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  • 1.
    Aurusell, Louise
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Ytbehandling baserad på hampolja2008Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The varieties of paint are today very big, but many of the more popular paints are less than environmental friendly. The uses of fossilized fuel in paints are common because these paints dry fast and are color true. It would be beneficial for the environment if more renewable source were used to produce paint. Linseed oil is an old base for oil paints. It is renewable and easily procured. But linseed oils have some aspects that give it a bad reputation. There are problems with the slow drying and the color turning yellow when exposed to darkness for long periods of time. Researchers at KTH have connected the yellowing to linolenic acid, one of the common fatty acids in linseed oil (Svensson, M. Johansson, M, Stenberg, C. Samuelsson, J. 2003). Hempseed oil is also a drying oil like linseed, but hempseed oil contains a larger amount of the fatty acid linoleic acid and a smaller amount of linolenic acid (http://en.wikipedia.org/wiki/Hempseed_oil). This might mean that oil paint based on hempseed-oil instead of linseed-oil might have fewer problems with yellowing.Experiments with the two oils have been executed side by side in order to compare results. Two oil paints have also been produced and tested. Test pieces painted with the two different oil paints were exposed to moisture, daylight and complete darkness and then compared.

  • 2.
    Bahrami, Alireza
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran.
    Matinrad, Sina
    Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran.
    Response of steel beam-to-column bolted connections to blast loading2019In: International Journal of Recent Technology and Engineering, ISSN 2277-3878, Vol. 8, no 3, p. 3639-3648Article in journal (Refereed)
    Abstract [en]

    In this research, response of steel beam-to-column bolted connections to blast loading is investigated. Nonlinear analyses of the connections are performed using the finite element software ABAQUS. In order to demonstrate the accuracy of the finite element modelling, an experimental test of a steel beam-to-column bolted connection is modelled. Comparison of the obtained result from the modelling with that of the corresponding experimental test verifies the modelling. Then, a 5-storey steel building is designed using ETABS software from which a beam-to-column connection of the ground floor is selected for the nonlinear analysis in ABAQUS. Thereafter, the components of the selected connection are designed. Finally, the connection is nonlinearly analysed considering parameters as the distance from the blast centre (2.5 m, 5 m, and 10 m) and blast power (500 kg, 1000 kg, and 2000 kg TNT equivalent mass of explosive). Effects of these parameters on the response of the connection are evaluated. Failure modes of the connections are assessed, too.

  • 3.
    Blom, Jonas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics.
    Optimizing spare-parts management2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Purpose:

    The purpose of the study is to develop a model that will facilitate the choice of maintenance strategy within the Swedish pulp and paper industry. Without compromising system availability, the model aims to reduce inventory holding costs.

    Methodology:

    At first, a literary research was conducted to create a holistic view over the chosen topic, in time it developed into a literature framework. Secondly, a case study was conducted in order to obtain empirical data. The data were obtained through interviews and archival records. The literature framework and the empirical data were then cross-analyzed with each other.

    Findings:

    In this thesis, a model has been developed based on previously applied and accepted methods. The methods have been identified and described in order to provide a strategy in which the inventory levels- and value could be lowered. The findings indicate that the organization must seek to assign ABC-classified and VED-analyzed components different maintenance actions in order to reduce the total cost.

    Theoretical contribution:

    This thesis contributes to a methodology development regarding spare parts management. It aims to add knowledge to the existing gap regarding spare parts order point and batch size. The thesis provides a procedure in which systems including critical and expensive components are evaluated in order to assign them the appropriate maintenance.

    Practical relevance:

    The model has only been exemplified by using a system position from Stora Enso Skutskär, the numerical values are examples. The model must be tested with real values and the risk analysis must be carried out with a group of employees with great insight regarding the selected component and system position.

    Limitations:

    This thesis is delimited to spare parts management and inventory management. The study only involves one Swedish organization, whereas the organization and its spare parts management illustrates the complexity concerning spares. The model will not be verified as the focus is to highlight the research gap and to develop the model.

  • 4. Carlsson, Thomas
    Fukttransport i autoklaverad lättbetong: inverkan av mikrostruktur1999Report (Other academic)
  • 5.
    Dominic, Chris
    Sustainability and Foresight, Innventia, Stockholm, Sweden.
    Packaging logistics performance and how to evaluate the packaging performance by applying the tool packaperforma2010In: 17th IAPRI World Conference on Packaging 2010, 2010, p. 245-250Conference paper (Other academic)
    Abstract [en]

    Packaperforma is a tool developed in order to increase the efficiency, effectiveness and differentiation in the future design of packaging systems. The tool is based on the theory Packaging Logistics Performance. Packaperforma is a further development of Packaging Scorecard and it could be utilized by packaging designers and supply chain managers to see the functions of the packaging system in the logistics processes. This means that the gap between packaging decisions and logistics decisions can be mitigated, as it can share the downstream information with the upstream and the designers. Packaperforma is used to conduct comparative studies in multiple Supply-Demand Chains. A study as such increases the quantity of data in the Packaperforma database that could be used to indicate the performances of the packaging, the agent and the Supply Demand Chains. The paper presents a study on Packaging Logistics Performance, how to evaluate packaging performance; how to collect feedback information from different agents and efficiently solve packaging related problem. Further the paper describes a web system based tool, packaging performance indicators and packaging performance database.

  • 6.
    Dominic, Chris
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management. University of Gävle, Center for Logistics and Innovative Production.
    Johansson, Jennie
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management. University of Gävle, Center for Logistics and Innovative Production.
    Building network integration solutions for locally produced foods: new requirements on supply chain, logistics and packaging2017In: International Agriculture Innovation and Cross-border EC Conference (IAICEC), Chiang Mai, Thailand, 18-19th October 2017 / [ed] Dr. Tzong-Ru Lee, Chiang Mai, 2017Conference paper (Refereed)
    Abstract [en]

    One important ongoing development in the grocery foods industry is the increase growth of Locally Produced Foods. This emerging market that based on the pillars of sustainability, demands new logistics challenges that requires innovative supply chain models . These chains are designed through the application of digitalized media. The paper presents an on-going study in establishing Network Integration for Locally Produced foods in Mid-Sweden Region. The objective of this study is to present an approach to explore locally produced foods. A case study based on logistics activities, supply chain management, packaging is presented. The data used in the study are from micro-producers of food, customers from local restaurants , consumers and the public sector from Mid-Sweden Region. The results indicates that th e main aspects of Network Integration actively contributes to better performance for this industry in almost all items considered in the study. This approach is considered particularly innovative, hence there are scarcity of literature that deals jointly with packaging, logistics and Network Integration from an empirical standpoint.

  • 7.
    Edqvist, Helena
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering.
    Hide and seek: Ett utforskande av nya materialupplevelser i ull2019Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The information that wool is burned in quantities while we are importing wool speaks its clearlanguage, something needs to be done. Wool, which is a durable and 100% renewablematerial with both historical connections as well as fantastic properties, is a huge waste ofresources to burn as if it were rubbish.

