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  • 124101. Yosef, Nir
    et al.
    Käll, Lukas
    KTH, School of Biotechnology (BIO), Gene Technology.
    From sequence to structure to networks2008In: Genome Biology, ISSN 1465-6906, E-ISSN 1474-760X, Vol. 9, no 11Article in journal (Refereed)
    Abstract [en]

    A report on the 7th European Conference on Computational Biology (ECCB), Cagliari, Italy, 22-26 September 2008.

  • 124102.
    Yosef, Sonia
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Sommer, Julia
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    High Yield – A Late Bloomer’s Time To Shine?2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Real estate companies are capital intense and bank loans represent the most common source of funding. However, the years following the latest financial crisis resulted in difficult terms and expensive bank loans, which cleared a path for alternative sources of funding. Small and me-dium-sized real estate companies displayed a particular interest in corporate bonds and ever since then the real estate sector have been overrepresented on the Swedish corporate bond mar-ket. Despite the growth during the past years, the Swedish market still appears to be underde-veloped compared to other countries. However, several trends are now indicating that High Yield is on the rise. New regulations that are currently being implemented will increase the costs for banks further and consequently make bank loans even more expensive. Simultane-ously, the current low interest-rate environment and volatile stock markets are increasing de-mand for High Yield alternatives among retail and institutional investors. This study investi-gates the High Yield market for small and medium-sized real estate companies and is built upon eleven interviews with professionals. It concludes that the market is underdeveloped because there has been no previous demand for it. Swedish banks and companies have traditionally had a synergetic relationship while investors relied on saving accounts and equities. The situation today is different; investors are demanding High Yield investments and the segment will most probably increase in the future. Real estate companies are positive to bonds and wish to increase the current ratio of their debt portfolio. There are however several barriers for continued growth, such as lack of knowledge, transparency, liquidity as well as fair pricing in the market. In the current state, corporate bond investments are suitable only for professional investors. The ex-emption is High Net Worth Individuals, who buy and hold, which are particularly suited for smaller corporate bonds.

  • 124103.
    Yosef, Sonia
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Sommer, Julia
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    High Yield – Tid Att Blomstra?: En studie av den svenska företagsobligationsmarknaden för små och medelstora fastighetsföretag2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 124104.
    Yoseff, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje).
    Yacoub, Eddie
    KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje).
    Undersökning av lagerhantering och värdeflöde2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This degre project has been conducted at GKN in Tullinge where the work deals with both the workshop and warehouse. In the inventory, the improvement opportunities are primarily in the work structure and in the workshop is a study of the value flow of interest to GKN.The purpose of this work was to propose an improvement proposal for more structured handling and storage of finished shafts and examine the flow of value in the production process in the hope of identifying possible wastes.A number of methods were used to carry out the work; unstructured observations, interviews, fishbone diagram with "five why", 5S and time and cost calculation.The results were a proposed improvement and structuring of the current mode of operation in the inventory using the 5S method. This means more efficient work in the form of, among other things, reducing time wastage and costing as well as applying standardization at different workstations. In addition, identified wastage in the workshop were highlighted and improvements were given to how these can be rectified. The total non-value creation time was estimated at 750 h / year and the cost that the company can save is 129.000 SEK.The conclusion was first of all that GKN would need to improve the current mode of operation in the warehouse by implementing 5S. This, for example, introduces floor markings for sorting different shaft lengths and moving part of the stool collars to a more efficient location. Even in the workshop flow, there are several possibilities for improvement, especially elimination of non-value-creating time (wastefulness). For example, by standardizing drying, washing and cooling times on the shafts and moving gear and materials closer to the operators, much waste can be eliminated.

  • 124105. Yoshida, M.
    et al.
    Ohira, T.
    Igarashi, K.
    Nagasawa, H.
    Aida, K.
    Hallberg, B. M.
    Divne, Christina
    KTH, Superseded Departments, Biotechnology.
    Nishino, T.
    Samejima, M.
    Production and characterization of recombinant Phanerochaete chrysosporium cellobiose dehydrogenase in the methylotrophic yeast Pichia pastoris2001In: Bioscience, biotechnology and biochemistry, ISSN 0916-8451, E-ISSN 1347-6947, Vol. 65, no 9, p. 2050-2057Article in journal (Refereed)
    Abstract [en]

    The hemoflavoenzyme cellobiose dehydrogenase (CDH) from the white-rot fungus Phanerochaete chrysosporium has been heterologously expressed in the methylotrophic yeast Pichia pastoris. After 4 days of cultivation in the induction medium, the expression level reached 1800 U/L (79 mg/L) of CDH activity, which is considerably higher than that obtained previously for wild-type CDH (wtCDH) and recombinant CDH (rCDH) produced by P. chrysosporium. Analysis with SDS-PAGE and Coomassie Brilliant Blue (CBB) staining revealed a major protein band with an approximate molecular mass of 100 kDa, which was identified as rCDH by Western blotting. The absorption spectrum of rCDH shows that the protein contains one flavin and one heme cofactor per protein molecule, as does wtCDH. The kinetic parameters for rCDH using cellobiose, ubiquinone, and cytochrome c, as well as the cellulose-binding properties of rCDH were nearly identical to those of wtCDH. From these results, we conclude that the rCDH produced by Pichia pastoris retains the catalytic and cellulose-binding properties of the wild-type enzyme, and that the Pichia expression system is well suited for high-level production of rCDH.

  • 124106. Yoshida, Motoharu
    et al.
    Fransén, Erik
    KTH, School of Computer Science and Communication (CSC), Computational Biology, CB.
    Hasselmo, Michael E.
    mGluR-dependent persistent firing in entorhinal cortex layer III neurons2008In: European Journal of Neuroscience, ISSN 0953-816X, E-ISSN 1460-9568, Vol. 28, no 6, p. 1116-1126Article in journal (Refereed)
    Abstract [en]

    Persistent firing is believed to be a crucial mechanism for memory function including working memory. Recent in vivo and in vitro findings suggest an involvement of metabotropic glutamate receptors (mGluRs) in persistent firing. Using whole-cell patch-recording techniques in a rat entorhinal cortex (EC) slice preparation, we tested whether EC layer III neurons display persistent firing due to mGluR activation, independently of cholinergic activation. Stimulation of the angular bundle drove persistent firing in 90% of the cells in the absence of a cholinergic agonist. The persistent firing was typically stable for > 4.5 min at which point persistent firing was terminated by the experimenter. The average frequency of the persistent firing was 2.1 Hz, ranging from 0.4 to 5.5 Hz. This persistent firing was observed even in the presence of atropine (2 mu M), suggesting that the persistent firing can occur independent of cholinergic activation. Furthermore, ionotropic glutamate and GABAergic synaptic blockers (2 mm kynurenic acid, 100 mu M picrotoxin and 1 mu M CGP55845) did not block the persistent firing. On the other hand, blockers of group I mGluRs (100 mu M LY367385 and 20 mu M MPEP) completely blocked or suppressed the persistent firing. An agonist of group I mGluRs (20 mu M DHPG) greatly enhanced the persistent firing induced by current injection. These results indicate that persistent firing can be driven through group I mGluRs in entorhinal layer III neurons, suggesting that glutamatergic synaptic input alone could enable postsynaptic neurons to hold input signals in the form of persistent firing.

  • 124107.
    Yoshida, Naoki
    KTH, Superseded Departments, Mechanics.
    Nonlinear wave phenomena in a magnetized plasma and in a relativistic gas1998Licentiate thesis, comprehensive summary (Other scientific)
  • 124108. Yoshida, Suguru
    et al.
    Ushioda, Kohsaku
    Abe, Yoshio R.
    Ågren, John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Kinetic Model of gamma to alpha Phase Transformation at Grain Boundaries in B-Bearing Low Alloy Steel2012In: Tetsu to hagane, ISSN 0021-1575, E-ISSN 1883-2954, Vol. 98, no 9, p. 24-32Article in journal (Refereed)
    Abstract [en]

    The effect of Boron (B) on nucleation and growth of ferrite from austenite grain boundaries is examined theoretically assuming the junction of 4-austenite grain boundaries as dominant nucleation sites of ferrite. B segregates to the austenite grain boundaries and reduces the grain boundary energy and thereby retards the ferrite nucleation at the grain boundary. The retardation is expressed as a decrease of nucleation frequency due to an increase of activation energy for nucleation and the calculated value of the fraction of active nucleation sites is in satisfactory agreed with experimental results. The reduction of the austenite grain boundary energy, obtained by applying the Gibbs isotherm for adsorption to the B segregation, is of the same order of as the one which is deduced from results of calculation for decrease in the nucleation frequency based on experimental result. The growth of ferrite is calculated using DICTRA yielding both the volume fraction and the grain size of transformed ferrite as a function of time, which agreed with the experimental results. This suggests the slight influence of B on growth rate. However, the increase of the diffusion cell size due to B addition is considered to be the main reason for the subtle larger grain size of ferrite as compared with B-free steel, which is in good accordance with the experimental fact.

  • 124109. Yoshida, Suguru
    et al.
    Ushioda, Kohsaku
    Ågren, John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Kinetic Model of the gamma to alpha Phase Transformation at Grain Boundaries in Boron-bearing Low-alloy Steel2014In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 54, no 3, p. 685-692Article in journal (Refereed)
    Abstract [en]

    The effect of boron on the nucleation and growth of ferrite at austenite grain boundaries is examined theoretically under the assumption that the junction of 4-austenite grain boundaries (i.e., the 4-grain junctions) are the dominant nucleation sites of ferrite. Boron segregates to the austenite grain boundaries and reduces the grain-boundary energy; it thereby retards ferrite nucleation at the grain boundary. The retardation is expressed as a decrease in nucleation density due to an increase in the critical activation energy for nucleation, and the calculated value of the fraction of active nucleation sites is in satisfactory agreement with the experimental results. The reduction of the austenite grain-boundary energy, which we obtained by applying the Gibbs isotherm for adsorption to the boron segregation, is of the same order of magnitude as the reduction is deduced from the results of calculations for a decrease in the nucleation density based on experimental results. The growth of ferrite was calculated using DICTRA, which yielded both the volume fraction and the grain size of transformed ferrite as functions of time; the results agreed with the experimental results. This agreement suggests that the influence of boron on the growth rate is negligible. However, the increase in the size of the diffusion cell due to the addition of boron is considered to be the main reason for the slightly larger grain size of ferrite compared with that in boron-free steel; this result is also in good agreement with experimental observations.

  • 124110.
    Yoshikawa, Masahiro
    et al.
    Central Research Institute of Electric Power Industry, Energy Engineering Research Laboratory, Kanagawa, Japan.
    Bodén, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Sparr, Mari
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Experimental determination of effective surface area and conductivities in the porous anode of molten carbonate fuel cell2006In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 158, no 1, p. 94-102Article in journal (Refereed)
    Abstract [en]

    Stationary polarization curves and electrochemical impedance spectroscopy of a porous nickel anode in a molten carbonate fuel cell were obtained in order to determine the active surface area and conductivities with varying degree of electrolyte filling for two anode feed-gas compositions, one simulating operation with steam reformed natural gas and the other one gasified coal. The active surface area for coal gas is reduced by around 70-80% compared to the standard gas composition in the case of Li/Na carbonate. Moreover, an optimal degree of electrolyte filling was shifted toward higher filling degree in the case of operation with coal gas.In order to evaluate the experimental data a one-dimensional model was used. The reaction rate at the matrix/electrode interface is about five times higher than the average reaction rate in the whole electrode in case of 10% electrolyte filling. This result suggests that the lower limit of the filling degree of the anode should be around 15% in order to avoid non-uniform distribution of the reaction in the electrode. Therefore, in the case of applying Li/Na carbonate in the MCFC, an electrolyte distribution model taking into account the wetting properties of the electrode is required in order to set an optimal electrolyte filling degree in the electrode.

  • 124111. Yoshimura, Kimiyasu
    et al.
    Davari, Mohammad Mehdi
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Stensson Trigell, Annika
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Studying Road Roughness Effect on Rolling Resistance Using Brush Tyre Model and Self-Affine Fractal Surfaces2016In: The Dynamics of Vehicles on Roads and Tracks - Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015, CRC Press, 2016, p. 273-280Conference paper (Refereed)
    Abstract [en]

    While there are many tyre and vehicle dependent factors that affect the rollingresistance, the road properties play also an influential role in the overall resistance on the vehicle.The aim of this study is to develop amodel that can estimate the effect of road roughness on rollingresistance of tyres where both the texture-dependent and independent factors are contributing tooverall rolling resistance. In this paper, a method based on the self-affine fractal surfaces is usedto model realistic road characteristics in order to couple it with a brush based tyre model to beable to study the influence of road roughness on tyre rolling resistance. The simulation resultssuggest that the rolling resistance increases with increased RMS-value and both the macro- andthe micro-texture have an influence on the rolling resistance while the macro-texture effect is moreinfluential. The results of this paper can be related to the estimation of fuel economy on differentroad textures, from macro-texture to micro-texture and further optimisation of road surfaces.

  • 124112.
    Yoshimura, T.
    et al.
    Natl Inst Nat Sci, Natl Inst Physiol Sci, Div Neurobiol & Bioinformat, Okazaki, Aichi 4448585, Japan.;SOKENDAI, Sch Life Sci, Dept Physiol Sci, Hayama, Japan..
    Handa-Narumi, M.
    Natl Inst Nat Sci, Natl Inst Physiol Sci, Div Neurobiol & Bioinformat, Okazaki, Aichi 4448585, Japan.;SOKENDAI, Sch Life Sci, Dept Physiol Sci, Hayama, Japan..
    Hayashi, A.
    Tokyo Univ Pharm & Life Sci, Dept Mol Neurobiol, Hachioji, Tokyo 19203, Japan..
    Yagi, H.
    Nagoya City Univ, Grad Sch Pharmaceut Sci, Dept Struct Biol & Biomol Engn, Nagoya, Aichi, Japan..
    Koike, T.
    Natl Inst Nat Sci, Natl Inst Physiol Sci, Div Neurobiol & Bioinformat, Okazaki, Aichi 4448585, Japan..
    Yamaguchi, Y.
    Tokyo Univ Pharm & Life Sci, Dept Mol Neurobiol, Hachioji, Tokyo 19203, Japan..
    Uchimura, K.
    Nagoya Univ, Grad Sch Med, Dept Biochem, Nagoya, Aichi 4648601, Japan..
    Kadomatsu, K.
    KTH, Dept Chem Engn & Technol, Prot Crystallizat Facil, Royal Inst Technol, Stockholm, Sweden..
    Sedzik, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Natl Inst Nat Sci, Natl Inst Physiol Sci, Div Neurobiol & Bioinformat, Okazaki, Aichi 4448585, Japan.
    Kitamura, K.
    Saitama Med Univ, Fac Hlth & Med Care, Hidaka, Japan..
    Kato, K.
    Nagoya City Univ, Grad Sch Pharmaceut Sci, Dept Struct Biol & Biomol Engn, Nagoya, Aichi, Japan.;Natl Inst Nat Sci, Inst Mol Sci, Okazaki, Aichi 4448585, Japan.;Natl Inst Nat Sci, Okazaki Inst Integrat Biosci, Okazaki, Aichi 4448787, Japan..
    Trapp, B. D.
    Cleveland Clin, Dept Neurosci, Lerner Res Inst, Cleveland, OH 44106 USA..
    Baba, H.
    Tokyo Univ Pharm & Life Sci, Dept Mol Neurobiol, Hachioji, Tokyo 19203, Japan..
    Ikenaka, K.
    Natl Inst Nat Sci, Natl Inst Physiol Sci, Div Neurobiol & Bioinformat, Okazaki, Aichi 4448585, Japan.;SOKENDAI, Sch Life Sci, Dept Physiol Sci, Hayama, Japan..
    GlcNAc6ST-1 regulates sulfation of N-glycans and myelination in the peripheral nervous system2015In: Journal of Neurochemistry, ISSN 0022-3042, E-ISSN 1471-4159, Vol. 134, p. 290-290Article in journal (Other academic)
  • 124113. Yoshimura, T.
    et al.
    Narumi, M.
    Yagi, H.
    Kitamura, K.
    Sedzik, Jan
    KTH, School of Biotechnology (BIO).
    Kato, K.
    Ikenaka, K.
    STRUCTURE DETERMINATION OF N-GLYCANS ON A FEW PMOL GLYCOPROTEIN AND ITS APPLICATION TO THE STRUCTURAL ANALYSIS OF N-GLYCANS ON P02011In: Journal of Neurochemistry, ISSN 0022-3042, E-ISSN 1471-4159, Vol. 118, p. 150-150Article in journal (Other academic)
  • 124114.
    Yoshimura, T.
    et al.
    Natl Inst Physiol Sci, Div Neurobiol & Bioinformat, Okazaki, Aichi 444, Japan..
    Sedzik, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Ikenaka, K.
    Natl Inst Physiol Sci, Div Neurobiol & Bioinformat, Okazaki, Aichi 444, Japan..
    ANALYSIS OF N-GLYCANS IN MYELIN2009In: Journal of Neurochemistry, ISSN 0022-3042, E-ISSN 1471-4159, Vol. 110, p. 112-112Article in journal (Other academic)
  • 124115. Yoshimura, Takeshi
    et al.
    Hayashi, Akiko
    Handa-Narumi, Mai
    Yagi, Hirokazu
    Ohno, Nobuhiko
    Koike, Takako
    Yamaguchi, Yoshihide
    Uchimura, Kenji
    Kadomatsu, Kenji
    Sedzik, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. National Institutes of Natural Sciences, Japan.
    Kitamura, Kunio
    Kato, Koichi
    Trapp, Bruce D.
    Baba, Hiroko
    Ikenaka, Kazuhiro
    GlcNAc6ST-1 regulates sulfation of N-glycans and myelination in the peripheral nervous system2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 42257Article in journal (Refereed)
    Abstract [en]

    Highly specialized glial cells wrap axons with a multilayered myelin membrane in vertebrates. Myelin serves essential roles in the functioning of the nervous system. Axonal degeneration is the major cause of permanent neurological disability in primary myelin diseases. Many glycoproteins have been identified in myelin, and a lack of one myelin glycoprotein results in abnormal myelin structures in many cases. However, the roles of glycans on myelin glycoproteins remain poorly understood. Here, we report that sulfated N-glycans are involved in peripheral nervous system (PNS) myelination. PNS myelin glycoproteins contain highly abundant sulfated N-glycans. Major sulfated N-glycans were identified in both porcine and mouse PNS myelin, demonstrating that the 6-O-sulfation of N-acetylglucosamine (GlcNAc-6-O-sulfation) is highly conserved in PNS myelin between these species. P-0 protein, the most abundant glycoprotein in PNS myelin and mutations in which at the glycosylation site cause Charcot-Marie-Tooth neuropathy, has abundant GlcNAc-6-O-sulfated N-glycans. Mice deficient in N-acetylglucosamine-6-O-sulfotransferase-1 (GlcNAc6ST-1) failed to synthesize sulfated N-glycans and exhibited abnormal myelination and axonal degeneration in the PNS. Taken together, this study demonstrates that GlcNAc6ST-1 modulates PNS myelination and myelinated axonal survival through the GlcNAc-6-O-sulfation of N-glycans on glycoproteins. These findings may provide novel insights into the pathogenesis of peripheral neuropathy.

  • 124116. Yoshioka, S.
    et al.
    Fransson, Jens H. M.
    KTH, Superseded Departments, Mechanics.
    Alfredsson, P. H.
    Evolution of disturbances in boundary layers with wall suction2003Conference paper (Refereed)
  • 124117. Yoshioka, S
    et al.
    Fransson, Jens H.M.
    KTH, Superseded Departments, Mechanics.
    Alfredsson, P. Henrik
    KTH, Superseded Departments, Mechanics.
    Free stream turbulence induced disturbances in boundary layers with wall suction2004In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 16, no 10, p. 3530-3539Article in journal (Refereed)
    Abstract [en]

    An experimental investigation of free stream turbulence (FST) induced disturbances in asymptotic suction boundary layers (ASBL) has been performed. In the present study four different suction rates are used and the highest is 0.40% of the free stream velocity, together with three different FST levels (Tu=1.6, 2.0, and 2.3%). A turbulence generating grid of the active type is used and offers the possibility to vary the Tu-level while the scales of the turbulence remain almost constant. It is known that FST induces elongated disturbances consisting of high and low velocity regions, usually denoted streaky structures, into the boundary layer. The experiments show that wall suction suppresses the disturbance growth and may significantly delay or inhibit the break-down to turbulence. Two-point correlation measurements in the spanwise direction show that the averaged streak spacing decreases with increasing FST-level, whereas the spanwise scale in the ASBL is more or less constant if scaled with the free stream velocity and viscosity. This is in contrast to what is observed in a Blasius boundary layer where streaks develop and adapt their spanwise scale close to the boundary layer thickness.

  • 124118.
    Yoshioka, Shuya
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Alfredsson, Henrik P.
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Control of turbulent boundary layers by uniform wall suction and blowing2006In: Fluid Mechanics and its Applications, ISSN 0926-5112, Vol. 78, p. 437-442Article in journal (Refereed)
    Abstract [en]

    The effect of uniform wall suction and blowing on a turbulent boundary layer was experimentally investigated. It was discovered that the development of the boundary layer is suppressed by suction and promoted by blowing. The turbulence intensity in the outer part increases with blowing and decreases with suction, however in the inner part the intensity is only slightly affected if scaled with the free-stream velocity.

  • 124119.
    Yoshioka, Takanori
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Parameters influencing inclusion compositions in Al-killed steel melts during a secondary refining process2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

         This study was carried out to clarify the factors influencing the evolution of inclusions in Al-killed steel melts during a secondary refining process. First, a case-hardening steel was the subject of study to understand the factors influencing the inclusion compositions in the steel melt. During the LF process, inclusions were transformed from the Al2O3 phase, which was the primary deoxidation product, to both MgO·Al2O3 and CaO-Al2O3-MgOliq phases simultaneously. This composition transition during the LF process occurred by composition evolutions toward thermodynamically stable phases. After the RH process, the inclusion compositions primarily consisted of the Al2O3 and CaO-Al2O3 phases. MgO·Al2O3 inclusions were removed, while the CaO-Al2O3 inclusions remained during the RH process. This behavior can be understood in terms of the interfacial properties of the oxide phases in a steel melt. The detected Al2O3 inclusions were considered to be generated by reoxidation during the RH treatment. Thus, it was confirmed that the equilibrium states, removal, and generation of inclusions determine the inclusion compositions in an Al-killed steel melt during an LF-RH refining process.

         Subsequently, the effect of high Al contents in a steel melt on the change in inclusion compositions during the LF-RH process was studied. Due to the high Al content in the steel melt, the thermodynamic driving forces for Al2O3 modification became lower than those in ordinary Al-killed steels. Therefore, the degree of inclusion evolution was restricted. This contributed to the low CaO contents in the inclusions. Due to the low CaO contents, the removability of the inclusions remained high throughout the LF-RH process. According to thermodynamic calculations, the low T.O contents in this steel grade are due to the low insoluble O contents. This can be explained by the fast removal of inclusions. Because the inclusions were removed smoothly, the CaO content in the inclusions was lower than that in the thermodynamically stable phase.

         In addition, a study was carried out to understand the formation and behavior of the CaS phase in an Al-killed high-S steel during the LF-RH process without Ca-treatment. In the initial stage of the LF process, a CaS phase was formed on the existing inclusions by a reaction between Ca and S. As the desulfurization of the steel melt progressed, the CaS phase started to be transformed into a CaO phase in the inclusions, which resulted in the formation of CaO-Al2O3-CaS inclusions. After desulfurization of the steel melt, the Al2O3 phase in the inclusions was transformed to the CaO-Al2O3liq phase without being hindered by a CaS phase. During the following RH process, the addition of FeS increased the activity of S, which then reacted with both CaO in the inclusions and with Ca, forming a CaS phase. Consequently, the majority of the inclusions consisted of the Al2O3-CaS phase. Thus, a CaS formation during the LF-RH process without Ca-treatment progresses under the thermodynamic driving forces of the following two reactions: the reaction between CaO in the inclusions and S and the reaction between Ca and S. Due to the formation of a CaS phase during the RH process, inclusions in the high S steel melt were covered by a CaS phase, which is difficult to remove from steel melts. Therefore, the castability of the high S steels can be deteriorated by the CaS inclusions, even without using Ca-treatment.

         In summary, it can be concluded that the removal of inclusions, generation, and composition evolution should be considered in order to control the inclusion compositions in Al-killed steel melts. In addition, steel components, such as Al and S, are important to monitor to control the inclusion evolution during secondary refining processes.

  • 124120.
    Yoshioka, Takanori
    et al.
    KTH.
    Ideguchi, Takahiro
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ohba, Yasuhide
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Study of formation behavior of CaO-Al2O3 inclusions in steel melts during an LF processManuscript (preprint) (Other academic)
    Abstract [en]

    Experiments were carried out during an LF process to investigate the formation behavior of CaO-Al2O3 inclusions in a steel melt. Samples were taken during the production of two different steel grades: a low-Al steel (Al=0.023%) and a high-Al steel (Al=1.1%). Liquid CaO-Al2O3 inclusions were detected in the low-Al steel samples. On the other hand, liquid CaO-Al2O3 inclusions were not detected in the high-Al steel samples. Instead, the inclusions consisted of MgO∙Al2O3 and Al2O3. The conditions of the LF operations, such as slag viscosities, temperatures, and gas flow rates, were almost the same in the two steel grades. This fact indicates that the detected liquid CaO-Al2O3 inclusions in the low-Al steel melt were not generated by slag entrapment, but by inclusion evolutions. In the low-Al steel, the thermodynamically stable phase of inclusion composition was calculated to be a liquid CaO-Al2O3 phase. On the other hand, the stable phase was found to be a CaO∙2Al2O3 phase in the high-Al steel. These differences in thermodynamic stable phases can influence the degree of inclusion evolution in the steel melts. However, in the high-Al steel, most inclusions have much lower CaO contents than that of the calculated phase (CaO∙2Al2O3). This large inconsistency between the detected and calculated inclusion compositions in the high-Al steel melt can be explained by two reasons: one is the low thermodynamic driving force of an Al2O3 modification and the other is the high removability of the inclusion types in the steel melt.

  • 124121.
    Yoshioka, Takanori
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ideguchi, Takahiro
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ohba, Yasuhide
    Jönsson, Pär Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The Effect of a High Al Content on the Variation of the Total Oxygen Content in the Steel Melt during a Secondary Refining Process2018In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 89, no 2, article id 1700287Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to clarify the mechanism of low total oxygen (T.O) contents in high-Al containing steel grades. Steel samples are taken from a ladle during an LF-RH process, and the compositions of both the steels and inclusions are determined. According to thermodynamic considerations, the low T.O contents of high Al steel grades are due to the low insoluble oxygen contents. Due to the high Al contents in a steel melt, thermodynamic driving forces of the Al2O3 modification are lower than those in ordinary Al-killed steels. Both the low thermodynamic driving force of the Al2O3 modification and the inclusion removal from the melts contribute to the low CaO contents in inclusions in high-Al steel melts. The contact angles of inclusions in high Al steel melts are higher than 90 degrees due to the low CaO content in inclusions. Therefore, the removal tendency of inclusions in high Al steel melts is kept high throughout an LF-RH process. Due to this high removal tendency, the T.O contents in high Al steel melts decreases remarkably during an LF refining process. Thereafter, they decrease further during the following RH treatment.

  • 124122.
    Yoshioka, Takanori
    et al.
    Sanyo Special Steel Co Ltd, Steelmaking Proc Grp, Ctr Res & Dev, Shikama Ku, 3007 Nakashima, Himeji, Hyogo 6728677, Japan.
    Nakahata, Kenichiro
    Kawamura, Takanori
    Ohba, Yasuhide
    Factors to Determine Inclusion Compositions in Molten Steel during the Secondary Refining Process of Case-Hardening Steel2016In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 56, no 11, p. 1973-1981Article in journal (Refereed)
    Abstract [en]

    A study was carried out to observe inclusions during the secondary refining process of case-hardening steel to understand the factors to determine inclusion compositions. During the LF refining, inclusions changed from the primary deoxidation product of Al2O3 to MgO·Al2O3 and the CaO-Al2O3 system. At the end of LF refining, the compositions were placed on the tie-line connecting the areas of MgO·Al2O3 and CaO-Al2O3-MgOliq in the CaO-Al2O3-MgO diagram. This change took place by the composition evolution targeting the thermodynamic equilibrium states. After the RH treatment, the inclusion compositions changed mainly to Al2O3 and the CaO-Al2O3 system because MgO·Al2O3 inclusions were removed, while the CaO-Al2O3 system inclusions, the most stable oxide, were remained. This behavior could be described by the interfacial properties between the oxides and the molten steel. Al2O3 inclusions were considered to be newly generated during the RH treatment. It was confirmed that three factors of (1) equilibrium state (2) removal and (3) generation of inclusions dominated to determine the inclusion compositions.

  • 124123.
    Yoshioka, Takanori
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Sanyo Special Steel Co., Japan.
    Shimamura, Y.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ohba, Y.
    Jönsson, Pär Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The effect of a sulfur addition on the formation and behavior of cas inclusions during a secondary refining process without using a Ca-treatment2018In: International Symposium on Materials Processing Fundamentals, 2018, Springer International Publishing , 2018, Vol. Part F2, 2018, p. 3-13Conference paper (Refereed)
    Abstract [en]

    This study aimed to elucidate the effect of a sulfur addition on the formation and behavior of CaS inclusions in steel melts during a secondary refining process without a Ca-treatment. Samples were taken during production for two different steel grades, namely a low-S steel (S = 0.005%) and a high-S steel (S = 0.055%). Thereafter, the inclusion characteristics were determined using an SEM combined with an EDS. The results show that the CaO content in the inclusions decreased and the CaS content increased after a sulfur addition during an RH process for the high-S steel. Furthermore, CaS-covered inclusions were frequently detected in the high-S steel samples after the S addition. Thermodynamic calculations were also performed to compare the CaS formation behavior in the two steels. The results showed that a CaS phase can thermodynamically be formed in the high-S steel melt even without a Ca-treatment. Also, it was indicated that a CaS phase can be formed in two ways, namely a reaction between Ca and S and a reaction between CaO in inclusions and S. From the viewpoint of interfacial features, inclusions covered by a CaS phase are thought to possess low contact angles to steel melts. Therefore, CaS-covered inclusions tend to remain in a steel melt. According to the results of this study, CaS inclusions can be formed and deteriorate the castability of high-S containing steels even without a Ca-treatment.

  • 124124.
    Yoshioka, Takanori
    et al.
    KTH.
    Shimamura, Yuta
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ohba, Yasuhide
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Mechanism of a CaS Formation in an Al-Killed High-S Containing Steel during a Secondary Refining Process without a Ca-Treatment2017In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 10, article id UNSP 1700147Article in journal (Refereed)
  • 124125.
    Yosifova, Eliz
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Baban, Zanwer
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Nybyggnation av hotell: Gestaltning av hotell på en ljudutsatt plats i Stockholms stad2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    One major problem today in Stockholm City is to be able to build functional housing and offices becuase of the impact from the noise large interchanges distribute in the City. In order to build housing and offices it is important to achieve the requirements that Boverkets Byggregler, which is the Swedish rules for constructions. The county in Stockholm has to plan and observe the noise exposed properties in the inner City. One obstacle to build more housing and offices which the city needs, is the rules and demands on the areas but also the growth of the traffic in Stockholm city. This problem results for increased noiselevels which also affects the acoustic comfort for housig and offices. To be able to solve the problem for the challenges that is caused by the lack of housing in Stockholm, hotels can be built on these areas that are located close to traffic in the city. In order to solve this problem a hotel that screen the exessive noise towards residental areas can be a solution, because Boverket does not require any guidelines and regulations for noise on hotel constructions. The fact that hotels can be built on properties that is close to the traffic can benefit the social development of the city. A hotel can open opportunities for different people and groups to meet in the same point which can be used to increase the city´s social development. The tourism in Stockholm City is developing a lot today and more visitors visits the city day by day. The increase of visitors creates challenges for the range of hotels in the city. Utilizing areas in the inner city of Stockholm and urban areas that are exposed to noise from traffic is an advantage to build a hotel since Boverket does not require any benchmarks for noise. To make use of these kinds of properties, can also increase the range of hotels for the visitors in the city. This project will present a hotel that is located in Årstafältet in the southern part of Stockholm City. Årstafältet is a place that is exposed to high noise because of the highway on Huddingevägen that passes through the place. The problem with the location is the traffic noise which has a negative effect on housing constructions in the area. The noise problem in the area gives the chosen property good conditions for building a hotel and allows the residents close to the hotel property, to be less affected by the noise level coming from the traffic jam.

  • 124126. You, L.
    et al.
    Yuan, D.
    Lei, L.
    Sun, S.
    Chatzinotas, S.
    Ottersten, Björn
    Institute for Infocomm Research, Agency for Science, Technology, and Research, Singapore, 138632, Singapore.
    Resource Optimization With Load Coupling in Multi-Cell NOMA2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 7, p. 4735-4749Article in journal (Refereed)
    Abstract [en]

    This paper investigates the problem of the interference among multiple simultaneous transmissions in the downlink channel of a multiantenna wireless system. A symbol-level precoding scheme is considered, in order to exploit the multiuser interference and transform it into useful power at the receiver side, through a joint utilization of the data information and the channel state information. In this context, this paper presents novel strategies that exploit the potential of symbol-level precoding to control the per-antenna instantaneous transmit power. In particular, the power peaks among the transmitting antennas and the instantaneous power imbalances across the different transmitted streams are minimized. These objectives are particularly relevant with respect to the nonlinear amplitude and phase distortions induced by the per-antenna amplifiers, which are important sources of performance degradation in practical systems. More specifically, this paper proposes two different symbol-level precoding approaches. The first approach performs a weighted per-antenna power minimization, under quality-of-service constraints and under a lower bound constraint on the per-antenna transmit power. The second strategy performs a minimization of the spatial peak-to-average power ratio, evaluated among the transmitting antennas. Numerical results are presented in a comparative fashion to show the effectiveness of the proposed techniques, which outperform the state-of-the-art symbol-level precoding schemes in terms of spatial peak-to-average power ratio, spatial dynamic range, and symbol error rate over nonlinear channels.

  • 124127.
    You, Yang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Li, Zuxing
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Optimal Privacy-Enhancing and Cost-Efficient Energy Management Strategies for Smart Grid Consumers2018In: 2018 IEEE Statistical Signal Processing Workshop, SSP 2018, Institute of Electrical and Electronics Engineers Inc. , 2018, p. 144-148Conference paper (Refereed)
    Abstract [en]

    The design of optimal energy management strategies that trade-off consumers' privacy and expected energy cost by using an energy storage is studied. The Kullback-Leibler divergence rate is used to assess the privacy risk of the unauthorized testing on consumers' behavior. We further show how this design problem can be formulated as a belief state Markov decision process problem so that standard tools of the Markov decision process framework can be utilized, and the optimal solution can be obtained by using Bellman dynamic programming. Finally, we illustrate the privacy-enhancement and cost-saving by numerical examples. 

  • 124128.
    You, Yang
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Qin, Chong
    Gong, Yi
    Resource Allocation for a Full-Duplex Base Station Aided OFDMA System2017In: PROCEEDINGS OF THE 2ND INTERNATIONAL CONFERENCE ON EDUCATIONAL MANAGEMENT AND ADMINISTRATION (COEMA 2017) / [ed] Kusumaningrum, D E, ATLANTIS PRESS , 2017Conference paper (Refereed)
    Abstract [en]

    Exploiting full-duplex (FD) technology on base stations (BSs) is a promising solution to enhancing the system performance. Motivated by this, we revisit a full-duplex base station (FD-BS) aided OFDMA system, which consists of one BS, several uplink/downlink users and multiple subcarriers. A joint 3-dimensional (3D) mapping scheme among subcarriers, down-link users (DUEs), uplink users (UUEs) is considered as well as an associated power allocation optimization. In detail, we first decompose the complex 3D mapping problem into three 2-dimensional sub ones and solve them by using the iterative Hungarian method, respectively. Then based on the Lagrange dual method, we sequentially solve the power allocation and 3-dimensional mapping problem by fixing a dual point. Finally, the optimal solution can be obtained by utilizing the sub-gradient method. Unlike existing work that only solves either 3D mapping or power allocation problem but with a high computation complexity, we tackle both of them and have successfully reduced computation complexity from exponential to polynomial order. Numerical simulations are conducted to verify the proposed scheme.

  • 124129.
    You, Yantian
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Cloud Auto-Scaling Control Engine Based on Machine Learning2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the development of modern data centers and networks, many service providers have moved most of their computing functions to the cloud.  Considering the limitation of network bandwidth and hardware or virtual resources, how to manage different virtual resources in a cloud environment so as to achieve better resource allocation is a big problem.  Although some cloud infrastructures provide simple default auto-scaling and orchestration mechanisms, such as OpenStack Heat service, they usually only depend on a single parameter, such as CPU utilization and cannot respond to the network changes in a timely manner.<p> This thesis investigates different auto-scaling mechanisms and designs an on-line control engine that cooperates with different OpenStack service APIs based on various network resource data.  Two auto-scaling engines, Heat orchestration based engine and machine learning based online control engine, have been developed and compared for different client requests patterns.  Two machine learning methods, neural network, and linear regression have been considered to generate a control signal based on real-time network data.  This thesis also shows the network’s non-linear behaviors for heavy traffic and proposes a scaling policy based on deep network analysis.<p> The results show that for offline training, the neural network and linear regression provide 81.5% and 84.8% accuracy respectively.  However, for online testing with different client request patterns, the neural network results are different than we expected, while linear regression provided us with much better results.  The model comparison showed that these two auto-scaling mechanisms have similar behavior for a SMOOTH-load Pattern.  However, for the SPIKEY-load Pattern, the linear regression based online control engine responded faster to network changes while heat orchestration service shows some delay.  Compared with the proposed scaling policy with fewer web servers in use and acceptable response latency, both of the two auto-scaling models waste network resources.

  • 124130.
    You, Yantian
    KTH, School of Information and Communication Technology (ICT).
    Sparsity Analysis of Deep Learning Models and Corresponding Accelerator Design on FPGA2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Machine learning has achieved great success in recent years, especially the deep learning algorithms based on Artificial Neural Network. However, high performance and large memories are needed for these models , which makes them not suitable for IoT device, as IoT devices have limited performance and should be low cost and less energy-consuming. Therefore, it is necessary to optimize the deep learning models to accommodate the resource-constrained IoT devices.

    This thesis is to seek for a possible solution of optimizing the ANN models to fit into the IoT devices and provide a hardware implementation of the ANN accelerator on FPGA. The contribution of this thesis mainly lies in two aspects: 1). analyze the sparsity in the two mainstream deep learning models – DBN and CNN. The DBN model consists of two hidden layers with Restricted Boltzmann Machines while the CNN model consists of 2 convolutional layers and 2 sub-sampling layer. Experiments have been done on the MNIST data set with the sparsity of 75%. The ratio of the multiplications resulting in near-zero values has been tested. 2). FPGA implementation of an ANN accelerator. This thesis designed a hardware accelerator for the inference process in ANN models on FPGA (Stratix IV: EP4SGX530KH40C2). The main part of hardware design is the processing array consists of 256 Multiply-Accumulators array, which can conduct multiply-accumulate operations of 256 synaptic connections simultaneously. 16-bit fixed point computation is used to reduce the hardware complexity, thus saving power and area.

    Based on the evaluation results, it is found that the ratio of the multiplications under the threshold of 2-5 is 75% for CNN with ReLU activation function, and is 83% for DBN with sigmoid activation function, respectively. Therefore, there still exists large space for complex ANN models to be optimized if the sparsity of data is fully utilized. Meanwhile, the implemented hardware accelerator is verified to provide correct results through 16-bit fixed point computation, which can be used as a hardware testing platform for evaluating the ANN models.

  • 124131. You, Yintao
    et al.
    Yang, Kunlong
    Yuan, Sijian
    Dong, Shiqi
    Zhang, Huotian
    Huang, Qinglan
    Gillin, William P.
    Zhan, Yiqiang
    Zheng, Lirong
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    An organic multilevel non-volatile memory device based on multiple independent switching modes2014In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 15, no 9, p. 1983-1989Article in journal (Refereed)
    Abstract [en]

    The demand for higher data density memory structures is greater today than ever before. Multilevel resistive organic memory devices (OMD) provide an ideal solution, in being easily fabricated, cost-effective and at the same time promising high storage capacity. However, conventional methods for multilevel OMDs impose demanding requirements on material properties and attain only limited performance. We hereby provide an alternative design concept that combines multiple switching modes in one device to realize multilevel function. The device possesses a simple structure by using a ferroelectric phase-separated blend as the active layer. Two switching modes, the ferroelectric switching and the metallic filament switching, are realized simultaneously in this device, and enable a ternary storage function. The cross-section scanning electron microscope (SEM) images provide a strong evidence of the formation and annihilation of the metallic filament.

  • 124132.
    Youhanan, Lena
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Environmental Assessment of Textile Material Recovery Techniques: Examining Textile Flows in Sweden2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The production of textiles, focusing on cotton and polyester, carries with it major environmental concerns such as significant water and chemical use as well as the use of non-renewable resources. Measures need to be taken to decrease those environmental burdens. The present study investigates four different recovery techniques in terms of specific environmental factors. The investigated recovery methods are the Re:newcell method, polyester recycling, textile to insulation material and biogas production from the digestion of textile waste. Incineration is also included as a reference alternative. Waste flows in Sweden are estimated through a literature review of conducted waste analyses and estimations as to the amount of secondary product that can be produced from that input are duly made. Further, the environmental implications of three potential locations for a sorting facility are investigated. Converting cotton into biogas was found to be an unrealistic approach since it is economically inviable and little or no energy is actually gained when transportation costs are taken into consideration. Further studies on the benefits and costs of recycling cotton into insulation material are needed. The unavoidable transportation related to collection, sorting and recycling are not to be underestimated and could in some cases hinder future environmental improvements.  Finally, the study found that fiber material recycling is the only treatment method that has the potential to decrease the environmental burdens related to primary production although, despite the fact it requires the most water and chemicals. However, the data reliability in the current study is a matter of concern and further research in the form of standardized data collection and the use of analytical and strategic tools in further assessments is recommended. Although the recovery of textile material is crucial for decreasing the environmental burdens from primary production of textiles, the work in preventing textile waste is even more vital. In the long run, the prevention of waste is far more important as recovery processes demands their own share of resources.

  • 124133. Younan, George
    Backend for an End User Portal2009Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper examines how the Backend of a web portal can be built, investigating different techniques required to deliver a fully qualified solution. The main goal is to converge services and information from remote systems to a single access point. The communication with remote systems adds a demand for flexible usage of the software. Two design patterns that provide means to easily change the implementation in use is regarded; Dependency Injection (DI) and Service Locator.

    Desired uses for the Portal was gathered and a number of these were successfully implemented with the use of DI in a prototype solution. Different standards and guidelines for remote access to home devices was evaluated, gathering the strengths and drawbacks of each one. The evaluation of remote access showed that there is no silver bullet, but rather compromises will be necessary when choosing a technique.

  • 124134. Younas, I.
    et al.
    Kamrani, F.
    Bashir, M.
    Schubert, J.
    KTH, School of Electrical Engineering and Computer Science (EECS). Swedish Defence Research Agency, Stockholm Sweden.
    Efficient genetic algorithms for optimal assignment of tasks to teams of agents2018In: Neurocomputing, ISSN 0925-2312, E-ISSN 1872-8286, Vol. 314, p. 409-428Article in journal (Refereed)
    Abstract [en]

    The problem of optimally assigning agents (resources) to a given set of tasks is known as the assignment problem (AP). The classical AP and many of its variations have been extensively discussed in the literature. In this paper, we examine a specific class of the problem, in which each task is assigned to a group of collaborating agents. APs in this class cannot be solved using the Hungarian or other known polynomial time algorithms. We employ the genetic algorithm (GA) to solve the problem. However, we show that if the size of the problem is large, then standard crossover operators cannot efficiently find near-optimal solutions within a reasonable time. In general, the efficiency of the GA depends on the choice of genetic operators (selection, crossover, and mutation) and the associated parameters. In order to design an efficient GA for determining the near-optimal assignment of tasks to collaborative agents, we focus on the construction of crossover operators. We analyze why a naive implementation with standard crossover operators is not capable of sufficiently solving the problem. Furthermore, we suggest modifications to these operators by adding a shuffled list and introduce two new operators (team-based and team-based shuffled list). We demonstrate that the modified and new operators with shuffled lists perform significantly better than all operators without shuffled lists and solve the presented AP more efficiently. The performance of the GA can be further enhanced by using chaotic sequences. Moreover, the GA is also compared with the particle swarm optimization (PSO) and differential evolution (DE) algorithms, demonstrating the superiority of the GA over these search algorithms. 

  • 124135.
    Younas, Irfan
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Using Genetic Algorithms for Large Scale Optimizationof Assignment, Planning and Rescheduling Problems2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There has always been a need to solve real-life large-scale problems, suchas efficiently allocating limited resources, and other complex and conflicting situations related to combinatorial optimization genre. A class of combinato- rial optimization problems is NP-hard and, among many well-known, several of them are assignment, planning and rescheduling problems. Assignment problems can deal with optimal assignment of teams of collaborating agents; planning problems can be effects-based planning that search for promising plans to get desired end states with minimal cost; rescheduling problems can be multi-criteria optimization of rescheduling resources that modify existing original schedule. These large scale optimization problems are complex with intractable and highly complex search spaces. Currently, there are no known algorithms with polynomial time complexity, which can solve these problems. Genetic Algorithms have been successfully applied to solve many complex optimization problems but not to the specific problems mentioned above.

    The aim of the research, presented in this thesis, is to use Genetic Algo- rithms for large scale optimization of assignment, planning and rescheduling problems. More specifically, the contributions of the thesis are to: (i) adapt existing and develop new efficient Genetic Algorithms to solve large scale as- signment problems, and (ii) adapt existing Genetic Algorithms to solve large scale effects-based planning, and multi-objective rescheduling optimization problems.In case of assignment, we solve a team assignment problem and investigate specific regions in a solution space for assignment problems with huge search spaces.

    For the team assignment, an existing Genetic Algorithm is adapted and applied for optimal assignment of tasks to teams of collaborating agents. The algorithm is scalable, stable, robust and produces a near optimal solution. The results of the team assignment problem show that the existing Genetic Algorithms are not efficient for optimal assignment of tasks to teams of agents. Hence, to solve larger instances of the problem efficiently, new Genetic Algo- rithms are developed with emphasis on the construction of crossover opera- tors. Since teams assignment can be multi-criteria, a multi-objective model is constructed and two widely used multi-objective evolutionary algorithms are applied. Further, for the assignment problems with huge search spaces, an existing Genetic Algorithm is adapted to extract possible combinations of input parameters from a specified solution space region. To solve the large scale effects-based planning, a multi-objective optimization problem is formu- lated for the evaluation of operational plans and a multi-objective Genetic Algorithm is adapted and applied to the problem. The results show that the suggested algorithm is much more efficient than A*. For the rescheduling problem, a multi-objective optimization model for rescheduling of resources is proposed and a multi-objective Genetic Algorithm is adapted and applied to obtain the Pareto-optimal solutions.

    The research presented in this thesis confirms that Genetic Algorithms can be used for large scale assignment, planning and rescheduling problems since they have shown to be suitable in solving these problems efficiently.

  • 124136.
    Younas, Irfan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Software and Computer Systems, SCS.
    Ayani, Rassul
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Software and Computer Systems, SCS.
    Schubert, Johan
    Swedish Defence Research Agency, Stockholm, Sweden.
    Using Genetic Algorithms for investigating specific regions of the solution space2011In: Proceedings of the 2011 African Conference on Software Engineering and Applied Computing (ACSEAC 2011), 2011Conference paper (Refereed)
    Abstract [en]

    In many practical cases decision makers are interested to understand the whole solution space, including possible outliers. By outlier we mean there is a solution that is theoretically possible, though with very low probability that it occurs. In many combinatorial problems, this is a very challenging task. During the past decade, the Data Farming community has done substantial work on developing methods and techniques for better understanding of the solution space. The data farming community has also looked at the design of experiments and used Latin hypercube (LH) techniques for this purpose. The LH is proven to be one of the important sampling methods for selecting a representative subset of the input space. In this paper, we consider a company X that wants to outsource m subprojects of a given project P. We assume that there are n potential subcontractors for each subproject. Thus, there will be n^m ways to assign the subprojects to the potential subcontractors. The project manager is interested to find those assignments that complete the project within a given time and a given cost frame. An exhaustive examination of all assignments is not feasible, if m and n are big numbers. We propose an objective-based genetic algorithm (GA) for finding the set of assignments that are mapped onto a given subset of the solution space. It means, as opposed to the design of experiment techniques, we start from the solution space and try to find the combinations of the input parameter values that can lead to a specific region of the solution space. By some numerical examples, we show how our GA identifies the set of such feasible assignments.

  • 124137.
    Younas, Irfan
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Ayani, Rassul
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Schubert, Johan
    Swedish Defense Research Agency (FOI).
    Asadi, Hirad
    Swedish Defense Research Agency (FOI).
    Using genetic algorithms in effects-based planning2013In: Proceedings of the 2013 IEEE International Conference on Systems, Man, and Cybernetics (SMC), IEEE Computer Society, 2013, p. 438-443Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a genetic algorithm-based method for evaluation of operational plans within effects-based planning. We formulate the effects-based planning problem as a bi-objective optimization problem, in which the distance from the initial state to the current state (g) and the distance from the current state to the desired end state (h) are minimized. To solve the problem, we adopt Non-dominated Sorting Genetic Algorithm-II (NSGA-II). Considering an expeditionary operation scenario, we simulate a subset of possible plans and present the decision maker with a set of promising plans which are capable of approaching the desired end state efficiently. In order to discuss the efficiency and effectiveness of the algorithm, we compare the results of NSGA-II with the results of A*. The computational results show that NSGA-II is much more efficient than A* with regard to g. On the other hand A* is a little more effective with regard to h.

  • 124138.
    Younas, Irfan
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Kamrani, Farzad
    Swedish Defence Research Agency, Stockholm, Sweden.
    Ayani, Rassul
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Optimization of assignment of tasks to teams using multi-objective metaheuristics2013In: GECCO 2013 - Proceedings of the 2013 Genetic and Evolutionary Computation Conference Companion, Association for Computing Machinery (ACM), 2013, p. 103-104Conference paper (Refereed)
    Abstract [en]

    A highly interesting but not thoroughly addressed optimization problem is a variation of the Assignment Problem (AP) where tasks are assigned to groups of collaborating agents (teams). In this paper, we address this class of AP as a bi-objective optimization problem, in which the cost is minimized and the quality is maximized. To solve the model, we adopt Non-dominated Sorting Genetic Algorithm-II (NSGAII) and Strength Pareto Evolutionary Algorithm 2 (SPEA2). We conduct several experiments on problems with varying sizes to compare the NSGA-II and SPEA2 algorithms.

  • 124139.
    Younas, Irfan
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Kamrani, Farzad
    Swedish Defense Research Agency (FOI).
    Moradi, Farshad
    Swedish Defense Research Agency (FOI).
    Ayani, Rassul
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Schubert, Johan
    Swedish Defense Research Agency (FOI).
    Håkansson, Anne
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Solving Battalion Rescheduling Problem Using Multi-objective Genetic Algorithms2013In: Asiasim 2013: 13th International Conference on Systems Simulation. Proceedings, Singapore, November 6-8, 2013., Springer Berlin/Heidelberg, 2013, p. 93-104Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider the problem of rescheduling human resources in a battalion where new activities are assigned to the battalion by higher headquarters, requiring modification of an existing original schedule. The problem is modeled as a multi-criteria optimization problem with three objectives: (i) maximizing the number of tasks that are performed, (ii) minimizing the number of high-priority tasks that are missed, and (iii) minimizing the difference between the original schedule and the modified one. In order to solve the optimization model, we adopt Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The accuracy of NSGA-II in this context is verified by considering a small-sized problem where it is easy to verify solutions. Furthermore, we consider a realistic problem instance for a battalion with 400 agents and 66 tasks in the initial schedule. We present the computational result of rescheduling when unpredictable activities emerge.

  • 124140.
    Younas, Irfan
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Kamrani, Farzad
    Swedish Defence Research Agency, Stockholm, Sweden.
    Schulte, Christian
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Ayani, Rassul
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Efficient Genetic Algorithms for Optimal Assignment of Tasks to Teamsof AgentsManuscript (preprint) (Other academic)
    Abstract [en]

    The problem of optimally assigning agents (resources) to a given set oftasks is known as the Assignment Problem (AP). The classical AP and manyof its variations have been discussed extensively in the literature. In thispaper, we present a specific class of Assignment Problems (APs) in which eachtask is assigned to a group of collaborating agents. In this AP, collaborationof all agents is required to perform the task and an agent cannot individuallydo it.

    We present a mathematical model for this type of AP and use GeneticAlgorithm (GA) to solve the model, since there are no known polynomial timealgorithms for this class of APs. We show that for larger instances of the problem,the GA with one-point crossover operator cannot efficiently find nearoptimalsolutions. In general, the efficiency of the GA depends on the choiceof genetic operators (selection, crossover, mutation) and associated parameters.In order to design an efficient GA for finding near optimal assignment oftasks to collaborative teams, we focus on construction of crossover operators.We compare and analyze the efficiency of several well-known crossover operatorssuch as one-point, two-point, three-point, position-based and order-basedcrossover operators. We suggest modifications to these operators by addinga shuffled repair list to them and show that their efficiency is enhanced forsolving the presented AP. Furthermore, we introduce two new crossover operators,team-based and team-based shuffled list crossover operators, whichsolve large-scale models of our AP efficiently.

  • 124141.
    Younas, Irfan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Software and Computer Systems, SCS (Closed 20120101).
    Kamrani, Farzad
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Software and Computer Systems, SCS (Closed 20120101).
    Schulte, Christian
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Software and Computer Systems, SCS (Closed 20120101).
    Ayani, Rassul
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Software and Computer Systems, SCS (Closed 20120101).
    Optimization of Task Assignment to Collaborating Agents2011In: IEEE SSCI 2011 - Symposium Series on Computational Intelligence - CISched 2011, Paris, France: IEEE Computational Intelligence Society , 2011, p. 17-24Conference paper (Refereed)
    Abstract [en]

    The classic task assignment problem (AP) assigns m agents to n tasks, where each task is assigned to exactly one agent. This problem and many of its variations, including the case where a task is assigned to a group of agents working independently, have been discussed extensively in the literature. We consider a specific class of task assignment problems where each task is assigned to a group of collaborating agents that work as a team. Thus, changing one of the group members may have a vital impact on the output of the group. We assume that each agent has a set of capabilities and each task has certain requirements. The objective is to assign agents to teams such that the gain is maximized.

    We suggest a Genetic Algorithm (GA) for finding a near optimal solution to this class of task assignment problems. To the best of our knowledge, this class of APs has not been considered in the literature, probably due to the difficulty of evaluating the performance of a team of agents. Recently, we have developed a formal method for measuring performance of a team which is used in this paper to formulate the objective function of our GA. We analyze the quality of the obtained solution by comparing the result of our GA with (a) the exact solution of some smaller problems, and (b) with the results of the exact solution of specific cases that can be obtained by the Hungarian algorithm. We provide experimental results on efficiency, stability, robustness and scalability of the solution obtained by our GA.

  • 124142.
    Young, Benjamin
    et al.
    McGill University, Montreal, Canada.
    Bryan, Jim
    Generating functions for colored 3D Young diagrams and the Donaldson-Thomas invariants of orbifolds: With an appendix by Jim Bryan2010In: Duke mathematical journal, ISSN 0012-7094, E-ISSN 1547-7398, Vol. 152, no 1, p. 115-153Article in journal (Refereed)
    Abstract [en]

    We derive two multivariate generating functions for three-dimensional (3D) Young diagrams (also called plane partitions). The variables correspond to a coloring of the boxes according to a finite Abelian subgroup G of SO (3). These generating functions turn out to be orbifold Donaldson-Thomas partition functions for the orbifold [C 3/G]. We need only the vertex operator methods of Okounkov, Reshetikhin, and Vafa for the easy case G = Z n; to handle the considerably more difficult case G = Z 2 × Z 2, we also use a refinement of the author's recent q-enumeration of pyramid partitions. In the appendix, we relate the diagram generating functions to the Donaldson-Thomas partition functions of the orbifold [C 3/G]. We find a relationship between the Donaldson-Thomas partition functions of the orbifold and its G-Hilbert scheme resolution. We formulate a crepant resolution conjecture for the Donaldson-Thomas theory of local orbifolds satisfying the hard Lefschetz condition.

  • 124143.
    Young, Donovan
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Form factors of chiral primary operators at two loops in ABJ(M)2013In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 6, p. 049-Article in journal (Refereed)
    Abstract [en]

    We calculate the colour-ordered form factor for chiral primary operators built from J scalar fields of ABJ(M) theory to J scalar final states. We work in the 't Hooft limit and show that the leading quantum correction is O(lambda(2)), where lambda is the 't Hooft coupling. We evaluate this leading correction using standard Feynman diagrams and dimensional regularization, and find that the leading divergence is 1/epsilon(2) where the spacetime dimension is d = 3 - 2 epsilon. We further find that the result respects maximal transcendentality.

  • 124144. Young, Donovan
    et al.
    Zarembo, Konstantin
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Stockholm, Sweden; Uppsala University, Uppsala, Sweden; ITEP, Moscow, Russian Federation .
    Holographic dual of the Eguchi-Kawai mechanism2014In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 6, p. 030-Article in journal (Refereed)
    Abstract [en]

    The holographic dual of N = 2*, D = 4 supersymmetric Yang-Mills theory has many features common to 5d CFT. We interpret this as a manifestation of Eguchi-Kawai mechanism.

  • 124145. Young, J. P.
    et al.
    Forsberg, Lars E.
    KTH, School of Computer Science and Communication (CSC), Centres, Parallel and Scientific Computing Institute, PSCI.
    Simulating activations with cytoarchitecture2005In: Anatomy and Embryology, ISSN 0340-2061, E-ISSN 1432-0568, Vol. 210, no 5-6, p. 407-410Article in journal (Refereed)
    Abstract [en]

    Cytoarchitectonic delineation of areas in post-mortem human brains provides the precise location of these areas. It has been possible to study the size and location of areas between post-mortem brains with multi-subject cytoarchitectonic data. If the structure-function relationship is assumed to be a one-to-one mapping for the purposes of inter-subject variability, then functional areas in the cortex will also adhere to the structure, and therefore, the location and size of cytoarchitectonic areas in the brain. Thus, it is possible to use the cytoarchitectonic data as being representative of the size and location of functional activations. Under this assumption, we simulated activations in cytoarchitectonic areas from ten post-mortem brains in this study. We then treated these data as we would a normal PET experiment. The purpose of this study is to demonstrate a standard PET image analysis on a simulated ten-subject PET study using cytoarchitecture to localize the activations. By doing so, we simulate activations with real inter-subject variability with the size and location of each area. Significant activations were obtained for activations simulated in areas 3a and 3b. A voxel-wise conjunction between simulated data and experimental data was made to better determine the underlying areas activated by the experimental tasks. This study presents a novel technique for demonstrating the effect of standard image analysis on the location and size of simulated activations as determined by cytoarchitectonic data from multiple subjects. Furthermore, this technique has been applied to better determine the underlying areas activated in an experiment.

  • 124146.
    Young, Pete Y
    et al.
    Massachusetts Institute of Technology.
    Malmqvist, Johan
    Chalmers University of Technology.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Kuttenkeuler, Jakob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Svensson, Thomas
    Linköping university.
    Cunningham, Goeffrey
    Queen's University Belfast.
    Design and development of CDIO student workspaces - Lessons learned2005In: 2005 ASEE Annual Conference and Exposition: The Changing Landscape of Engineering and Technology Education in a Global World, 2005, p. 2867-2880Conference paper (Refereed)
    Abstract [en]

    CDIO project, which is an initiative that aims to develop a new model for engineering education, was discussed. A prominent attribute of the CDIO initiative has been the design and implementation of a new class of student workspaces that enable students to design, build and test project-based courses. A large number of factors were considered for the proper set-up of a student workspace that supports design-build-test education experiences. The factors are ownership, functionality, staff competence, costs, safety, security and sustainability.

  • 124147.
    Young, Steve M.
    et al.
    Naval Res Lab, Ctr Computat Mat Sci, Washington, DC 20375 USA..
    Wieder, Benjamin J.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden..
    Filling-Enforced Magnetic Dirac Semimetals in Two Dimensions2017In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 118, no 18, article id 186401Article in journal (Refereed)
    Abstract [en]

    Filling-enforced Dirac semimetals, or those required at specific fillings by the combination of crystalline and time-reversal symmetries, have been proposed in numerous materials. However, Dirac points in these materials are not generally robust against breaking or modifying time-reversal symmetry. We present a new class of two-dimensional Dirac semimetal protected by the combination of crystal symmetries and a special, antiferromagnetic time-reversal symmetry. Systems in this class of magnetic layer groups, while having broken time-reversal symmetry, still respect the operation of time-reversal followed by a half-lattice translation. In contrast to 2D time-reversal-symmetric Dirac semimetal phases, this magnetic Dirac phase is capable of hosting just a single isolated Dirac point at the Fermi level, one that can be stabilized solely by symmorphic crystal symmetries. We find that this Dirac point represents a new quantum critical point, existing at the boundary between Chern insulating, antiferromagnetic topological crystalline insulating, and trivial insulating phases, and we discuss its relationship with condensed matter fermion doubling theorems. We present density functional theoretic calculations which demonstrate the presence of these 2D magnetic Dirac points in FeSe monolayers and discuss the implications for engineering quantum phase transitions in these materials.

  • 124148. Younus, M. D. I.
    et al.
    Ismail, Mohammed
    Phase calibration technique for mismatch optimization in image-reject receivers2006In: Analog Integrated Circuits and Signal Processing, ISSN 0925-1030, E-ISSN 1573-1979, Vol. 46, no 2, p. 165-168Article in journal (Refereed)
    Abstract [en]

    This paper presents phase calibration technique without using any external tone for weaver image-reject receiver. Error signal (phase mismatch information) is generated using a simple algorithm and this signal is used for mismatch elimination. Calibration system has been implemented using simulink which shows an image rejection ratio of 59.5 dB can be achieved for RF signal operating at 1.8 GHz.

  • 124149.
    Yous, Nora
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Solvallastadens skola2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A Kindergarden and Primary School for 240 childern and 40 teachers. The school is located in the not yet buildt suburb "Solvallastaden" in Stockholm, Sweden.

  • 124150. Yousafzai, Muhammad Sulaiman
    et al.
    Coceano, Giovanna
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Bonin, Serena
    Niemela, Joseph
    Scoles, Giacinto
    Cojoc, Dan
    Investigating the effect of cell substrate on cancer cell stiffness by optical tweezers2017In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 60, p. 266-269Article in journal (Refereed)
    Abstract [en]

    The mechanical properties of cells are influenced by their microenvironment. Here we report cell stiffness alteration by changing the cell substrate stiffness for isolated cells and cells in contact with other cells. Polydimethylsiloxane (PDMS) is used to prepare soft substrates with three different stiffness values (173, 88 and 17 kPa respectively). Breast cancer cells lines, namely HBL-100, MCF-7 and MDA-MB-231 with different level of aggressiveness are cultured on these substrates and their local elasticity is investigated by vertical indentation of the cell membrane. Our preliminary results show an unforeseen behavior of the MDA-MB-231 cells. When cultured on glass substrate as isolated cells, they are less stiff than the other two types of cells, in agreement with the general statement that more aggressive and metastatic cells are softer. However, when connected to other cells the stiffness of MDA-MB-231 cells becomes similar to the other two cell lines. Moreover, the stiffness of MDA-MB-231 cells cultured on soft PDMS substrates is significantly higher than the stiffness of the other cell types, demonstrating thus the strong influence of the environmental conditions on the mechanical properties of the cells. 

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