Digitala Vetenskapliga Arkivet

Change search
Refine search result
1234567 1 - 50 of 1288
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Aamir Latif, Muhammad
    University of Borås, School of Engineering.
    Radar scattering from bodies of revolution using an efficient partial differential equation algorithm2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    A technique is presented for solving the problem of scattering by a three-dimensional body of revolution using a partial differential equation (PDE) technique, employed in conjunction with radiation boundary condition applied in the Fresnel region of the scatterer. The radiation boundary condition, which is used to truncate the PDE mesh, is based upon an asymptotic expansion derived by Wilcox. Numerical results illustrating the procedure and verifying the accuracy of the results are included. These results are compared with other theoretical calculations for perfectly conducting bodies of revolution of arbitrary shape.

    Download full text (pdf)
    FULLTEXT01
  • 2.
    Abbasi, Maisam
    University of Borås, School of Engineering.
    Perspectives of Complexity and Intelligence on Logistics and Supply Chain Management2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    In recent decades, millions of articles, books and journals have been written and thousands seminars and conferences have been held to present increasing importance of supply chain management both in practice and theory. Undoubtedly, nowadays, success is not tied-up just in processes of a focal company but in processes of all its value chain and network. In order to survive in highly competitive markets, it sounds essential that all processes and entities of the supply and demand network be analyzed and value-adding ones be separated from those which are not. One of the origins of non-value adding processes is non-value adding complexity. So, a systematic study and analysis of supply chain complexity and rendering remedies for simplicity are essential. In this thesis, at first, some definitions as well as causes of supply chain complexity based on its complication and complexity are mentioned. In the next step, embodiments of some themes of complexity science in discipline of supply chains are explained. Later, a recipe for studying complexity is offered. Ingredients of this recipe are identification, classification, measurement, modeling, and simplification. Finally, implementation of intelligent agents as assured tools for simplification of supply chains complexity is described.

    Download full text (pdf)
    FULLTEXT01
  • 3. Abbaszadeh, A
    et al.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Effect of extraction conditions on yield and purity of citrus pectin by sulfuric and hydrochloric acids2009Conference paper (Refereed)
  • 4. Abedinifar, Sorahi
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Khanahmadi, Morteza
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Ethanol production by Mucor indicus and Rhizapus oryzae from rice straw by separate hydrolysis and fermentation2009In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 33, no 5, p. 828-833Article in journal (Refereed)
    Abstract [en]

    Rice straw was successfully converted to ethanol by separate enzymatic hydrolysis and fermentation by Mucor indicus, Rhizopus oryzae, and Saccharomyces cerevisiae. The hydrolysis temperature and pH of commercial cellulase and beta-glucosidase enzymes were first investigated and their best performance obtained at 45 degrees C and pH 5.0. The pretreatment of the straw with dilute-acid hydrolysis resulted in 0.72 g g (1) sugar yield during 48 h enzymatic hydrolysis, which was higher than steam-pretreated (0.60 g g (1)) and untreated straw (0.46 g g(-1)). Furthermore, increasing the concentration of the dilute-acid pretreated straw from 20 to 50 and 100 g L-1 resulted in 13% and 16% lower sugar yield, respectively. Anaerobic cultivation of the hydrolyzates with M. indicus resulted in 0.36-0.43 g g(-1) ethanol, 0.11-0.17 g g(-1) biomass, and 0.04-0.06 g g(-1) glycerol, which is comparable with the corresponding yields by S. cerevisiae (0.37-0.45 g g(-1) ethanol, 0.04-0.10 g g(-1) biomass and 0.05-0.07 glycerol). These two fungi produced no other major metabolite from the straw and completed the cultivation in less than 25 h. However, R. oryzae produced lactic acid as the major by-product with yield of 0.05-0.09 g g(-1). This fungus had ethanol, biomass and glycerol yields of 0.33-0.41, 0.06-0.12, and 0.03-0.04 g g(-1), respectively. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

  • 5. Aboh, I. J. Kwame
    et al.
    Henriksson, Dag
    University of Borås, School of Engineering.
    Laursen, Jens
    Lundin, Magnus
    University of Borås, School of Engineering.
    Gormon Ofosu, Francis
    Pind, Niels
    Selin Lindgren, Eva
    University of Borås, School of Engineering.
    Wahnström, Tomas
    University of Borås, School of Engineering.
    Identification of Aerosol Particle Sources in Semi-rural of Kwabenya, near Accra, Ghana2008Conference paper (Other academic)
  • 6. Aboh, I. J. Kwame
    et al.
    Henriksson, Dag
    University of Borås, School of Engineering.
    Laursen, Jens
    Selin Lindgren, Eva
    Lundin, Magnus
    University of Borås, School of Engineering.
    Pind, Niels
    Wahnström, Tomas
    University of Borås, School of Engineering.
    Air Pollution and Meteorology: Ambient PM2.5 Aerosol Origin Studied by Factor Analysis of Elemental Composition Related to Wind Data2008Conference paper (Other academic)
  • 7.
    Abrahamsson, Pontus
    et al.
    University of Borås, School of Engineering.
    Svedberg, Pierre
    University of Borås, School of Engineering.
    Sanering av kontaminerad mark2008Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    På uppdrag av Nexans IKO Sweden AB har MK Bygg AB genomfört saneringsarbete av kontaminerad mark i Tranemo kommun. 1947 ändrade Nexans IKO Sweden AB verksamhet från att har brutit torv till att tillverka kablar. Denna verksamhet genererade en del spillkabel och i denna fanns den värdefulla metallen koppar. På Nexans IKO Swedens område brändes spillkablar för att komma åt kopparen. Detta skedde mellan åren 1947 och 1967. Då kabeln innehöll PVC bildades vid förbränningen dioxiner och furaner. P.g.a. denna hantering behövde området saneras. MK Bygg AB:s uppdrag har huvudsakligen bestått av att schakta bort jordmassor från det kontaminerade området. De massor som har varit mindre kontaminerade har fraktats till Nexans angränsande egendeponi. Syftet med denna rapport har varit att hjälpa MK Bygg AB med delar av kontrollen och utvärderingen av saneringsarbetet. Underlag har tagits fram för godkännande av länsstyrelsen. Detta underlag har sedan använts för att upprätta egenkontrollplanen. Egenkontrollen omfattar huvudsakligen kontroller av schaktning, jord och spridningsförhindring. Den viktigaste delen av egenkontrollen har varit har förhindra spridning av kontaminerat material vid saneringsarbetet. Utifrån de undersökningar och bestämmelser som var framtagna av Envipro Miljöteknik och DGE mark och miljö AB har saneringsarbetet utförts på ett noggrant sätt. Eftersom ett flertal industrier tidigare inte har tagit hand om avfall på ett lämpligt sätt så kommer saneringsarbeten att behöva utföras under de närmaste åren. Vi tror att det i framtiden kommer att ställas hårdare krav på sanering av kontaminerade områden. Detta är något som vi anser kommer att bidra till större möjligheter att utnyttja markområden och framförallt till en bättre miljö.

    Download full text (pdf)
    FULLTEXT01
  • 8. Abtahi, F.
    et al.
    Gyllesten, I. C.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Software Tool for Analysis of Breathing Related Errors in Transthoracic Electrical Bioimpedance Spectroscopy Measurements2012Conference paper (Refereed)
  • 9. Abtahi, F
    et al.
    Seoane, F
    University of Borås, School of Engineering.
    Lindecrantz, K
    University of Borås, School of Engineering.
    Electrical bioimpedance spectroscopy in time-variant systems: Is undersampling always a problem?2014In: Journal of Electrical Bioimpedance, E-ISSN 1891-5469, Vol. 5, no 1, p. 28-33Article in journal (Refereed)
    Abstract [en]

    During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied mainly by using the frequency-sweep technique, across a range of many different applications. Traditionally, the tissue under study is considered to be time-invariant and dynamic changes of tissue activity are ignored by treating the changes as a noise source. A new trend in EBIS is simultaneous electrical stimulation with several frequencies, through the application of a multi-sine, rectangular or other waveform. This method can provide measurements fast enough to sample dynamic changes of different tissues, such as cardiac muscle. This high sampling rate comes at a price of reduction in SNR and the increase in complexity of devices. Although the frequency-sweep technique is often inadequate for monitoring the dynamic changes in a variant system, it can be used successfully in applications focused on the time-invariant or slowly-variant part of a system. However, in order to successfully use frequency-sweep EBIS for monitoring time-variant systems, it is paramount to consider the effects of aliasing and especially the folding of higher frequencies, on the desired frequency e.g. DC level. This paper discusses sub-Nyquist sampling of thoracic EBIS measurements and its application in the case of monitoring pulmonary oedema. It is concluded that by considering aliasing, and with proper implementation of smoothing filters, as well as by using random sampling, frequency-sweep EBIS can be used for assessing time-invariant or slowly-variant properties of time-variant biological systems, even in the presence of aliasing. In general, undersampling is not always a problem, but does always require proper consideration.

  • 10. Abtahi, Farhad
    et al.
    Aslamy, Benjamin
    Boujabir, I
    Seoane, Fernando
    University of Borås, School of Health Science.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    An Affordable ECG and Respiration Monitoring System Based on Raspberry PI and ADAS1000: First Step towards Homecare Applications2014In: 16th Nordic-Baltic Conference on Biomedical Engineering / [ed] Mindedal H., Persson M., Springer International Publishing , 2014, p. 5-8Conference paper (Refereed)
    Abstract [en]

    Homecare is a potential solution for problems associated with an aging population. This may involve several physiological measurements, and hence a flexible but affordable measurement device is needed. In this work, we have designed an ADAS1000-based four-lead electrocardiogram (ECG) and respiration monitoring system. It has been implemented using Raspberry PI as a platform for homecare applications. ADuM chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 and IEC 60950 for patient safety. The result proved the potential of Raspberry PI for the design of a compact, affordable, and medically safe measurement device. Further work involves developing a more flexible software for collecting measurements from different devices (measuring, e.g., blood pressure, weight, impedance spectroscopy, blood glucose) through Bluetooth or user input and integrating them into a cloud-based homecare system.

  • 11. Abtahi, Zhohreh
    et al.
    Millati, Ria
    Niklasson, Claes
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Ethanol production by Mucor indicus at high glucose and ethanol concentrations2010In: Minerva biotecnologica (Testo stampato), ISSN 1120-4826, E-ISSN 1827-160X, Vol. 22, no 3-4, p. 83-89Article in journal (Refereed)
    Abstract [en]

    Mucor indicus was cultivated under aerobic and anaerobic conditions to study its tolerance against high concentration of glucose up to 350 g/L and ethanol up to 120 g/L present in the medium. The fungus could grow well even in 350 g/L glucose and produce ethanol, but it was able to assimilate the entire glucose when its concentration was less than 200 g/L. On the other hand, M. indicus produced ethanol as the main product with yield and concentration up to 0.45 g/g and 73 g/L, respectively, while glycerol, its only major byproduct, was produced up to 24 g/L. However, the fungus was not so tolerant against exogenously added ethanol, and it could not grow with more than 40 g/L added ethanol to the culture. Under aerobic conditions, M. indicus displayed different morphology, switching from long filamentous to yeast-like growth forms by increasing initial glucose concentration. This implies that yeast-like growth can be induced by growing M. indicus at high glucose concentration. Under anaerobic conditions, only one yeast-like form was observed.

  • 12.
    Abtahi, Zohreh
    University of Borås, School of Engineering.
    Ethanol and glucose tolerance of M.indicus in aerobic and anaerobic conditions2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Over the last few decades, ethanol production from renewable resources has been of interest as an alternative fuel to the current fossil fuel, due to the unstable oil market and in order to decrease net emission of carbon dioxide which leads to global warming. According to analyses of DG Transport and Energy (TREN), it is not possible to reach the current biofuels directive promoting 5,75 % biofuel by the year 2010, due to the markets and technologies, but by the year 2020 achievement of 6.9% is expected. This new law will increase biofuel demand by 3,1 %. Lignocelluloses materials, which are relatively cheap and plentiful, are considered to be the main source of feedstock’s for low-cost bio-ethanol production. The general procedure to convert lignocelluloses material to bioethanol is hydrolysis of the hemicelluloses and the cellulose to its monomer sugars, fermentation and distillation. Bacteria, yeasts and filamentous fungi are able to ferment hydrolysates from different plants and convert it to bioethanol. Mucor indicus is a filamentous fungus; it is able to utilize a wide range of hexoses, phentoses and disaccharides (cellobiose) in order to produce ethanol. The Ethanol yield and productivity of this microorganism from hexoses are as same as Saccharomyces cerevisiae. But the reason that it is one of the candidates for ethanol production is the fungus ability to utilize xylose. The cell wall of M.indicus contains significant quantity of chitosan/chitin which can be easily extracted. Chitosan is the deacetylated products of chitin. They have many applications in chemistry, biotechnology, medicine, veterinary, dentistry, agriculture, food processing, environmental protection, water purification, cosmetic and textile industries. The results of the current work show that the glucose concentration in the medium had a great impact on the lag phase, glucose consumption and ethanol production in both aerobic and anaerobic conditions. The lag phase increased as the initial concentration of glucose increased. While the glucose concentration increased above 190 g/l in the medium the glucose consumption and ethanol production decreased in both aerobic and anaerobic conditions. The glucose tolerance of M.indicus in both aerobic and anaerobic condition is about 190 g/l and in the anaerobic condition the ethanol tolerance of this fungus is around 70 g/.

    Download full text (pdf)
    FULLTEXT01
  • 13.
    Adams, Zechariah
    et al.
    University of Borås, School of Engineering.
    Shadram, Farshid
    University of Borås, School of Engineering.
    Köldbryggor i kantbalkar UNORM/DAVID-322011Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    En köldbrygga uppstår i en byggnadsdel vars isoleringsförmåga är lägre än omslutande material. Detta innebär att värmeförlusterna ökar och att den varma ytan blir lokalt kallare, vilket kan leda till nedsmutsning, mögel och kondensation. I examensarbetet har vi inriktat oss på grundkonstruktioner, närmare bestämt L-element med både lätt och tung vägg som komplement. I rapporten framgår hur vi räknat genom handberäkning och med hjälp av UNORM, ett datorprogram för beräkning av köldbryggor. För att redovisa resultatet jämförs handberäkningen med datorberäkningen, dels för att kontrollera resultatet och se skillnaden samt att se om det finns risk för mögel och kondensation med de olika L-elementen.

    Download full text (pdf)
    FULLTEXT01
  • 14.
    Adekunle, K.
    et al.
    University of Borås, School of Engineering.
    Cho, S.-W.
    University of Borås, School of Engineering.
    Ketzscher, R.
    Skrifvars, M.
    University of Borås, School of Engineering.
    Mechanical properties of natural fiber hybrid composites based on renewable thermoset resins derived from soybean oil, for use in technical applications2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 124, no 6, p. 4530-4541Article in journal (Refereed)
    Abstract [en]

    Natural fiber composites are known to have lower mechanical properties than glass or carbon fiber reinforced composites. The hybrid natural fiber composites prepared in this study have relatively good mechanical properties. Different combinations of woven and non-woven flax fibers were used. The stacking sequence of the fibers was in different orientations, such as 0°, +45°, and 90°. The composites manufactured had good mechanical properties. A tensile strength of about 119 MPa and Young's modulus of about 14 GPa was achieved, with flexural strength and modulus of about 201 MPa and 24 GPa, respectively. For the purposes of comparison, composites were made with a combination of woven fabrics and glass fibers. One ply of a glass fiber mat was sandwiched in the mid-plane and this increased the tensile strength considerably to 168 MPa. Dynamic mechanical analysis was performed in order to determine the storage and loss modulus and the glass transition temperature of the composites. Microstructural analysis was done with scanning electron microscopy.

  • 15.
    Adekunle, K.
    et al.
    University of Borås, School of Engineering.
    Cho, S.-W.
    University of Borås, School of Engineering.
    Patzelt, C.
    Blomfeldt, T.
    Skrifvars, M.
    University of Borås, School of Engineering.
    Impact and flexural properties of flax fabrics and Lyocell Fiber reinforced bio-based thermoset for automotive and structural applications2012Conference paper (Refereed)
  • 16.
    Adekunle, K.
    et al.
    University of Borås, School of Engineering.
    Ghoreishi, R.
    Ehsani, M.
    Cho, S.-W.
    University of Borås, School of Engineering.
    Skrifvars, M.
    University of Borås, School of Engineering.
    Jute fiber reinforced methacrylated soy bean oil based thermoset composites prepared by vacuum injection molding technique2012In: Journal of Biobased Materials and Bioenergy, ISSN 1556-6560, E-ISSN 1556-6579, Vol. 6, no 2, p. 172-177Article in journal (Refereed)
    Abstract [en]

    Bio-based composites based on soybean oil thermoset resin were manufactured with vacuum injection molding technique. Methacrylated soybean oil (MMSO) was processed with vacuum injection molding technique without blending with styrene. The composites produced had comparatively good mechanical properties like jute composite reinforced acrylated epoxidised soybean oil (AESO) resin blended with styrene. Although the tensile strength of the jute reinforced AESO composites are slightly higher than the jute reinforced MMSO composites which was attributed to blending of AESO with styrene. However, the difference in Youngs' modulus was negligible because they have approximately equal stiffness between 2.6 GPa and 2.8 GPa. The jute reinforced AESO composites showed relatively higher flexural strengths and moduli than the MMSO counterparts. This difference was also attributed to the blending of AESO with reactive diluent such as styrene. In order to determine the dimensional stability of the composite manufactured, water absorption test was carried out and the conclusion was that the moisture uptake of the jute reinforced composites was the same, this was expected.

  • 17.
    Adekunle, Kayode
    University of Borås, School of Engineering.
    Bio-based Composites from Soybean Oil Thermosets and Natural Fibers2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In order to reduce over-dependency on fossil fuels and to create an environment that is free of non-degradable plastics, and most importantly to reduce greenhouse gas emission, bio-based products are being developed from renewable resources through intense research to substitute conventional petrochemical-based plastics with renewable alternatives and to replace synthetic fibers with natural fibers. Many authors have done quite a lot of work on synthesizing polymers from renewable origin. Polylactic acid (PLA) has been developed and characterized, and it was found that it has enormous potential and can serve as an alternative to conventional thermoplastics in many applications. Modification of the plant oil triglycerides has been discussed by many authors, and research is still going on in this area. The challenge is how to make these renewable polymers more competitive in the market, and if possible to make them 100% bio-based. There is also a major disadvantage to using a bio-based polymer from plant oils because of the high viscosity, which makes impregnation of fibers difficult. Although natural fibers are hydrophilic in nature, the problem of compatibility with the hydrophobic matrix must be solved; however, the viscosity of the bio-based resin from plant oils will complicate the situation even more. This is why many authors have reported blending of the renewable thermoset resin with styrene. In the process of solving one problem, i.e reducing the viscosity of the renewable thermoset resin by blending with reactive diluents such as styrene, another problem which we intended to solve at the initial stage is invariably being created by using a volatile organic solvent like styrene. The solution to this cycle of problems is to synthesize a thermoset resin from plant oils which will have lower viscosity, and at the same time have higher levels of functionality. This will increase the crosslinking density, and they can be cured at room temperature or relatively low temperature. In view of the above considerations, the work included in this thesis has provided a reasonable solution to the compounded problems highlighted above. Three types of bio-based thermoset resins were synthesized and characterized using NMR, DSC, TGA, and FT-IR, and their processability was studied. The three resins were subsequently reinforced with natural fibers (woven and non-woven), glass fibers, and Lyocell fiber and the resulting natural fiber composites were characterized by mechanical, dynamic mechanical, impact, and SEM analyses. These composites can be used extensively in the automotive industry, particularly for the interior components, and also in the construction and furniture industries. Methacrylated soybean oil (MSO), methacrylic anhydride-modified soybean oil (MMSO), and acetic anhydride-modified soybean oil (AMSO) were found to be suitable for manufacture of composites because of their lower viscosity. The MMSO and MSO resins were found to be promising materials because composites manufactured by using them as a matrix showed very good mechanical properties. The MMSO resin can completely wet a fiber without the addition of styrene. It has the highest number of methacrylates per triglyceride and high crosslink density.

    Download (pdf)
    sammanfattning
  • 18.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Patzelt, Christian
    Blomfeldt, Thomas
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Impact and flexural properties of flax fabrics and Lyocell fiber-reinforced bio-based thermoset2011In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 30, no 8, p. 685-697Article in journal (Refereed)
    Abstract [en]

    A bio-based thermoset resin was reinforced with flax fabrics and Lyocell fiber. The effect of different weave architectures was studied with four flax fabrics with different architectures: plain, twill (two different types), and dobby. The effect of the outer ply thickness was studied and characterized with flexural and impact testing. Composites manufactured with plain weave reinforcement had the best mechanical properties. The tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength were 280 MPa, 32 GPa, 250 MPa, 25 GPa, and 75 kJ/m2, respectively. Reinforcements with twill-weave architecture did not impart appreciable flexural strength or flexural modulus even when the outer thickness was increased. Plain- and dobby (basket woven style)-weave architectures gave better reinforcing effects and the flexural properties increased with an increase in outer thickness.Water absorption properties of the composites were studied and it was observed that the hybridization with Lyocell fiber reduced the water uptake. Fieldemission scanning electron microscopy was used to study the micro-structural properties of the composites.

    Download full text (pdf)
    FULLTEXT01
  • 19.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Ketzscher, Richard
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    High performance natural fibre hybrid composites based on biobased thermoset resins for use in technical applications2009Conference paper (Other academic)
    Abstract [en]

    Health related issues, stringent environmental protection policies, search for cost effective and alternative materials and quest for renewability, sustainability and high performance materials for technical applications has led to an intense research in manufacturing biobased composites which are based on renewable thermosetting resins and natural fibres. The combination of biobased thermosetting resins with two different natural fibre reinforcements could lead to improved mechanical properties of the composite. Biobased thermoset polymers are comparable to the synthetic thermosetting polymers from petrochemicals. In this study, two different biobased resins were used as matrix and both non woven flax fibre and woven flax fabric were combined as reinforcements. The composites were made by compression moulding process. The fibres were hand laid-up and impregnation was done manually. The curing temperature was 170°С and at 40 bar. The stacking sequence of the fibres was in different orientations such as 0º, +45º and 90º. The manufactured hybrid composites have high tensile strength and stiffness and the flexural strength and modulus was also high. These composites can compete favourably with glass fibre reinforced composites in terms of strength and stiffness.1, 2 A tensile strength of about 119 MPa and Young’s modulus of 13.8 GPa was achieved, while the flexural strength and modulus is about 201 MPa and 24 GPa respectively. For the purpose of comparison, composites were made with the combination of woven fabric and e-glass fibre. One ply of an e-glass fibre mat was put in the mid-plane and this increased the tensile strength considerably up to 168 MPa. Some of the composites were made with the resin blended with styrene and the results show a higher modulus.

  • 20.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Patzelt, Christian
    Kalantar, Adib
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mechanical and Viscoelastic Properties of Soybean Oil Thermoset Reinforced with Jute Fabrics and Carded Lyocell Fiber2011In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 122, no 5, p. 2855-2863Article in journal (Refereed)
    Abstract [en]

    Composites and hybrid composites were manufactured from renewable materials based on jute fibers, regenerated cellulose fibers (Lyocell), and thermosetting polymer from soybean oil. Three different types of jute fabrics with biaxial weave architecture but different surface weights, and carded Lyocell fiber were used as reinforcements. Hybrid composites were also manufactured by combining the jute reinforcements with the Lyocell. The Lyocell composite was found to have better mechanical properties than other composites. It has tensile strength and modulus of about 144 MPa and 18 GPa, respectively. The jute composites also have relatively good mechanical properties, as their tensile strengths and moduli were found to be between 65 and 84 MPa, and between 14 and 19 GPa, respectively. The Lyocell-reinforced composite showed the highest flexural strength and modulus, of about 217 MPa and 13 GPa, respectively. In all cases, the hybrid composites in this study showed improved mechanical properties but lower storage modulus. The Lyocell fiber gave the highest impact strength of about 35 kJ/m2, which could be a result of its morphology. Dynamic mechanical analysis showed that the Lyocell reinforced composite has the best viscoelastic properties.

    Download full text (pdf)
    fulltext
  • 21.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Patzelt, Christian
    Kalantar, Adib
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mechanical properties of renewable soyean oil thermoset reinforced with jute fabricsand lyocell fiber2011Conference paper (Refereed)
    Download full text (pdf)
    FULLTEXT01
  • 22.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthesis of reactive soybean oils for use as thermoset resins in composites.2007Conference paper (Refereed)
  • 23.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Bakare, Fatimat
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Bio-based thermoset resins from soybean and linseed oils for structural composites2011Conference paper (Refereed)
    Download full text (pdf)
    FULLTEXT01
  • 24.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Biobased Composites Prepared by Compression Molding with a Novel Thermoset Resin from Soybean Oil and a Natural-Fiber Reinforcement2010In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 116, no 3, p. 1759-1765Article in journal (Refereed)
    Abstract [en]

    Biobased composites were manufactured with a compression-molding technique. Novel thermoset resins from soybean oil were used as a matrix, and flax fibers were used as reinforcements. The air-laid fibers were stacked randomly, the woven fabrics were stacked crosswise (0/90 ), and impregnation was performed manually. The fiber/resin ratio was 60 : 40. The prepared biobased composites were characterized by impact and flexural testing. Scanning electron microscopy of knife-cut cross sections of the specimens was also done to investigate the fiber–matrix interface. Thermogravimetric analysis of the composites was carried out to provide indications of thermal stability. Three resins from soybean oil [methacrylated soybean oil, methacrylic anhydride modified soybean oil (MMSO), and acetic anhydride modified soybean oil] were used as matrices. The impact strength of the composites with MMSO resin reinforced with air-laid flax fibers was 24 kJ/m2, whereas that of the MMSO resin reinforced with woven flax fabric was between 24 and 29 kJ/m2. The flexural strength of the MMSO resin reinforced with air-laid flax fibers was between 83 and 118 MPa, and the flexural modulus was between 4 and 6 GPa, whereas the flexural strength of the MMSO resin reinforced with woven fabric was between 90 and 110 MPa, and the flexural modulus was between 4.87 and 6.1 GPa.

  • 25.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Biobased Composites Prepared by Compression Moulding using a Novel Thermoset Resin from Soybean oil and a Natural Fibre Reinforcement2009Conference paper (Other academic)
    Abstract [en]

    Biobased composites were manufactured by using a compression moulding technique. Novel thermoset resins from soybean oil were used as matrix while flax fibres were used as reinforcement. The airlaid fibres were stacked randomly while woven fabrics were stacked crosswisely (90°) and impregnation was done manually. The fibre/ resin ratio was 60% to 40%.

    Download full text (pdf)
    FULLTEXT01
  • 26.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Preparation of biobased composites using novel thermoset polymers from soybean oil and a natural fibre reinforcement2009Conference paper (Other academic)
    Abstract [en]

    Health related issues, stringent environmental protection policies, search for cost effective and alternative materials, crave for renewability and sustainability and quest for high performance materials for structural applications give the motivation for research in polymer composites and material science. Due to the health, safety and environmental concerns over the conventional synthetic materials and the legislation against their usage both in domestic and industrial applications, alternatives sources that will be comparable in properties are being sought. There is an emerging market for biodegradable polymers which is expected to increase substantially in the coming years.[1] Preparation of Composites Airlaid and woven flax fibre mats were first treated with 4% sodium hydroxide solution for one hour and then washed with plenty of water. This was done in order to remove any residual impurities. The fibres were dried at room temperature for 24 hr and then dried in a vacuum oven for 1hr at a temperature of 105°С. The 8 sheets of the fibre were hand laid cross- wisely and the impregnation was done manually. The fibre/ resin ratio was about 60% to 40%. Methacrylated soybean oil, methacrylic anhydride and acetic anhydride modified soybean oil were the synthesized matrices used. The compression moulding was done at a temperature of 170°С for 5 min at 40bar. Characterisations The tensile testing was performed based on an ISO-test method for tensile tests on plastic materials. The Charpy impact strength of unnotched specimens was evaluated in accordance with ISO 179 using a Zwick test instrument and scanning electron microscopy analysis was done on the fractured specimens. The composites showed various mechanical properties, having impact strengths between 24 and 63 kJ/m² and tensile strength up to 51MPa.

  • 27.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthesis of reactive soybean oils for use as a biobased thermoset resins in structural natural fiber composites2009In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 115, no 6, p. 3137-3145Article in journal (Refereed)
    Abstract [en]

    Biobased thermosets resins were synthesized by functionalizing the triglycerides of epoxidized soybean oil with methacrylic acid, acetyl anhydride, and methacrylic anhydride. The obtained resins were characterized with FTIR, 1H-NMR, and 13C-NMR spectroscopy to confirm the functionalization reactions and the extent of epoxy conversion. The viscosities of the methacrylated soybean oil resins were also measured for the purpose of being used as a matrix in composite applications. The cross-linking capability was estimated by UV and thermally initiated curing experiments, and by DSC analysis regarding the degree of crosslinking. The modifications were successful because up to 97% conversion of epoxy group were achieved leaving only 2.2% of unreacted epoxy groups, which was confirmed by 1H-NMR. The 13C-NMR confirms the ratio of acetate to methacrylate methyl group to be 1 : 1. The viscosities of the methacrylated soybean oil (MSO) and methacrylic anhydride modified soybean oil (MMSO) were 0.2 and 0.48 Pas, respectively, which indicates that they can be used in resin transfer molding process.

  • 28.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthesis of reactive soybean oils for use as biobased thermoset resins in structural natural fibre composites2008Conference paper (Refereed)
  • 29.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthetic modification of reactive soybean oils for use as biobased thermoset resins in structural natural fiber composites2008Conference paper (Other academic)
  • 30.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthetic modification of reactive soybean oils for use as biobased thermoset resins in structural natural fiber composites2008In: Polymer Preprints, ISSN 0551-4657, Vol. 49, no 1, p. 279-Article in journal (Refereed)
  • 31.
    Adevåg, Fredrik
    et al.
    University of Borås, School of Engineering.
    Mujakic, Amir
    University of Borås, School of Engineering.
    Temo, Kodia
    University of Borås, School of Engineering.
    Kartläggning och effektivisering av bilar inom äldreomsorg2009Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Detta examensarbete gjordes på uppdrag av Norrbys kommundel som är en del av Borås. Syftet med arbetet var att kartlägga och analysera äldreomsorgens nyttjande av bilarna som de förfogar över samt undersöka om det finns ett behov av att effektivisera organisationen och användandet av bilarna och även hur detta skall gå till. För att genomföra detta uppdrag och få en teoretisk grund att stå på har lämplig litteratur och olika metoder för informationsinsamling studerats. Ett flertal intervjuer med handledaren samt ett möte med alla enhetschefer inom äldreomsorgen har genomförts för att få ingående information om verksamheten. Norrby kommundel som omfattar ett flertal stadsdelar i västra Borås däribland de utanförliggande delarna Byttorp, Tullen, Hestra, Ekås och Viared har sitt huvudkontor i stadsdelen Norrby som ligger i västra delen av Borås centralort. Logistik har varierande syften beroende på företag och vilken bransch de befinner sig i. Ett av syftena kan vara att förbättra effektiviteten i verksamheten och därmed att i slutändan åstadkomma en positiv resultatpåverkan. Genom förändringar i den organisatoriska strukturen, i det fysiska varuflödet samt genom bättre planerings- och styrsystem kan effektiviteten i logistikprocessen förbättras. Effektivitet kan utryckas med hjälp av olika effektivitetsvariabler. För att få en verksamhetsriktning som stämmer överens med företagets övergripande strategi och mål kan man uttrycka dessa i termer av effektivitetsvariabler samt mäta och följa upp dem. Minskning av det totala transportbehovet kan ske med bra transportplanering genom bra utnyttjande och ett effektivt användande av transportresurserna. För att genomföra planeringen måste det först och främst bestämmas hur nätverket av anläggningar och kunder ska se ut och hur tjänsterna ska flöda mellan dem. Nätverksplanering är en bestämning av geografisk placering och kapacitet i anläggningar, till exempel från vilken anläggning sjuksköterskor skall åka ifrån, mellan vilka områden de skall färdas och var de vilar efter besöken. Ett av målen med detta kan vara att försöka minimera de totala logistikkostnaderna samtidigt som leveransservicen ska öka. För att uppnå effektivisering krävs det en ständig förbättringsprocess. Denna process innebär förändringar av verksamheten vilka kan uppfattas som extra arbete, stora omställningar och extra kostnader. Som anställd känner man sig trygg i den nuvarande kretsen och kan uppfatta förändringar som något negativt. Det kan bero på att man koncentrerar sig på ett kortsiktigt perspektiv och inte ser en helhetsbild på längre sikt. För att motverka denna inställning bör de anställda informeras för att de ska få en bättre klarhet över vad meningen är med förändringarna. Det har visat sig att Norrby kommundel har brister i kommunikation och planering av verksamheten vilket leder till ineffektivitet. För att åtgärda detta krävs det kontroll över enheternas bilar samt även koordination mellan enheterna. Dessa arbetsuppgifter kan fördelas på enhetscheferna som träffas regelbundet för samordning eller så läggs ansvaret på en enskild person inom kommundelen.

    Download full text (pdf)
    FULLTEXT01
  • 32.
    Adnan Abid, Muhammad
    University of Borås, School of Engineering.
    Various methods of water marsh utilization for domestic sewage waste water treatment2011Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Different methods are being used for the removal of unwanted material from waste sewage water such as mini sewage treatment plant, infiltration and filter bed. But as compared to all above methods introduction of marsh is more beneficial, as marsh efficiency is much better then above mentioned methods. Marshes also have important role in biodiversity. Domestic waste sewage water contains organic material, viruses, bacteria and pathogens, nitrate and phosphate. These all factor influence the external environment. Removal of nitrate and phosphate is necessary because if they are not removed they may cause rapid increase in the growth of algae. Algae have short life span so they die. Bacteria use a lot of oxygen for the decomposition of algae. So as a result there becomes deoxygenating in the marsh. Most of the animals die because of lack of oxygen in the water source. Marsh method is better as compared to other methods for the removal of organic material and nutrients. Subsurface flow is needed in wetland for getting the best result. Subsurface flow wetland system will make the process better and it will minimize the effect of odor and insects and these both things directly create bad effect on external environment. In the subsurface flow wetland Phragmites australis and similar plants are used. Bacteria grow on the roots of these plants and break down the nutrients. Waste water treatment marshes are best suited for smaller towns, villages and single family homes. They work best under relatively warm conditions, but many are used in temperate climate as well. For the removal of microorganisms, chlorine is to be used, as it is best way for the removal of it. A de-chlorination process is also necessary, otherwise this water will create bad effect on aquatic life.

    Download full text (pdf)
    FULLTEXT01
  • 33.
    Adnan Abid, Muhammad
    et al.
    University of Borås, School of Engineering.
    ur Rehman, Atiq
    University of Borås, School of Engineering.
    Anees, Muhammad
    University of Borås, School of Engineering.
    How to minimize the defects rate of final product in textile plant by the implementation of DMAIC tool of Six Sigma2010Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Defects rate of product plays a very important role for the improvement of yield and financial conditions of any company. Actually defects rate causes a direct effect on the profit margin of the product and decrease the quality cost during the manufacturing of product. Companies strive to decrease the defects rate of the product during the manufacturing process as much as possible. By checking and inspection of defects of product at different point in a production cycle and management implement some changes specifically at those points in production where more defects are likely to happen. The project of defects rate of textile product in the yarn manufacturing process is so important in industry point of view. This process has large departments where the cotton passes in different process and may be effects the quality of yarn when it reaches the package form. A thousand defects opportunities create in the final package of yarn. That’s’ why it is decided to do work and implement DMAIC methodology in winding departments where the final package of yarn is make. Final package of yarn is the end product and from it is direct send to the customers and if any final product passes with some defects and may chance the customer complaint. The main thing of this project is to give the understanding of different problems in different departments in quality point of view and how to reduce the problems by taking preventive action against any defects produce during process. For quality of product and enhance the customer satisfaction, it is decided to more work on final end product in the form of DMAIC tool to reduce the defects rate of product before going to customer. Now days, defects rate reduction is so important especially in recession days, when every company wants to improve the financial goals and reduce quality cost of product. DMAIC methodology is a problem solving technique where process data is analyzed from different tools and indentify the problems which cause the defects produce in the product.

    Download full text (pdf)
    FULLTEXT01
  • 34.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Aim, Karel
    Dohrn, Ralf
    Elliott, J Richard
    Jackson, George
    Jaubert, Jean Noël
    Rebello de A. Macedo, Maria Eugénia
    Pokki, Juha-Pekka
    Reczey, Kati
    Victorov, Alexey
    Fele Zilnik, Ljudmila
    Economou, Ioannis
    A Survey of the Role of Thermodynamics and Transport Properties in ChE University Education in Europe and the USA2010In: Chemical Engineering Education, ISSN 0009-2479, Vol. 44, no 1, p. 35-43Article in journal (Refereed)
    Abstract [en]

    Thermodynamics and Transport Properties (TTP) is a central subject in the majority of chemical engineering curricula worldwide and it is thus of interest to know how it is taught today in various countries if chemical engineering education is to be improved. A survey of graduate thermodynamics education in the USA was performed a few years ago by Visco et al. [1] but as far as we know no systematic study of the undergraduate thermodynamics education has been performed, at least in recent years. In the present study, a survey about TTP education in Europe and the USA is presented. Results were obtained from nearly twenty different European countries and the USA and in total answers from about 150 universities were used for this study. The study is performed under the auspices of the Working Party of Thermodynamics and Transport Properties of the European Federation of Chemical Engineering. The survey was performed using a web based surveying system for which invitations were sent out to the universities by local representatives who were responsible for one or more countries each. Of the universities that answered more than 70 % offer BSc education 65 % offer MSc education and 55 % offer PhD education. Most universities offer at least two courses of thermodynamics. The following discussion is mainly based on the first two (undergraduate) courses reported. Half of these are taught to chemical engineers exclusively whereas the rest are taught with other branches of engineering, mainly mechanical and / or process engineering. In general two sets of course lengths were observed, corresponding either to a full semester of full time studies or to quarter of a semester. Most courses are centered around lectures and exercise classes with little or no laboratory work whereas home assignments are given in the vast majority (70-80 %) of the courses. The first course is mainly centered around the first and second law of thermodynamics whereas the second course is frequently more concentrated on phase equilibria. Both of these courses are mainly comprising of classical thermodynamics whereas the molecular interpretation often is touched upon. An analysis of the differences between thermodynamics education in Europe and the USA in presently being undertaken and results from this will also be presented. An investigation of the use of thermodynamics within industry is also on-going within the Working Party and results will be reported in the near future. [1] S.K.Dube, D.P. Visco, Chem. Eng. Ed., 2005, 258-263.

    Download full text (pdf)
    FULLTEXT01
  • 35.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Aim, Karel
    Dohrn, Ralf
    Elliott, J. Richard
    Jackson, George
    Jaubert, Jean-Noel
    Rebello de A. Macedo, Maria Eugénia
    Pokki, Juha-Pekka
    Reczey, Kati
    Victorov, Alexey
    Fele Zilnik, Ljudmila
    Economou, Ioannis
    A Survey of Thermodynamics and Transport Properties in Chemical Engineering Education in Europe and the USA2008In: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008Conference paper (Refereed)
    Download full text (pdf)
    FULLTEXT01
  • 36.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Gebäck, Tobias
    University of Borås, School of Engineering.
    Johansson, Erik
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Water absorption in polymers2010Conference paper (Other academic)
    Abstract [en]

    In this work two different examples of water absorbtion in polymers are studied by Monte Carlo simulations. Both of them are of large technical and commercial impotance. The first example is the water absorption in polyethylene cables where the water absorption plays a crucial role in the degradation of the cable insulation and thus should be as low as possible. The second example is bio-based superabsorbents made from denatured protein where water absorption capability is the prime desired property. Methods Gibbs Ensemble Monte Carlo simulations [1] were used to study the hydration of polymers. All simulations are performed with two boxes, one of which is filled with water at the start of the simulation, whereas the other contains polymer molecules and possible ions. The polymer molecules are not allowed to swap boxes whereas the water molecules are allowed to do so thus constituting an osmotic Gibbs ensemble [2]. For the polyethylene a connectivity-altering algorithm was used whereas the protein molecules were simulated using a side-chain regrowth model in addition to traditional Monte Carlo moves. For the polyethylene, the TraPPE [3] force field was used and the protein molecules, the Amber force field [4] was used. Water was modelled using simple point charge models [5]. Electrostatic interactions are treated using Ewald summation methods. The protein molecules were of different amino acid compositions and in different conformations, e.g., β-turns and random coils obtained using the amorphous cell method[6]. Studies were made with different degrees of charging on, e.g., lysine side chains mimicking different ionization states. Results The studies of polyethylene revealed the importance of ions left from the polymerisation catalyst for the absorbtion of water and the concomitant degradation of polyethylene cable insulation. Also the absorption properties of the protein molecules is strongly related to the presence of charged groups and fully charged protein molecules absorb large amounts of water. However, neither native nor denatured protein molecules show superabsorbing properties (i.e. absorbing hundreds of times their own mass) as they show in experimental studies and the reasons for this discrepancy will be discussed. References 1. A.Z. Panagiotopoulos, Mol. Phys. 61, 813 (1987). 2. E. Johansson, K. Bolton, D.N. Theodorou, P. Ahlström, J. Chem. Phys., 126, 224902 (2007). 3. M.G. Martin, and J.I. Siepmann, J. Phys. Chem. B, 103, 4508-4517 (1999). 4. W.D. Cornell, P. Cieplak, C.I. Bayly, I.R. Gould, K.M. Merz Jr, D.M. Ferguson, D.C. Spellmeyer, T. Fox, J.W. Caldwell, P.A. Kollman (1995). J. Am. Chem. Soc. 117, 5179–5197. 5. H. J. C. Berendsen, J. P. M. Postma and W. F. van Gunsteren, in Intermolecular Forces, B. Pullman, ed. (Reidel, Dordrecht, 1981) p. 331; H. J. C. Berendsen, J. R. Grigera and T. P. Straatsma, J. Phys. Chem. 91, 6269 (1987). 6. D.N. Theodorou, U.W. Suter, Macromolecules, 18, 1467 (1985).

    Download full text (pdf)
    FULLTEXT01
  • 37.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Moodley, Suren
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Ramjugernath, D.
    University of Borås, School of Engineering.
    Computer Simulations of Vapor-Liquid-Liquid Equilibria Involving Hydrocarbons and Water2008In: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008, CHPC National Meeting, Durban, South Africa, December 9-10, 2008, AlChe Annual Meeting, Philadelphia, November 15-21, 2008, 2008Conference paper (Other academic)
    Download full text (pdf)
    FULLTEXT01
  • 38.
    Ahmadzadeh, Amir Masoud
    University of Borås, School of Engineering.
    Capacity and Cell-Range Estimation for Multitraffic Users in Mobile WiMAX2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The fundamentals for continued growth of broadband wireless remain sound. According to the Ericsson’s official forecasts, the addressable global market of wireless internet broadband connectivity reaches to 320 million users by the end of 2010. The opportunity for BWA/WiMAX to serve those who want to switch to broadband service is huge in many parts of the world where wireline technologies may not be feasible. The current document (Capacity and Cell-range Estimation for Multitraffic Users in Mobile WiMAX) is prepared as a master’s program final thesis to peruse the service provision capabilities of Mobile WiMAX innovate technology in more details. An elaborate excerpt of the technical subjects of IEEE-802.16e-2005 standard is gathered in the first chapter to provide the reader with a practical concept of Mobile WiMAX technology. The following chapter is aimed to collect the required knowledge for WiMAX planning problem. An innovate methodology to calculate the system’s actual throughput and a traffic model for mixed application users are proposed with a step by step description to derive an algorithm to determine the maximum number of subscribers that each specific Mobile WiMAX sector may support. The report also contains a Matlab code –enclose in the appendix– that tries to implement the entire algorithm for different system parameter and traffic cases to ease the Mobile WiMAX planning problem. The last chapter introduces the mostly used propagation models that suit the WiMAX applications. The presented methodology would help those operators that plan to implement a wide coverage network in a city. Using the introduced methodology, service providers will be able to estimate the number of base stations and hence the network investment and profitability.

    Download full text (pdf)
    FULLTEXT01
  • 39.
    Aiha, Marcus
    University of Borås, School of Engineering.
    Beräkningsprogram för dimensionering av gavelbalk i stålbyggnader2009Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    I detta examensarbete som har gjorts tillsammans med EAB AB har syftet varit att skapa ett beräkningsprogram, som en applikation i Microsoft Excel. För att dimensionera gavelbalkar i stålbyggnader. För att skaffa sig en uppfattning om hur man handberäknar snittkrafterna i en statiskt obestämd balk, gjordes det en litteraturstudie. Denna ledde till att det valdes olika metoder för att beräkna snittkrafterna, bland annat valdes Cross-metod för att beräkna momentet i stöden. Beräkningarna av snittkrafterna gjordes i alla balkens stöd. Under dimensioneringsprocessen gjordes bland annat interaktionskontroller mellan moment och normalkraft i varje stöd. Detta gjordes för att få en så noggrann dimensionering som möjligt. Dimensioneringen gjordes enligt BSK 07. Målet med detta examensarbete är att ge EAB AB ett verktyg för att effektivisera sin dimensioneringsprocess, detta har uppnåtts. Det finns också en bra mall för att kunna fortsätta arbetet med att effektivisera EAB AB:s arbete med att dimensionera stålbyggnader.

    Download full text (pdf)
    FULLTEXT01
  • 40. Akbari, H.
    et al.
    Karimi, K
    University of Borås, School of Engineering.
    Lundin, M
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Optimization of baker's yeast drying in industrial continuous fluidized-bed dryer2012In: Food and Bioproducts Processing, ISSN 0960-3085, E-ISSN 1744-3571, Vol. 90, no 1, p. 52-57Article in journal (Refereed)
    Abstract [en]

    Instant active dry baker's yeast is a well-known product widely used for leavening of bread, produced by fermentation, and usually dried by hot air to 94–96% dry matter content. Multi-stage fluidized bed drying process is a commercial effective method for yeast drying. In this work, optimum operating parameters of an industrial continuous fluidized bed dryer for the production of instant active dry yeast were investigated. The dryer contained four zones separated with moving weirs. The operating conditions such as temperature, loading rate of compressed yeast granules, and hot air humidity had direct effects on both yeast activity and viability. The most important factors that affected the quality of the product were loading rate and the operational temperature in each zone on the bed. Optimization was performed for three loading rates of the feed to the dryer, using response surface methodology for the experimental design. The most significant factor was shown to be the loading rate with mean fermentation activity values of 620, 652, and 646 cm3 CO2/h for 300, 350, and 400 kg/h loading rates, respectively. The data analysis resulted in an optimal operating point at a loading rate of 350 kg/h and temperatures of zones 1, 2, 3, and 4 controlled at 33, 31, 31, and 29 °C, respectively. The best activity value was predicted as 668 ± 18 cm3 CO2/h, and confirmation experiments resulted in 660 ± 10 cm3 CO2/h. At the same operating point, the average viability of the cells was predicted as 74.8 ± 3.7% and confirmed as 76.4 ± 0.6%. Compared with the normal operating conditions at the plant, the optimization resulted in more than 12% and 27% improvement in the yeast activity and viability, respectively.

  • 41. Akbari, H.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Optimization of baker´s yeast drying in industrial continuous fluidized-bed dryer2008Conference paper (Refereed)
  • 42.
    Akhand, Md. Moniruzzaman
    et al.
    University of Borås, School of Engineering.
    Méndez Blancas, Abraham
    University of Borås, School of Engineering.
    Optimization of NMMO pre-treatment of straw for enhanced biogas production2012Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Modern society depends on fossil fuels to fulfill the increasing energy demand, which could cause further damages in the environment. Therefore, it is mandatory to develop technologies for the production of efficient alternative renewable energy sources, like biofuels. Agricultural waste streams, such as wheat straw, produced in larger amount can be utilized for these purposes, and can be used as raw materials for both ethanol and biogas production. However, the compact structure of lignocelluloses present in these materials makes their biological degradation difficult. In order to enhance the biogas production, wheat straw milled to 2mm size was pretreated with N-methylmorpholine-N-oxide (NMMO) at 90°C for 7-30 hours in this study. 90°C was applied as treatment temperature for the treatment to be able to investigate if the district heating system could be utilized in the treatment process in the future. The effects of the different pretreatment conditions were then evaluated by running batch anaerobic digestion assays for 45 days at 55°C. The best result was achieved after 7h treatment, leading to 0.47 Nm3/kg VS of straw methane production, corresponding to an increase by 47% compared to methane production obtained for the untreated straw. Furthermore, it was possible to recover up to 91.33% of the straw after the NMMO pretreatment. There were no significant changes in the chemical composition of the straw caused by the treatment, however structural analyses, like FTIR for the determination of crystallinity and and Simon Staining for the determination of porosity of the material showed that the crytallinity decreased, while the porosity increased as results of the treatment. Soaking in water for 72h prior to NMMO treatment was also applied to see whether it can improve the diffusion of NMMO into the material, but without success, due to the dilution of the treatment chemical caused by the soaking. The findings made during the experimental stage indicated that it is possible to run the NMMO pretreatment at an industrial temperature, further evaluation for the economical feasibility of this treatment method is however needed in the future.

    Download full text (pdf)
    FULLTEXT01
  • 43.
    Akinbomi, Julius
    et al.
    University of Borås, School of Engineering.
    Brandberg, Tomas
    University of Borås, School of Engineering.
    Sanni, Adebayo
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Development and dissemination strategies for accelerating biogas production in Nigeria2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 3, p. 5707-5737Article in journal (Refereed)
    Abstract [en]

    Following the worsening energy crisis of unreliable electricity and unaffordable petroleum products coupled with the increase number of poverty-stricken people in Nigeria, the populace is desperately in need of cheap alternative energy supplies that will replace or complement the existing energy sources. Previous efforts by the government in tackling the challenge by citizenship sensitization of the need for introduction of biofuel into the country’s energy mix have not yielded the expected results because of a lack of sustained government effort. In light of the shortcomings, this study assesses the current potential of available biomass feedstock for biogas production in Nigeria, and further proposes appropriate biogas plants, depending on feedstock type and quantity, for the six geopolitical zones in Nigeria. Besides, the study proposes government-driven biogas development systems that could be effectively used to harness, using biogas technology, the estimated 270 TWh of potential electrical energy from 181 million tonnes of available biomass, in the advancement of electricity generation and consequent improvement of welfare in Nigeria.

    Download full text (pdf)
    fulltext
  • 44.
    Akinbomi, Julius
    et al.
    University of Borås, School of Engineering.
    Brandberg, Tomas
    University of Borås, School of Engineering.
    Sanni, Sikiru A.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Development and Dissemination Strategies for Accelerating Biogas Production in Nigeria2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 3Article in journal (Refereed)
    Abstract [en]

    Following the worsening energy crisis of unreliable electricity and unaffordable petroleum products coupled with the increase number of poverty-stricken people in Nigeria, the populace is desperately in need of cheap alternative energy supplies that will replace or complement the existing energy sources. Previous efforts by the government in tackling the challenge by citizenship sensitization of the need for introduction of biofuel into the country’s energy mix have not yielded the expected results because of a lack of sustained government effort. In light of the shortcomings, this study assesses the current potential of available biomass feedstock for biogas production in Nigeria, and further proposes appropriate biogas plants, depending on feedstock type and quantity, for the six geopolitical zones in Nigeria. Besides, the study proposes government-driven biogas development systems that could be effectively used to harness, using biogas technology, the estimated 270 TWh of potential electrical energy from 181 million tonnes of available biomass, in the advancement of electricity generation and consequent improvement of welfare in Nigeria.

    Download full text (pdf)
    FULLTEXT01
  • 45.
    Alander, Monika
    University of Borås, School of Engineering.
    Förstudie:tillverkningsmetoder för ny kägelteknik till hydraulventiler2008Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Syftet med examensarbetet är att ta fram förslag på tillverkningsmetoder för ny kägelteknik som skall bli ett komplement till dagens slidteknik, som används till hydraulventiler. Inom ramen för examensarbetet skall olika tillverkningsmetoder för två detaljer som räknas som strategisk kritiska undersökas. Ett viktigt ställningstagande i denna process är om detaljerna skall köras i egen produktion eller köpas in. Examensarbetet är ett förarbete till ett underlag för beslut om egenproduktion eller köp. Beslutet kommer att tas inom en snar framtid. För fortsatt utvecklingsarbete är en LEAN-3P pärm framtagen som är ett verktyg i produkt- och processförberedelsen.

    Download full text (pdf)
    FULLTEXT01
    Download (pdf)
    bilaga
  • 46.
    Albertsson, Josefin
    et al.
    University of Borås, School of Engineering.
    Augustsson, Partic
    University of Borås, School of Engineering.
    Klassificering av vägbeläggningens kvalitet baserat på signaler från bilens befintliga givare2008Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Syftet med detta examensarbete har varit att utreda möjligheten att klassificera en vägbeläggnings kvalitet genom att utnyttja signaler från en bils befintliga givare. Vidare är examensarbetet en förstudie till ett eventuellt större projekt, som skall leda till utvecklingen av ett komplett klassificeringssystem som underlättar för väghållaren (t.ex. Vägverket) att inventera vägbeläggningens kvalitet. Uppdragsgivare har varit Semcon AB i Göteborg. I arbetet ingick att sätta systemavgränsningar beträffande olika beläggningstyper som skall kunna detekteras, vilka hastigheter som skall tillämpas vid mätningarna samt vilka signaler från bilens givare som är relevanta att utnyttja. Arbetet bestod i huvudsak av insamling av mätdata samt analys av denna i MATLAB1. Utifrån den information som den insamlade mätdatan gav, kunde sedan ett robust klassificeringssystem skapas, vilket med god precision klarar av att klassificera fyra olika beläggningstyper. Examensarbetet visar att det finns goda möjligheter till ett fördjupat arbete som kan resultera i ett för väghållaren mycket effektivt klassificeringsverktyg som underlättar att upprätthålla statusinformationen beträffande vägbeläggningens kvalitet. Ett sådant system blir både miljömässigt och ekonomiskt effektivt då inga onödiga utsläpp från mätbilar belastar miljön då mätningarna utförs av fordon som ändå rullar på vägarna. Därmed skulle också ekonomiska resurser från dagens inventeringar kunna frigöras. Till exempel så skulle Vägverket Konsult (och andra intressenter) kunna utföra mera ”riktade” och effektivare inventeringar av vägkvaliteten med detta nya klassificeringssystem.

    Download full text (pdf)
    FULLTEXT01
  • 47.
    Alexandersson, Cecilia
    University of Borås, School of Engineering.
    Effektivisering av det interna flödet på Godsmottagningen: Autoliv Sverige AB2009Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Autoliv koncernen är ett högteknologiskt globalt företag med ca 42 000 anställda i 32 länder världen över. Företagets vision är att drastiskt reducera trafikolyckor, trafikskador och olyckor med dödlig utgång. Examensarbetet utfördes på koncernens dotterbolag Autoliv Sverige AB i Vårgårda (ALS) med syftet att hitta förbättringar, som ger möjligheter till en effektivare godsmottagning och utökad kapacitetsutnyttjande. ALS producerar i huvudsak airbags och specialkomponenter och har ca 1000 anställda. Examensarbetet inleddes med en förundersökning på godsmottagningen. De metoder som användes har varit intervjuer, enkäter och andra uppföljningsblanketter. Enkätsvaren och analyserna gav information om de problem, som påverkar materialflödet på godsmottagningen och vilka veckodagar som arbetsbelastningen var extra tungt och stressigt. Dessutom genomfördes också transportanalys avseende inleveransfönster för att stämma av hur väl leverantörer och transportörer följer dessa. Resultatet av förundersökningen presenterades företagets referensgrupp för att besluta om examensarbetets fortsatta inriktning. Gruppen beslutade att den fortsatta analysen skulle fokusera på de svenska leverantörerna och de tre slingrutterna i Sverige. Analysen bekräftade att slingbilarna i dagsläget inte utnyttjas optimalt och har således outnyttjad kapacitet kvar, som varierar mellan 1/3 och 2/3 av lastutrymmet. Företaget kommer att arbeta vidare med optimeringsfrågan och i möjligaste mån komplettera med flera svenska leverantörer och finslipa transportsträckorna efter att examensarbetet avslutats, vilket kommer med stor sannolikhet att resultera i kostnadsbesparingar. I samband med analys av godsmottagningen konstaterades behovet av att generellt förbättra medarbetarnas förstående för orsak och verkan av sitt handlande så att alla kan se verksamheten i ett bredare perspektiv. Det kan exempelvis handla om att förstå vilka konsekvenser en bristfällig upphandling kan innebära för godsmottagning och produktionen. Organisationen är ett team där alla ska arbeta mot ett gemensamt mål och försöka förstå varandras arbetssätt, processer och arbetssituation. Ledning, styrning och uppföljning är viktigt för att bland annat kunna se hur leverantörssamarbetet fungerar. Företaget har utomordentligt bra dokumentation i form av standarder hur samarbetet ska se ut, men frågan är hur väl regelverket efterlevs i verkligheten. Författaren rekommenderar att ALS fullföljer uppföljning av leverantörssamarbetet och åtgärdar de affärsrelationer som inte är tillfredsställande. Trimning av leveransfönster är också en möjlighet för att kunna skapa ett jämnare materialflöde, vilket dock måste harmonisera med produktionens JIT-filosofi (Just In Time). I samband med denna analys rekommenderas också en genomgång av eventuella justeringsbehov av bemanningen på godsmottagningen. Optimering av slingbilarna är nödvändigt för att kunna uppnå kostnadsbesparingar dels genom att upprätta mer effektiva transportsträckor och dels genom att maximera lastvolymer genom att i möjligaste mån komplettera med fler svenska leverantörer.

    Download full text (pdf)
    FULLTEXT01
  • 48.
    Algestam, Sara
    University of Borås, School of Engineering.
    Ledarskap ur två perspektiv: En jämförelse mellan chefers och dess medarbetares syn på ledarskap2009Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Detta examensarbete är utfört under vårterminen 2009 på Högskolan i Borås på uppdrag av Brämhults kommundel/Borås Stad. Borås Stad är uppdelad i tio kommundelar som alla ansvarar för äldreomsorg av sina invånare. Brämhults kommundel, som ligger i fokus för detta arbete, består av sju områden; Boda, Brämhult, Främgärde, Hässleholmen, Hyberg, Svensgärde och Sörbo. Inom kommundelen arbetar cirka 900 anställda; 400 inom äldreomsorg, 500 inom förskola/skola och de resterade 150 arbetar som vikarier. Syftet med detta arbete är att ta reda på vad som är utmärkande för ett bra ledarskap. Sex personer intervjuades, tre enhetschefer respektive tre medarbetare med avsikt att ta reda på om det finns någon skillnad mellan deras bild av ett framgångsrikt ledarskap. Genom intervjuerna erhölls även en bild av hur ledarskapsituationen ser ut inom organisationen. Ledarna och medarbetarnas svar jämfördes sedan med ledarskapslitteratur inom området för att ta reda på om det finns någon skillnad på teorin och den faktiska situationen i Brämhults kommundel. För att kunna jämföra intervjumaterialet med ledarskapsteorier inleds studien med en teoretisk referensram. Teoridelen inleds med en beskrivning av chefskap respektive ledarskap samt förklaring av formellt- och informellt ledarskap. Därefter beskrivs tre huvudgrenar inom ledarskapsforskning; egenskapsbaserat-, beteendebaserat- och situationsanpassat ledarskap. Studien visar att ledarna och medarbetarna har många gemensamma åsikter om det goda ledarskapet. Samtidigt finns vissa skiljaktigheter mellan deras syn på ett framgångsrikt ledarskap. Detsamma gäller respondenterna och ledarskapsteorierna där vissa delar överensstämmer medan andra går emot varandra.

    Download full text (pdf)
    FULLTEXT01
  • 49.
    Algestam, Sara
    et al.
    University of Borås, School of Engineering.
    Kılıçaslan, Ertuğrul
    University of Borås, School of Engineering.
    Fulfilling customer demand Customer requirements and demands on e-commerce2011Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    This thesis has been carried out during second semester 2010 at University College of Borås in Collaboration with Halens AB. Halens Holding AB is one of Sweden’s leading e-commerce companies. The company contains of four subsidiaries which together create Halens Holding AB. The concern includes Halens AB, Cellbes AB, Time Finans AB and New Bubbleroom Sweden AB. The main office of Halens Holding AB is located in Borås, the company has a turnover of 1.1 billion SEK and employs 300 people. Halens Holding AB has a wide range of products; fashion, home textile, furniture’s, home electronics and beauty- and health products. Halens has recently expanded their market, and now have Swedish, Norwegian, Finnish, Danish, Estonian, Latvian, Czech, Polish, Slovakian, Russian, Swiss, Slovenian and Turkish customers. The purpose of this thesis was to investigate customer requirements and demands on e-commerce. Furthermore, the intention was also to compare customers from the different subsidiaries. The purpose could be concluded with following three bullets; Identify customer demand on; product, lead-time, service and cost. Investigate differences in customer demand at two of the subsidiaries; Halens and Cellbes. Determine different consequences to the identified customer demand; purchase, non-purchase, purchase followed by return, uncollected package. A survey was made in order to find real time information about customer behavior. The objective of the survey was to understand customers’ demands of e-commerce in general. The next step was to investigate if Halens and Cellbes fulfilled those requirements. Moreover, observations were made in order to capture the customers’ use of the web-pages. These observations provided a deeper insight of the customer requirements and demands. With survey answers and observations as a base, different customer segments could be spotted. Furthermore, the task was to find problem areas or errors from the customers’ point of view in order to improve the system. Suggested areas for improvement were presented in order to get a better match between customer demand and customer experience. During this project, a clear view of the demand and requirements of Halens and Cellbes customers has been obtained. There were not major difference between the two subsidiaries, to the contrary; the results showed that there were very similar. It can be concluded that Halens and Cellbes can improve their businesses with smaller changes. Several proposals for improvement have been developed in order to better fulfill customer demand.

    Download full text (pdf)
    FULLTEXT01
  • 50.
    Algestam, Sara
    et al.
    University of Borås, School of Engineering.
    Kılıçaslan, Ertuğrul
    University of Borås, School of Engineering.
    Optimering av lageraktiviteter och transporter: Flügger AB2009Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Detta examensarbete har utförts under höstterminen 2008 på Högskolan i Borås på uppdrag av Flügger AB i Bollebygd. År 1994 köpte Flügger A/S upp HP Färg & Kemi och kedjan Flügger AB startades i Sverige. Idag har Flügger i Bollebygd 150 anställda, vilket gör dem till en av Bollebygds största arbetsgivare. Dagens fabrik i Bollebygd är uppdelad i fyra producerande enheter; Alkyd-, Latex-, Kemi- och Spackelfabrik. Fabrikerna rymmer produktion av vattenbaserad- och terpentinbaserad färg, träskydd, spackelprodukter, rengöringsmedel för industri och biltvättsanläggningar, samt målningsrelaterade rengöringsmedel. I Bollebygd finns även ett råvaru- och emballagelager som ansvarar för materialtillförsel till de fyra produktionsenheterna. Syftet med detta arbete är att hitta förbättringar och effektiviseringsförslag för nuvarande interna transporter från råvaru- och emballagelager. Målsättningen är även att hitta lösningar för mellanlagringsplatser, samt förslag till utformning av råvaru- och emballagelager. En ytterligare uppgift är att hitta ett tillvägagångssätt som förbättrar beställningsrutiner och returhantering. Behovssvängningar skall jämnas ut genom att sprida ut de interna beställningarna till råvaru- och emballagelagret. I och med att företaget är certifierat enligt ISO 14 001 skall ovanstående punkter utföras med hänsynstagande till miljön. Genom intervjuer med de anställda på Flügger har information erhållits om de problem som finns inom internlogistik och lagerhantering. Intervjuer har även gjorts för att ta vara på de eventuella förbättringsförslag de anställda besitter. För att få en sådan korrekt helhetsbild som möjligt har både lagerpersonal och fabrikspersonal intervjuats. Observationer har gjorts på lagret såväl som på produktionsenheterna. På lagret har även tidtagning av lageraktiviteter utförts. En klar bild av Flüggers interna logistik och lageraktiviteter har erhållits under arbetets gång. Utifrån den bilden dras slutsatsen att aktiviteterna kan effektiviseras och att Flügger med relativt små medel kan förändra bilden till det bättre. Ett antal förbättringsförslag har framtagits inom de olika problemområdena. Dessa innehåller bland annat en presentation av lagerutformning, beställningsrutin samt effektivisering av lageraktiviteter.

    Download full text (pdf)
    FULLTEXT01
1234567 1 - 50 of 1288
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf