ämnet.

  • 330. Gunnarsson, Carina C.
    et al.
    Mattsson Petersen, Cecilia
    Dalarna University, School of Technology and Business Studies, Statistics.
    Water hyacinths as a resource in agriculture and energy production: a literature review2007In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 27, no 1, p. 117-129Article, review/survey (Refereed)
    Abstract [en]

    Water hyacinths are becoming a problem in lakes, ponds and waterways in many parts of the world. This paper contains a literature study of different ways to use water hyacinths, mainly in agricultural or alternative energy systems. The literature review indicated that water hyacinths can be rich in nitrogen, up to 3.2% of DM and have a C/N ratio around 15. The water hyacinth can be used as a substrate for compost or biogas production. The sludge from the biogas process contains almost all of the nutrients of the substrate and can be used as a fertiliser. The use of water hyacinth compost on different crops has resulted in improved yields. The high protein content makes the water hyacinth possible to use as fodder for cows, goats, sheep and chickens. Water hyacinth, due to its abundant growth and high concentrations of nutrients, has a great potential as fertiliser for the nutrient deficient soils of Africa and as feed for livestock. Applying the water hyacinths directly without any other processing than sun drying, seems to be the best alternative in small-scale use due to the relatively small losses of nutrients and workload required. To meet the ever-growing energy demand, biogas production could be one option but it requires investments and technological skills that would impose great problems in developing countries where the water hyacinth is often found. Composting as an alternative treatment has the advantage of a product that is easy to work into the soil compared with dried water hyacinths, because of the decomposed structure. Harvesting and transport of water hyacinths can be conducted manually on a small scale and does not require a new harvesting technique to be introduced. Transporting of fresh water hyacinths means, if used as fertiliser in amounts large enough to enhance or effect crop growth, an unreasonably large labour requirement. Based on the labour need and the limited access to technology, using dried water hyacinths, as green manure is a feasible alternative in many developing countries. (c) 2006 Elsevier Ltd. All rights reserved.

  • 331.
    Gunnarsson, Martin
    Dalarna University, School of Technology and Business Studies, Computer Engineering.
    Utformning av optimal lösenordskomplexitet för tangenttryckningsautentisering2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This work is on the subject of

    "keystroke authentication" and identifies what type of password is best suited for the authentication method to get as consistent and accurate authentication results as possible.

    A variety of password recommendations have been compared. Based on these recommendations, password categories of different complexities were created that vary in both content and number of characters. Then, passwords were created that met the complexity requirements of the categories.

    In order to compute the categories' temporal properties and compare which category is most consistent and accurate when inputted, a web tool was developed. The tool's task was to receive password entries from selected test subjects and to check

    which keys were pressed and when the keystrokes were made. The test subjects consisted of individuals with varying personal qualities as well as varied computer skills.

    The tool registered the keycode of the pressed key as well as time stamps for each keypress and key release. These could then be used for calculation and comparison of accuracy. The accuracy was the time difference between the entries for those passwords within the same password category. Then a comparison between each password category could be made. A survey was also conducted to get an insight into the test subjects who participated in the keystroke survey.

    The result shows that passphrases consisting of 12 characters from 4 different character categories and containing at least two Swedish words provide the most consistent and accurate input result. Hence, this type of password is recommended for keystroke authentication to get as consistent and accurate authentication results as possible.

    The result also shows that special characters is the character category that affects the temporal accuracy the most. It also shows that the most accurate keystroke function varies depending on the complexity of the password used.

    All results are based on 1476 unique password entries from 41 different test subjects.

  • 332.
    Guo, Shengqiang
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Computation and application of the spatial zero inflated count response2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Generalized linear models and its extensions are widely used for analyzing non-normal data. But Poisson mixed model may exhibit inadequate fitting and inference when encounter excessive zero counts. Mixed hurdle model is a preferable method to solve the problem. Nevertheless, it is still a challenge to use the mixed hurdle model to deal with correlated data. There are a few computational procedure for hurdle model can be used to calculate, particularly for the model with random effects being correlated between non-zero and zero response parts. In our paper we display a method to fit the hurdle model with conditionally autoregressive random effects for the spatial data. Based on the extended algorithm, some modifications are made to the existing procedure in R to help us to fit the data. We conduct Monte-Carlo simulation to study the finite sample properties of our model. The result shows that the new procedure fit the model well. The estimation becomes better with the increase of measurement in each subject. At last, we apply the new procedure to a real problem. The dataset is about reindeer spatial distribution related to the wind power establishments at Storliden Mountain in North Sweden. The new procedure gives a better fit of the real problem than a usual Poisson mixed model