    From a sustainability perspective as well as a personal interest, based on my years as astylist, I have investigated the sensual properties of the wool to find new materialexperiences in one of the world's oldest textile materials. The climate issue that is mostup-to-date, which we all have to relate to in one way or another, and that I want to make myresearch available to everyone, means that my work is relevant from a sustainabilityperspective.

    I have worked from a material-driven design, where the meaning of the material has beenimportant in order to weave the emotional connection to a material. With an artisticapproach, I wanted to take on my work in exploring, evaluating and questioning myself andmy work in a material-driven process, in which I turn materials and user tests to contributewith new material experiences of wool. I hope that my work contributes to seeing Swedishwool with new eyes. With new associations and perspectives. To see opportunities insteadof impossibilities.

  • 8.
    Elgammal, Karim
    et al.
    Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Kista, Sweden; SeRC (Swedish e-Science Research Center), KTH Royal Institute of Technology, Stockholm, Sweden.
    Hugosson, Håkan Wilhelm
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Physics.
    Smith, Anderson D.
    Department of Integrated Devices and Circuits, School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden; Department of Microtechnology and Nanoscience, Electronics Materials Systems Laboratory, Chalmers Institute of Technology, Gothenburg, Sweden.
    Råsander, Mikael
    Department of Materials, Imperial College London, London, United Kingdom.
    Bergqvist, Lars
    Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Kista, Sweden; SeRC (Swedish e-Science Research Center), KTH Royal Institute of Technology, Stockholm, Sweden.
    Delin, Anna
    Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Kista, Sweden; SeRC (Swedish e-Science Research Center), KTH Royal Institute of Technology, Stockholm, Sweden; Department of Physics and Astronomy, Materials Theory Division, Uppsala University, Uppsala, Sweden.
    Density functional calculations of graphene-based humidity and carbon dioxide sensors: effect of silica and sapphire substrates2017In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 663, p. 23-30Article in journal (Refereed)
    Abstract [en]

    We present dispersion-corrected density functional calculations of water and carbon dioxide molecules adsorption on graphene residing on silica and sapphire substrates. The equilibrium positions and bonding distances for the molecules are determined. Water is found to prefer the hollow site in the center of the graphene hexagon, whereas carbon dioxide prefers sites bridging carbon-carbon bonds as well as sites directly on top of carbon atoms. The energy differences between different sites are however minute – typically just a few tenths of a millielectronvolt. Overall, the molecule-graphene bonding distances are found to be in the range 3.1–3.3 Å. The carbon dioxide binding energy to graphene is found to be almost twice that of the water binding energy (around 0.17 eV compared to around 0.09 eV). The present results compare well with previous calculations, where available. Using charge density differences, we also qualitatively illustrate the effect of the different substrates and molecules on the electronic structure of the graphene sheet.

  • 9.
    Eriksson Skytt, Linda
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Brink, Christian
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Tvärkraftsförstärkning av limträ: En undersökning av metoder med förstärkningselement av träribbor2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is to examine the shear capacity of glulam beams through various designs of reinforcement with wooden bars. A literature study is conducted to identify previous research on the subject. There are a number of tested reinforcement methods of glulam available, however, only a few of them are about shear capacity.

    This work is an extension of a previous study of Ahlskog and Ross (2015). Their study is based on a method where glulam beams were reinforced for shear breakage by strengthening wooden bars glued to the beam with PVAc.

    Five different test series have been examined for shear capacity. To obtain a statistical basis each series contained eight specimens. One series was unreinforced, two series were reinforced with glued wooden bars and two series were reinforced with milled in wooden bars. The reinforcement bars were put at an angle to take tensile or compressive force in the different methods.

    The capacity of the reinforcement bars is tested with a tensile and compressive testing machine which recorded deformation and compression force. The measured values were treated by a statistical analysis and normal distribution curves were drawn for the entire number of specimens based on the assumption that the test results were normally distributed. The four series were compared with both the unreinforced series and the other reinforced methods.

    The work resulted in an increase of shear capacity by 16% for the average of the sample series with milled in wooden bars subjected to compressive force. It has also been found that the characteristic value of shear capacity increased by 14% in the test series with the glued wooden bars exposed to traction.

  • 10.
    Gudmundsson, Kjartan
    et al.
    School of Civil and Architectural Engineering, KTH.
    Sjöström, Christer
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Norberg, Peter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Trinius, Wolfram
    Twumasi, Ebenezer
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Durable and robust vacuum insulation technology for buildings2011In: XII DBMC: 12th International Conference on Durability of Building Materials and Components (Vol. 4) / [ed] Michael A. Lacasse, Vasco Peixoto de Freitas, Helena Corvacho, Porto: FEUP Edições , 2011, , p. 8Conference paper (Refereed)
    Abstract [en]

    Vacuum insulation panels (VIPs) provide unprecedented opportunities for obtaining excellent thermal insulation with light and slender constructions. This article discusses the performance over time of VIPs, and the possibilities to overcome the current problems related to fragility and limited durability. Aerogels are together with fumed silica among the most competitive core materials for VIP's. The use of classical aerogels, as produced in autoclaves is, however, limited due to the high production costs. The fumed silica on the other hand requires vacuum levels that are difficult to maintain with the currently available vacuum envelopes. A material with comparatively smaller pores will on the other hand allow obtaining low thermal conductivity at higher pressure (less vacuum) and will therefore reduce the pressure difference over the envelope. There is therefore much to be gained by reducing the pore size. New cost and performance efficient silica aerogels offers opportunities to enhance the properties of the panels by customizing the pore structure and pore size distribution. Building technologies and how the panels are applied in a manner that improves the structural, thermal and hygroscopic performances of vacuum insulated constructions have been studied and are discussed.

  • 11.
    Hallberg, Daniel
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Stojanovic, Bojan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Analytical and numerical thermal modelling & analysis of an building integrated unglazed solar collector: PhD course paper2007In: Mathematics for PhD-students in building science, Stockholm: Architecture and the Built Environment, Royal Institute of Technology , 2007Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    The objective of this report is to derive an analytical and numerical USC model for thermal analysis. These models are meant to calculate USC temperature variation across the USC duct as well as the fluid temperature along the USC. The main purpose of the analytical model is to attain a detailed steady state tool for USC (as in this report) design and dimensioning. The numerical model is meant to calculate the time dependant USC thermal performance as well as being a benchmark for the analytical model.

  • 12.
    Hallberg, Daniel
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Stojanovic, Bojan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Akander, Jan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building engineering.
    Status, needs and possibilities for service life prediction and estimation of district heating distribution networks2012In: Structure and Infrastructure Engineering, ISSN 1573-2479, E-ISSN 1744-8980, Vol. 8, no 1, p. 41-54Article, review/survey (Refereed)
    Abstract [en]

    An optimised and proactive maintenance strategy aims to maximise the economical profit, minimise environmental impacts and keep the risk of failure to a low level. Implementation of such strategy in the context of district heating requires efforts and abilities for predicting future performances and estimating service life of district heating components. A literature review on failures (damages and performance reductions) occurring on district heating pipes, reveals that failures in district heating pipes are mainly leaks due to corrosion or mechanical impacts and reduced thermal insulation performance: leaks being the more serious damage type. A feasible service life estimation method for this type of damage is the Factor Method. Since the application of this method within the context of DH pipes has not been found in other publications, this paper focuses on describing the method and discusses the possibilities on how to apply it in two specific cases with respect to leakage: service life estimation of repaired district heating pipe sections (i.e. maintenance of district heating network) and of district heating pipes in new or extended district heating networks. A particular attention is paid on which modifying factors to consider and how to quantify them.

