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  • 1. Abas, N
    et al.
    Kalair, A
    Seyedmahmoudian, Mehdi
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Campana, P
    Khan, N
    Dynamic simulation of solar water heating system using supercritical CO2 as mediating fluid under sub-zero temperature conditions2019In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606Article in journal (Refereed)
  • 2.
    Abas, Naeem
    et al.
    University of Gujrat, Hafiz Hayat Campus, Pakistan.
    Kalair, Ali Raza
    COMSATS University Islamabad, Pakistan.
    Seyedmahmoudian, Mehdi
    Swinburne University, Australia.
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Campana, Pietro Elia
    Mälardalen University, Sweden.
    Khan, Nasrullah
    COMSATS University Islamabad, Pakistan.
    Dynamic simulation of solar water heating system using supercritical CO2 as mediating fluid under sub-zero temperature conditions2019In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 161, article id 114152Article in journal (Refereed)
    Abstract [en]

    CO2 is becoming increasingly important as a mediating fluid, and simulation studies are indispensable for corresponding developments. In this study, a simulation-based performance investigation of a solar water heating system using CO2 as a mediating fluid under sub-zero temperature condition is performed using the TRNSYS (R) software. The maximum performance is achieved at a solar savings fraction of 0.83 during July. The as lowest solar savingss fraction of 0.41 is obtained during December. The annual heat production of the proposed system under Fargo climate is estimated to be about 2545 kWh. An evacuated glass tube solar collector is designed, fabricated and tested for various climate conditions. Moreover, a detailed comparison of the system's performance at sub/supercritical and supercritical pressures shows that the annual heat transfer efficiency of the modeled system is 10% higher at supercritical pressure than at sub/supercritical pressures. This result can be attributd to the strong convection flow of CO2 caused by density inhomogeneities, especially in the near critical region. This condition resuls in high heat transfer rates.

  • 3. Abdel-Rehim, M.
    et al.
    Carlsson, Gunilla
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Bielenstein, M.
    Arvidsson, T.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Evaluation of Solid-Phase microextraction (SPME) for Study of the protein Binding in Human Plasma Samples,2000In: J. Chromatogr. Sci., 38 (2000) 458-464Article in journal (Refereed)
  • 4.
    Abrahamsson, Linnéa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energianvändning vid pelletering: En undersökning av strömningsenergins betydelse för den totala energianvändningen vid pelletering2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Biofuels make up 25% of Sweden’s energy supply and the majority of biofuels used are made from wood. Wood pellets is one type of biofuel and in Sweden, 1.6 million tonnes of wood pellets were produced in 2018. Different pellet properties such as durability and energy use for production is often tested in a single pellet press. The total energy use for making a pellet in an industrial scale machine is the sum of the energy required for three different component sequences, compression, friction and flow. Flow is when the material that lies on the surfaces between the press channel openings is compressed and pushed downwards towards the coned openings and the materiel in the coned opening is deformed and pushed down to the press channel.

    Only compression and friction can be studied using a conventional single pellet press. Thus, this study focuses on the impact of the flow component on the total energy use for pelletizing. In order to do this, energy used for compression, friction and flow, as well as the power required for the material to enter the flow component, Fflow, has been studied for three different particle sizes.

    Fresh spruce with a moisture content of 10% has been pressed in different dies. With these pressings, the impact of the flow component, as well as the impact of pressing material located around the coned press channel opening on the total energy use was determined.

    Particle size did not affect energy use. Fflow was higher for pressings with material located on the surface around the coned opening, compared to pressings without. This resulted in an increased compression energy for pressings with material around the coned opening. The material located around the press channel opening affected the pelletizing so that the produced pellet was 1 mm shorter, which resulted in a lower energy use for the friction component. Energy used by the flow component made up over 43-57% of the total energy use. The part of the flow energy that is needed to compress the material around the press channel opening and move that material towards the opening stood for 35-52% of the total energy use for palletization.

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  • 5. Almgren, M.
    et al.
    Alsins, J.
    van Stam, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Fluorescence Decay Studies of Structures and Dynamics in Ionic Micellar Solutions1988In: Ordering and Organization in Ionic Solutions, World Scientific, Singapore: World Scientific, 1988, p. 225-232Chapter in book (Refereed)
  • 6.
    Almlöf Ambjörnsson, Heléne
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Mercerization and Enzymatic Pretreatment of Cellulose in Dissolving Pulps2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with the preparation of chemically and/or enzymatically modified cellulose. This modification can be either irreversible or reversible. Irreversible modification is used to prepare cellulose derivatives as end products, whereas reversible modification is used to enhance solubility in the preparation of regenerated cellulose.

    The irreversible modification studied here was the preparation of carboxymethyl cellulose (CMC) using extended mercerization of a spruce dissolving pulp. More specifically the parameters studied were the effect of mercerization at different proportions of cellulose I and II in the dissolving pulp, the concentration of alkali, the temperature and the reaction time. The parameters evaluated were the degree of substitution, the filterability and the amount of gel obtained when the resulting CMC was dissolved in water. Molecular structures of CMC and its gel fractions were analysed by using NIR FT Raman spectroscopy. It was found that the alkali concentration in the mercerization stage had an extensive influence on the subsequent etherification reaction. FT Raman spectra of CMC samples and their gel fractions prepared with low NaOH concentrations (9%) in the mercerization stage indicated an incomplete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Low average DS values of the CMC, i.e. between 0.42 and 0.50 were obtained. Such CMC dissolved in water resulted in very thick and semi solid gum-like gels, probably due to an uneven distribution of substituents along the cellulose backbone. FT Raman spectra of CMC samples and their gel fractions mercerized at higher alkaline concentration, i.e. 18.25 and 27.5% in the mercerization stage, indicated on the other hand a complete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Higher average DS values of the CMC, i.e. between 0.88 and 1.05 were therefore obtained. When dissolved in water such CMC caused gel formation especially when prepared from dissolving pulp with a high fraction of cellulose II.

    The reversible modification studied was the dissolution of cellulose in NaOH/ZnO. Here the effect of enzyme pretreatment was investigated by using two mono-component enzymes; namely xylanase and endoglucanase, used in consecutive stages. It was found that although the crystallinity and the specific surface area of the dissolving pulp sustained minimal change during the enzymatic treatment; the solubility of pulp increased in a NaOH/ZnO solution from 29% for untreated pulp up to 81% for enzymatic pretreated pulp.