  • 333.
    Guruswamy Aarumugam, Bhupathi Rajan
    Dalarna University, School of Technology and Business Studies, Computer Engineering.
    Independent Domain of Symmetric Encryption using Least SignificantBit: Computer Vision, Steganography and Cryptography Techniques2011Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The rapid development of data transfer through internet made it easier to send the data accurate and faster to the destination. There are many transmission media to transfer the data to destination like e-mails; at the same time it is may be easier to modify and misuse the valuable information through hacking. So, in order to transfer the data securely to the destination without any modifications, there are many approaches like cryptography and steganography. This paper deals with the image steganography as well as with the different security issues, general overview of cryptography, steganography and digital watermarking approaches.

     The problem of copyright violation of multimedia data has increased due to the enormous growth of computer networks that provides fast and error free transmission of any unauthorized duplicate and possibly manipulated copy of multimedia information. In order to be effective for copyright protection, digital watermark must be robust which are difficult to remove from the object in which they are embedded despite a variety of possible attacks.

    The message to be send safe and secure, we use watermarking. We use invisible watermarking to embed the message using LSB (Least Significant Bit) steganographic technique. The standard LSB technique embed the message in every pixel, but my contribution for this proposed watermarking, works with the hint for embedding the message only on the image edges alone. If the hacker knows that the system uses LSB technique also, it cannot decrypt correct message. To make my system robust and secure, we added cryptography algorithm as Vigenere square. Whereas the message is transmitted in cipher text and its added advantage to the proposed system. The standard Vigenere square algorithm works with either lower case or upper case. The proposed cryptography algorithm is Vigenere square with extension of numbers also. We can keep the crypto key with combination of characters and numbers. So by using these modifications and updating in this existing algorithm and combination of cryptography and steganography method we develop a secure and strong watermarking method.

    Performance of this watermarking scheme has been analyzed by evaluating the robustness of the algorithm with PSNR (Peak Signal to Noise Ratio) and MSE (Mean Square Error) against the quality of the image for large amount of data. While coming to see results of the proposed encryption, higher value of 89dB of PSNR with small value of MSE is 0.0017. Then it seems the proposed watermarking system is secure and robust for hiding secure information in any digital system, because this system collect the properties of both steganography and cryptography sciences.

  • 334.
    Gustafson, Karolina
    et al.
    Dalarna University, School of Technology and Business Studies, Graphic Arts Technology.
    Bergenfelz, Charlotte
    Dalarna University, School of Technology and Business Studies, Graphic Arts Technology.
    Grafisk profil åt Borlänge Bandy: Framtagning av en sportförenings visuella profil2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Borlänge Bandy is a sports association based in Borlänge. Before this work took place they had no visual identity. To help Borlänge Bandy create better perception, a visual identity was created. The goal was to create a visual identity supported by the target group’s views. To investigate the target group's opinions on Borlänge Bandy’s visual appearance several surveys was conducted. These formed the basis for a renewal of Borlänge Bandy’s logotype. Material to the visual identity was analyzed in a focus group. This then led to an updated version of the logotype along with graphic material. An evaluative focus group then checked that the goal had been achieved. The result was a new visual identity with associated graphic identity manual to Borlänge Bandy that contains information about typography, colors, logotype, visual identity imagery, correspondence materials, business products and graphic elements. If the graphic material is handled with consistency it will create recognition. The conclusions were that the new visual identity is perceived as unified, harmonious, and related throughout the manual. 