  • 13.
    Hedén, Caroline
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Wellpapp: Början på en ny våg2006Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 14.
    Jarl, Magnus
    et al.
    Örebro Universitet.
    Enghag, Per
    Lundberg, Sven-Erik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Mechanical Engineering.
    Chapter 6: Manufacture of Steel Wire and Steel Wire Products2017In: The Making, Shaping and Treating of Steel: Long Products Volume / [ed] Lundberg, S.-E., Warrendale, PA: Association for Iron & Steel Technology (AIST) , 2017, p. 571-656Chapter in book (Other academic)
  • 15.
    Jeppsson, Ola
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Nya material - Nya möjligheter: En applikation av ett cellulosabaserat material2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The interest in replacing oil based materials with the equivalent from cellulose increases in the same rate as we consume the resources of our community. The cellulose based materials and their attributes are researched and the presented new materials are more or less ready for production. There are a large number of different materials available to choose from when developing and manufacturing a new product. The traditional and well established materials are thoroughly researched and their attributes are also well known and well documented. This is not always the case when new materials emerge from science research and  development. An opinion is that it can be difficult for a new material to evolve from being a new interesting material to find its way into production or to be implemented in a product.

    The purpose of this project is for it to be a help to people involved in the developing of a new material in understanding what interested parties need to know about a new material. The primary questions this project proposes to answer are:• Who is an interested party in a new material?• What does an interested party initially need to know about a new material?• How can the attributes of a new material be presented to a specific target group the best way possible.A series of interviews were committed at the beginning of the project where the need for information about a new material from especially the industrial designer’s point of view. The survey shows that there are more important aspects in choosing materials than only the technical attributes of the material. It also shows that it’s hard to determine what kind of information is needed when not having a specific case to relate to. Three different strategies were formed to show how a new material can evolve from being a new interesting material to find its way into a production. The three strategies were:• Develop a product of your own • Replace a detail in an existing product• Replace a material

    In an attempt to exemplify one of these strategies a working case was formed. The material for the case was decided to be DuraPulp from Södra, the production method was pressure forming, the industry was the furniture industry and the product was the conference chair Yin from Kinnarps. There were a series of practical tests performed on material and production method to determine the suitability of the material concept. A tool for testing the material concept was also produced. The project resulted in a cellulose based material concept targeted for the furniture industry. The concept can be applied to the existing production line with advantages in efficiency for the production. The concept also contains environmental and sustainable aspects. The material concept shows good potential in replacing plastic in some cases and manages complicated shapes in the pressure forming process.

  • 16. Johansson, Gun-Britt
    et al.
    Rohlin, Lennart
    Svarvning och borrningi metallmatriskompositer (MMC)1993Report (Other academic)
    Abstract [sv]

    Fyra gjutna metallmatriskompositer (MMC) har bearbetats vid svarvning och borrning. De fyra MMC-materialen bestod av aluminiummatriser förstärkta med partiklar av kiselkarbid (Sirp) i volymshalter mellan 10 och 20 %.

    Målet med arbetet har varit dels att utreda arbetsmaterialets inverkan på bearbetningen, dels att klarlägga prestanda för PCD och andra verktygsmaterial.

    Svarvning har utförts med verktyg av polykristallin diamant (PCD), diamantbelagda skär av hårdmetall och kiselnitrid, belagd och obelagd hårdmetall samt keramisict skär. Vid borrförsöken användes borr med skruvade skär av hårdmetall (U-borr från Sandvik Coromant) och lödd spiralborr (Deltaborr från Sandvik Coromant), med variation av hårdmetallsort och slipning av borrgeometrierna.

    Vi har inte sett någon större skillnad mellan de olika matrismaterialen. Högre volymshalt SiC-partiklar ger som förväntat högre förslitning.

    Vid både svarvning och borrning i aluminiumbaserade MMC år PCD ett oslagbart verktygsmaterial. PCD ger en utslitningstid på 10 minuter vid en skärhastighet på 437 m/minut. Bra resultat visar också de diamantbelagda verktygen, så länge diamantskiktet är intakt. Bästa resultat bland övriga testade verktyg uppvisar whiskersförstärkt keramik (CC670), beroende på dess kombination av hårdhet i grundmaterialet och seghet genom whiskersförstärkningen.

    Vid borrning med U-borr, var skåren utslitna redan efter 10 mm borrad längd. Beläggning gav ingen förbittring i det extremt abrasiva materialet, ej heller slipad egg. Vid testerna med Deltaborr (vars geometri är gynnsammare för borrning i MMC) höll borrarna längre, ca 200 mm. Här erhölls lägre förslitning med specialslipad egg jämfört med standardegg. Vid borrning med spiralborr av PCD borrades 2500 mm utan att borrarna var utslitna.

    Skärkraftsmätning i olika arbetsmaterial visade ingen signifikant skillnad. Skärkrafterna stiger snabbare för de keramiska skären i jämförelse med PCD, vilket tyder på att de keramiska skären förslits under skärkraftsmätningen medan diamantens eggskärpa år intakt.

  • 17.
    Jonsson, Chatrine
    University of Gävle, Faculty of Engineering and Sustainable Development.
    A GreenHanger: En galge i DuraPulp2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today the clothing industry is just growing and growing, in average every swede consumes 15kg clothing a year and every year 8kg clothes is thrown. In Sweden clothes is purchased for around 71 billion swedish kronor a year. The shopping and the constant demand subjects great strain on both the environment and the humans on the earth. With every garments a hanger is included which is made of either plastic, metal or wood. The idea of the project was to come up with a proposition of a hanger made of the material DuraPulp. Also to take a stand wether it is possible to replace such a commercial product like the plastic hanger with a hanger made of DuraPulp and what that would mean.

    DuraPulp is a relatively new material from lab research and it has the same characteristics as plastic. What sepa- retes the materials is that DuraPulp is made from paper pulp with the unique binding agent PLA compared to plastic which is a product from oil. With heat and pres- sure the binding agent is activated and encloses the fibers so the material is percieved and acts just like plastic.

    The project has been executed in cooperation with the clothing company H&M which has provided information and knowledge in their work with hangers. The company Södra has also contributed with knowledge and experi- ence around DuraPulp.

    Costumers and clerks in shops around Gävle center has been interviewed on their experience and also wishes around hangers. The project resulted in a hanger in DuraPulp and alu- minium with the appropriate sale concept. The project has focused on making a clear environmental profile of the hanger based on the interviews and also to strengthen the company brand. The sale concept has been formed according to required demands and abilities.

    The DuraPulp hanger has through a simpler life cycle analysis, with the projects interpretation of the real- ity, been compared with a plastic hanger. This has been done to visualize every step from cradle to grave and to illustrate the difference though an environmental point of view.

  • 18.
    Kus, Hulya
    et al.
    Institutionen för teknik och byggd miljö.
    Marteinsson, Björn
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Norberg, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Temperature and moisture conditions in materials: effects on risk for degradation of rendered autoclaved aerated concrete2005In: Paper TT1-107, 2005, p. 60-67Conference paper (Other academic)
    Abstract [en]

    Temperature and moisture conditions are, in general, the two major factors influencing the long-term performance of external walls made of porous mineral building materials. Degradation of wall components is accelerated by temperature and moisture induced stresses which lead to cracks and in turn a surface more vulnerable to other degradation agents. The degradation rate depends on both the environmental conditions and the material-inherent and component design properties. Extreme and rapid temperature fluctuations as well as moderate diurnal and seasonal temperature cycles cause thermal stresses and strains in the material, resulting in expansion or contraction and eventual deformation such as cracking or fracture. Material properties such as thermal expansion, elasticity and tensile strength determine if cracking occurs either immeadiately when the surface temperature drops below the initial temperature after rapid cooling or after a period of time if alternating or repeated stresses result in creep and fatigue.

    In this paper an attempt is made to evaluate the temperature effects on the risk for degradation of external walls made of rendered autoclaved aerated concrete (AAC) based on temperature measurement data and the material properties. The measurement results are obtained from the continuous microenvironment monitoring carried out on a test cabin built on the roof of the Centre for Built Environment building in Gävle, Sweden. A finite element model (FEM) is used to simply calculate the temperature induced stresses in two different cases; with and without creep and relaxation in the material. According to the microenvironment measurement results the test panels attain maximum surface temperatures up to about 60 °C during summer and experience surface temperature fluctuations between day and night up to about 55 °C during winter. Rapid changes in surface temperatures frequently occur particularly throughout late spring and early summer. The preliminary calculated results indicate that the tensile forces built up during cold spells may be sufficient to crack the surface of AAC panels but the risk for fatigue damages due to combined moisture and temperature cycles induced by radiation from the sun seems to be small. Further studies are needed for better knowledge and reliable information on the degradation mechanisms related to temperature by complementary measurements of stress-strain, stress relaxation, creep and fatigue behaviour of AAC panels under different and cyclic temperature loading.

  • 19. Kus, Hulya
    et al.
    Norberg, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Monitoring of moisture in rendered autoclaved aerated concrete wall by nail electrodes2001In: The international conference on building envelope systems and technologies (ICBEST) 2001, Vol 1, 2001, p. 237-242Conference paper (Other academic)
  • 20.
    Kus, Hulya
    et al.
    University of Gävle, Department of Technology and Built Environment.
    Nygren, Kjell
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Norberg, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    In-use performance of rendered autoclaved aerated concrete walls by long-term moisture monitoring2004In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 39, no 6, p. 677-687Article in journal (Refereed)
    Abstract [en]

    The importance of long-term performance and durability of building materials and components has received increasing consideration with regard to a sustainable built environment. Degradation due to exposure to environment conditions, particularly driving rain, play a significant role in the service life of porous materials used in external wall components. Microenvironment monitoring data are presented in this paper to show how different surface coatings can contribute to moisture performance of external walls made of autoclaved aerated concrete (AAC). Renderings modifed with hydrophobic products on AAC substrate prove to have less wetting and better drying properties than unmodified renderings according to the performance assessment based on the amount and duration of moisture measured in the material.

  • 21.
    Kus, Hülya
    et al.
    stanbul Technical University , Faculty of Architecture, Turkey.
    Norberg, Peter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental engineering.
    Sjöström, Christer
    Building Science, KTH, Stockholm.
    Durability assessment of external renderings on AAC based on 10-year long-term monitoring data2013In: Third International Conference  on  Sustainable construction Materials and Technologies: Conference proceedings / [ed] Peter Claisse, 2013Conference paper (Refereed)
    Abstract [en]

    Long-term performance and durability of external walls made of rendered autoclaved aerated concrete was investigated within a research project, based on continuous monitoring of temperature and moisture in the materials employed in the weathering test conducted in Gavle, Sweden. The details of natural exposure test set-up and preliminary measurement and experiment results were published elsewhere. Among the external rendering systems applied on AAC wall panels, a variety of coatings including inorganic and organic coatings with and without hydrophobic agents were tested. Together with the surface and bulk temperatures and moisture contents of the tested materials, microclimate parameters were also continuously measured. In this paper, monitoring data collected during 10 years of natural exposure are examined, and some results, particularly on moisture performance of external rendering systems, are presented and briefly discussed. 

  • 22.
    Lundberg, Sven-Erik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Mechanical Engineering.
    Chapter 3: Roll Pass Design2017In: The Making, Shaping and Treating of Steel: Long Products Volume / [ed] Lundberg, S.-E., Warrendale, PA: Association for Iron & Steel Technology (AIST) , 2017, p. 337-412Chapter in book (Other academic)
  • 23.
    Lundberg, Sven-Erik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Mechanical Engineering.
    The Making, Shaping and Treating of Steel: Long Products Volume2017Collection (editor) (Other academic)
    Abstract [en]

    This book provides a detailed description of what long products are, how they are classified, how they are produced, as well as the types of equipment that produce long products. The volume provides a comprehensive overview of long product production from describing the roll pass design, to the different shapes and sections, to the manufacturing of wire and wire products, to tubular products, and finally to high-alloy steel semi-finished products by casting and ingots.

  • 24.
    Lundberg, Sven-Erik
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Mechanical Engineering.
    Allgood, Lee E.
    Lamb, Charles W.
    Ragger, Katharina Sophie
    Materials Center Leoben Forschung GmbH, Leoben, Austria.
    Paal, Jürgen
    Schoeller Bleckmann Edelstahlrohr GmbH (SBER), Ternitz, Austria.
    Buchmayr, Bruno
    Materials Center Leoben Forschung GmbH, Leoben, Austria.
    Chapter 7: Manufacture of Steel Tubular Products2017In: The Making, Shaping and Treating of Steel: Long Products Volume / [ed] Lundberg, S.-E., Warrendale, PA: Association for Iron & Steel Technology (AIST) , 2017, p. 657-729Chapter in book (Other academic)
  • 25.
    Lundberg, Sven-Erik
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Mechanical Engineering.
    Toschi, Francesco
    Primetals Technology, Castellanza, Italy.
    Head, Mel
    Chapter 4: Production of Bar and Light Sections2017In: The Making, Shaping and Treating of Steel: Long Products Volume / [ed] Lundberg, S.-E., Warrendale, PA: Association for Iron & Steel Technology (AIST) , 2017, p. 413-507Chapter in book (Other academic)
  • 26.
    Lundström, Hans
    University of Gävle, Faculty of Engineering and Sustainable Development, BMG laboratory.
    Improving long-term stability of hot-wire anemometer sensors by means of annealing2015In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 8, article id 086104Article in journal (Refereed)
    Abstract [en]

    Annealing procedures for hot-wire sensors of platinum and platinum-plated tungsten have been investigated experimentally. It was discovered that the two investigated sensor metals behave quite differently during the annealing process, but for both types annealing may improve long-term stability considerably. Measured drift of sensors both without and with prior annealing is presented. Suggestions for suitable annealing temperatures and times are given. 

  • 27.
    Martinez, Pablo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Quenching a steel plate by water - impinging jets and different simultaneous flow rates2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Regarding the great importance of fast cooling in steel industry for the production processes, a deep understanding of heat transfer and fluid dynamics must be held. A steel plate is heated up until a maximum temperature of 700 ⁰ C to be the n cooled down seconds later by a configuration of multi ple impinging water jets. Different flow rates are used simultaneously by different adjacent jets to perform quenching over the sample, so different hardness is obtained in the material over a small area . Temperature drop in time i s measured and monitored by embedded thermocouples and LabVIEW program. To achieve greater understanding of the quenching performance with different flow rates , several parameters are selected to be varied in order to achieve the best working conditions. Jet diameter takes values between 4 and 10 mm, initial temperature of quenching varies from 400 to 700 ⁰ C , subcooling temperature is tested for 65 and 75 K, and jet velocity varies between 1.9 and 3.9 m/s. The result of total number of 9 expe riments shown that v ariation of jet diam eter does not influence substantially on the cooling rate if flow rate is kept constant. High initial quenching temperature (600 - 700 ⁰ C ) led to slightly higher cooling rate in the stagnation region of water jets. The peak value of heat transfer rate in the upwash flow zone was more highlighted for initial quenching temperature 600 ⁰ C and below it. High er values of subcooling and jet velocity produce better cooling rates. The result shown higher jet velocity at one column of water jets changes position of upw ash flow slightly toward the adjacent column of jets with lower jet velocity. In general, the result shown that all the studied parameters did not have negative effect on obtaining various cooling rates over the steel plate.

  • 28.
    Matero, Markus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Quartzene i gips: Densitet och hållfasthet2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 29.
    Norberg, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Hampberedning med tornadoteknik: En förstudie2009Report (Other academic)
    Abstract [sv]

    Möjligheterna att bereda hampa med tornadoteknik har studerats. Företaget Airgrinder AB i Skelleftehamn har en pilotanläggning som utnyttjats för att testköra hampa som skördats vid olika tillfällen under året. Tekniken innebär att hampan både sönderdelas och torkar under inverkan av den kraftiga luftström som pressas genom en speciellt utformad cyklon. Hampans fibrer passerar relativt opåverkade medan resten av stjälken samt eventuella blad och jordrester pulveriseras. Fibrerna kan därefter sållas fram och tillvaratas separat medan resten kan användas som t ex bränsle.

    För tornadotekniken spelar det ingen roll när på året hampan skördas. Separeringstekniken fungerar lika bra för fuktig höstskördad hampa som för torr vårskördad hampa. Fiberkvaliteten beror av skördetillfället och den återfinns givetvis även i slutprodukten. Kapaciteten för processen är däremot starkt beroende av det ingående materialets fukthalt. Detta innebär att hampa med hög fukthalt kräver en längre uppehållstid i tornadon än vad ett torrare material gör.

    Fibermaterialets egenskaper gör det lämpligt att användas som värmeisolering och provningar visar att egenskaperna blir lika bra som för andra cellulosabaserade isoleringsmaterial. Fibrerna kan även med fördel användas som armering i olika typer av kompositmaterial. För gips åstadkoms en förbättring av böjdraghållfastheten med 33% tack vare en tillsats av mindre än 0.5 vikt-% av tornadohampan. Liknande förbättringar är att räkna med även för andra kompositer med matriser av betong, plast och trä.

    En investeringskalkyl utvärderad enligt nettonuvärdesmetoden har genomförts för en anläggning som kan betjäna en odling på ungefär 250 ha. Investeringskostnaden för en anläggning bestående av tornsilos med volymen 2000 m3 samt en tornado från Airgrinder AB uppskattats till 7 MSEK. Lönsamheten bestäms av en mängd olika faktorer där skördens storlek per hektar är särskilt betydelsefull. Även andelen fibrer i förhållande till andelen skävor samt fukthalten i det ingående materialet är viktiga parametrar i kalkylen. I slutänden spelar priset på fibrer och även skävor en avgörande roll. Mindre genomslag på investeringens lönsamhet har allt som förknippas med odling och skörd, löner, energipriser och underhållskostnader. Utnyttjande av spillvärme samt andra samkörningsmöjligheter med intilliggande industrier förbättrar kapaciteten hos anläggningen markant och därmed även lönsamheten.

  • 30.
    Norberg, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Lösullsisolering med hampa2009In: Bygg & teknik, ISSN 0281-658X, no 5, p. 28-32Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Lösullsisolering gjord av hampfiber varken tillverkas eller säljs som en kommersiell produkt i Sverige idag. Möjligheterna är emellertid goda att på olika sätt få igång en inhemsk lokal produktion. Beredning av fibrerna med tornadoteknik kan vara ett sätt att åstadkomma ett utgångsmaterial lämpligt för bl a lösull. Försök visar att lösullsprodukter av hampfiber går att åstadkomma med egenskaper som är likvärdiga de hos träbaserad cellulosaisolering.

  • 31.
    Norberg, Peter
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Krigsvoll, Guri
    Gumucio, Juan Carlos
    Maintaining the traditional churches of Chiloé2004In: Interaction between science, technology and architecture in timber construction: Proceedings of Culture 2000 project: Greek, Norwegian and Italian actions, Paris: Elsevier SAS , 2004, p. 405-421Chapter in book (Other academic)
    Abstract [en]

    The 16 churches of Chiloé in southern Chile, recently inscribed on UNESCO’s World Heritage List, represent the only example in Latin America of a rare form of ecclesiastical wooden architecture. They were built on the initiative of the Jesuit Peripatetic Mission in the 17th and 18th centuries and bear testimony to a successful fusion of indigenous and European culture and technical expertise. Most of these churches are in immediate need of restoration and maintenance. The present paper summarises experience and impressions acquired by the authors during a trip made to Chile in June 2002. The purpose of the trip was to establish contacts with people and organisations that are linked to the care and maintenance of the traditional wooden churches of Chiloé. In this context it has been of mutual interest to find out in what possible ways Scandinavian resources and know-how could be utilised and implemented in the process of restoring and maintaining these churches. The recently developed Maintenance Management System (MMS), capable of structuring condition surveys and assessments, as well as being an aid to plan and follow up conservation and maintenance work, might prove a suitable and elaborate alternative to traditional systems of building management and documentation. In addition, a brief description is presented of various tasks identified that could tentatively be the basis for mutual exchange of know-how, culture and traditions as well as of researchers, students and other resources, between the partners in Chile and in Sweden and Norway. These tasks address issues linked to aspects of both the physical maintenance of these churches and of their socio-cultural significance today and in the future.

  • 32.
    Norberg, Peter
    et al.
    University of Gävle, Department of Technology and Built Environment.
    Lindahl, Lars G
    Abrahamsson, Jörgen
    University of Gävle, Department of Technology and Built Environment.
    En metod för framställning av agglomerat av utfällt silikamaterial, ett mikroporöst material innefattande sådan agglomerat och användning därav2007Patent (Other (popular science, discussion, etc.))
    Abstract [sv]

    Föreliggande uppfinning avser en metod att producera ett material som innefattar agglomererade partiklar av utfälld kiseldioxid, innefattande framställning av en lösning av åtminstone ett metallsalt (M), där metalljonen/-jonerna är tvåvärd(a) eller flervärd(a). En lösning av alkalimetall (M) silikat med ett molförhållande SiO2/M2O om 0.5 - 100 framställs. Lösningarna blandas och blandningen omrörs, och ett koagel tillåts bildas. Koaglet uppsamlas och behandlas för att tillhandahålla ett material som har en torrsubstans om >15, företrädesvis >97%. Ett material som kan erhållas med processen tillhandahålles också.

  • 33.
    Osto, Emanuele
    et al.
    Primetals Technology, Castellanza, Italy.
    Giacomini, Luigi
    Primetals Technology, Castellanza, Italy.
    Lundberg, Sven-Erik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Mechanical Engineering.
    Lagergren, Jonas
    Åkers AB, Åkers Styckebruk, Sweden.
    Oppitz, Mattias
    Ellis, Glyn
    Kocks Pittsburgh Co., Pittsburgh, PA, USA.
    Fabro, Mario
    SMS group.
    Thorstenson, Eric
    Russula, A Coruña, Spain.
    Fernández, Silvia
    Russula, A Coruña, Spain.
    Sánchez, Daniel
    Russula, A Coruña, Spain.
    Chapter 2: Design and Construction of Rolling Mills for Long Products2017In: The Making, Shaping and Treating of Steel: Long Products Volume / [ed] Lundberg, S.-E., Warrendale, PA: Association for Iron & Steel Technology (AIST) , 2017, p. 101-336Chapter in book (Other academic)
  • 34.
    Rajapakshe, Chinthana
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering. Royal Institute of Technology.
    HEAT STORAGE APPLICATION IN ELECTRIC MOTOR COOLING SYSTEM: SMOKE VENTILATION MOTORS2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 35.
    Råsander, Mikael
    et al.
    Department of Materials, Imperial College London, London, UK.
    Hugosson, Håkan W.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Physics.
    Delin, Anna
    Department of Applied Physics, Kungliga Tekniska Hogskolan, Stockholm, Sweden.
    Density functional study of carbon vacancies in titanium carbide2018In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 30, no 1, article id 015702Article in journal (Refereed)
    Abstract [en]

    It is well established that TiC contains carbon vacancies not only in carbon-deficient environments but also in carbon-rich environments. We have performed density functional calculations of the vacancy formation energy in TiC for C- as well as Ti-rich conditions using several different approximations to the exchange-correlation functional, and also carefully considering the nature and thermodynamics of the carbon reference state, as well as the effect of varying growth conditions. We find that the formation of carbon vacancies is clearly favorable under Ti-rich conditions, whereas it is slightly energetically unfavorable under C-rich conditions. Furthermore, we find that the relaxations of the atoms close to the vacancy site are rather long-ranged, and that these relaxations contribute significantly to the stabilization of the vacancy. Since carbon vacancies in TiC are experimentally observed also in carbon-rich environments, we conclude that kinetics may play an important role. This conclusion is consistent with the experimentally observed high activation energies and sluggish diffusion of vacancies in TiC, effectively causing a freezing in of the vacancies.&#13.

  • 36.
    Samuelsson, Martin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    En designguide för framtidens källsortering2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    The aim was to examine people’s perceptions of recyclingon a personal and general level and based on thatdesigning an improved sorting product for today’s households. The goal was to present a documented knowledgebase about how future recycling products should bedesigned for the partner Hammarplast Consumer AB. From the users responses at the initial survey severalareas of concern were identified and dealt with using designmethodology and various analytical methods. The first questions that were examined were the placementof the sorting product in homes and which role thekitchen’s historical development has played for householdwaste management. Another question was if anew recycling product should be adapted for houses andapartments with specific years of construction or not andalso the amounts and volumes of waste today’s Swedishhouseholds are to manage. Throughout the project differentarguments and conclusions were visually explainedand examined through illustrations, photos, and othergraphical elements, and in the end it all boils down to apresentation of a new type of recycling product. Finally there is a discussion about the philosophy behindchoosing materials and which materials that is best suitedfor the generated concept from an economic, technicaland environmental perspective.

  • 37.
    Smith, Richard H.
    et al.
    Carpenter Technology Corp., Reading, PA, USA.
    Wennström, Henrik
    Morgårdshammar AB, Smedjebacken, Sweden.
    Lundberg, Sven-Erik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Mechanical Engineering.
    Chapter 8: Production of High-Alloy Semi-Finished Steel Products by Ingot Casting, Rolling and Forging2017In: The Making, Shaping and Treating of Steel: Long Products Volume / [ed] Lundberg, S.-E., Warrendale, PA: Association for Iron & Steel Technology (AIST) , 2017, p. 731-895Chapter in book (Other academic)
  • 38.
    Stojanovic, Bojan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Energy performance and absorber coating degradation of a solar collector: PhD course paper, Byggnaders livslängd och karakterisering av nedbrytningsmiljö, KTH research school - University of Gävle, Gävle, Sweden2004Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The use of solar collectors has grown in Sweden during the last 20 years. At the present the fastest growing collector applications are Domestic Hot Water (DHW) systems. The life performance of these systems is important due to their intended long use. This applies emphasis on the system durability and service life, which is in consent with the European Construction Products Directive (CPD). It states that the essential requirements on constructed work should be met during the intended working life of the building; this results in essence in a performance requirement on all building products. The life performance of building materials and products has to be assessed and declared. This paper presents a literature study of the degradation of flat plate solar collectors used in DHW systems. The scope of the paper is limited to the selective absorber coating of the collector and is focused on the research made in the IEA Task X programme. The objective is to investigate the potentials of computer simulations of collector system performance reduction, due to absorber coating degradation. The Task X study used an approach of accelerated testing to access the extent of absorber coating degradation. Mathematical models of the coating degradation were used to transform the accelerated test results to in-service conditions. A model of the microclimate in a flat plate solar collector was also developed. Results from the study shows that the accelerated testing procedure is in fairly good agreement, although it contains a number of simplifications, when compared with specimens from in-service collectors that have been working for 3 to 15 years. By using in-service microclimate data and accelerated test results, calculations of approximated real time degradation can be made. The developed microclimate model, which was intended for computer simulations, gave deviating result when compared with measurements, showing that further development is needed. The methodologies from the Task X study could also be useful when assessing the effects of absorber coating degradation on other types of collector systems, e.g. a solar-assisted heat pump system, if the system performance criterion, which is related to the spectral properties of the absorber coating, is declared.

  • 39.
    Stojanovic, Bojan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Life performance assessment methodologies for combined solar energy technologies: a case study on system parts in Nordic climates2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main questions concerning energy technologies today are their economical and environmental impacts. These entities are (at the present) assessed on the basis that operations proceed as newly installed/designed systems, during an assumed working life period. While this is the common way of perceiving energy systems, performance-over-time will change as an effect of (e.g. material) degradation and not solely of different operation scenarios. How and to what extent, is the question that needs assessing in order to evaluate if these changes will jeopardise the intended system performance requirement. In turn, this pro-active assessment and analysis is in line with today’s performance based directives, laws, regulations and concepts; of which the working life is an essential part. The main context of the thesis, is a contribution to the R&D topic on life performance of energy technologies, with papers on a literature review and case study on two system parts: solar collector and ground heat exchanger (borehole); within the energy technology area of combined solar energy technologies/systems utilised in buildings. The thesis specifically presents a general description of requirements on constructed works and their material, components and systems. It also gives an insight to the energy technology R&D and engineering sector, regarding durability and service life assessment methodologies; and also to the durability of constructed works sector, regarding the needs for assessing material degradation in relation to system performance. The case studies presented in the thesis, show how durability of energy technologies may be sought-after, as well as specific knowledge and useful tools, methodologies and test setups for assessing long-term performance of combined solar energy technologies (in this case a solar-assisted heat pump system utilising a building integrated Unglazed Solar Collector and energy storage). The utilisation of solar collectors and heat pumps (primarily for space and domestic tap water heating) has rapidly increased in Sweden during the last decades. Sweden has today the largest heat pump market in Europe. During recent years, there has also been an increased interest in heating systems that combine heat pumps with solar collectors (glazed and unglazed) and energy storages; with the aim of attaining a system that provides higher energy and greater economical performances than individual solar collector or heat pump systems. If these systems are to be successful they must be economically feasible; placing emphasis on the cost, durability and performance of the system. The main issue on life performance of energy technologies is how and to what extent, performance reduction in individual materials and components influences the overall system performance; as the essence of energy system sustainability is system performance.

  • 40.
    Stojanovic, Bojan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Lifetime performance assessment of thermal systems: studies on building, solar and district heating applications2009Doctoral thesis, comprehensive summary (Other academic)
  • 41.
    Stojanovic, Bojan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    On Reduced Energy Performance of a Solar-Assisted Heat Pump System due to Absorber Coating Degradation2005In: 10th DBMC International Conference on durability of building materials and components, 2005, p. 876-883Conference paper (Refereed)
    Abstract [en]

    This paper presents a literature study of the degradation of flat plate solar collectors used in Domestic Hot Water (DHW) systems. The scope of the paper is limited to the selective absorber coating of the collector and is focused on the research made in the IEA Task X study. The objective is to investigate the potentials of computer simulations of performance reduction of a solar-assisted heat pump system, due to absorber coating degradation. The Task X study used an approach of accelerated testing to access the extent of absorber coating degradation. Mathematical models describing the coating degradation were used to transform the accelerated results into in-service conditions. A mathematical model of the microclimate in a flat plate collector was also developed. Results showed that the accelerated test procedure is in fairly good agreement, although it contains a number of simplifications, when compared with specimens from in-service collectors that have been working for 3 to 15 years. By using in-service microclimate data and accelerated test results, calculations into approximated real time degradation can be made. The microclimate model that was intended for simulations gave deviating results when compared with measurements, showing that further development is needed. The methodologies from the Task X study could also be useful when assessing the effects of absorber coating degradation on other types of collector systems, e.g. a solar-assisted heat pump system. Such a system is under evaluation in the ongoing EU project named: Endothermic Technology for Energy Efficient Housing in the EU (ENDOHOUSING). The project uses solar-assisted heat pumps to provide the thermal energy to meet space heating, cooling and hot water requirements for domestic houses in different regions of the EU throughout the year. Six demonstration houses (endohouses) will be established and equipped accordingly across the EU and evaluated during the project. If these systems are to be commercially installed and used they must be economically feasible. This places emphasis on the cost, durability and performance of the system. A solar collector is exposed to various strains that will contribute to a degradation of the collector materials, which will decrease its energy performance. These changes will in turn be transposed throughout the system lowering its degree of efficiency that directly relates to the economical aspect of the system. As a result of these changes a performance over time assessment is needed for this type of system, which in turn is in line with the European Construction Products Directive (CPD).

  • 42.
    Stojanovic, Bojan
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Long-Term Thermal Performance Modelling and Simulations of a Borehole2005Conference paper (Refereed)
    Abstract [en]

    This paper presents the long-term thermal performance modelling and simulation of a single heat extraction borehole with a U-shaped pipe, by applying the Macro Element Modelling (MEM) method, developed by Schmidt (2004). The dynamic thermal performance of the ground around the borehole is analysed in the frequency domain. Thereafter, the ground properties are transformed into a network of discrete resistances and capacitances (RC’s) that together with the pipe, models the thermal performance of the borehole. The method allows the parameters of the RC-network components to be estimated and optimised for time domain simulations. The advantage of this modelling method is that it establishes a simplified yet accurate thermal borehole model, which requires less computing time and power compared to a traditional finite difference/element model. This makes it easier to perform several decades of long-term thermal performance simulations. In this paper the U-pipe was modelled by applying a star resistance network that calculates the weighted heat fluxes between the solid borehole and the U-pipe. The presented work shows that at small temperature increases and at relative large fluid velocities the U-pipe fluid temperature can be seen as rising linearly. This provides the borehole modelling with the possibility to model the entire borehole construction by using only one macro element. To compensate for any errors when using the linearly increasing fluid temperature for calculating the energy extraction from the borehole, the total U-pipe star resistance network is compensated. The U-pipe star network was also compared with a FEM (Finite Element Method) simulation, showing that the correspondence between the two models is good. The half 5-node network that was used by Schmidt (2004) for modelling the solid construction of the borehole was modified in this paper, with an additional resistance to ensure the stability of the network when simulation long-term heat extraction periods. The borehole RC-network was optimised for a time period of 100 years. The results from the long-term performance simulation made with the derived borehole model, were also compared to other presented borehole simulations. The model proved to have, at a first stage of comparison, a good correspondence with the other presented results.

  • 43.
    Stojanovic, Bojan
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Akander, Jan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Oglasade takintegrerade solfångare: Ett energitekniskt aktivt byggnadsskal2008In: Bygg & Teknik, ISSN 0281-658X, no 4Article in journal (Other (popular science, discussion, etc.))
  • 44.
    Stojanovic, Bojan
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Use of a Peltier Element to Increase Time of Wetness of Unglazed Solar Collector Specimens in a Natural Field Exposure Test2008In: Durability of Building Materials & Components 11 (11DBMC), Istanbul, Turkey, 11-14 May 2008, 2008, p. 1169-1175Conference paper (Refereed)
    Abstract [en]

    In accelerated testing, material specimens are exposed to completely artificial environments, where exposure to individual degradation agents is enhanced. In contrast, field-testing exposes specimens to multiple degradation agents. When performing a semi-natural test, the influence of a selected degradation agent may be increased while the specimen is still situated in its natural environment. Moisture is such an agent. In an experimental set-up for evaluating long-term optical performance of an building integrated Unglazed Solar Collector, a sub-task was to increase Time of Wetness (TOW) for several collector specimens for two reasons: to “simulate” an active cooling of the component as is the case for solar collectors; and to assess the role of TOW on optical degradation of the solar collector. Specimen cooling and increase in TOW was achieved by utilisation of a Direct-Air Peltier Element. TOW was estimated through measurements with WETCORR sensors (monitoring surface temperatures and moisture) and climate parameters (temperature and relative humidity) at site. At this particular test site in Gävle, Sweden, TOW was more than doubled in comparison to non-cooled surfaces. The Peltier Element proved to be inexpensive and flexible for this purpose.

  • 45.
    Stojanovic, Bojan
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Akander, Jan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Eriksson, Bengt
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Natural and semi-natural field exposure testing and analysis, on optical degradation of a building integrated unglazed solar collector surface2008In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 41, no 6, p. 1057-1071Article in journal (Refereed)
    Abstract [en]

    Durability is of great importance when considering sustainable energy systems. In turn it lays emphasis on assessing performance over time of energy systems and components. This paper presents a study on optical degradation of a building-integrated Unglazed Solar Collector (USC) surface, by exposing USC specimens to a natural and semi-natural field exposure test. Particular interest is devoted to the semi-natural field exposure test method evaluation, and the degradation of optical properties. The study showed that about 11 months of field exposure testing did not cause any significant optical (total solar absorptance and IR emittance) or material (surface coating) degradation; although measurements revealed a decrease in specular reflectance as diffuse increased. It was likely due to surface pollution that predominantly consisted of quartz. The study also showed that it is possible to achieve a considerable increased moisture exposure on test surfaces (seminatural field exposure test), through a relatively simple cooling device (Direct-Air Peltier-Element) and rough control strategy.

  • 46.
    Stojanovic, Bojan
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Akander, Jan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för byggnadskvalitet.
    Oostendrop, Peter
    TNO.
    Kronström, Urban
    IVT.
    Improvements in Heat Pumps for Endothermic Systems: ENDOHOUSING deliverable D7b2006Report (Other academic)
  • 47.
    Stojanovic, Bojan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Hallberg, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Buildning science - material science.
    Akander, Jan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building engineering.
    A steady state thermal duct model derived by fin-theory approach and applied on an unglazed solar collector2010In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 84, no 10, p. 1838-1851Article in journal (Refereed)
    Abstract [en]

    This paper presents the thermal modelling of an unglazed solar collector (USC) flat panel, with the aim of producing a detailed yet swift thermal steady-state model. The model is analytical, one-dimensional (ID) and derived by a fin-theory approach. It represents the thermal performance of an arbitrary duct with applied boundary conditions equal to those of a flat panel collector. The derived model is meant to be used for efficient optimisation and design of USC flat panels (or similar applications), as well as detailed thermal analysis of temperature fields and heat transfer distributions/variations at steady-state conditions; without requiring a large amount of computational power and time. Detailed surface temperatures are necessary features for durability studies of the surface coating, hence the effect of coating degradation on USC and system performance. The model accuracy and proficiency has been benchmarked against a detailed three-dimensional Finite Difference Model (3D FDM) and two simpler ID analytical models. Results from the benchmarking test show that the fin-theory model has excellent capabilities of calculating energy performances and fluid temperature profiles, as well as detailed material temperature fields and heat transfer distributions/variations (at steady-state conditions), while still being suitable for component analysis in junction to system simulations as the model is analytical. The accuracy of the model is high in comparison to the 3D FDM (the prime benchmark), as long as the fin-theory assumption prevails (no 'or negligible' temperature gradient in the fin perpendicularly to the fin length). Comparison with the other models also shows that when the USC duct material has a high thermal conductivity, the cross-sectional material temperature adopts an isothermal state (for the assessed USC duct geometry), which makes the ID isothermal model valid. When the USC duct material has a low thermal conductivity, the heat transfer course of events adopts a 1D heat flow that reassembles the conditions of the 1D simple model (for the assessed USC duct geometry); ID heat flow through the top and bottom fins/sheets as the duct wall reassembles a state of adiabatic condition.

  • 48.
    Strandvik, Max
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Kommunikativt miljöhus: Nya lösningar för soprummet2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 49.
    Söderlind, Andreas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Forsström, August
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Riktlinjer för styrning av gastryck vid gasatomisering samt kartläggning av pulveregenskaper2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    High quality powder steel is manufactured through gas atomization at Erasteel Kloster AB in Söderfors. During their batches they have a problem with varying weight of capsules which can cause problems with bending capsules and unreliable exchange. Bent capsules risk damaging the equipment and cannot be used.The work was performed with the purpose to investigate the source for varying weights of capsules during batches and with the goal to account for a solution on how the varying capsule weights can be reduced.Powder samples were taken during five batches aiming to investigate the cause for varying capsule weights. The powders characteristics were analyzed with different methods which presented the powders size distribution, fill density, tap density and flowability. The Lubanska equation which calculates powders mean diameter was simplified and adjusted for the Erasteel plant with the intention to control gas pressure depending on the metal flow rate.Analyzes showed that the powder size distribution was changing during every batch. The amount of larger particles decreased more than the amount of small particles increased meanwhile the width of the powders size distribution decreased. This gave the largest width of size distribution half-way into the batch and the highest capsule weights were obtained at this moment.The simplified equation was applied to the moment when highest capsule weights was obtained and gave guidelines on how the gas pressure should be controlled to achieve similar size distribution. Further analyzes showed that the metal flow rate was proportional to the gas temperature due to it is measured after being in contact the melt stream.Since the equation was simplified and verified on five batches more tests needs to be extracted. It needs to be done not only to get a more reliable equation but also for an opportunity to test it in practice. With samples collected from more batches, there is a possibility to control the gas pressure with gas temperature and an automatic control of the gas pressure could be performed.

  • 50.
    Twumasi Afriyie, Ebenezer
    et al.
    Kungliga tekniska högskolan (KTH).
    Karami, Peyman
    Kungliga tekniska högskolan (KTH).
    Norberg, Peter
    Kungliga tekniska högskolan (KTH).
    Gudmundsson, Kjartan
    Kungliga tekniska högskolan (KTH).
    Textural and thermal conductivity properties of a low density mesoporous silica material2014In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 75, p. 210-215Article, review/survey (Refereed)
    Abstract [en]

    In this study, the pore structure, tapped density and thermal conductivity properties of a new type of nanoporous silica material have been studied. We have applied nitrogen physisorption, high resolution scanning microscopy and Transient Plane Source thermal conductivity measurements to investigate these properties. The new mesoporous silica SNP have large BET surface area, 400–439 m2 g−1 and possess high porosity in the range of 95–97%. The results further show pore diameter centred at 43 nm or 47 nm for the two materials studied. Tapped densities as low as 0.077 g/cm3 have so far been obtained and the thermal conductivity of these materials has been measured to 0.0284 and 0.0294 W (m K)−1 at room temperature and atmospheric pressure. The effects of tapped density, pore size diameter and particle morphology on thermal conductivity are discussed.

12 1 - 50 of 55
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