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  • 3051.
    Akhand, Victoria
    KTH, School of Chemical Science and Engineering (CHE).
    Mass Balance Model of Impurities for the WoodRoll Process2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The depletion time for fossil fuels calculated from 2009 is 35 years for oil, 37 years for gas

    and 107 years for coal. Hence, it has become essential to reduce the dependence on fossil

    fuels by switching over to renewable resources. This in turn will also help in combating the

    negative effects on the environment like global warming. Thermochemical processes such as

    pyrolysis and gasification of biomass are considered the most efficient technology for

    converting biomass to useful energy carriers. Cortus Energy AB is a Swedish company that

    has developed a patented gasification technology called WoodRoll

    ® for gasification of fuels derived from biomass. However, ash in a thermochemical conversion process can cause

    corrosion, sintering, slag and poisoning of catalysts, which leads to operational problems. In

    addition, heavy metals such as Zn, Pb and Cd are environmentally problematic. These metals

    contribute to environmental pollution by contaminating the soil, which in turn can harm

    humans and the ecosystem via the food chain. The undesired elements should therefore be

    identified to minimize their impact on the overall thermochemical process and to reduce the

    emission of these harmful substances.

    The objective of this master thesis project, on behalf of Cortus Energy AB, was to investigate

    possible key numbers that can be used to describe and predict how the ash behaves in their

    patented WoodRoll® process. The key numbers that have been identified are empirically

    developed based on experience of coal combustion. These key numbers are regularly used for

    fuel derived from biomass by companies specializing in analyzing, although knowledge about

    whether they can actually be used on biomass is limited. In order to ensure that the use of

    these for biomass is correct, they must be experimentally verified in the future. In addition, a

    theoretical investigation is conducted to study which species can form and in what phase this

    occurs. The investigation reveals that there are no clear trends for how the inorganic elements

    behave since contradicting results from different studies have been reported. Formation of

    species and their phase depends on several parameters such as temperature, heating rate,

    particle size, volatility, quantity and interaction between the elements in the biomass. The

    thesis project ends with a mass balance model on selected inorganic elements for wood

    residues, as well as for bark. The model could be a tool for Cortus Energy AB to identify

    approximately how much of each element is present in each stream in the WoodRoll® process.

    The models are verified with analysis results. Inorganic elements that affect the

    overall process and its equipment have been selected for modelling. The volume percent of

    H2, CO, CO2 and CH4 in the models agree well with the values obtained by Cortus Energy

    AB. This shows that the thermodynamic equilibrium calculations performed are reasonable.

  • 3052.
    Akhand, Victoria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Celsi, Adrian
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lagerberg, Tove
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Sångberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Plastfilm från rapshalm2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this project is to extract hemicellulose from the rape straw by using alkali- and water extraction, and thereafter to produce a film with these polymers. The intention with this film is to eventually replace the present oxygen barrier made of aluminium in applications such as food packaging made of cardboard, among other things. The film is composed of hemicellulose and additives, either the CMC or sorbitol molecules. Many analyses were conducted on the extracts and the films in order to draw conclusions about the structure and properties. The NMR analysis showed that the extracts contained the expected sugars and that the main deacetylation of O-acetyl groups happened during the extraction with low alkali. The SEC analysis gave low values of Đ. The tensile testing gave exceptional results, namely elongations of 10-60%, depending on the composition of the films. Two of the most significant analyses are the ion chromatography and the oxygen permeability test, which could not be implemented because of technical difficulties. Low alkali is to be preferred as solvent, used to extract the polymers, with respect to the environment, the economy and the mechanical properties. Furthermore, high addition of CMC is preferred when producing films because low CMC and sorbitol resulted in sticky films. For future work it would be recommended to analyse the films by conducting the ion chromatography and the oxygen permeability test. Additionally, it would be desirable to find the optimal addition amount of the CMC.

  • 3053.
    Akhlaghi, Shahin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Degradation of acrylonitrile butadiene rubber and fluoroelastomers in rapeseed biodiesel and hydrogenated vegetable oil2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biodiesel and hydrotreated vegetable oil (HVO) are currently viewed by the transportation sector as the most viable alternative fuels to replace petroleum-based fuels. The use of biodiesel has, however, been limited by the deteriorative effect of biodiesel on rubber parts in automobile fuel systems. This work therefore aimed at investigating the degradation of acrylonitrile butadiene rubber (NBR) and fluoroelastomers (FKM) on exposure to biodiesel and HVO at different temperatures and oxygen concentrations in an automated ageing equipment and a high-pressure autoclave. The oxidation of biodiesel at 80 °C was promoted by an increase in the oxygen partial pressure, resulting in the formation of larger amounts of hydroperoxides and acids in the fuel. The fatty acid methyl esters of the biodiesel oxidized less at 150 °C on autoclave aging, because the termination reactions between alkyl and alkylperoxyl radicals dominated over the initiation reactions. HVO consists of saturated hydrocarbons, and remained intact during the exposure. The NBR absorbed a large amount of biodiesel due to fuel-driven internal cavitation in the rubber, and the uptake increased with increasing oxygen partial pressure due to the increase in concentration of oxidation products of the biodiesel. The absence of a tan δ peak (dynamical mechanical measurements) of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was caused by the detachment of bound rubber from particle surfaces. A significant decrease in the strain-at-break and in the Payne-effect amplitude of NBR exposed to biodiesel was explained as being due to the damage caused by biodiesel to the rubber-carbon-black network. During the high-temperature autoclave ageing, the NBR swelled less in biodiesel, and showed a small decrease in the strain-at-break due to the cleavage of rubber chains. The degradation of NBR in the absence of carbon black was due only to biodiesel-promoted oxidative crosslinking. The zinc cations released by the dissolution of zinc oxide particles in biodiesel promoted reduction reactions in the acrylonitrile part of the NBR. Heat-treated star-shaped ZnO particles dissolved more slowly in biodiesel than the commercial ZnO nanoparticles due to the elimination of inter-particle porosity by heat treatment. The fuel sorption was hindered in HVO-exposed NBR by the steric constraints of the bulky HVO molecules. The extensibility of NBR decreased only slightly after exposure to HVO, due to the migration of plasticizer from the rubber. The bisphenol-cured FKM co- and terpolymer swelled more than the peroxide-cured GFLT-type FKM in biodiesel due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. The FKM rubbers absorbed biodiesel faster, and to a greater extent, with increasing oxygen concentration. It is suggested that the extensive biodiesel uptake and the decrease in the strain-at-break and Young’s modulus of the FKM terpolymer was due to dehydrofluorination of the rubber by the coordination complexes of biodiesel and magnesium oxide and calcium hydroxide particles. An increase in the CH2-concentration of the extracted FKM rubbers suggested that biodiesel was grafted onto the FKM at the unsaturated sites resulting from dehydrofluorination.

  • 3054.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Amir Masoud, Pourrahimi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ulf W., Gedde
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Degradation of fluoroelastomers in rapeseed biodiesel at different oxygen concentrations2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 136, p. 10-19Article in journal (Refereed)
    Abstract [en]

    The degradation of fluoroelastomers (FKM) based on different monomers, additives and curing systems was studied after exposure to rapeseed biodiesel at 100 °C and different oxygen partial pressures. The sorption of fuel in the carbon black-filled FKM terpolymer was promoted by the fuel-driven cavitation in the rubber. The bisphenol-cured rubbers swelled more in biodiesel than the peroxide-cured FKM, presumably due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. With any of the selected types of monomer, the FKM rubbers absorbed biodiesel faster and to a greater extent with increasing oxygen partial pressure due to the increase in concentration of the oxidation products of biodiesel. Water-assisted complexation of biodiesel on magnesium oxide and calcium hydroxide particles led to dehydrofluorination of FKM, resulting in an extensive fuel uptake and a decrease in the strain-at-break and the Young's modulus of the rubbers. An increase in the CH2-concentration determined by infrared spectroscopy, and the appearance of biodiesel flakes in scanning electron micrographs of the extracted rubbers, were explained as being due to the presence of insoluble biodiesel grafted onto FKM on the unsaturated sites resulting from dehydrofluorination. The extensibility of the GFLT-type FKM was the least affected on exposure to biodiesel because this rubber contained less unsaturation and metal oxide/hydroxide particles.

  • 3055.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. Scania CV AB, Sweden.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Brana, Maria T. Conde
    Bellander, Martin
    Deterioration of automotive rubbers in liquid biofuels: A review2015In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 43, p. 1238-1248Article, review/survey (Refereed)
    Abstract [en]

    Concerns over the fast depletion of fossil fuels, environmental issues and stringent legislation associated with petroleum-based fuels have triggered a shift to bio-based fuels, as an alternative to meet the growing energy demand in the transportation sector. However, since conventional automobile fuel systems are adapted to petroleum-based fuels, switching to biofuels causes a severe deterioration in the performance of currently used rubber components. The degradation of the rubber materials in biofuels is complicated by the presence of different additives in biofuels and rubber compounds, by oxidation of biofuels and by the effects of thermomechanical loadings in the engine. This paper presents a comprehensive review of the effects of different types of biofuels, particularly biodiesel and bioethanol, on the physical, mechanical, morphological and thermal properties of elastomers under different exposure conditions. In addition, the literature data available on the variation of rubbers' resistance to biofuels with the changes in their monomer type and composition, cure system and additives content was also studied. The review essentially focuses on the compatibility of biofuels with acrylonitrile butadiene rubber, fluoroelastomers, polychloroprene rubber and silicon rubber, as the most commonly used automotive rubbers coming into contact with fuels during their service. The knowledge summarized in this study can help to develop a guideline on the selection of rubber for automotive parts designed to withstand biofuels.

  • 3056.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Brana, M. T. Conde
    Bellander, M.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Deterioration of acrylonitrile butadiene rubber in rapeseed biodiesel2015In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 111, p. 211-222Article in journal (Refereed)
    Abstract [en]

    The deterioration of acrylonitrile butadiene rubber (NBR) exposed to rapeseed biodiesel at 90 degrees C was studied. The oxidation of biodiesel and NBR during ageing was monitored by H-1 NMR and infrared spectroscopy, HPLC and titration methods. The oxidation of biodiesel was impeded in the presence of NBR, but promoted in biodiesel-exposed rubber. This was explained as being due to the migration of stabilizer from the rubber to biodiesel, the diffusion of dissolved oxygen from biodiesel into NBR and the absorption of oxidation precursors of biodiesel by the rubber. The resemblance between the anomalous sorption kinetics of biodiesel in NBR and the equilibrium benzene uptake by the aged rubbers revealed that biodiesel caused a network defect in NBR, resulting in a gradual increase in the equilibrium swelling. The cleavage of crosslinks was implausible since the Young's modulus of the rubber at low strains, disregarding an initial decrease, increased with increasing exposure time. The appearance of 'naked' carbon black particles in the scanning electron micrographs of the aged rubbers and a drastic decrease in the strain-at-break of NBR after exposure to biodiesel suggests that internal cavitation was caused by the attack of biodiesel on the acrylonitrile units of NBR.

  • 3057.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pourrahimi, A. M.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ulf W., Gedde
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Effects of ageing conditions on degradation of acrylonitrile butadiene rubber filled with heat-treated ZnO star-shaped particles in rapeseed biodiesel2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Article in journal (Refereed)
    Abstract [en]

    The degradation of acrylonitrile butadiene rubber (NBR) after exposure to biodiesel at different oxygen partial pressures in an automated ageing equipment at 80 °C, and in a high-pressure autoclave at 150 °C was studied. The oxidation of biodiesel was promoted by an increase in oxygen concentration, resulting in a larger uptake of fuel in the rubber due to internal cavitation, a greater decrease in the strain-at-break of NBR due to the coalescence of cavity, and a faster increase in the crosslinking density and carbonyl index due to the promotion of the oxidation of NBR. During the high-temperature autoclave ageing, less fuel was absorbed in the rubber, because the formation of hydroperoxides and acids was impeded. The extensibility of NBR aged in the autoclave decreased only slightly due to the cleavage of rubber chains by the biodiesel attack. The degradation of NBR in the absence of carbon black was explained as being due to oxidative crosslinking. The dissolution of ZnO crystals in the acidic components of biodiesel was retarded by removing the inter-particle porosity and surface defects through heat treating star-shaped ZnO particles. The rubber containing heat-treated ZnO particles swelled less in biodiesel than a NBR filled with commercial ZnO nanoparticles, and showed a smaller decrease in the strain-at-break and less oxidative crosslinking.

  • 3058.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Pourrahimi, Amir Masoud
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Sjöstedt, C.
    Bellander, M.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Degradation of carbon-black-filled acrylonitrile butadiene rubber in alternative fuels: Transesterified and hydrotreated vegetable oils2016In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 123, p. 69-79Article in journal (Refereed)
    Abstract [en]

    The deterioration of acrylonitrile butadiene rubber (NBR), a common sealing material in automobile fuel systems, when exposed to rapeseed biodiesel and hydrotreated vegetable oil (HVO) was studied. The fuel sorption was hindered in HVO-exposed rubber by the steric constraints of bulky HVO molecules, but it was promoted in biodiesel-exposed rubber by fuel-driven cavitation in the NBR and by the increase in diffusivity of biodiesel after oxidation. The absence of a tan δ peak of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was made possible in biodiesel-aged rubber by the detachment of bound rubber from particle surfaces. The HVO-exposed NBR showed a small decrease in strain-at-break due to the migration of plasticizer from the rubber, and a small increase in the Young’s modulus due to oxidative crosslinking. A drastic decrease in extensibility and Payne-effect amplitude of NBR on exposure to biodiesel was explained as being due to the damage caused by biodiesel to the continuous network of bound rubber-carbon black. A decrease in the ZnO crystal size with increasing exposure time suggested that the particles are gradually dissolved in the acidic components of oxidized biodiesel. The Zn2+ cations released from the dissolution of ZnO particles in biodiesel promoted the hydrolysis of the nitrile groups of NBR.

  • 3059. Akhmadaliev, S.
    et al.
    Albiol, F.
    Amaral, P.
    Berglund, S.
    Lund-Jensen, Bengt
    KTH, Superseded Departments, Physics.
    Lundquist, J.
    Sellden, B.
    Soderqvist, J.
    Zolnierowski, Y. P.
    et al,
    Results from a new combined test of an electromagnetic liquid argon calorimeter with a hadronic scintillating-tile calorimeter2000In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 449, no 3, p. 461-477Article in journal (Refereed)
    Abstract [en]

    A new combined test of an electromagnetic liquid argon accordion calorimeter and a hadronic scintillating-tile calorimeter was carried out at the CERN SPS. These devices are prototypes of the barrel calorimeter of the future ATLAS experiment at the LHC. The energy resolution of pions in the energy range from 10 to 300 GeV at an incident angle a of about 12 degrees is well described by the expression sigma/E = ((41.9 +/- 1.6)%/root E + (1.8 +/- 0.1)%)circle plus(1.8 +/- 0.1)/E, where E is in GeV. The response to electrons and muons was evaluated. Shower profiles, shower leakage and the angular resolution of hadronic showers were also studied. Results are compared with those from the previous beam test.

  • 3060. Akhmadaliev, S.
    et al.
    Amaral, P.
    Ambrosini, G.
    Amorim, A.
    Anderson, K.
    Johansson, E.
    Lund-Jensen, Bengt
    KTH, Superseded Departments, Physics.
    Soderqvist, J.
    Zolnierowski, Y. P.
    et al,
    Hadron energy reconstruction for the ATLAS calorimetry in the framework of the non-parametrical method2002In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 480, no 03-feb, p. 508-523Article in journal (Refereed)
    Abstract [en]

    This paper discusses hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter (consisting of a lead-liquid argon electromagnetic part and an iron-scintillator hadronic part) in the framework of the non-parametrical method. The non-parametrical method utilizes only the known e/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to an easy use in a first level trigger. The reconstructed mean values of the hadron energies are within +/-1% of the true values and the fractional energy resolution is [(58+/-3)%/rootE+(2.5+/-0.3)%]circle plus(1.7+/-0.2)/E. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74+/-0.04 and agrees with the prediction that e/h > 1.66 for this electromagnetic calorimeter. Results of a study of the longitudinal hadronic shower development are also presented. The data have been taken in the H8 beam line of the CERN SPS using pions of energies from 10 to 300 GeV.

  • 3061.
    Akhmedov, Evgeny
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Duality in left-right symmetric seesaw2007In: Nuclear physics B, Proceedings supplements, ISSN 0920-5632, E-ISSN 1873-3832, Vol. 168, p. 369-371Article in journal (Refereed)
    Abstract [en]

    A reconstruction of the mass matrix of heavy right-handed Majorana neutrinos is performed in the framework of the left-right symmetric type I+II seesaw mechanism. An intriguing pairwise duality relation between different solutions is shown to exist.

  • 3062.
    Akhmedov, Evgeny
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Neutrino oscillations: Theory and phenomenology2011In: Nuclear Physics B - Proceedings Supplements, ISSN 0920-5632, Vol. 221, p. 19-25Article in journal (Refereed)
    Abstract [en]

    A brief overview of selected topics in the theory and phenomenology of neutrino oscillations is given. These include: oscillations in vacuum and in matter; phenomenology of 3-flavour neutrino oscillations; CP and T violation in neutrino oscillations in vacuum and in matter; matter effects on ν μ↔ν τ oscillations; parametric resonance in neutrino oscillations inside the earth; oscillations below and above the MSW resonance; unsettled issues in the theory of neutrino oscillations.

  • 3063.
    Akhmedov, Evgeny
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Blennow, Mattias
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Hällgren, Tomas
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Konstandin, Thomas
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Stability and leptogenesis in the left-right symmetric seesaw mechanism2007In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 4, p. 022-1-022-25Article in journal (Refereed)
    Abstract [en]

    We analyze the left-right symmetric type I+II seesaw mechanism, where an eight-fold degeneracy among the mass matrices of heavy right-handed neutrinos M-R is known to exist. Using the stability property of the solutions and their ability to lead to successful baryogenesis via leptogenesis as additional criteria, we discriminate among these eight solutions and partially lift their eight-fold degeneracy. In particular, we find that viable leptogenesis is generically possible for four out of the eight solutions.

  • 3064.
    Akhmedov, Evgeny
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Frigerio, M.
    Duality in left-right symmetric seesaw2006In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T127, p. 59-61Article in journal (Refereed)
    Abstract [en]

    We perform a reconstruction of the mass matrix of heavy right-handed Majorana neutrinos in the framework of the left - right symmetric type I + II seesaw mechanism. An intriguing pairwise duality relation between different solutions is shown to exist.

  • 3065.
    Akhmedov, Evgeny
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Frigerio, Michele
    Interplay of type I and type II seesaw contributions to neutrino mass2007In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 1, p. 043-Article in journal (Refereed)
    Abstract [en]

    Type I and type II seesaw contributions to the mass matrix of light neutrinos are inherently related if left-right symmetry is realized at high energy scales. We investigate implications of such a relation for the interpretation of neutrino data. We proved recently that the left-right symmetric seesaw equation has eight solutions, related by a duality property, for the mass matrix of right-handed neutrinos M-R. In this paper the eight allowed structures of M-R are reconstructed analytically and analyzed numerically in a bottom-up approach. We study the dependence of right-handed neutrino masses on the mass spectrum of light neutrinos, mixing angle theta(13), leptonic CP violation, scale of left-right symmetry breaking and on the hierarchy in neutrino Yukawa couplings. The structure of the seesaw formula in several specific SO(10) models is explored in the light of the duality. The outcome of leptogenesis may depend crucially on the choice among the allowed structures of M-R and on the level crossing between right-handed neutrino masses.

  • 3066. Akhmedov, Evgeny
    et al.
    Huber, Patrick
    Lindner, Manfred
    Ohlsson, Tommy
    KTH, Superseded Departments, Physics.
    T violation in neutrino oscillations in matter2001In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 608, no 02-jan, p. 394-422Article in journal (Refereed)
    Abstract [en]

    We consider the interplay of fundamental and matter-induced T violation effects in neutrino oscillations in matter. After discussing the general features of these effects we derive a simple approximate analytic expression for the T-violating probability asymmetry DeltaP(ab)(T) for three-flavour neutrino oscillations in a matter with an arbitrary density profile in terms of the two-flavour neutrino amplitudes. Explicit examples are given for the cases of a two-layer medium and for the adiabatic Emit in the general case. We then discuss implications of the obtained results for long baseline experiments. We show, in particular, that asymmetric matter effects cannot hinder the determination of the fundamental CP- and T-violating phase delta (CP) in the long baseline experiments as far as the error in this determination is larger than 1% at 99% CL. Since there are no T-violating effects in the two-flavour case, and in the limits of vanishing theta (13) or Deltam(21)(2) the three-flavour neutrino oscillations effectively reduce to the two-flavour ones, studying the T-violating asymmetries ApT ab can in principle provide us with a complementary means of measuring theta (13) and Deltam(21)(2).

  • 3067. Akhmedov, Evgeny K.
    et al.
    Johansson, Robert
    KTH, Superseded Departments, Physics.
    Lindner, Manfred
    Ohlsson, Tommy
    KTH, Superseded Departments, Physics.
    Schwetz, Thomas
    Series expansions for three-flavor neutrino oscillation probabilities in matter2004In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2004, no 04, p. 078-Article in journal (Refereed)
    Abstract [en]

    We present a number of complete sets of series expansion formulas for neutrino oscillation probabilities in matter of constant density for three flavors. In particular, we study expansions in the mass hierarchy parameter alpha = Deltam(21)(2)/Deltam(31)(2) and mixing parameter s(13) = sin theta(13) up to second order and expansions only in alpha and only in s(13) up to first order. For each type of expansion we also present the corresponding formulas for neutrino oscillations in vacuum. We perform a detailed analysis of the accuracy of the different sets of series expansion formulas and investigate which type of expansion is most accurate in different regions of the parameter space spanned by the neutrino energy E, the baseline length L, and the expansion parameters alpha and s(13). We also present the formulas for series expansions in alpha and in s(13) up to first order for the case of arbitrary matter density profiles. Furthermore, it is shown that in general all the 18 neutrino and antineutrino oscillation probabilities can be expressed through just two independent probabilities.

  • 3068.
    Akhmedov, Evgeny Kh
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Neutrino oscillations: Theory and phenomenology2006In: NEUTRINO - Proc. Int. Conf. Neutrino Phys. Astrophys., 2006, p. 16-22Conference paper (Refereed)
    Abstract [en]

    A brief overview of selected topics in the theory and phenomenology of neutrino oscillations is given. These include: oscillations in vacuum and in matter; phenomenology of 3-flavour neutrino oscillations; CP and T violation in neutrino oscillations in vacuum and in matter; matter effects on νμ ↔ ντ oscillations; parametric resonance in neutrino oscillations inside the earth; oscillations below and above the MSW resonance; unsettled issues in the theory of neutrino oscillations.

  • 3069.
    Akhmedov, Evgeny
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Maltoni, Michele
    Smirnov, Alexei Yu.
    1-3 leptonic mixing and the neutrino oscillograms of the Earth2007In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, p. 077-Article in journal (Refereed)
    Abstract [en]

    We develop a detailed and comprehensive description of neutrino oscillations driven by the 1-3 mixing in the matter of the Earth. The description is valid for the realistic (PREM) Earth density profile in the whole range of nadir angles and for neutrino energies above 1 GeV. It can be applied to oscillations of atmospheric and accelerator neutrinos. The results are presented in the form of neutrino oscillograms of the Earth, i.e. the contours of equal oscillation probabilities in the neutrino energy-nadir angle plane. A detailed physics interpretation of the oscilligrams, which includes the MSW peaks, parametric ridges, local maxima, zeros and saddle points, is given in terms of the amplitude and phase conditions. Precise analytic formulas for the probabilities are obtained. We study the dependence of the oscillation pattern on theta(13) and find, in particular, that the survival probability P-ee < 1/2 appears for sin(2) 2 theta(13) as small as similar to 0.009. We consider the dependence of the oscillation pattern on the matter density profile and comment on the possibility of the oscillation tomography of the Earth.

  • 3070. Akhmetova, D.
    et al.
    Kestor, G.
    Gioiosa, R.
    Markidis, Stefano
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Laure, Erwin
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    On the application task granularity and the interplay with the scheduling overhead in many-core shared memory systems2015In: Proceedings - IEEE International Conference on Cluster Computing, ICCC, IEEE , 2015, p. 428-437Conference paper (Refereed)
    Abstract [en]

    Task-based programming models are considered one of the most promising programming model approaches for exascale supercomputers because of their ability to dynamically react to changing conditions and reassign work to processing elements. One question, however, remains unsolved: what should the task granularity of task-based applications be? Fine-grained tasks offer more opportunities to balance the system and generally result in higher system utilization. However, they also induce in large scheduling overhead. The impact of scheduling overhead on coarse-grained tasks is lower, but large systems may result imbalanced and underutilized. In this work we propose a methodology to analyze the interplay between application task granularity and scheduling overhead. Our methodology is based on three main points: 1) a novel task algorithm that analyzes an application directed acyclic graph (DAG) and aggregates tasks, 2) a fast and precise emulator to analyze the application behavior on systems with up to 1,024 cores, 3) a comprehensive sensitivity analysis of application performance and scheduling overhead breakdown. Our results show that there is an optimal task granularity between 1.2x10^4 and 10x10^4 cycles for the representative schedulers. Moreover, our analysis indicates that a suitable scheduler for exascale task-based applications should employ a best-effort local scheduler and a sophisticated remote scheduler to move tasks across worker threads.

  • 3071.
    Akhmetova, Dana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Cebamanos, L.
    Iakymchuk, Roman
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Rotaru, T.
    Rahn, M.
    Markidis, Stefano
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Laure, Erwin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Bartsch, V.
    Simmendinger, C.
    Interoperability of GASPI and MPI in large scale scientific applications2018In: 12th International Conference on Parallel Processing and Applied Mathematics, PPAM 2017, Springer Verlag , 2018, p. 277-287Conference paper (Refereed)
    Abstract [en]

    One of the main hurdles of a broad distribution of PGAS approaches is the prevalence of MPI, which as a de-facto standard appears in the code basis of many applications. To take advantage of the PGAS APIs like GASPI without a major change in the code basis, interoperability between MPI and PGAS approaches needs to be ensured. In this article, we address this challenge by providing our study and preliminary performance results regarding interoperating GASPI and MPI on the performance crucial parts of the Ludwig and iPIC3D applications. In addition, we draw a strategy for better coupling of both APIs. 

  • 3072.
    Akhmetova, Dana
    et al.
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Iakymchuk, Roman
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Ekeberg, Örjan
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Laure, Erwin
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Performance study of multithreaded MPI and Openmp tasking in a large scientific code2017In: Proceedings - 2017 IEEE 31st International Parallel and Distributed Processing Symposium Workshops, IPDPSW 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 756-765, article id 7965119Conference paper (Refereed)
    Abstract [en]

    With a large variety and complexity of existing HPC machines and uncertainty regarding exact future Exascale hardware, it is not clear whether existing parallel scientific codes will perform well on future Exascale systems: they can be largely modified or even completely rewritten from scratch. Therefore, now it is important to ensure that software is ready for Exascale computing and will utilize all Exascale resources well. Many parallel programming models try to take into account all possible hardware features and nuances. However, the HPC community does not yet have a precise answer whether, for Exascale computing, there should be a natural evolution of existing models interoperable with each other or it should be a disruptive approach. Here, we focus on the first option, particularly on a practical assessment of how some parallel programming models can coexist with each other. This work describes two API combination scenarios on the example of iPIC3D [26], an implicit Particle-in-Cell code for space weather applications written in C++ and MPI plus OpenMP. The first scenario is to enable multiple OpenMP threads call MPI functions simultaneously, with no restrictions, using an MPI THREAD MULTIPLE thread safety level. The second scenario is to utilize the OpenMP tasking model on top of the first scenario. The paper reports a step-by-step methodology and experience with these API combinations in iPIC3D; provides the scaling tests for these implementations with up to 2048 physical cores; discusses occurred interoperability issues; and provides suggestions to programmers and scientists who may adopt these API combinations in their own codes.

  • 3073.
    Akhondi, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Pelletäppan, tennishall med bristfällig konstruktion: En fallstudie av massiv limträkonstruktion2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Detta arbete bygger på en jämförelse mellan Boverkets Byggregler och Eurokoder för en befintlig limträkonstruktion. Referensobjektet är en tennishall belägen i Botkyrka kommun. Objektet byggdes under början på 90-talet i form av en treledsram med taktäckning av PVC duk som vilar direkt på limträbalkarna, inklusive en inre duk med mellanliggande isolering och luftspalt. Under de senaste åren har konstruktionen uppvisat tecken på svagheter med bl.a. stora sprickor i limträbalkarna, dessa skador kulminerade i att på begäran av kommunen stänga av anläggningen för fortsatta spel.

    Oavsett om beräkningarna utförs med BKR eller Eurokoder som är norm idag så har stommen inte tillräckligt bärighet för sin egentyngd och dagens snölast. Detta kan tyckas vara märkligt men förklaringen kan vara att man utförde byggnaden med tanke på att snön glider av hallen och inte ackumuleras. Med detta i åtanke skulle snön glida av om yttertaken hade hållits varm, mycket tyder på att så skulle ha varit fallet om fläktarna som luftar spalten i takkonstruktionen hade varit igång. Enligt Roger Vintemar, verksamhetschef för Idrott och Anläggning på Botkyrka kommun, har fläktaggregatets på/av knapp placerats lättillgängligt i spelargången och det finns anledning att misstänka att fläktaggregatet har varit avstängd vid långa perioder. Sprickorna i bågarna kan bero på överlast eftersom snön har ackumulerats och inte glidit av. Med avseende på hur konstruktionen är utformad och att det har blivit vattenansamlingar på spelbanan är det inte orimligt att ifrågasätta dragstagets rostskydd. Skulle dragstaget som håller ihop de två bågarna brista finns det en överhängande risk för s.k. sprött brott med ett snabbt ras till följd.

  • 3074.
    Akhras, Michael S.
    KTH, School of Biotechnology (BIO).
    Nucleic Acid Based Pathogen Diagnostics2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Pathogenic organisms are transmitted to the host organism through all possible connected pathways, and cause a myriad of diseases states. Commonly occurring curable infectious diseases still impose the greatest health impacts on a worldwide perspective. The Bill & Melinda Gates Foundation partnered with RAND Corporation to form the Global Health Diagnostics Forum, with the goal of establishing and interpreting mathematical models for what effects a newly introduced point-of-care pathogen diagnostic would have in developing countries. The results were astonishing, with potentially millions of lives to be saved on an annual basis.

    Golden standard for diagnostics of pathogenic bacteria has long been cultureable medias. Environmental biologists have estimated that less than 1% of all bacteria are cultureable. Genomic-based approaches offer the potential to identify all microbes from all the biological kingdoms. Nucleic acid based pathogen diagnostics has evolved significantly over the past decades. Novel technologies offer increased potential in sensitivity, specificity, decreased costs and parallel sample management. However, most methods are confined to core laboratory facilities. To construct an ultimate nucleic acid based diagnostic for use in areas of need, potential frontline techniques need to be identified and combined.

    The research focus of this doctoral thesis work has been to develop and apply nucleic acid based methods for pathogen diagnostics. Methods and assays were applied to the two distinct systems i) screening for antibiotic resistance mutations in the bacterial pathogen Neisseria gonorrhoeae, and ii) genotype determination of the cancer causative Human Papillomavirus (HPV). The first part of the study included development of rapid, direct and multiplex Pyrosequencing nucleic acid screenings. With improved methodology in the sample preparation process, we could detect an existence of multiple co-infecting HPV genotypes at greater sensitivities than previously described, when using the same type of methodology. The second part of the study focused on multiplex nucleic acid amplification strategies using Molecular Inversion Probes with end-step Pyrosequencing screening. The PathogenMip assay presents a complete detection schematic for virtually any known pathogenic organism. We also introduce the novel Connector Inversion Probe, a padlock probe capable of complete gap-fill reactions for multiplex nucleic acid amplifications.

  • 3075.
    Akhras, Michael
    et al.
    KTH, School of Biotechnology (BIO).
    Thiyagarajan, Sreedevi
    Stanford Univ, Stanford Genome Technol Ctr.
    Villablanca, Andrea C.
    Stanford Univ, Stanford Genome Technol Ctr.
    Davis, Ronald W.
    Stanford Univ, Stanford Genome Technol Ctr.
    Nyrén, Pål
    KTH, School of Biotechnology (BIO).
    Pourmand, Nader
    Stanford Univ, Stanford Genome Technol Ctr.
    PathogenMip Assay: A Multiplex Pathogen Detection Assay2007In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 2, no 2, p. e223-Article in journal (Refereed)
    Abstract [en]

    The Molecular Inversion Probe (MIP) assay has been previously applied to a large-scale human SNP detection. Here we describe the PathogenMip Assay, a complete protocol for probe production and applied approaches to pathogen detection. We have demonstrated the utility of this assay with an initial set of 24 probes targeting the most clinically relevant HPV genotypes associated with cervical cancer progression. Probe construction was based on a novel, cost-effective, ligase-based protocol. The assay was validated by performing pyrosequencing and Microarray chip detection in parallel experiments. HPV plasmids were used to validate sensitivity and selectivity of the assay. In addition, 20 genomic DNA extracts from primary tumors were genotyped with the PathogenMip Assay results and were in 100% agreement with conventional sequencing using an L1-based HPV genotyping protocol. The PathogenMip Assay is a widely accessible protocol for producing and using highly discriminating probes, with experimentally validated results in pathogen genotyping, which could potentially be applied to the detection and characterization of any microbe.

  • 3076.
    Akhras, Michael
    et al.
    KTH, School of Biotechnology (BIO).
    Unemo, Magnus
    Örebro Univ Hosp, Dept Clin Microbiol.
    Thiyagarajan, Sreedevi
    Stanford Univ, Stanford Genome Technol Ctr.
    Nyrén, Pål
    KTH, School of Biotechnology (BIO).
    Davis, Ronald W.
    Stanford Univ, Stanford Genome Technol Ctr.
    Fire, Andrew Z.
    Stanford Univ.
    Pourmand, Nader
    Univ Calif Santa Cruz.
    Connector Inversion Probe Technology: A Powerful One- Primer Multiplex DNA Amplification System for Numerous Scientific Applications2007In: PLoS ONE, ISSN 1932-6203, Vol. 2, no 9, p. e915-Article in journal (Refereed)
    Abstract [en]

    We combined components of a previous assay referred to as Molecular Inversion Probe (MIP) with a complete gap filling strategy, creating a versatile powerful one-primer multiplex amplification system. As a proof-of-concept, this novel method, which employs a Connector Inversion Probe (CIPer), was tested as a genetic tool for pathogen diagnosis, typing, and antibiotic resistance screening with two distinct systems: i) a conserved sequence primer system for genotyping Human Papillomavirus (HPV), a cancer-associated viral agent and ii) screening for antibiotic resistance mutations in the bacterial pathogen Neisseria gonorrhoeae. We also discuss future applications and advances of the CIPer technology such as integration with digital amplification and next-generation sequencing methods. Furthermore, we introduce the concept of two-dimension informational barcodes, i. e. "multiplex multiplexing padlocks'' (MMPs). For the readers' convenience, we also provide an on-line tutorial with user-interface software application CIP creator 1.0.1, for custom probe generation from virtually any new or established primer-pairs.

  • 3077.
    Akhtar, Faiza
    et al.
    UET, ACTSENA Res Grp, Taxila 47050, Pakistan..
    Naqvi, Syeda Iffat
    UET, ACTSENA Res Grp, Taxila 47050, Pakistan..
    Arshad, Farzana
    UET, ACTSENA Res Grp, Taxila 47050, Pakistan..
    Amin, Yasar
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. UET, ACTSENA Res Grp, Taxila 47050, Pakistan.
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. Univ Turku, TUCS, FIN-20520 Turku, Finland..
    A Flexible and Compact Semicircular Antenna for Multiple Wireless Communication Applications2018In: Radioengineering, ISSN 1210-2512, E-ISSN 1805-9600, Vol. 27, no 3, p. 671-678Article in journal (Refereed)
    Abstract [en]

    This work presents a compact, quad-band planar antenna intended for assimilation into flexible and conformal devices. The CPW-fed semicircular shaped prototype with rake-shaped slots is designed, realized and characterized experimentally. The frequency bands covered by the proposed radiator are centered at 2.5, 3.7, 5.5 and 8 GHz with measured impedance bandwidths of 16%, 13.5%, 11.8% and 14.63%, respectively. The proposed antenna is thus enabled to support WLAN, ISM, Bluetooth, WiMAX LTE and X-band applications. The antenna exhibits a significant gain. The radiation characteristics of the proposed radiator are measured in concave and convex bent shapes at various radii to analyze its flexibility. Performance of the antenna remains almost unaffected in the bent situation. Measurements demonstrate good coherence with simulations. The compactness and good performance of the design both in bent and unbent conditions proves it to be the better contender for future multiband conformal wireless applications.

  • 3078.
    Akhtar, Malik Usman
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Variable speed drive as an alternative solution for a micro-hydro power plant2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This diploma work is mainly focused on developing the control strategy for avariable speed drive as an alternative solution to a micro-hydro power plant. The detailed mathematical model for a micro-hydro system including a Kaplan turbine, mechanical shaft and electrical machines is presented and validated through simulations. A control strategy for an autonomous operation of a doubly-fed induction machine-based drive is developed for a wide range of speed. The drive can operate at a unity power factor.The possible applications of the analyzed system are also presented. As a positive side of the system, it is found that the direct interaction between the power electronic converters and the utility grid can be avoided by exploiting the proposed topology, which might lead to a better quality of the produced power in terms of harmonics. This could also lead to removal or reduction of the size of the harmonic filters that are being used in conventional doubly-fed induction generator installations. As regards to the drawbacks of the system, a comparison of converter and generator ratings between the analyzed solution and the conventional solution was performed. While the converters rating remain the same, there is one more electrical machine and the doubly-fed generator rating is slightly increased. Losses are also slightly larger due to the presence of the second machine.

  • 3079. Akhtar, Nadeem
    et al.
    Markendahl, Jan
    Univ Surrey.
    Moessner, Klaus
    Analysis of Complexity and Transaction Costs For Cooperating Networks2007In: 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9, 2007, p. 4270-4274Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate the impact that introduction of new Ambient Networks (AN) functionality will have on usage of system resources and on connection delay. The signalling load for multiple attachment and negotiation procedures is assessed by modelling signalling sequences for a WLAN system enabled with AN technology. The load is computed for varying numbers of users and for users with different levels of “willingness to evaluate and negotiate offers”. The results show that the most important parameter is the number of attachment attempts per time unit, which is an indicator of user activity level. In the investigated scenarios, the relative load of signalling is 0.1 – 1.0 % of the transferred user data. The delay depends on the current load situation of the network.

  • 3080.
    Akhtar, Nadeem
    et al.
    University of Surrey, UK.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Queseth, Olav
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Analysis of Signaling Load and Negotiation Complexity using Network Composition2007Conference paper (Refereed)
    Abstract [en]

    In future mobile communications networks using Ambient Networks (AN) technology, users will be able to connect to a multitude of networks operated by different business entities. The technology enablers are advertising of access and service offers, multi-radio access, network selection and roaming support, negotiation of terms and conditions for attachment to networks. In this paper, we investigate the additional load on users and network resources for establishment and management of multiple network connections and business relations. The administrative load is analyzed using commercial uses cases and scenarios with a number of available networks, service providers and payment and ID providers. The signaling load for multiple attachment and negotiation procedures is estimated by modeling signaling sequences for a WLAN system enabled with AN technology. The signaling load is computed for varying numbers of users and for users with varying "willingness to evaluate and negotiate offers". The results show that the most important parameters are the number of attachment attempts per time unit. In the investigated scenarios, the relative load of business related signaling is 0.1 -1.0 % of the transferred user data. Although a large of number of different networks may be used, the number of business agreements and network connections that need to be handled simultaneously will be quite low.

  • 3081.
    Akhtar, Shahid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Shaikh, Md. Robiul Haque
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Micro Porosity Development in Directionally Solidified A356 Castings Doped with Anodized Plates and Sintered Aluminium2011In: European Congress and Exhibition on Advanced Materials and Processes (EUROMAT) 2011, Symposium C52: Processing and characterizing techniques, 2011Conference paper (Refereed)
  • 3082.
    Akhtar, Suleman
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Material Factors Influencing Crack Initiation and Propagation During Seamless Tube Rolling of Low Carbon Steel Grades2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Lower hot ductility can lead to cracks in steels. Hot ductility is affected by grain boundary sliding at temperatures higher than A3 and by the presence of thin films of ferrite at grain boundaries at temperatures lower than A3. Grain boundary sliding might occur because of the segregation of harmful elements like sulphur, etc. While thin films of ferrite at grain boundaries lead to easy interlinking of MnS precipitates at grain boundaries and ultimately may cause cracks in the material. Also, stress concentration is higher at thin ferrite films at grain boundaries which for being softer as compared to austenite matrix lead to cracks in the material. Elongated  (Fe, Mn)S sulphides are more detrimental for the hot ductility as compared to round ones. Higher aspect ratio of the precipitates is also dependent on sulphur content. The higher the sulphur content, the higher would be the hot ductility. Silicon, being a ferrite stabilizer, causes the volume fraction of ferrite to increase which improves the hot ductility of the steels. Hot ductility can be improved by adding Boron that segregates to grain boundaries instead of sulphur improving the strength of grain boundaries. Increasing silicon content can lead to higher volume fraction of ferrite thus improving ductility because stress would uniformly be distributed across the grain and not merely on the grain boundaries. Apart from that, decreasing the solution treatment temperature and increasing holding time on solution treatment temperature can lead to lower dissolved content of sulphur and coarser MnS precipitates hence improving hot ductility. 

  • 3083.
    Akhter, Shirin
    et al.
    Swedish Univ Agr Sci, Linnean Ctr Plant Biol, Uppsala Bioctr, Dept Plant Biol, Uppsala, Sweden..
    Kretzschmar, Warren W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Nordal, Veronika
    Swedish Univ Agr Sci, Linnean Ctr Plant Biol, Uppsala Bioctr, Dept Plant Biol, Uppsala, Sweden..
    Delhomme, Nicolas
    Swedish Univ Agr Sci, Dept Forest Genet & Plant Physiol, Umea Plant Sci Ctr, Umea, Sweden..
    Street, Nathaniel R.
    Umea Sweden, Dept Plant Physiol, Umea Plant Sci Ctr, Umea, Sweden..
    Nilsson, Ove
    Swedish Univ Agr Sci, Dept Forest Genet & Plant Physiol, Umea Plant Sci Ctr, Umea, Sweden..
    Emanuelsson, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Sundström, Jens F.
    Swedish Univ Agr Sci, Linnean Ctr Plant Biol, Uppsala Bioctr, Dept Plant Biol, Uppsala, Sweden..
    Integrative Analysis of Three RNA Sequencing Methods Identifies Mutually Exclusive Exons of MADS-Box Isoforms During Early Bud Development in Picea abies2018In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 9, article id 1625Article in journal (Refereed)
    Abstract [en]

    Recent efforts to sequence the genomes and transcriptomes of several gymnosperm species have revealed an increased complexity in certain gene families in gymnosperms as compared to angiosperms. One example of this is the gymnosperm sister Glade to angiosperm TM3-like MADS-box genes, which at least in the conifer lineage has expanded in number of genes. We have previously identified a member of this subclade, the conifer gene DEFICIENS AGAMOUS LIKE 19 (DAL19), as being specifically upregulated in cone-setting shoots. Here, we show through Sanger sequencing of mRNA-derived cDNA and mapping to assembled conifer genomic sequences that DAL19 produces six mature mRNA splice variants in Picea abies. These splice variants use alternate first and last exons, while their four central exons constitute a core region present in all six transcripts. Thus, they are likely to be transcript isoforms. Quantitative Real-Time PCR revealed that two mutually exclusive first DAL19 exons are differentially expressed across meristems that will form either male or female cones, or vegetative shoots. Furthermore, mRNA in situ hybridization revealed that two mutually exclusive last DAL19 exons were expressed in a cell-specific pattern within bud meristems. Based on these findings in DAL19, we developed a sensitive approach to transcript isoform assembly from short-read sequencing of mRNA. We applied this method to 42 putative MADS-box core regions in P abies, from which we assembled 1084 putative transcripts. We manually curated these transcripts to arrive at 933 assembled transcript isoforms of 38 putative MADS-box genes. 152 of these isoforms, which we assign to 28 putative MADS-box genes, were differentially expressed across eight female, male, and vegetative buds. We further provide evidence of the expression of 16 out of the 38 putative MADS-box genes by mapping PacBio Iso-Seq circular consensus reads derived from pooled sample sequencing to assembled transcripts. In summary, our analyses reveal the use of mutually exclusive exons of MADS-box gene isoforms during early bud development in P. abies, and we find that the large number of identified MADS-box transcripts in P. abies results not only from expansion of the gene family through gene duplication events but also from the generation of numerous splice variants.

  • 3084.
    Akhter, Tahmina
    KTH, School of Computer Science and Communication (CSC).
    Implementation of Conduction Delay and Collective Communication in a Parallel Spiking Neural Network Simulator.2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Tahmina Akther

    Implementation of conduction delay and collective communication in a parallel spiking neural network simulator

    As we know neural networks have a parallel structure and it is well suited for implementations in a parallel environment. The Bayesian Confidence Propagation Neural Network (BCPNN) which has been developed past thirty years is the main subject this thesis. An important issue is the implementation of communications between the processors. The aim of this thesis is to investigate point to point and collective communication methods and check how it works in real time. A second goal is to introduce time delay in point-to-point communication. These schemes have been implemented on Blue Gene Supercomputer using Message Passing Interface (MPI). At the end of thesis, the comparison between the two communication methods and the results of the two different models are shown.

  • 3085.
    Akhter, Tasmiah
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Mohsin, Mael
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Lean produktion i två olika branscher: - En jämförelse mellan sjukvård och industri2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Lean production is a well-known concept in the industry that aims to become resource efficient and improved with a customer focus. In lean production there are several methods and philosophies to consider and this report deals with 5S method, seven wastes and commitment in an organization. The success of lean production in manufacturing has led to implementation across several different industries, especially health care. This implementation has been met with varying opinions.

    The purpose of this report is to examine if the implementation of lean production in health care can be just as effective as in industry. The implementation of Lean in health care has partially been proved successful, but often the set goals are not achieved. With the aid of three sub-questions, the main question can be answered: Can the implementation of lean production be as effective in the health care as in the industry?

    Through field trips and interviews from both health care and industry, empirical data will be gathered to gain an understanding of how the implementation is today. Karolinska University Hospital in Huddinge represents the health care and Scania represents the industry. After these interviews a comparison was created between health care and industry implementations and a score-table is formed to see how well the organizations meets lean production according to the theory.

    The comparison between the health care and the industry resulted in the conclusion that health care can be just as effective as the industry with its implementation of lean production. The efficiency potential was seen in the majority of the steps of the methods concerned. In seven of the ten steps there are scope for rationalization, where the health care can apply lean as well as the industry.

  • 3086.
    AKHTER, TASMIAH
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    ÅKERLIND, TOBIAS
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Agile IT Infrastructure Transformation: A Case Study of a Nordic Incumbent Telco2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In a growing digital economy, where demands for network services and competition from various communication-over-the-network service providers intensify, telecommunication companies need to keep up in an ever-changing environment. As there is a need to reduce time-to-market for new network services, agility becomes restrained by having to operate within large legacy IT infrastructure environments. While agile methodologies in modern time have attained recognition in the field of software development for the way they help to manage changing customer demands and deliver early value incontinuous increments, it is yet uncertain how agile methodologies can best be adopted for IT infrastructure deliveries to achieve the same purpose. Hence, this study explores how legacy IT infrastructure can be transformed in an agile way into modernized infrastructure landscapes supporting the business with fast enough development, release and deployment of new network services in demand. More precisely, the study investigates how larger IT infrastructure transformation projects can be executed by the help of agile practices. In order to investigate this, the study carries out a case study at Telia Company, a large Nordic incumbent telecommunications company possessing a big legacy of IT infrastructure. The study conducts internal interviews with Telia employees as well as external interviews with agile experts. Also, benchmarking is conducted with a well-established Swedish bank to better understand the challenges and how agile practices can best be applied.The study concludes that agile practices influenced by agile frameworks Scrum and Kanban can advantageously be applied at team level for more agile execution. However, the surrounding organizational business landscape greatly sets the limits for agile deliveries, due to dependencies on cooperation from the business side in the execution phase and the need to be aligned with business needs and stakeholder requirements. Further, the study also shows that the application of agile practices at team level in combination with a close dialogue with stakeholders and a scaled agile approach requiring investing in automation, is the key for more agile infrastructure deliveries. In this way, aligned end-to-end delivery processescan be better developed and infrastructure needs better understood and implemented at the right time. As a contribution, the study proposes a model with inspiration from agile frameworks Scrum, Kanban and SAFe, for how this may work in practice.

  • 3087.
    Akiki, Maroun
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Falk, Agneta
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Ett bostadshus i prefabricerad trästomme: Ett gestaltningsarbete anpassat efter volymelementsbyggande2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is a compilation of the planning of a 5-storey residential building. The building in question has been designed to be built entirely in a wooden frame mainly consisting of a modular building system. Modules also referred to as prefabricated volume elements are room units that have been constructed through industrial means. These room units can be developed enough to be delivered with complete facades or even fixtures. Since the planning of the residential building has been made based on a modular building system, adaptations to the project has had to been made as to accommodate necessary requirements. A practical example of this is how the apartment plan has been affected based on laws concerning the maximum amount of allowed width/height during transportation on public roads. These laws control the size of how big volume elements can become and as a result the apartment layout.

    The report consists of a study into the area of industrial wood construction, but foremost it treats the practical challenges and possibilities that have surfaced as a consequence of planning residential housing based on a modular basis.

  • 3088.
    Akillioglu, Hakan
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Demand Responsive Planning: A dynamic and responsive planning framework based on workload control theory for cyber-physical production systems2015Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Recent developments in the area of Cyber-Physical Production Systems prove that high technology readiness level is already achieved and industrialization of such technologies is not far from today. Although these technologies seem to be convenient in providing solutions to environmental uncertainties, their application provides adaptability only at shop floor level. Needless to say, an enterprise cannot reach true adaptability without ensuring adaptation skills at every level in its hierarchy. Commonly used production planning and control approaches in industry today inherit from planning solutions which are developed in response to historical market characteristics. However, market tendency in recent years is towards making personalized products a norm. The emerging complexity out of this trend obliges planning systems to a transition from non-recurring, static planning into continuous re-planning and re-configuration of systems. Therefore, there is a need of responsive planning solutions which are integrated to highly adaptable production system characteristics.

    In this dissertation, Demand Responsive Planning, DRP, is presented which is a planning framework aiming to respond to planning needs of shifting trends in both production system technologies and market conditions. The DRP is based on three main constructs such as dynamicity, responsiveness and use of precise data. These features set up the foundation of accomplishing a high degree of adaptability in planning activities. By this means, problems from an extensive scope can be handled with a responsive behavior (i.e. frequent re-planning) by the use of precise data. The use of precise data implies to execute planning activities subject to actual demand information and real-time shop floor data. Within the context of the DRP, both a continuous workload control method and a dynamic capacity adjustment approach are developed. A test-bed is coded in order to simulate proposed method based on a system emulation reflecting the characteristics of cyber-physical production systems at shop floor level.

    Continuous Precise Workload Control, CPWLC, method is a novel approach aiming at precise control of workload levels with the use of direct load graphs. Supported by a multi-agent platform, it generates dynamic non-periodic release decisions exploiting real time shop floor information. As a result, improved shop floor performances are achieved through controlling workload levels precisely by the release of appropriate job types at the right time.

    Presented dynamic capacity adjustment approach utilizes rapid re-configuration capability of cyber-physical systems in achieving more frequent capacity adjustments. Its implementation architecture is integrated to the CPWLC structure. By this means, a holistic approach is realized whereby improved due date performance is accomplished with minimized shop floor congestion. Hence, sensitivity to changing demand patterns and urgent job completions is improved.

  • 3089.
    Akillioglu, Hakan
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Evolvable Production Systems: Demand Responsive Planning2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dynamic and unforeseeable characteristic of the current market and production environment is not feasible to be met through pre-set parameters being dependent on the predictions. Handling this matter requires to keep focus on production system adaptability. Evolvable Production System has achieved fully system reconfigurability through process oriented modularity and multi agent based distributed control system architecture. One of the essential enhancements provided by EPS on the shop floor is achieving minimized/eliminated system setup time in response to changing product requirements.

    Manufacturing planning and control system, on the other hand, follows hierarchical principles which are quite much reliant on the predicted information so to structure production and planning environment on it. Production system limitations, such as lack of adaptability in response to changing conditions, are in fact influencing the planning system to be structured on the predictions. The enhancements which are ensured by the architecture of EPS enable to relax the constraints on planning system which are imposed by the limitations of production system. These enhancements have an effect at different levels in the planning hierarchy. On the light of these improvements, the planning framework as it is used so far in the industry becomes invalid and this arise a requirement for planning system structure to be designed according to a fully reconfigurable system to be able to benefit such a production system by all means.

    This thesis targets to enlighten the relation between the production system characteristics and planning system structure by emphasizing the planning problems and proposing a planning reference architecture solution to be able achieve a responsive planning framework.

  • 3090.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Dias-Ferreira, Joao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Maffei, Antonio
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Neves, Pedro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Continuous precise workload control method2014In: IEEE International Conference on Industrial Engineering and Engineering Management, 2014, p. 511-515Conference paper (Refereed)
    Abstract [en]

    The diversity of requirements and the frequency of change in the market can only be competed with dynamicity and responsiveness in both production and planning systems. In this sense, working principles of a novel workload control method, called continuous precise workload control are presented in this paper. The implementation of the method is based on a multi-agent based architecture. The presented approach generates dynamic non periodic release decisions exploiting real time shop floor information. The performance of the system and correlation of norm value against the assessment range are investigated through an experimented test case.

  • 3091.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Dias-Ferreira, Joao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Characterization of Continuous Precise Workload Control and Analysis of Idleness Penalty2014In: CIE 44 and IMSS14 proceedings, 2014, p. 1998-2011Conference paper (Refereed)
    Abstract [en]

    The variability in the market conditions is growing in terms of its frequency of change and range of diversity. In response to this new industrial panorama, research on production systems is aiming to achieve truly reconfigurable shop floors. Frequent changes in such systems require also frequent re-planning with updated information. In this regard the Continuous Precise Workload Control method, is a recent approach aiming at precise control of workload in the shop floor with the use of direct load graphs. Supported by a multi-agent platform, it generates dynamic non-periodic release decisions exploiting real time shop floor information. The study in this paper is two folded; (1) in order to highlight its distinctive characteristics, the presented workload approach is defined in terms of eight dimensions of the workload control concept and (2) the penalty of idleness which affects the decision of release is analyzed by an experiment design in order to investigate its correlation with two critical parameters, norm value and assessment range. The results show that the idleness penalty factor decreases the idleness of the resources up to a point where the adverse effect is initiated. Besides there are strong indications towards the correlation of idleness penalty factor with the norm value.

  • 3092.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Dias-Ferreira, João
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Characterization of continuous precise workload control and analysis of idleness penalty2016In: Computers & industrial engineering, ISSN 0360-8352, E-ISSN 1879-0550, Vol. 102, p. 351-358Article in journal (Refereed)
    Abstract [en]

    The variability in the market conditions is growing in terms of its frequency of change and range of diversity. In response to this new industrial panorama, research on production systems is aiming to achieve highly reconfigurable shop floors. Frequent changes in such systems require also frequent re-planning with updated information. In this regard the Continuous Precise Workload Control method, is a recent approach aiming at precise control of workload in shop floor with the use of direct load graphs. Supported by a multi-agent platform, it generates dynamic non-periodic release decisions exploiting real time shop floor information. The study in this paper is two folded; (1) the presented workload approach is defined in terms of eight dimensions of the workload control concept in order to highlight its distinctive characteristics and (2) the impact of idleness penalty factor is analyzed by an experiment design in order to investigate its effect on the job release decision. The results show that the idleness penalty factor decreases the idleness of the resources up to a point where the adverse effect is initiated.

  • 3093.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Ferreira, Joao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Demand responsive planning: workload control implementation2013In: Assembly Automation, ISSN 0144-5154, E-ISSN 1758-4078, Vol. 33, no 3, p. 247-259Article in journal (Refereed)
    Abstract [en]

    Purpose – Evolvable production systems enable fully reconfiguration capabilities on the shop floor through process-oriented modularity and multiagent-based distributed control. To be able to benefit architectural and operational characteristics of evolvable systems, there is a need of a newplanning approach which links shop floor characteristics and planning operations. This paper seeks to address these issues.

    Design/methodology/approach – Evolvable production system has a structured methodology in itself. Consistent to this, a reference planningarchitecture is developed aiming to achieve agility on planning activities. Besides a workload control method is proposed and implemented as a part ofthe planning architecture.

    Findings – First applications of evolvable systems have been implemented through European research projects. Shop floor working principles andarchitectural characteristics are consistent to facilitate more agility on planning activities which are framed at a planning reference architecture calleddemand responsive planning. As an implementation case, an agent-based workload control method is proposed and implemented. The characteristicsof EPS and proposed planning architecture enable continuous and dynamic workload control of the shop floor to be implemented.

    Originality/value – This paper presents a new planning model compatible with evolvable production systems targeting to agility to demand onplanning and control activities benefiting shop floor enhancements of a fully reconfigurable system which enables to relax constraints imposed fromproduction systems to planning. In addition, a continuous and dynamic workload control method is proposed and implemented.

  • 3094.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Maffei, Antonio
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Neves, Pedro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Ferreira, Joao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Operational characterization of evolvable productionsystems2012In: 4th CIRP Conference on Assembly Technologies and Systems – CATS 2012, 2012, p. 85-90Conference paper (Refereed)
    Abstract [en]

    On the way to achieve mass customization production systems have to obtain the capability of rapid reconfiguration of not only physical components but also from control point of view. Evolvable Production System targets highly adaptable mechanical and control solutions that can enhance reusability and interoperability of modules, enabling lifetime extension of the modules. The focus of EPS paradigm is to achieve overall system adaptability by autonomous modules which are dedicated to specific processes with the capability of short deployment time at shop floor without reprogramming effort. From the operational point of view EPS brings significant enhancements considering shop floor dynamics and performances therefore positioning of EPS principles and approaches in production system typology from different perspectives is essential. This has been done by two means which are process flow structure and customer order decoupling point location.

  • 3095.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Neves, Pedro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Evolvable Assembly Systems: Mechatronic Architecture Implications and Future Research2010Conference paper (Refereed)
    Abstract [en]

    The balance between assembly process optimality and their system’s ability to adapt to new requirements is a key to success for assembly companies. To increase SME’s survivability, an effective methodology is needed to handle the requirements of both agility and mass customization. Evolvable Assembly Systems (EAS) paradigm is a next generation assembly systems focused on these issues. Three key issues are here in focus: process-oriented approach, fine modular granularity, and module intelligence through lighter multi-agent technology at the shop floor level. These issues

  • 3096.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Evolvable production systems and impacts on production planning2011Conference paper (Other academic)
    Abstract [en]

    Production planning and control strategies have been changing in line with the constant change on product and customer requirements, under the light of technological and scientific advancements. Production systems which are based on mass production became obsolete in time hence companies, being profit oriented, are in need of new solutions towards mass customization to handle rapidly changing market conditions. To deal with this issue, production systems and production planning strategies have to be complementing each other. In this paper Evolvable Production Systems and its compatibility to Just in Time (JIT) Production compared to Material Requirement Planning (MRP) will be discussed.

  • 3097.
    Akin, Danny E.
    et al.
    Richard B. Russell Agricultural Research Center, Agricultural Research Service, US Department of Agriculture, Athens.
    Henriksson, Gunnar
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Evans, J. D.
    South Central Poultry Research Laboratory, Agricultural Research Service, US Department of Agriculture, USA.
    Adamsen, A. S. P.
    Agro Business Par, Denmark.
    Foulk, J. A.
    Cotton Quality Research Station, Agricultural Research Service, US Department of Agriculture, USA.
    Dodd, R. B.
    Department of Agricultural and Biological Engineering, Clemson University.
    Progress in enzyme-retting of flax2004In: Journal of Natural Fibers, ISSN 1544-0478, Vol. 1, no 1, p. 21-47Article in journal (Refereed)
    Abstract [en]

    New methods for retting flax are sought to overcome problems in the current method of dew-retting of flax. Published data are reviewed and new data presented on the development and testing of a method to ret flax using pectinase-rich enzyme mixtures plus chelators based on cost and fiber yield and properties. In spray enzyme retting (SER), flax stems are crimped to physically disrupt the plant's protective barrier and then sprayed until soaked with, or briefly immersed in, an enzyme/ chelator formulation. Flax is then incubated at temperatures optimal for enzyme activity, washed, and dried. Pilot scale tests, conducted with 10 kg samples of flax retted with a series of formulations, showed that this method effectively retted flax stems from a variety of sources, including fiber flax, mature fiber flax, and linseed straw. Fiber yield, strength, and fineness were significantly influenced by variations in enzyme-chelator amounts. Cellulases in pectinase mixtures appeared to preferentially attack dislocations in fibers and fiber bundles resulting in loss of fiber strength. Polygalacturonases alone effectively separated fiber from non-fiber components. The SER method proved to be an effective framework for further tests on enzyme-chelator formulations that now must be integrated with physical processing to optimize the extraction of flax fibers based on cost and fiber yield and properties.

  • 3098.
    Akisheva, Yulia
    et al.
    KTH, School of Electrical Engineering (EES).
    Farid, Ramin
    KTH, School of Electrical Engineering (EES).
    Radiation Dose Analysis of the MIST Satellite2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 3099.
    Akius, Kim
    KTH, School of Information and Communication Technology (ICT).
    Approaching micrometer size graphene flakes on an insulating substrate with STM2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this study, a method for landing with a Scanning Tunneling Microscope (STM) on a µm size ake of graphene was developed. Two approaches were explored, one using physical guides to navigate on the sample and another one using capacitive pickup in the system. We show that with no modication of the STM that was used, we could land on a micrometer size ake of graphene.

  • 3100.
    Akkaya, Deniz
    KTH, School of Information and Communication Technology (ICT).
    Wireless Inspirational Bits for Facilitating Early Design2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Proof of concept systems are the significant examples of technology designs to test and analyze technology ideas. Toolkits enable technology developers to decrease the complexity and time to create draft designs with many iterations. Toolkits with combinations of sensors and actuators may lead technology designers to new design spaces and opportunities by decreasing design difficulties. This thesis proposes a new wireless toolkit, called Earl, for beginner level technology designers. Without being experienced on engineering skills Earl allows technology designers to create proof of concept systems in shorter time than implementing the system from scratch. For experiencing with sensors and actuators, this toolkit has a vision to design plug and experience systems. By using Earl, designers can connect analog actuators and sensors by plugging them to toolkit. Additionally, Earl is designed to increase the experience time by lowering the power consumption as much as possible. Therefore, application developers can use Earl portably in long term experiments. Furthermore, Earl is designed in Internet of Things concept. By using Earl web services, technology designer can access the data sent from the sensors and can control the actuators connected to hardware toolkit from a web browser. Earl hardware toolkit aims to provide long experiment time as much as possible. This is why, Earl hardware toolkit is designed to lower the power consumption if hardware toolkit is not actively handling processes. In sensing only mode, technology developers can use Earl hardware toolkit more than 1 month without recharging the toolkit battery. Using actuators in application may change power consumption of the hardware toolkit. Therefore, applications with actuators may have lower experiment time.

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