  • 335.
    Gustafsson, Annica
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Granberg, Per
    Dalarna University, School of Technology and Business Studies, Construction.
    Energieffektivisering av klimatskal i tropiskt klimat: Fallstudie av en byggnad i Surabaya, Indonesien2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Studien omfattar en undersökning av en byggnad i Surabaya, Indonesien

    belägen på universitet UBAYA. Användningen av luftkonditionering ökar kraftigt i

    utvecklingsländer. Detta gör att behovet av förbättringar i såväl

    klimatanläggningar som i byggnader kommer att vara nödvändiga för att inte

    orsaka ytterligare påfrestningar på miljön genom ökad energianvändning

    Syftet med studien är att hitta energibesparande åtgärder på byggnadens

    klimatskal med hänsyn till det tropiska klimatet utan att orsaka fuktproblem i

    ingående byggnadsdelar.

    Byggnaden fungerar i dagsläget bra ur fuktsynpunkt och har inga direkt synliga

    skador orsakade av fuktproblem i konstruktionen. Däremot påvisar det höga uvärdet

    för byggnaden dess ineffektivitet gällande energibehov. Fyra olika

    åtgärdsförslag med utgångspunkt i den nuvarande konstruktionen presenteras i

    studien. Åtgärdsförslagen utvärderas ur fuktsynpunkt med programmet WUFI

    samt ur ett energimässigt perspektiv med programmet Polysun.

    Resultatet visar att störst energibesparing kan ske genom att isolera taket då det

    visar sig vara en stor värmekälla till byggnaden. Denna åtgärd innebär samtidigt

    en viss risk för fuktproblem på grund av höga relativa fukthalter och

    temperaturer. Även en tätning av de nuvarande läckagen i byggnaden påverkar

    energiförbrukningen i stor utsträckning, vilket gör dessa två åtgärder till den

    bästa kombinationen för att sänka energiförbrukningen. Att byta ut nuvarande

    englaskassetter mot tvåglas samt isolera de befintliga ytterväggarna är de

    åtgärder som påverkar energibehovet minst.

    Några av de slutsatser som dras ur studien är att totalt sett kan byggnadens

    energiförbrukning sänkas med 50 % om samtliga åtgärdsförslag genomförs.

    Fuktriskerna ökar vid isoleringsåtgärder men är genomförbara.

  • 336.
    Gustafsson, Elina
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Persson, Jannika
    Dalarna University, School of Technology and Business Studies, Construction.
    Miljövänliga material i villakonstruktion: En jämförande studie av fyra olika vägg- och vindsbjälklagsförslag gällande miljö och hälsa, med fuktanalys och U-värdesberäkningar.2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Environmental awareness today is larger than ever, and continues to expand. The increasing knowledge has led to a rising demand of using environmental friendly materials and the interest of building and living in a way that is good for the health and environment has grown with it. The small house manufacturer Fiskarhedenvillan, has noticed this demand and that is why this study has been done.

    The purpose of this study is to investigate what opportunities there is to replace one or some of the chosen materials from Fiskarhedenvillans construction to materials that fulfills higher demands at being environment- and healthfriendly. The U-value of the suggestions should be equivalent or improved. The most important aspect otherwise was to investigate how well the new suggestions manage moisture impact. The suggested materials have been windbarrier board, insulation, waterproofing, vapour barrier, tape and interior lining.

    The study was performed by a thorough investigation of the materials that could be of interest. This was done by searching for relevant information through databases, reports, manufacturers homepages and from other construction related books and internet sources. The moisture simulations and U-value calculations were done in the simulation program WUFI pro 5.3. A survey was sent out to Fiskarhedenvillans agents to investigate the housing markets interest in changing to environmental-friendly materials.

    The investigations resulted in four functional suggestions on external wall construction with loft floor, which was chosen based on the purposes. The results show that all constructions successfully handled the moisture exposure, except the wallconstruction with cellulose based insulationboards, where the relative humidity during the whole year stays at such high levels that risk of mould- and moisturedamage is existing. The result of the U-value calculations shows that the suggestions have similar U-value to Fiskarhedenvillans current constructions. However, the proposal with hempinsulation had to be extended 10cm in order to meet this requirement. For the loft floor with hempinsulation it was accepted that the U-value was somewhat lesser than the others. The result from the survey shows that more than half of the agents have experienced a demand from potential customers to change materials to more environment-friendly.

    The most important conclusion is that it is possible to change materials in a house and maintain its construction capacity while managing the impact of moisture as well. Since customers appear willing to pay more for changing materials, we believe that it would not be a problem for Fiskarhedenvillan to establish at least one construction possibility with environmental-friendly materials.