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    Mercerization and Enzymatic Pretreatment...
  • 7.
    Almlöf Ambjörnsson, Heléne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Östberg, Linda
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Schenzel, Karla
    Martin Luther University Halle-Wittenberg, Department of Natural Scinence III, Institute of Agriculture and Nutritional Science.
    Larsson, Per Tomas
    Innventia AB, Fibre and Material Science Business area Biorefining, Stockholm.
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Enzyme pretreatment of dissolving pulp as a way to improve the following dissolution in NaOH/ZnO2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 4, p. 385-391Article in journal (Refereed)
  • 8.
    Almssad, Asaad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Betongkonstruktion2015Book (Other academic)
    Abstract [sv]

    Betongkonstruktion behandlar dimensionering och utförande av betongkonstruktioner enligt Eurocode 2. Boken består av en teoridel som innefattar:• Böjning och böjning med normalkraft• Pelare och väggar• Genomstansning• Plattor• Beräkning i bruksgränstillståndet

    Bokens konkreta pedagogiska värden är, utöver ett stort antal övnings­exempel med lösningar och svar, ett avsnitt med utvecklande övningsuppgifter som studenterna kan lösa själva.Svaren till dessa uppgifter finns i boken och utförliga lösningsförslag finns att tillgå på webben, www.studentlitteratur.se/39041.

  • 9.
    Almssad, Asaad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Almusaed, Amjad
    Archcrea Institute.
    Bio-Ecological Sustainable Windows2005In: The International Conference Sustainable Building 2005 SB05, Tokyo: SB05Tokyo National Conference Board , 2005, p. 31-34Conference paper (Refereed)
    Abstract [en]

    Window is a vital part of any house they permit natural light into the house as long as views and fresh air. In the same time we can consider that the window is an extremely influential factor in climatic design, as the weakest climatic element of the building envelope. Well designed and protected windows improve comfort year round and reduce the need for heating in winter and cooling in summer. Aesthetics appearance, view, and optical performance, are usually quite important to the occupant. In reality, the serious lighting designer cannot take any notice of the energy implications of window choices. New technologies help to resolve the historic problem of the transaction between windows that reflect unwanted solar gains in the summer and those that admit a maximum quantity of useful light. Well-designed windows and shading devices allow solar heat gain in winter and shade and ventilation in summer while providing enough day lighting. Solar gain achieved by heaving 60% of the building’s windows orientated correctly can reduce the heating load of  house by _22%.In houses, low solar heat gain coefficient glazing should be used on east and west orientations, while high glazing should be used when passive solar and day lighting are being utilized.

    Today’s window technologies can replace more primitive strategies for shielding interior spaces from unwanted sunlight, such as tinted windows and curtains.

  • 10.
    Almssad, Asaad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Almusaed, Amjad
    Archcrea Institute.
    Efficient daylighting approach by means of light-shelve device adequate for habitat program in Aarhus City2014In: International Journal of Smart Grid and Clean Energy, ISSN 2315-4462, Vol. 3, no 4, p. 441-453Article in journal (Refereed)
    Abstract [en]

    The concepts of light shelves consist of windows that have face towards the sun, which receive a vast quantity of energy that could be used for healthy day lighting. This paper debates a main assessment, investigates the optimization of daylight requirement by means of light shelves system. An experimental test was carried out assessing the measurements and lighting simulations of a model of a building in order to elucidate the characteristics of indoor lighting. Light shelf is an architectural element that permits daylight to enter deep into a building. It constitutes an optimal solution for an incorrect building orientation and less sunny days. The essential objective of this study is to highlight the vital role of light shelves in residential buildings in northern Europa where the requirement is to improve the daylight in the interior functional spaces. The main objects of this paper are to investigate the effect of daylight in the interior functional spaces using light shelves, the effect of natural light diffusion in interior space in the period of low daylight season, and glare effect in this field. This paper investigates a procedure for analysing the daylight performance using software habitat function

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  • 11.
    Almssad, Asaad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Almusaed, Amjad
    Albasrah University, Albasrah, Iraq.
    Environmental reply to vernacular habitat conformation from a vast areas of Scandinavia2015In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 48, p. 825-834Article in journal (Refereed)
    Abstract [en]

    There are many original ideas and useful system inputs embedded in the building of human settlements in Scandinavian regions, where the landscape and habitat are strongly interconnected. A cold climate and strong winds are the most prominent risks that affect habitats. The Longhouse is the foremost traditional habitat in the Scandinavian region, dating back to the Iron Age, 2000 BC. This study examines the influence of climate on the conformation of habitats. Climate had a solid impact on the conceptions of habitat form and internal space. Wind and extreme temperatures had firming consequences on the housing arrangements, layouts, orientations, and building materials used in the construction process. Habitats from this region were located in an optimal arrangement, and the south orientation was used effectively. This investigation will provide an evaluative interpretation and analysis of the real facts of vernacular habitats in the context of energy efficiency and ecological concepts, considering human settlement patterns, architectural creation and building material uses. (C) 2015 Elsevier Ltd. All rights reserved.

  • 12.
    Almssad, Asaad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Almusaed, Amjad
    Archcrea Institute.
    Green housing: The optimal Solution To Combat The Negative Effects Of Global Climatechange2010In: 3rd International Conference Palenc 2010 jointly organised with EPIC 2010 & 1st Cool Roofs Conference, University of Athens, Greece , 2010Conference paper (Refereed)
    Abstract [en]

    No Architectural concept is complete without green areas. The vital mission of biophilic architecture is to revised conceptualization of architecture in response to a myriad of contemporary concerns about the effects of human activity. Our earth is warming more rapidly than it has in the past according to the research of scientists. The green building of biophilic architecture combines the interests of sustainability, environmental consciousness, green areas of the large nature, and organic approaches to evolve design solutions from these requirements and from the characteristics of the site, its neighborhood context, and the local microclimate and topography. The biophilic concept provides us with the opportunity to reach extremely low levels of energy consumption by employing high quality, cost-efficient measures to general architectural components - such measures are in turn off advantage to the ecology and economy sector. Our essential task of this research is to make of the green covering a human strategy in urban and architectural manner and to be a human culture with helping of local governments; we can acquire the competent legislation, which protect our life and environment.

  • 13.
    Almssad, Asaad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Almusaed, Amjad
    Jönköping universitet / Department of Construction Engineering and Lighting Science.
    Housing Policy Matters2018In: Housing / [ed] Amjad Almusaed & Asaad Almusaed, London: INTECH, 2018Chapter in book (Refereed)
    Abstract [en]

    This book is proposed as both a general reading of the discipline for students in architecture and urban planning, and offers a variety of materials for professionals of local and international organizations. It brings together studies with new perspectives and relevant subjects from different geographical areas. The book gathers the contributions of international researchers and experts. It is divided into three parts and eight chapters: Part I, "Introduction to Housing Affairs," includes a chapter that discusses a general reading of housing as meaning and action in social, economic, and environmental city life. Part II, "Case Studies Upon Housing Policies," includes four chapters. It consists of many examples from different geographical areas and domains. Part III, "Housing Quality and Affordability," includes three chapters; housing quality, sustainability, and development are the main subjects for this part.

  • 14.
    Almssad, Asaad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Almusaed, Amjad
    Jönköping University.
    Overview of a Competent Sustainable Building2018In: Sustainable Buildning: Interaction Between a Holistic Conceptual Act and Materials Properties / [ed] Amjad Almusaed & Asaad Almssad, London: InTech, 2018, p. 3-16Chapter in book (Refereed)
    Abstract [en]

    This book has been written to represent the efficient applications of sustainability upon building designs. The book intends to illustrate various techniques of action of sustainability on building conceptions. The book is divided into four parts and eight chapters. Part I "Introduction into Target Theme" includes a chapter with title "Introductory Chapter." It makes an overview of the meaning and the target of sustainable building and sustainable building material. Part II "Sustainable Building Design, Process, and Management" discusses many forms and concepts of sustainable building and includes three chapters. Part III "Sustainable Building by Using Energy Efficiency in Building Design" includes one chapter. Part IV "Sustainability in Building Materials: Study Cases" includes three chapters.

  • 15.
    Almssad, Asaad
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Almusaed, Amjad
    Archcrea Institute.
    Kalil Almusaed, Zaki
    Heat Island Effects Upon The Human Life On The City Of Basrah2007In: Building Low Energy Cooling and Advanced Ventilation Technologies in the 21st Century: 2nd PALENC Conference 28th AIVC Conference / [ed] M. Santamouris, P. Wouters, Crete island: University of Athens , 2007, p. 45-47Conference paper (Refereed)
    Abstract [en]

    After the terrible consequence of the Iraq –Iran war and recently USA attack over Iraq the urban green covering disappeared from large areas of the city, beside the extension of the building over the green areas. The negative effects of this phenomenon over human’s thermal comfort become more perceptive. Today we can observe clearly the negative effect of urban heat island in the center of Basra city, precisely in physical frameworks of the city; we can observe a typical phenomenon with a large negative effect for the period of summer heating that is a natural thermodynamic phenomenon. In the surfaces of physical framework, in the core of day between 12-15 pm, the sun is shining perpendicular above the earth surfaces (framework physic). Consequently the temperature on the earth surfaces increases surprisingly up to 60 ºC. Therefore there occurs a difference of temperature between the earth surfaces and cosmos space which conduce to generate a gigantic colonization of air from the earth surface to cosmos space, such resultants of this phenomenon is no air zones and under pressure on earth surfaces, with the intention of making a nasal bleeding, which seeking for a medical intervention aide.

  • 16.
    Almusaed, Amjad
    et al.
    Archcrea Institute.
    Almssad, Asaad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Bioclimatic Interpretation Over Vernacular Houses From Historical city Basrah.2006In: PLEA 2006: 23rd International Conference on Passive and Low Energy Architecture., Geneve: Universite de Geneve , 2006, p. 87-91Conference paper (Refereed)
    Abstract [en]

    Basrah’s climate is hot, dry summer, mild to cold winter, and a pleasant spring and fall. The old builders from this region putted a big effort to create passive bioclimatic houses that corresponds the negative effects Basrah’s macroclimate. The courtyard is the central and dominant space in the house plan with a direct access to the living spaces. Houses from the city are compact with interior courtyard; the streets are sinuous and pass through houses volumes. The shady interior courtyard has the effect that the rooms do not communicate directly with the overheated air outside, but through intermediate buffer spaces. In the mean time between courtyard and street at least a wall or a building is always interposed. The House plan had an endomorphic form, (open tree form). The volumes were concept to create shadow which helps to move the air by natural movement to the deep superior side, that can be achieve through special holes. The architectural elements are strongly decorated, reproducing special typologies and traditional houses. Open spaces, covered by large roofs, are interesting due to the mix of diffuse light and shade that are an essential aesthetic factor in these buildings.

  • 17.
    Almusaed, Amjad
    et al.
    Basra University, Iraq.
    Almssad, Asaad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Alasadi, Asaad
    Basra University, Iraq.
    Analytical interpretation of energy efficiency concepts in the housing design process from hot climate2019In: Journal of Building Engineering, ISSN 2352-7102, Vol. 21, p. 254-266Article in journal (Refereed)
    Abstract [en]

    The classical understanding of an architectural product shows architecture as a series of complex activities, which aims to create an optimal material framework with well-organized functional spaces that can meet the material and human spiritual requirements. The vision of a multifaceted architecture shows that it is necessary to design and work cooperatively with an architectural theory to transform the lateral conceptual viewer of the multilateral design process. The effort has to focus on ensuring the active collaboration of sciences and techniques with the creative building design process. The real stages of house design theory still insufficiently incorporate natural phenomena such as thermography, climatology, aerodynamics, and thermodynamics in the building design approach. The primary target of this research is to define an efficient method of building design in which essential aspects are considered during the first phase of design ideas. The study concluded that using a classical design model is respectable. However, it can bring many mistakes in the confirmation of a holistic design assignment related to energy, thermal comfort, and economic factors that represents an essential tool for architectural creation products where the innovative model proceeds with all design elements, activities and space roles which can reunify in the interpretation of functional spaces by creating an interspace with a consistency habitat environment.

  • 18. Almusaed, Amjad
    et al.
    Almusad, Asaad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Natural Lighting Efficiency By Means of Sun- Skylight-Tubes2014In: International Journal of Engineering and Advanced Technology, ISSN 2249-8958, E-ISSN 2249-8958, Vol. 3, no 3, p. 16-20Article in journal (Refereed)
    Abstract [en]

    The notion of comfort a luminous ambience refers to the distribution of luminance and chromatic ties on the interior envelope of a space that is one of different fields of vision for a subject within an ambience. Luminance and chromatic ties are at present not often studied as far as comfort in buildings is concerned. Sun lighting and bioclimatic concept is inseparable considerations when designing a building because of the historical and practical significance of natural lighting in architecture. Sunlight is as old as architecture itself. Human life gets sufficient sunlight, in fact, we use more of 90 % of our day indoor, for this reason, specialists are now seeing how architecture can ameliorate the indoor-outdoor links. At present, by biological and technological investigation the trend is to search backwards towards the previous philosophies and advantages of more indoor / outdoor relationship. Plus homeowners who want to have healthy home environments might want to renew the most relevant facts of technology and biology.

  • 19.
    Amruth, C.
    et al.
    Lodz University of Technology, Poland.
    Luszczynska, Beata
    Lodz University of Technology, Poland.
    Szymanski, Marek Zdzislaw
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Örebro University, Sweden.
    Ulanski, Jacek
    Lodz University of Technology, Poland.
    Albrecht, Ken
    Tokyo Institute of Technology, Japan; Kyushu University, Japan.
    Yamamoto, Kimihisa
    Tokyo Institute of Technology, Japan.
    Inkjet printing of thermally activated delayed fluorescence (TADF) dendrimer for OLEDs applications2019In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 74, p. 218-227Article in journal (Refereed)
    Abstract [en]

    This study presents the inkjet printing of a novel OLED device with fully solution-processed organic layers that employ TADF material as an emitting layer. The ink was formulated using new TADF material, triazine core carbazole dendrimers with tert-butyl group at the periphery (tBuG2TAZ), dissolved in a mixture of two non-chlorinated solvents. The influence of the print resolution and the substrate temperature on morphology of the printed films was studied and optimized in ambient conditions. The optimized TADF dendrimer layer was then incorporated in the OLEDs as the emitting layer. The best-printed OLEDs exhibited a maximum current efficiency of 18 cd/A and maximum luminance of 6900 cd/m(2). Such values are comparable to the values obtained in spin coated devices made of the same TADF dendrimer. Further, the mobility of charge carriers extracted from transient electroluminescence measurements of printed OLEDs, when compared to reference OLEDs made by spin coating technique, showed similar values. Finally, we have demonstrated the possibility of patterning of emission the area of complex shapes merely by selectively printing the emission layer. These results demonstrate the potential application of the new dendrimer TADF emitters for the fabrication of efficient OLEDs by an inkjet printing technique.

  • 20.
    Amruth, C.
    et al.
    Lodz University of Technology, Poland.
    Szymanski, Marek Zdzislaw
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Örebro University.
    Luszczynska, Beata
    Lodz University of Technology, Poland.
    Ulanski, Jacek
    Lodz University of Technology, Poland.
    Inkjet printing of super yellow: Ink formulation, film optimization, OLEDs fabrication, and transient electroluminescence2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, p. 1-10, article id 8493Article in journal (Refereed)
    Abstract [en]

    Inkjet printing technique allows manufacturing low cost organic light emitting diodes (OLEDs) in ambient conditions. The above approach enables upscaling of the OLEDs fabrication process which, as a result, would become faster than conventionally used vacuum based processing techniques. In this work, we use the inkjet printing technique to investigate the formation of thin active layers of well-known light emitting polymer material: Super Yellow (poly(para-phenylene vinylene) copolymer). We develop the formulation of Super Yellow ink, containing non-chlorinated solvents and allowing stable jetting. Optimization of ink composition and printing resolution were performed, until good quality films suitable for OLEDs were obtained. Fabricated OLEDs have shown a remarkable characteristics of performance, similar to the OLEDs fabricated by means of spin coating technique. We checked that, the values of mobility of the charge carriers in the printed films, measured by transient electroluminescence, are similar to the values of mobility measured in spin coated films. Our contribution provides a complete framework for inkjet printing of high quality Super Yellow films for OLEDs. The description of this method can be used to obtain efficient printed OLEDs both in academic and in industrial settings.

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  • 21.
    Andersson, Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Sociala krav i byggentreprenader: En tillfällig trend eller här för att stanna?2014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Europe has, since the economic crisis of 2007, gained increasing social segregation. The gap between rich and poor has increased and the large number of hidden statistics regarding people excluded from the labor market is greater than in many years. Social exclusion has thus taken a toll on community groups that already before the crisis had a hard time getting included. Groups such as young, elderly, immigrants and people with mental of physical disabilities. To curb this development, the European Commission have, since the 2004 directives, enabled public sector clients to, through procurement of goods, services and contracts, include measures that promote social consideration.

    Social consideration is a term that have been a part of Swedish procurement legislation since 2007, and was updated in 2010. This update meant that the meaning of this term was given greater weight and that clients were more clearly encouraged to use the term.

    The term social consideration have proven to be an unclear term, both in European tutorials and governmental investigations. Investigators describe the possibility as difficult to interpret and legally complex. To enable a smooth implementation, an open dialogue between clients and contractors have been recommended. A dialogue which, according to this study based on personal interviews, is being missing, partly or completely, in many places around central Sweden.

    The goal and purpose of this study is based on a range of issues surrounding the concept of social consideration and its impact on the public sector in Sweden. What is being done, what is wanted and why. The personal interviews where conducted with municipal housing companies and municipalities in order to reconcile the current state of the new contract term.

    These interviews clearly show that the term social consideration is known by the majority of public clients in central Sweden. However, only one out of seven interviewees have hitherto pushed through a work contract with predetermined requirements on social considerations. Notable though, is that three out of seven interviewees where in the process of publishing work contracts with the instituted social demands criterion.

    The justification for why the remaining parties did not, or where not planning to, set social standards in public work contracts was motivated mainly by the absence of knowledge in the subject. Clearer evidence and better guidance was considered a linchpin for future implementation. It was consistently put forth that social responsibility can lead to good future synergies for both society and their own company. But the design of how to set the requirement or requirements and in what stage, is something that every interviewed party had its own opinion about.

    Despite divided opinions on how and at what stage social considerations should be included in public procurement, there is a unified voice among the interviewed parties saying that the concept of social responsibility and consideration is here to stay.

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    Sociala krav i byggentreprenader
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    Arkivfil
  • 22. Andersson, Caisa
    et al.
    Järnström, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Water-vapour permeability of barrier dispersion coating2001Conference paper (Other (popular science, discussion, etc.))
  • 23.
    Andersson, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Torkning integrerat med kraftvärmeverk: Påverkan av energibalanser i torksystem vid integrering till kraftvärmeverk2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    I Sveg finns ett pneumatiskt torksystem. Systemet har sedan 1989 torkat torv till briketter men har på senare tid torkat både trä och torv för produktion av bränsle i form av pellets och briketter. Idag består anläggningen av två symmetriska torklinjer. I torklinjerna används en värmepumpkrets för återvinning av råvaruånga. I värmepumpkretsen används en kompressor driven av inköpt elenergi. Planerna är att integrera en av linjernas nuvarande torkprocess till ett kraftvärmeverk genom installation av ångpanna med bränslet torv och således producera el istället för att köpa el. Integrationen till kraftvärmeverket ger torklinjens värmepumpkrets ett nytt utseende. Kompressorn tas bort i utvald torklinje och ersätts av två lågtrycksturbiner. Det nya utseendet av värmepumpkretsen kommer innebära ett samspel mellan torkning och kraftvärmeverk. I värmepumpkretsen används olika ångflöden beroende av vilket råvarumaterial som torkas. Därför beräknades och användes olika ångflöden beroende av olika fukthalter och inmatningar i torksystemet för att se hur el- och fjärrvärmeproduktionen i kraftvärmeverket påverkades. Samtidigt jämfördes nuvarande torksystem med torksystem integrerat med kraftvärmeverk ur ett energiperspektiv genom förändring av el, fjärrvärmeproduktion och biobränsle.

    Fjärrvärmeproduktionen i kraftvärmeverket ökade vid ångflödena 31,0 ton/h och 24,0 ton/h ”till kompressor” men på grund av större beräkningsosäkerhet bortsågs dessa. Detta gav en varierad sammanlagd fjärrvärmeproduktion av systemen mellan 23,0-23,8 MW respektive 22,0-22,5 MW vid torkning av torv respektive trä (bortseende av torvscenario 1 vid fukthalten 65 %). En fjärrvärmeproduktion i den storleken, jämfört med Svegs fjärrvärmebehov, kan sägas vara för stort. En stor problematik blir därför vad all spillvärme ska användas till, framförallt på sommaren.

    Vid integrering till kraftvärmeverk minskade ”bränsle” medan ”fjärrvärme” och ”el” ökade. Beroende av vilket råvarumaterial som torkades gav en integrering ett större resultat för ”el” men mindre ”fjärrvärme” och ”bränsle” vid torkning av trä. Därför rekommenderas torkning av trä eftersom större resultat av ”el” minskar inköpt elenergi samt mindre ”fjärrvärme” resulterar till mindre spillvärme.

    Vid beräkningarna användes Simulink, ett verktyg för grafisk lösning av differentialekvationer, som ingår i programvaran MATLAB från Mathworks. I Simulink formerades olika ekvationer i statiska beräkningsmodeller för beräkning av energibalanserna i nuvarande torksystem och torksystem integrerat med kraftvärmeverk. Energibalanserna i nuvarande torksystem undersökte svårplacerade effektförluster samt genom olika energibalanskontroller kontrollerade och bedömde trovärdigheten i beräkningsmodellen. Resultaten för energibalanskontrollerna kallades ”beräkningsosäkerhet” vilket var en av flera parametrar som framlade bevis för ett variabelberoende, känsligt, komplext och svårtydande torksystem där övriga effektförluster var svåra att placera. Ett mer korrekt resultat av nuvarande system kan därför möjligtvis uppnås vid användande av en dynamisk istället för statisk modell samt användande enbart av mätdata istället för dimensionerande värden och således göra effektförlusterna lättare att placera.

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  • 24.
    Andersson, N.
    et al.
    BTG Instruments AB, Box 602, Säffle.
    Wilke, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Impact of dissolved lignin in peroxide bleaching2017In: PEERS Conference 2017: Maximizing Success Through Innovation, TAPPI Press , 2017, p. 597-604Conference paper (Refereed)
    Abstract [en]

    It has been demonstrated in previous studies that dissolved lignin carryover has a significant impact in oxygen delignification and chlorine dioxide stages. Specifically for chlorine dioxide stages, it has been shown that the total kappa number of the pulp, i.e. the sum of the fiber kappa number and the filtrate kappa number, corresponds very well to its bleach demand and should be used for accurate feedforward based control. Since peroxide also is commonly used for pulp bleaching, and gaining in popularity, the present study was conducted in order to investigate the basic relations and mechanisms, using laboratory peroxide bleaching experiments comparing different carryover lignin concentrations and types. The results show that in particular chlorine dioxide filtrates have significant negative impact on delignification and brightening, likely due to alkali consumption of e.g. dissolved lignin, and that compensation using a higher alkali charge will result in lower brightness at a given kappa number. The paper also touches upon the opportunities using advanced process control systems for bleach plants, and the process and economic improvements which can be made by properly accounting for disturbances such as carryover variability.

  • 25. Andersson, Niclas
    et al.
    Germgård, Ulf
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Johansson, Kristina
    Ljungqvist, Carl-Henrik
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Determining the strain to failure for constrained pulp fibres by means of single-fibre2002In: Appita Journal, Vol. vol 55 no 3Article in journal (Refereed)
  • 26. Andersson, Niclas
    et al.
    Germgård, Ulf
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Johansson, Kristina
    Ljungqvist, Carl-Henrik
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Determining the strain to failure for constrained pulp fibres by means of single-fibre fragmentation2002In: Appita Journal 55(2002)3, 224-229Article in journal (Refereed)
  • 27.
    Andersson, Niclas
    et al.
    BTG Process Solutions, Sweden.
    Wilke, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). BTG Process Solutions, Sweden.
    Akhlesh, Mathur
    BTG Process Solutions, Singapore.
    Smith, Dan
    BTG Process Solutions, USA.
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Measurement of Dissolved Lignin, and its Impact in Fiberline Unit Operations2017Conference paper (Refereed)
  • 28.
    Andersson, Niclas
    et al.
    BTG Instruments AB, Saffle, Sweden..
    Wilke, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Biazzo, Tom
    BTG Instruments AB, Saffle, Sweden..
    Van Fleet, Rick
    BTG Instruments AB, Saffle, Sweden..
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    A new sensor and a novel control concept for optimized fiber line operation2014In: TAPPI Journal, ISSN 0734-1415, Vol. 13, no 10, p. 39-45Article in journal (Refereed)
    Abstract [en]

    Kraft and sulfite pulp mills use several consecutive process stages for pulp production. However, usually only one key pulp parameter is used for process control and that is the lignin content in the fibers, typically expressed as the kappa number. Even so, to improve process efficiency, more variables need to be monitored. To do that, a new sensor was developed, the dissolved lignin transmitter (DLT), along with a new control concept. The DLT measures the dissolved lignin content in the pulp slurry using a unique principle based on optical measurements. The device can measure the dissolved lignin inline at low consistency and at medium consistency. The sensor has two major applications: 1) improving the efficiency in washing stages and 2) optimizing chemical charges. Results from several mill trials have shown that the contribution from dissolved lignin in the filtrate portion of the pulp is up to 30% of the total bleach load, i.e., fiber and filtrate kappa number combined into the bleach plant. Hence, chemical savings can be achieved taking this component into account compared to only measuring the washed fiber kappa number. Application: The results of this study can help mills understand how to better control the pulping stages, which might lead to significant economic savings and better pollution control.

  • 29.
    Andersson, Niclas
    et al.
    BTG Instruments AB.
    Wilke, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). BTG Instruments AB.
    Biazzo, Tom
    BTG Americas Inc. .
    van Fleet, Rick
    BTG Americas Inc. .
    Germgård, Ulf
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    A new sensor and a novel control concept for optimized fiberline operation2013In: 2013 PEERS Conference, Co-located with the 2013 International Bioenergy and Bioproducts Conference, TAPPI Press, 2013, p. 190-215Conference paper (Refereed)
  • 30.
    Andersson, Niclas
    et al.
    BTG Instruments.
    Wilke, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. BTG Instruments.
    Biazzo, Tom
    BTG Americas Inc.
    Van Fleet, Rick
    BTG Americas Inc..
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Beder-Miller, Sandra
    BTG Americas Inc..
    Is Conductivity the Best Measurement of Bleach Plant Carryover?2015In: Pulp & paper Canada, ISSN 0316-4004, p. 1-6Article in journal (Refereed)
  • 31.
    Andersson, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    A dynamic Na/S balance of a kraft pulp mill: Modeling and simulation of a kraft pulp mill using WinGEMS2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 32.
    Andersson, Tim
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Computer Modeling of Thermodynamic Flows in Reactors for Activated Carbon Production2014Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    There's a big demand for activated carbon in Ghana, it's used for the country's mining industry as well as in a multitude of other applications. Currently all activated carbon is imported despite the fact that the country has a large supply of agricultural waste that could be used for its production. This study focuses on activated carbon production from oil palm kernel shells from the nations palm oil industry.

    Earlier research points to a set of specific conditions needed for the production. The pyrolysis process produces biochar from the biomass and the process is set to take place for 2 h at 600  °C after a initial heating of 10 °C/min. The activation process then produces the activated carbon from the biochar and is set to take place for 2 h at 850 °C with a heating rate of 11.6 °C/min.

    Two reactors are designed to meet the desired conditions. The reactors are both set up to use secondary gases from diesel burners to heat the biomass. The heating is accomplished by leading the hot gases in an enclosure around a rotating steel drum that holds the biomass. To improve the ability to control the temperature profile in the biomass two outlet pipes are set up on top of the reactor, one above the biomass inlet and one above the biomass outlet. By controlling how much gas that flows to each outlet both the heating rate and the stability of the temperature profile can be controlled. The secondary gas inlet is set up facing downwards at the transition between the heating zone (area of initial heating) and the maintaining zone (area of constant temperature).

    The two reactors are modeled the physics simulation software COMSOL Multiphysics. Reference operating parameters are established and these parameters, as well as parts of the design, are then changed to evaluate how the temperature profile in the biomass and biochar can be controlled. A goal area was set up for the profile in the biomass where it was required to maintain a temperature of between 571.5 and 628.5 °C after the initial heating to be seen as acceptable. Similarly a goal area was set for the biochar between 809 °C and 891 °C after the initial heating.

    It's found from the simulations that the initial design of the reactors work well and can be used to produce the desired temperature profiles in the biomass and biochar. Furthermore it's concluded that the initial design for the pyrolysis reactor can be improved by having the gas outlet pipe situated by the biomass inlet face downwards instead of upwards. The redesign improves the overall efficiency of the reactor by increasing the heating rate and maintained temperature.

    The evaluation of the operating parameters led to the conclusion that the secondary gas inlet temperature effects the temperature profile to a greater extent than the gas mass flow in both reactors thereby making them more energy efficient. The increase in efficiency comes with a drawback of more unstable temperature profile. If the temperature profile becomes too unstable it will include temperatures that are too high or too low to be seen as acceptable.

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  • 33.
    Andreas, Svensson
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Nabrink, Robin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    GNSS-Styrning: Information för platschefer2013Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
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    GNSS-control
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    arkivfil
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    arkivfil bilaga
    Download (pdf)
    Bilaga B
  • 34.
    Annergren, Goran
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Process aspects for sulfite pulping2014In: Appita journal, ISSN 1038-6807, ISSN 1038-6807, Vol. 67, no 4, p. 270-276Article in journal (Refereed)
    Abstract [en]

    Sulfite pulping of wood, with the aim of producing a paper product, can be carried out under acidic, neutral or alkaline conditions. However, if a dissolving pulp is required to be achieved, only acidic conditions may be employed. The main reason for this specific requirement for dissolving pulps is the high level of cellulose purity required. The hemicellulose content should therefore be low and hemicellulose molecules are best removed at low pH. Another difference is that in paper pulps it is the fibre properties that are of a dominant interest, while in a dissolving pulp the cellulose properties are of significant interest. However, one similarity for both paper and dissolving sulfite pulps is the risk of uncontrolled side-reactions, which can lead to severe lignin condensation reactions, and in extreme cases even to a totally black pulp. Thus, sulfite pulping is a relatively complex chemical process and an overview of the most important parameters is thus presented.

  • 35.
    Annergren, Göran
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Instability of acidic sulfite cooking of softwoods2013Other (Other academic)
  • 36. Annergren, Göran
    et al.
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Sulfate cooking - a commercially dominating and continously improving pulping process2014Report (Other academic)
    Abstract [en]

    Sulfite cooking was earlier the dominating pulping process but sulfate (kraft) cooking is today the most important process for the production of chemical pulps and high-yield pulps. One important reason for this development of the sulfate process is its ability to efficiently use different wood species, in particular different hardwood species. Another reason is that bleached hardwood sulfate pulps have become a strong competitor to bleached softwood sulfite pulps. The pros and cons of sulfate cooking are discussed in this report and compared with sulfite cooking.

     

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    Sulfate_cooking
  • 37. Annergren, Göran
    et al.
    Kvarnlöf, Niklas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Sulfitmassa: Översikt kring Processfrågor, Marknad och Framtid2014Report (Other academic)
    Abstract [sv]

    Karlstads universitet har tagit på sig uppgiften att försöka sammanställa det kunnande som idag finns inom landet kring sulfitmassa och sulfitprocesser. Eftersom antalet massabruk som tillverkar sulfitmassa sakta sjunker är detta en viktig uppgift för att i någon mån kunna behålla det stora kunnande som en gång fanns kring denna process.

    Denna rapport belyser bl.a. viktiga processfrågor kring framställningen av pappers- och dissolvingmassor från sulfitprocessen.

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    Sulfitmassa_KUS2014_22
  • 38.
    Anukam, Anthony
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Famewo, Elizabeth Bosede
    University of Fort Hare, South Africa.
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Improving the understanding of the bonding mechanism of primary components of biomass pellets through the use of advanced analytical instruments2019In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, p. 1-18Article in journal (Refereed)
    Abstract [en]

    Previous studies have attempted to explain forces holding particles together in densified biomass pellets using theories of forces of attraction between solid particles, forces of adhesion and cohesion, solid bridges and mechanical interlocking bonds including interfacial forces and capillary pressure. This study investigated the bonding mechanism of primary biomass components in densified pellets through the use of advanced analytical instruments able to go beyond what is visible to the naked eye. Data obtained were used to predict how primary biomass components combine to form pellets based on the theory of functional groups and the understanding of structural chemistry. Results showed that hydroxyl and carbonyl functional groups played key roles in helping to identify the type of forces acting between individual particles, at a molecular level. At a microscopic level, morphological examination of the pellet clearly showed solid bridges caused by intermolecular bonding from highly electronegative polar functional groups linked to cellulose and hemicellulose.

  • 39.
    Anukam, Anthony Ike
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Bosede Famewo, Elisabeth
    University of Fort Harare, South Africa.
    Nyamukamba, Pardon
    Cape Peninsula University, South Africa.
    Characterization of pure and blended pellets made from Norway spruce and pea starch: A comparative study of bonding mechanism relevant to quality2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 23, p. 1-22, article id 4415Article in journal (Refereed)
    Abstract [en]

    The mechanism of bonding in biomass pellets is such a complex event to comprehend, as the nature of the bonds formed between combining particles and their relevance to pellet quality are not completely understood. In this study, pure and blended biomass pellets made from Norway spruce and pea starch were characterized using advanced analytical instruments able to provide information beyond what is visible to the human eye, with intent to investigate differences in bonding mechanism relevant to quality. The results, which were comprehensively interpreted from a structural chemistry perspective, indicated that, at a molecular level, the major disparity in bonding mechanism between particles of the pellets and the quality of the pellets, defined in terms of strength and burning efficiency, were determined by variation in the concentration of polar functional groups emanating from the major organic and elemental components of the pellets, as well as the strength of the bonds between atoms of these groups. Microscopic-level analysis, which did not provide any clear morphological features that could be linked to incongruity in quality, showed fracture surfaces of the pellets and patterns of surface roughness, as well as the mode of interconnectivity of particles, which were evidence of the production of pellets with dissimilarities in particle bonding mechanism and visual appearance.

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  • 40. Anukam, Anthony
    et al.
    Mohammadi, A
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Granström, Karin
    A Review of the Chemistry of Anaerobic Digestion: Methods of Accelerating and Optimizing Process Efficiency2019In: Processes, ISSN 2227-9717Article in journal (Refereed)
  • 41.
    Anukam, Anthony
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Mohammadi, Ali
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Granström, Karin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    A Review of the Chemistry of Anaerobic Digestion: Methods of Accelerating and Optimizing Process Efficiency2019In: Processes, Vol. 7, no 8, p. 1-19, article id 504Article, review/survey (Refereed)
    Abstract [en]

    The anaerobic digestion technology has been in existence for centuries and its underlying theory established for decades. It is considered a useful technology for the generation of renewable energy, and provides means to alleviate problems associated with low access to energy. However, a great deal of current research is targeted towards the optimization of this technology under diverse digestion process conditions. This review presents an in-depth analysis of the chemistry of anaerobic digestion and discusses how process chemistry can be used to optimize system performance through identification of methods that can accelerate syntrophic interactions of different microorganisms for improved methanogenic reactions. Recent advances in addition to old research are discussed in order to offer a general but comprehensive synopsis of accumulated knowledge in the theory of anaerobic digestion, as well as an overview of previous research and future directions and opportunities of the AD technology. Achieving a sustainable energy system requires comprehensive reforms in not just economic, social and policy aspects, but also in all technical aspects, which represents one of the most crucial future investments for anaerobic digestion systems.

  • 42.
    Anukam, Anthony
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). University of Fort Hare, South Africa.
    Okoh, Omobola
    University of Fort Hare, South Africa.
    Mamphweli, Sampson
    Stellenbosch University, South Africa.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    A comparative analysis of the gasification performances of torrefied and untorrefied bagasse: Influence of feed size, gasifier design and operating variables on gasification efficiency2018In: International Journal of Engineering & Technology, E-ISSN 2227-524X, Vol. 7, no 2, p. 859-867Article in journal (Refereed)
    Abstract [en]

    This study conducted a comparative assessment of the gasification performances of torrefied and untorrefied bagasse with emphasis on feed size, gasifier design and operating conditions that would influence gasification efficiency. Torrefaction greatly improved the characteristics of bagasse and had significant impact on its gasification performance. The gasifier design parameters studied were throat angle and throat diameter. Temperature of input air and feed input were the gasifier operating conditions examined in the course of the gasification processes of both torrefied and untorrefied bagasse. These parameters were considered the most critical operating parameters that affect gasifier performance and, correlation between the parameters was established in the course of gasification. The results obtained showed higher gasification efficiency for torrefied bagasse in comparison to untorrefied bagasse under varied conditions of gasification, which was attributed mainly to changes in the characteristics of the torrefied material.  

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  • 43.
    Arslan, Muhammad
    et al.
    University of Engineering and Technology, Pakistan..
    Farooq, Muhammad
    University of Engineering and Technology, Pakistan..
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Sultan, Umair
    MNS University of Agriculture, Pakistan..
    Tahir, Zia-ur-Rehman
    University of Engineering and Technology, Pakistan..
    Nawaz, Saad
    University of Engineering and Technology, Pakistan..
    Waheed, Nazim
    University of Engineering and Technology, Pakistan..
    Naqvi, Salman Raza
    National University of Sciences and Technology, Pakistan.
    Ali, Qasim
    University of Sargodha, Pakistan..
    Tariq, M. Suleman
    University of Engineering and Technology, Pakistan..
    Chaudhry, Ijaz Ahmad
    University of Management and Technology, Pakistan..
    Anderson, John M.
    Heriot-Watt University, Scotland..
    Anukam, Anthony
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Impact of Varying Load Conditions and Cooling Energy Comparison of a Double-Inlet Pulse Tube Refrigerator2020In: Processes, ISSN 2227-9717, Vol. 8, no 3, article id 352Article in journal (Refereed)
    Abstract [en]

    Modeling and optimization of a double-inlet pulse tube refrigerator (DIPTR) is very difficult due to its geometry and nature. The objective of this paper was to optimize-DIPTR through experiments with the cold heat exchanger (CHX) along the comparison of cooling load with experimental data using different boundary conditions. To predict its performance, a detailed two-dimensional DIPTR model was developed. A double-drop pulse pipe cooler was used for solving continuity, dynamic and power calculations. External conditions for applicable boundaries include sinusoidal pressure from an end of the tube from a user-defined function and constant temperature or limitations of thermal flux within the outer walls of exchanger walls under colder conditions. The results of the system's cooling behavior were reported, along with the connection between the mass flow rates, heat distribution along pulse tube and cold-end pressure, the cooler load's wall temp profile and cooler loads with varied boundary conditions i.e. opening of 20% double-inlet and 40-60% orifice valves, respectively. Different loading conditions of 1 and 5W were applied on the CHX. At 150 K temperature of the cold-end heat exchanger, a maximum load of 3.7 W was achieved. The results also reveal a strong correlation between computational fluid dynamics modeling results and experimental results of the DIPTR.

  • 44.
    Arvsell, Karin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Termofil aerob rening av skogsindustriellt avloppsvatten: Ett försteg till en luftad damm2014Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The production of pulp and paper requires a large amount of energy and also large amounts of water which, by advantage, can be taken from a nearby lake or river. The wastewater passes through several different purification steps, such as mechanical, chemical and biological treatment before being reintroduced to the recipient. During aerobic biological treatment, a degradation and oxidation of the organic material occurs and is performed by microorganisms which require oxygen. Aeration consumes about half of the external plant's total energy and is aggravated by extractives present in the trees. At Stora Enso Skoghall mill an aerated pond is used as biological treatment, but there are troubles to get the oxygen to last for the entire pond. If a pre-treatment is placed before the pond this would be able to reduce the substances which demands oxygen. The implementation of the pre-treatment would be a MBBR (Moving Bed Biofilm Reactor) containing carriers and where thermophilic bacteria form biofilms.

    The experimental setups were built up in a laboratory at the University of Karlstad. The aerated ponds would resemble the aerated pond at Skoghall mill, with an identical retention time and contain equivalent microorganisms. The wastewater was continuously pumped into the experimental setups and was received from Skoghall mill and contained only CTMP water and CTMP mixed with water from the bleach plant and evaporation plant. As evaluation of the experiments analyzes of COD, TOC, SS, SVI, surface tension, extractives and microscopy were done.

    The results showed a relatively uniform COD and TOC reduction for the aerated ponds at around 70 %, which is comparable with the real pond at Skoghall mill. For the thermophilic MBBR with a temperature of 45° C and with probe 10-water, a capacity of reduction at 30 - 40% was noticed. The result with water containing only CTMP showed a reduction of 30%. Measurements of surface tension and extractives show if the concentration of extractives is decreasing in the thermophilic pre-treatments and also in the aerated ponds, which indicates a more effective oxygenation of the water. It was also found that the biofilm in the thermophilic stages are very sensitive and relatively easy to decimate if the conditions for the thermophilic bacteria are not optimal or if the incoming water contains any toxic substance.

    The sludge in all aerated ponds consisted of bacteria, protozoa and metazoa. The reference pond showed large and dense flocks while for the ponds that were preceded by thermophilic MBBR indicated less sludge and less dense flocks. For pond containing CTMP-water the flocks were small, but in addition, floating sludge was detected and foam problems arose.

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  • 45.
    Azeem, Babar
    et al.
    Univ Teknol Petronas.
    KuShaari, KuZilati
    Univ Teknol Petronas.
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Keong, Lau Kok
    Univ Teknol Petronas.
    Almesfer, Mohammed Khaloofah
    King Khalid University.
    Al-Qodah, Zakaria
    Al Balqa Appl University Ammam Jordan; Taibah University, Madinah, Saudi Arbaia.
    Naqvi, SR
    Natl Univ, Islamabad Pakistan.
    Elboughdiri, Noureddine
    Natl University Saudia Arabia; ENIG, Lab Modelisat & Commande Syst, Dept Genie Chim Proc Gabes, Tunisia.
    Production and Characterization of Controlled Release Urea Using Biopolymer and Geopolymer as Coating Materials2020In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 12, no 2, article id 400Article in journal (Refereed)
    Abstract [en]

    Synthetic polymers-based controlled release urea (CRU) leaves non-biodegradable coating shells when applied in soil. Several alternative green materials are used to produce CRU, but most of these studies have issues pertaining to nitrogen release longevity, process viability, and the ease of application of the finished product. In this study, we utilized tapioca starch, modified by polyvinyl alcohol and citric acid, as coating material to produce controlled release coated urea granules in a rotary fluidized bed equipment. Response surface methodology is employed for studying the interactive effect of process parameters on urea release characteristics. Statistical analysis indicates that the fluidizing air temperature and spray rate are the most influential among all five process parameters studied. The optimum values of fluidizing air temperature (80 degrees C), spray rate (0.13 mL/s), atomizing pressure (3.98 bar), process time (110 min), and spray temperature (70 degrees C) were evaluated by multi-objective optimization while using genetic algorithms in MATLAB((R)). Urea coated by modified-starch was double coated by a geopolymer to enhance the controlled release characteristics that produced promising results with respect to the longevity of nitrogen release from the final product. This study provides leads for the design of a fluidized bed for the scaled-up production of CRU.

  • 46. Backfolk, K.
    et al.
    Johansson, Caisa
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre.
    Peltonen, J.
    Association between a sodium salt of a linear dodecylbenzene sulphonate and a non-ionic fatty alcohol ethoxylate surfactant during film formation of styrene/butadiene latex2006In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006, 291 (1-3), 38-44Article in journal (Refereed)
  • 47.
    Barbier, Christophe
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Beghello, L
    Magnetic printing for packaging industry: methods and feasibility2006Conference paper (Refereed)
  • 48.
    Barbier, Christophe
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences, Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Larsson, Per-Lennart
    Östlund, Sören
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Karathanasis, Michael
    On material characterization of paper coating materials by microindentation testing2005In: JCT: Journal of Coatings Technology, ISSN 0361-8773, Vol. 2, no 6, p. 463-471Article in journal (Refereed)
    Abstract [en]

    Microindentation as a method for determining important material properties of paper coating materials is studied experimentally and numerically. The bulk of the investigation is concentrated upon the short-lived elastic part of a spherical indentation test, but determination of the failure stress of the coating is also discussed. The results indicate that microindentation can be a powerful tool for material characterization of these materials, but only if careful efforts are made to account for the influence from plasticity as well as from boundary effects

  • 49.
    Barbier, Christophe
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences, Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Larsson, PL
    KTH Stockholm.
    Östlund, S
    Experimental investigation of damage at folding of coated papers2002In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 17, no 1, p. 34-Article in journal (Refereed)
    Abstract [en]

    To achieve a better understanding of the folding properties of coated papers pertinent to the mechanical behaviour, a microscopic investigation was performed. The influence on the damage levels in the coating from such features as delamination, humidity and paper thickness have been studied

  • 50.
    Barbier, Christophe
    et al.
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Larsson, PL
    Östlund, S
    Numerical investigation of folding of coated papers2005In: Composite StructuresArticle in journal (Refereed)
    Abstract [en]

    Folding of coated paper is examined numerically using the finite element method. Particular emphasis is put on the behaviour of field variables relevant for cracking of the coating layers. In the numerical analysis, the basepaper is modelled as an anisotropic elasticplastic material (both elastic and plastic anisotropy is accounted for) while the constitutive behaviour of the coating layers are approximated by classical (Mises) elastoplasticity. The numerical results suggest, among other things, that particular forms of plastic anisotropy can substantially reduce the maximum strain levels in the coating. It is also shown that delamination buckling, in the present circumstances, will have a very small influence on the strain levels in the coating layer subjected to high tensile loading

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