  • 337.
    Gustafsson, Emil
    Dalarna University, School of Technology and Business Studies, Materials Technology. Luleå tekniska universitet.
    Design and application of experimental methods for steel sheet shearing2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Shearing is the process where sheet metal is mechanically cut between two tools. Various shearing technologies are commonly used in the sheet metal industry, for example, in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material. The constant development of sheet metals toward higher strength and formability leads to increased forces on the shearing equipment and tools.

    Shearing of new sheet materials imply new suitable shearing parameters. Investigations of the shearing parameters through live tests in the production are expensive and separate experiments are time consuming and requires specialized equipment. Studies involving a large number of parameters and coupled effects are therefore preferably performed by finite element based simulations. Accurate experimental data is still a prerequisite to validate such simulations. There is, however, a shortage of accurate experimental data to validate such simulations.

    In industrial shearing processes, measured forces are always larger than the actual forces acting on the sheet, due to friction losses. Shearing also generates a force that attempts to separate the two tools with changed shearing conditions through increased clearance between the tools as result. Tool clearance is also the most common shearing parameter to adjust, depending on material grade and sheet thickness, to moderate the required force and to control the final sheared edge geometry.

    In this work, an experimental procedure that provides a stable tool clearance together with accurate measurements of tool forces and tool displacements, was designed, built and evaluated. Important shearing parameters and demands on the experimental set-up were identified in a sensitivity analysis performed with finite element simulations under the assumption of plane strain. With respect to large tool clearance stability and accurate force measurements, a symmetric experiment with two simultaneous shears and internal balancing of forces attempting to separate the tools was constructed.

    Steel sheets of different strength levels were sheared using the above mentioned experimental set-up, with various tool clearances, sheet clamping and rake angles. Results showed that tool penetration before fracture decreased with increased material strength. When one side of the sheet was left unclamped and free to move, the required shearing force decreased but instead the force attempting to separate the two tools increased. Further, the maximum shearing force decreased and the rollover increased with increased tool clearance.

    Digital image correlation was applied to measure strains on the sheet surface. The obtained strain fields, together with a material model, were used to compute the stress state in the sheet. A comparison, up to crack initiation, of these experimental results with corresponding results from finite element simulations in three dimensions and at a plane strain approximation showed that effective strains on the surface are representative also for the bulk material.

    A simple model was successfully applied to calculate the tool forces in shearing with angled tools from forces measured with parallel tools. These results suggest that, with respect to tool forces, a plane strain approximation is valid also at angled tools, at least for small rake angles.

    In general terms, this study provide a stable symmetric experimental set-up with internal balancing of lateral forces, for accurate measurements of tool forces, tool displacements, and sheet deformations, to study the effects of important shearing parameters. The results give further insight to the strain and stress conditions at crack initiation during shearing, and can also be used to validate models of the shearing process.

  • 338.
    Gustafsson, Emil
    Dalarna University, School of Technology and Business Studies, Materials Technology. Luleå tekniska universitet.
    Experiments on Sheet Metal Shearing2013Licentiate thesis, comprehensive summary (Other academic)
  • 339.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Karlsson, Lars
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Experimental study of forces and energies during shearing of steel sheet with angled tools2016In: International Journal of Mechanical and Materials Engineering, ISSN 2198-2791, Vol. 11, article id 10Article in journal (Refereed)
    Abstract [en]

    Shearing is a fast and inexpensive method to cut sheet metal that has been used since the beginning of the industrialism. Consequently, published experimental studies of shearing can be found from over a century back in time. Recent studies, however, are due to the availability of low cost digital computation power, mostly based on finite element simulations that guarantees quick results. Still, for validation of models and simulations, accurate experimental data is a requisite. When applicable, 2D models are in general desirable over 3D models because of advantages like low computation time and easy model formulation. Shearing of sheet metal with parallel tools is successfully modelled in 2D with a plane strain approximation, but with angled tools the approximation is less obvious. Therefore, plane strain approximations for shearing with angled tools were evaluated by shear experiments of high accuracy. Tool angle, tool clearance, and clamping of the sheet were varied in the experiments. The results showed that the measured forces in shearing with angled tools can be approximately calculated using force measurements from shearing with parallel tools. Shearing energy was introduced as a quantifiable measure of suitable tool clearance range. The effects of the shearing parameters on forces were in agreement with previous studies. Based on the agreement between calculations and experiments, analysis based on a plane strain assumption is considered applicable for angled tools with a small (up to 2 degrees) rake angle.

  • 340.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Karlsson, Lars
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Oldenburg, Mats
    Luleå University of Technology.
    Experimental study of strain fields during shearing of medium and high-strength steel sheet2016In: International Journal of Mechanical and Materials Engineering, ISSN 2198-2791, Vol. 11, no 1, article id 14Article in journal (Refereed)
    Abstract [en]

    There is a shortage of experimentally determined strains during sheet metal shearing. These kinds of data are a requisite to validate shearing models and to simulate the shearing process. In this work, strain fields were continuously measured during shearing of a medium and a high strength steel sheet, using digital image correlation. Preliminary studies based on finite element simulations, suggested that the effective surface strains are a good approximation of the bulk strains below the surface. The experiments were performed in a symmetric set-up with large stiffness and stable tool clearances, using various combinations of tool clearance and clamping configuration. Due to large deformations, strains were measured from images captured in a series of steps from shearing start to final fracture. Both the Cauchy and Hencky strain measures were considered, but the difference between these were found negligible with the number of increments used (about 20 to 50). Force-displacement curves were also determined for the various experimental conditions. The measured strain fields displayed a thin band of large strain between the tool edges. Shearing with two clamps resulted in a symmetric strain band whereas there was an extended area with large strains around the tool at the unclamped side when shearing with one clamp. Furthermore, one or two cracks were visible on most of the samples close to the tool edges well before final fracture. The fracture strain was larger for the medium strength material compared with the high-strength material and increased with increasing clearance.

  • 341.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Marth, Stefan
    Luleå University of Technology.
    Karlsson, Lars
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Oldenburg, Mats
    Luleå University of Technology.
    Strain and stress conditions at crack initiation during shearing of medium- and high-strength steel sheet2017In: International Journal of Mechanical and Materials Engineering, ISSN 2198-2791, Vol. 12, no 1, p. 10-Article in journal (Refereed)
    Abstract [en]

    Strain and stress conditions in sheet metal shearing are of interest for calibration of various fracture criteria. Most fracture criterion are governed by effective strain and stress triaxiality. This work is an attempt to extend previous measurements of strain fields in shearing of steel sheets with the stress state calculated from the measured displacement fields. Results are presented in terms of von Mises stress and stress triaxiality fields, and a comparison was made with finite element simulations. Also an evaluation of the similarities of the stress conditions on the sheet surface and inside the bulk material were presented. Strains and von Mises stresses were similar on the surface and the bulk material, but the stress triaxiality was not comparable. There were large gradients in strain and stress around the curved tool profiles that made the results resolution dependent and comparisons of maximum strain and stress values difficult. The stress state on the sheet surface calculated from displacement field measurements is still useful for validation of a three dimensional finite element model.

  • 342.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Oldenburg, Mats
    Jansson, Anders
    Design and validation of a sheet metal shearing experimental procedure2014In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 214, no 11, p. 2468-2477Article in journal (Refereed)
    Abstract [en]

    Throughout the industrial processes of sheet metal manufacturing and refining, shear cutting is widely used for its speed and cost advantages over competing cutting methods. Industrial shears may include some force measurement possibilities, but the force is most likely influenced by friction losses between shear tool and the point of measurement, and are in general not showing the actual force applied to the sheet. Well defined shears and accurate measurements of force and shear tool position are important for understanding the influence of shear parameters. Accurate experimental data are also necessary for calibration of numerical shear models. Here, a dedicated laboratory set-up with well defined geometry and movement in the shear, and high measurability in terms of force and geometry is designed, built and verified. Parameters important to the shear process are studied with perturbation analysis techniques and requirements on input parameter accuracy are formulated to meet experimental output demands. Input parameters in shearing are mostly geometric parameters, but also material properties and contact conditions. Based on the accuracy requirements, a symmetric experiment with internal balancing of forces is constructed to avoid guides and corresponding friction losses. Finally, the experimental procedure is validated through shearing of a medium grade steel. With the obtained experimental set-up performance, force changes as result of changes in studied input parameters are distinguishable down to a level of 1%.

  • 343.
    Gustafsson, Emil
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Oldenburg, Mats
    Jansson, Anders
    Experimental study on the effects of clearance and clamping in steel sheet metal shearing2016In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 229, p. 172-180Article in journal (Refereed)
    Abstract [en]

    Shear cutting is common within several sheet metal industry processing steps, e.g. in cut to length lines, slitting lines, end cropping. Shearing is fast and cheap relative to competing cutting methods like laser and plasma cutting, but involves large forces on the equipment that increase with increased sheet material strength. Accurate shear experiments are a prerequisite to increase the knowledge of shearing parameters, improve industrial shearing, and provide data for validation of numerical shear models. Here, the two shear parameters clearance and clamp configuration, identified as important to the shear results, were studied in an experimental set-up with well defined tool movement and high measurability of tool position and force. In addition to force measurements, the sheared edge geometry was characterized. Steels of low, medium, and high strength were selected for the study. Throughout the experimental study, the shear tool penetration before fracture decreased with increased material strength. The required shear force decreased and the force attempting to separate the two shear tools increased when one side of the sheet was left unclamped and free to move. Further, the maximum shear force increased with decreased clearance. Clearance changes were small and moreover continuously measured during all shear experiments.

  • 344. Gustafsson, M.
    et al.
    Rönnelid, Mats
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Trygg, L.
    Karlsson, B.
    CO2 emission evaluation of energy conserving measures in buildings connected to a district heating system: Case study of a multi-dwelling building in Sweden2016In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 111, p. 341-350Article in journal (Refereed)
    Abstract [en]

    When taking action to fulfill the directives from the European Union, energy conserving measures will be implemented in the building sector. If buildings are connected to district heating systems, a reduced heat demand will influence the electricity production if the reduced heat demand is covered by combined heat and power plants.This study analyze five different energy conserving measures in a multi-dwelling building regarding how they affect the marginal production units in the district heating system in Gävle, Sweden. For CO2 emission evaluations, two different combinations of heat and electricity conserving measures are compared to an installation of an exhaust air heat pump.The different energy conserving measures affect the district heating system in different ways. The results show that installing an exhaust air heat pump affects the use/production of electricity in the district heating system most and electricity conserving measures result in reduced use of electricity in the building, reduced use of electricity for production of heat in the district heating system and an increase of electricity production.The conclusion is that electricity use in the building is the most important factor to consider when energy conserving measures are introduced in buildings within the district heating system in Gävle.

  • 345.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology. KTH.
    Energy efficient and economic renovation of residential buildings with low-temperature heating and air heat recovery2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    With the building sector accounting for around 40% of the total energy consumption in the EU, energy efficiency in buildings is and continues to be an important issue. Great progress has been made in reducing the energy consumption in new buildings, but the large stock of existing buildings with poor energy performance is probably an even more crucial area of focus. This thesis deals with energy efficiency measures that can be suitable for renovation of existing houses, particularly low-temperature heating systems and ventilation systems with heat recovery. The energy performance, environmental impact and costs are evaluated for a range of system combinations, for small and large houses with various heating demands and for different climates in Europe. The results were derived through simulation with energy calculation tools.

    Low-temperature heating and air heat recovery were both found to be promising with regard to increasing energy efficiency in European houses. These solutions proved particularly effective in Northern Europe as low-temperature heating and air heat recovery have a greater impact in cold climates and on houses with high heating demands. The performance of heat pumps, both with outdoor air and exhaust air, was seen to improve with low-temperature heating. The choice between an exhaust air heat pump and a ventilation system with heat recovery is likely to depend on case specific conditions, but both choices are more cost-effective and have a lower environmental impact than systems without heat recovery. The advantage of the heat pump is that it can be used all year round, given that it produces DHW.

    Economic and environmental aspects of energy efficiency measures do not always harmonize. On the one hand, lower costs can sometimes mean larger environmental impact; on the other hand there can be divergence between different environmental aspects. This makes it difficult to define financial subsidies to promote energy efficiency measures.

  • 346.
    Gustafsson, Marcus
    Dalarna University, School of Technology and Business Studies, Energy Technology. KTH, Strömnings- och klimatteknik.
    Energy Efficient Renovation Strategies for Swedish and Other European Residential and Office Buildings2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The high energy use in the European building stock is attributable to the large share of old buildings with poor energy performance. Energy renovation of buildings is therefore vital in the work towards energy efficiency and reduced environmental impact in the EU. Yet, the strategies and energy system implications of this work have not been made clear, and the rate of building renovation is currently very low.

    The aim of this thesis is to investigate the economic and environmental aspects of energy renovation strategies, with two main objectives:

    • Renovation of Swedish district heated multi-family houses, including life-cycle cost and environmental analysis and impact on the local energy system;

    • Renovation of European residential and office buildings, including life-cycle cost and environmental analysis and influence of climatic conditions.

    Buildings typical for the respective regions and the period of construction 1945-1970 were simulated, in order to determine the feasibility and energy saving potential of energy renovation measures in European climates. A variety of systems for heating, cooling and ventilation were studied, as well as solar energy systems, with focus on heat pumps, district heating, low-temperature heating systems and air heat recovery.

    Compared to normal building renovation, energy renovation can often reduce the life-cycle costs and environmental impact. In renovation of typical European office buildings, as well as Southern European multi-family houses, more ambitious renovation levels can also be more profitable.

    Exhaust air heat pumps can be cost-effective complements in district heated multi-family houses, while ventilation with heat recovery is more expensive but also more likely to reduce the primary energy use. From a system perspective, simple exhaust ventilation can reduce the primary energy use in the district-heating plant as much as an exhaust air heat pump, due to the lower electricity use.

  • 347.
    Gustafsson, Marcus
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology. KTH.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Holmberg, Sture
    KTH.
    Techno-economic analysis of three HVAC retrofitting options2014Conference paper (Refereed)
    Abstract [en]

    Accounting for around 40% of the total final energy consumption, the building stock is an important area of focus on the way to reaching the energy goals set for the European Union. The relatively small share of new buildings makes renovation of existing buildings possibly the most feasible way of improving the overall energy performance of the building stock. This of course involves improvements on the climate shell, for example by additional insulation or change of window glazing, but also installation of new heating systems, to increase the energy efficiency and to fit the new heat load after renovation. In the choice of systems for heating, ventilation and air conditioning (HVAC), it is important to consider their performance for space heating as well as for domestic hot water (DHW), especially for a renovated house where the DHW share of the total heating consumption is larger.

    The present study treats the retrofitting of a generic single family house, which was defined as a reference building in a European energy renovation project. Three HVAC retrofitting options were compared from a techno-economic point of view: A) Air-to-water heat pump (AWHP) and mechanical ventilation with heat recovery (MVHR), B) Exhaust air heat pump (EAHP) with low-temperature ventilation radiators, and C) Gas boiler and ventilation with MVHR. The systems were simulated for houses with two levels of heating demand and four different locations: Stockholm, Gdansk, Stuttgart and London. They were then evaluated by means of life cycle cost (LCC) and primary energy consumption. Dynamic simulations were done in TRNSYS 17.

    In most cases, system C with gas boiler and MVHR was found to be the cheapest retrofitting option from a life cycle perspective. The advantage over the heat pump systems was particularly clear for a house in Germany, due to the large discrepancy between national prices of natural gas and electricity. In Sweden, where the price difference is much smaller, the heat pump systems had almost as low or even lower life cycle costs than the gas boiler system. Considering the limited availability of natural gas in Sweden, systems A and B would be the better options. From a primary energy point of view system A was the best option throughout, while system B often had the highest primary energy consumption. The limited capacity of the EAHP forced it to use more auxiliary heating than the other systems did, which lowered its COP. The AWHP managed the DHW load better due to a higher capacity, but had a lower COP than the EAHP in space heating mode. Systems A and C were notably favoured by the air heat recovery, which significantly reduced the heating demand.

    It was also seen that the DHW share of the total heating consumption was, as expected, larger for the house with the lower space heating demand. This confirms the supposition that it is important to include DHW in the study of HVAC systems for retrofitting.

  • 348.
    Gustafsson, Marcus
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology. KTH.
    Dermentzis, Georgios
    Univeristy of Innsbruck.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Ochs, Fabian
    Univeristy of Innsbruck.
    Holmberg, Sture
    KTH.
    Feist, Wolfgang
    Energy performance comparison of three innovative HVAC systems for renovation through dynamic simulation2014In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 82, p. 512-519Article in journal (Refereed)
    Abstract [en]

    In this paper, dynamic simulation was used to compare the energy performance of three innovativeHVAC systems: (A) mechanical ventilation with heat recovery (MVHR) and micro heat pump, (B) exhaustventilation with exhaust air-to-water heat pump and ventilation radiators, and (C) exhaust ventilationwith air-to-water heat pump and ventilation radiators, to a reference system: (D) exhaust ventilation withair-to-water heat pump and panel radiators. System A was modelled in MATLAB Simulink and systems Band C in TRNSYS 17. The reference system was modelled in both tools, for comparison between the two.All systems were tested with a model of a renovated single family house for varying U-values, climates,infiltration and ventilation rates.It was found that A was the best system for lower heating demand, while for higher heating demandsystem B would be preferable. System C was better than the reference system, but not as good as A or B.The difference in energy consumption of the reference system was less than 2 kWh/(m2a) betweenSimulink and TRNSYS. This could be explained by the different ways of handling solar gains, but also bythe fact that the TRNSYS systems supplied slightly more than the ideal heating demand.

  • 349.
    Gustafsson, Marcus
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Dipasquale, C.
    Poppi, Stefano
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Bellini, A.
    Fedrizzi, R.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Ochs, F.
    Sié, M.
    Holmberg, S.
    Economic and environmental analysis of energy renovation packages for European office buildings2017In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 148, p. 155-165Article in journal (Refereed)
    Abstract [en]

    A large share of the buildings in Europe are old and in need of renovation, both in terms of functional repairs and energy efficiency. While many studies have addressed energy renovation of buildings, they rarely combine economic and environmental life cycle analyses, particularly for office buildings. The present paper investigates the economic feasibility and environmental impact of energy renovation packages for European office buildings. The renovation packages, including windows, envelope insulation, heating, cooling and ventilation systems and solar photovoltaics (PV), were evaluated in terms of life cycle cost (LCC) and life cycle assessment (LCA) through dynamic simulation for different European climates. Compared to a purely functional renovation, the studied renovation packages resulted in up to 77% lower energy costs, 19% lower total annualized costs, 79% lower climate change impact, 89% lower non-renewable energy use, 66% lower particulate matter formation and 76% lower freshwater eutrophication impact over a period of 30 years. The lowest total costs and environmental impact, in all of the studied climates, were seen for the buildings with the lowest heating demand. Solar PV panels covering part of the electricity demand could further reduce the environmental impact and, at least in southern Europe, even reduce the total costs. © 2017 Elsevier B.V.

  • 350.
    Gustafsson, Marcus
    et al.
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology. KTH.
    Myhren, Jonn Are
    Dalarna University, School of Technology and Business Studies, Construction.
    Bales, Chris
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Comparison of two HVAC renovation solutions: A case study2013Conference paper (Refereed)
    Abstract [en]

    Within the aging building stock of Europe, there is great potential of saving energy through renovation and upgrading to modern standards, and to thereby approach the internationally set goals of lower energy use. This paper concerns the planned renovation of the building envelope and HVAC systems in a multi-family house in Ludwigsburg, Germany. Five systemic HVAC solutions were compared, with special focus on two systems: A) Balanced ventilation with HRC + Micro heat pump, and B) Forced exhaust ventilation + Heat pump with exhaust air HRC + Ventilation radiators. Given the predicted heating demand and ventilation rate of the house after renovation, the performance of the two systems was compared, alongside three common systems for reference. Calculations were made using TMF Energi, a tool developed by SP Technical Research Institute of Sweden.

       Both systems A and B were found to have the lowest electrical energy use together with the ground source heat pump system for the assumed conditions. For other assumptions, including different climate and degree of insulation, some differences between these three systems were noted. Most significant is the increased electrical use of system B for higher heating loads due to limitations in the power available from the heat source, exhaust air, which is dependent on the ventilation rate.

45678910 301 - 350 of 1341
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf