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  • 2901. Ahuja, R.
    et al.
    Rekhi, S.
    Saxena, S. K.
    Johansson, Börje
    High-pressure structural phase transitions in RuO2 and its geophysical implications2001In: Journal of Physics and Chemistry of Solids, ISSN 0022-3697, E-ISSN 1879-2553, Vol. 62, no 11, p. 2035-2037Article in journal (Refereed)
  • 2902. Ahuja, Rajeev
    et al.
    da Silva, A. F.
    Persson, Clas
    Osorio-Guillen, J. M.
    Pepe, I.
    Jarrendahl, K.
    Lindquist, O. P. A.
    Edwards, N. V.
    Wahab, Q.
    Johansson, Börje
    Optical properties of 4H-SiC2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 4, p. 2099-2103Article in journal (Refereed)
    Abstract [en]

    The optical band gap energy and the dielectric functions of n-type 4H-SiC have been investigated experimentally by transmission spectroscopy and spectroscopic ellipsometry and theoretically by an ab initio full-potential linear muffin-tin-orbital method. We present the real and imaginary parts of the dielectric functions, resolved into the transverse and longitudinal photon moment a, and we show that the anisotropy is small in 4H-SiC. The measurements and the calculations fall closely together in a wide range of energies.

  • 2903.
    Ahuja, Rajeev
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Li, Sa
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Johansson, Börje Örje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    High pressure structural transitions in Cm metal2006In: Mater Res Soc Symp Proc, 2006, p. 247-254Conference paper (Refereed)
    Abstract [en]

    The high pressure behaviour of Cm metal is investigated theoretically using ab initio electronic structure methods. Our calculations reproduce the structural phase transitions which are obsereved in recent experiment performed by Heatman et al. [Science 309, 110 (2005)]. Calculated transition pressures are in reasonable agreement with the experimental values. Calculations performed for an antiferromagnetic state is essential to reproduce the stability of Cm-III phase. Thus, the stability of the Cm-III phase is related to the spin polarization of its 5f electrons.

  • 2904.
    Ahuja, Rajeev
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Li, Sa
    Luo, Wei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    High-pressure structural transitions in Cm and Am0.5Cm0.5 binary alloy2006In: High Pressure Research, ISSN 0895-7959, E-ISSN 1477-2299, Vol. 26, no 4, p. 377-381Article in journal (Refereed)
    Abstract [en]

    The high-pressure behaviour of Cm and Am0.5Cm0.5 binary alloy is investigated theoretically using ab initio electronic structure methods. Our calculations reproduce the structural phase transitions, which are observed in recent experiment performed by Heathman et al. [S. Heathman, R.G. Haire, I Le Bihan et al., Science 309 110 (2005)] and Lindbaum et al. [A. Lindbaum, S. Heathman, T. Le Bihan et al., J. Phys: Condens. Matter 15 S2297 (2003)]. Calculated transition pressures are in reasonable agreement with the experimental values. Calculations performed for an antiferromagnetic state are essential to reproduce the stability of Cm-III phase.

  • 2905.
    Ahuja, Rajeev
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Osorio-Guillen, J. M.
    de Almeida, J. S.
    Holm, B.
    Ching, W. Y.
    Johansson, Börje
    KTH, Superseded Departments, Materials Science and Engineering.
    Electronic and optical properties of gamma-Al2O3 from ab initio theory2004In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 16, no 16, p. 2891-2900Article in journal (Refereed)
    Abstract [en]

    We report on a density functional theory calculation of the electronic structure and optical properties of gamma-Al2O3. We have made a comparison between the optical and electronic properties of the alpha and gamma phases of alumina. The calculated bulk modulus of the gamma phase is slightly lower than that of the a phase. The calculated static dielectric function and the optical constant of the gamma phase are very close to those of the alpha phase.

  • 2906.
    Ahuja, Rajeev
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Persson, Clas
    da Silva, A. F.
    de Almeida, J. S.
    Araujo, C. M.
    Johansson, Börje
    KTH, Superseded Departments, Materials Science and Engineering.
    Optical properties of SiGe alloys2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 7, p. 3832-3836Article in journal (Refereed)
    Abstract [en]

    The optical properties of Si1-xGex have been investigated theoretically using a full-potential linear muffin-tin-orbital method. We present the density-of-states as well as the real and imaginary parts of the dielectric function. The calculated dielectric function was found to be in good agreement with the spectroscopic ellipsometry measurements by J. Bahng , J. Phys.: Condens. Matter 13, 777 (2001), and we obtained a static dielectric constant of epsilon(0)=12.19+2.45x in the Si rich regime (xless than or equal to0.5).

  • 2907.
    Ai, Yuejie
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Theoretical studies on photophysics and photochemistry of DNA2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Theoretical studies on biological systems like nucleic acid and protein have been widely developed in the past 50 years and will continue to be a topic of interest in forefronts of natural science. In addition to experimental science, computational modeling can give useful information and help us to understand biochemical issues at molecular, atomic and even electronic levels.

    Deoxyribonucleic acid (DNA), the hereditary basis of life’s genetic identity, has always been major topic of discussions since its structure was built in 1953. However, harmful UV radiation from sunlight can make damage to DNA molecules and eventually give rise to DNA damaging biological consequences, like mutagenesis, carcinogenesis, and cell death. Photostability, photodamage, and photorepair are of vital importance in the photophysics and photochemistry of DNA. In this thesis, we have applied high level computer-aided theoretical methods to explore the underlying mechanisms for these three critical issues of DNA. Special attentions are paid to the following aspects: the properties of the excited states, the design of relevant computational models and the effects of biological environments.

    We have systematically studied the excited state properties of DNA from single base to base pair and oligonucleotides, where the concerted base pairing and base stacking effects was found to play important roles in DNA photostability. The UV-light induced isomerization mechanism between two photoproducts of DNA photodamage has been revealed in different biological environments. In association with DNA photodamage, the related photorepair processes have been proposed for different lesions in photolyase which is a catalytic enzyme for DNA, and the calculated results well explained the experimental observations. In particular, the internal and external properties of flavin cofactors have been extensively studied by combining the electronic structure and spectroscopic calculations. We have examined the effects of the intramolecular hydrogen bond on spectroscopic properties of flavins. The good agreements with the experimental spectra indicated that the biological self-regulation acted critical role in these biological systems.

  • 2908.
    Ai, Yuejie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Cui, Ganglong
    Beijing Normal University.
    Fang, Qiu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Fang, Weihai
    Beijing Normal University.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Exploring concerted effects of base pairing and stacking on the excited-state nature of DNA oligonucleotides by DFT and TD-DFT studies2011In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 111, no 10, p. 2366-2377Article in journal (Refereed)
    Abstract [en]

    We have taken (dA)5, (dT)5, and (dA)5•(dT)5 as model systems to study concerted effects of base pairing and stacking on excited-state nature of DNA oligonucleotides using density functional theory (DFT) and time dependent DFTmethods. The spectroscopic states are determined to be of a partial A →A charge transfernature in the A•T oligonucleotides. The T → T charge-transfer transitionsproduce dark states, which are hidden in the energy region of the steady-stateabsorption spectra. This is different from the previous assignment that the T → Tcharge-transfer transition is responsible for a shoulder at the red side of the first strongabsorption band. The A →T charge-transfer states were predicted to have relativelyhigh energies in the A•T oligonucleotides. The present calculations predict that the T→A charge-transfer states are not involved in the spectra and excited-state dynamics ofthe A•T oligonucleotides. In addition, the influence of base pairing and stacking on thenature of the 1nΠ* and 1ΠΠ* states are discussed in detail.

  • 2909. Ai, Yuejie
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ji, Yongfei
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Song, Wei-Guo
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hydrophobicity and Hydrophilicity Balance Determines Shape Selectivity of Suzuki Coupling Reactions Inside Pd@meso-SiO2 Nanoreactor2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 19, p. 10244-10251Article in journal (Refereed)
    Abstract [en]

    Molecular sorting and catalysis directed by shape selectivity have been extensively applied in porous extended frameworks for a low-carbon, predictable, renewable component of modern industry. A comprehensive understanding of the underlying recognition mechanism toward different shapes is unfortunately still missing, owing to the lack of structural and dynamic information under operating conditions. We demonstrate here that such difficulties can be overcome by state-of-the-art molecular dynamics simulations which provide atomistic details that are not accessible experimentally, as exemplified by our interpretation for the experimentally observed aggregation induced shape selectivity for Suzuki C-C coupling reaction catalyzed by Pd particles in mesoporous silica. It is found that both aggregation ability and aggregating pattern of the reactants play the decisive role in controlling the shape selectivity, which are in turn determined by the balance between the hydrophobicity and hydrophilicity of the reactants, or in other words, by the balance between the noncovalent hydrogen bonding interaction and van der Waals forces. A general rule that allows prediction of the shape selectivity of a reactant has been proposed and verified against experiments. We show that molecular modeling is a powerful tool for rational design of new mesoporous systems and for the control of catalytic reactions that are important for the petrochemical industry.

  • 2910.
    Ai, Yue-Jie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Liao, Rongzhen
    Stockholm University.
    Chen, Shilu
    Beijing Institute of Technology.
    Hua, Wei-Jie
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Fang, Wei-Hai
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Repair of DNA Dewar Photoproduct to (6-4) photoproduct in (6-4) Photolyase2011In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 115, no 37, p. 10976-10982Article in journal (Refereed)
    Abstract [en]

    Dewar photoproduct (Dewar PP) is the valence isomer of (6-4) photoproduct ((6-4)PP) in photodamaged DNA. Compared to the extensive studied CPD photoproducts, the underlying repair mechanisms for the (6-4)PP, and especially for the Dewar PP, are not well-established to date. In this paper, the repair mechanism of DNA Dewar photoproduct T(dew)C in (6-4) photolyase was elucidated using hybrid density functional theory. Our results showed that, during the repair process, the T(dew)C has to isomerize to T(6-4)C photolesion first via direct C6'-N3' bond cleavage facilitated by electron injection. This isomerization mechanism is energetically much more efficient than other possible rearrangement pathways. The calculations provide a theoretical interpretation to recent experimental observations.

  • 2911.
    Ai, Yue-Jie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Liao, Rong-zhen
    Chen, Shu-feng
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Fang, Wei-Hai
    Theoretical Studies on Photoisomerizations of (6-4) and Dewar Photolesions in DNA2010In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, no 44, p. 14096-14102Article in journal (Refereed)
    Abstract [en]

    The (6-4) photoproduct ((6-4) PP) is one of the main lesions in UV-induced DNA damage. The (6-4) PP and its valence isomer Dewar photoproduct (Dewar PP) can have a great threat of mutation and cancer but gained much less attention to date. In this study, with density functional theory (DFT) and the complete active space self-consistent field (CASSCF) methods, the photoisomerization processes between the (6-4) PP and the Dewar PP in the gas phase, the aqueous solution, and the photolyase have been carefully examined. Noticeably, the solvent effect is treated with the CASPT2//CASSCF/Amber (QM/MM) method. Our calculations show that the conical intersection (Cl) points play a crucial role in the photoisomerization reaction between the (6-4) PP and the Dewar PP in the gas and the aqueous solution. The ultrafast internal conversion between the S-2 ((1)pi pi*) and the So states via a distorted intersection point is found to be responsible for the formation of the Dewar PP lesion at 313 nm, as observed experimentally. For the reversed isomeric process, two channels involving the "dark" excited states have been identified. In addition to the above passages, in the photolyase, a new electron-injection isomerization process as an efficient way for the photorepair of the Dewar PP is revealed.

  • 2912.
    Ai, Yue-Jie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Liao, Rong-Zhen
    Fang, Wei-Hai
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Theoretical studies on the isomerization mechanism of the ortho-green fluorescent protein chromophore2012In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 14, no 38, p. 13409-13414Article in journal (Refereed)
    Abstract [en]

    We present a systematic theoretical investigation on the overall ground state and excited-state isomerization reaction mechanism of ortho-green fluorescent protein chromophore (o-HBDI) using the density functional theory and the multireference methods. The calculated results and subsequent analysis suggest the possible isomerization mechanism for o-HBDI. By comparison with experimental observation and detailed analysis, it is concluded that as initiated by the excited-state intramolecular proton transfer reaction, the conical intersection between the ground state and the excited state along the C4-C5 single-bond rotational coordinate is responsible for the rapid deactivation of o-HBDI.

  • 2913.
    Ai, Yuejie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tian, Guangjun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Liao, Rongzhen
    Stockholm University.
    Zhang, Qiong
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Fang, Weihai
    Beijing Normal University.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Intrinsic property of flavin mononucleotide controls its optical spectra in three redox states2011In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 12, no 16, p. 2899-2902Article in journal (Refereed)
  • 2914.
    Ai, Yue-Jie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tian, Guangjun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Role of non-Condon vibronic coupling and conformation change on two-photon absorption spectra of green fluorescent protein2013In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 111, no 9-11, p. 1316-1321Article in journal (Refereed)
    Abstract [en]

    Two-photon absorption spectra of green fluorescent proteins (GFPs) often show a blue-shift band compared to their conventional one-photon absorption spectra, which is an intriguing feature that has not been well understood. We present here a systematic study on one- and two-photon spectra of GFP chromophore by means of the density functional response theory and complete active space self-consistent field (CASSCF) methods. It shows that the popular density functional fails to provide correct vibrational progression for the spectra. The non-Condon vibronic coupling, through the localised intrinsic vibrational modes of the chromophore, is responsible for the blue-shift in the TPA spectra. The cis to trans isomerisation can be identified in high-resolution TPA spectra. Our calculations demonstrate that the high level ab initio multiconfigurational CASSCF method, rather than the conventional density functional theory is required for investigating the essential excited-state properties of the GFP chromophore.

  • 2915.
    Ai, Yuejie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Zhang, Feng
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Chen, Shufeng
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Fang, Weihai
    Importance of the Intramolecular Hydrogen Bond on the Photochemistry of Anionic Hydroquinone (FADH-) in DNA Photolyase2010In: Journal of Physical Chemisty Letters, ISSN 1948-7185, Vol. 1, p. 743-747Article in journal (Refereed)
    Abstract [en]

    The design of a proper molecular model with a good balance between the size of the model system and the computational capacity is essential for theoretical modeling of biological systems. We have shown in this letter that the often used model system, a lumiflavin (7,8-dimethy-10-methyl-isoalloxazine), can not correctly describe geometrical and electronic structures of FADHin DNA photolyase. The intramolecular hydrogen bond between the isoalloxazine ring and the ribityl moiety is found to play a significant role in controlling photochemical properties of FADHin DNA photolyase

  • 2916.
    Ai, Yue-Jie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Zhang, Feng
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Cui, Gang-Long
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Fang, Wei-Hai
    Ultrafast deactivation processes in the 2-aminopyridine dimer and the adenine-thymine base pair: Similarities and differences2010In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 133, no 6, p. 064302-Article in journal (Refereed)
    Abstract [en]

    2-aminopyridine dimer has frequently been used as a model system for studying photochemistry of DNA base pairs. We examine here the relevance of 2-aminopyridine dimer for a Watson-Crick adenine-thymine base pair by studying UV-light induced photodynamics along two main hydrogen bridges after the excitation to the localized (1)pi pi(*) excited-state. The respective two-dimensional potential-energy surfaces have been determined by time-dependent density functional theory with Coulomb-attenuated hybrid exchange-correlation functional (CAM-B3LYP). Different mechanistic aspects of the deactivation pathway have been analyzed and compared in detail for both systems, while the related reaction rates have also be obtained from Monte Carlo kinetic simulations. The limitations of the 2-aminopyridine dimer as a model system for the adenine-thymine base pair are discussed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3464485]

  • 2917. Aiba, N
    et al.
    Giroud, C
    Honda, M
    Delabie, E
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Saarelma, S
    Hillesheim, J
    Pamela, S
    Wiesen, S
    Maggi, C
    Urano, H
    Drewelow, P
    Leyland, M
    Moulton, D
    Menmuir, S
    Diamagnetic MHD Equations for Plasmas with Fast Flow and its Application to ELM Analysis in JT-60U and JET-ILW2016In: 26th IAEA Fusion Energy Conference, 17-22 October 2016, 2016Conference paper (Refereed)
  • 2918. Aiba, N.
    et al.
    Giroud, C.
    Honda, M.
    Delabie, E.
    Saarelma, S.
    Frassinetti, L
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Lupelli, I.
    Casson, F. J.
    Pamela, S.
    Urano, H.
    Maggi, C. F.
    Numerical analysis of ELM stability with rotation and ion diamagnetic drift effects in JET2017In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, no 12, article id 126001Article in journal (Refereed)
    Abstract [en]

    Stability to the type-I edge localized mode (ELM) in JET plasmas was investigated numerically by analyzing the stability to a peeling-ballooning mode with the effects of plasma rotation and ion diamagnetic drift. The numerical analysis was performed by solving the extended Frieman-Rotenberg equation with the MINERVA-DI code. To take into account these effects in the stability analysis self-consistently, the procedure of JET equilibrium reconstruction was updated to include the profiles of ion temperature and toroidal rotation, which are determined based on the measurement data in experiments. With the new procedure and MINERVA-DI, it was identified that the stability analysis including the rotation effect can explain the ELM trigger condition in JET with ITER like wall (JET-ILW), though the stability in JET with carbon wall (JET-C) is hardly affected by rotation. The key difference is that the rotation shear in JET-ILW plasmas analyzed in this study is larger than that in JET-C ones, the shear which enhances the dynamic pressure destabilizing a peeling-ballooning mode. In addition, the increase of the toroidal mode number of the unstable MHD mode determining the ELM trigger condition is also important when the plasma density is high in JET-ILW. Though such modes with high toroidal mode number are strongly stabilized by the ion diamagnetic drift effect, it was found that plasma rotation can sometimes overcome this stabilizing effect and destabilizes the peeling-ballooning modes in JET-ILW.

  • 2919. Aiba, N
    et al.
    Giroud, C
    Honda, M
    Delabie, E
    Saarelma, S
    Lupelli, I
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Maggi, C
    Impact of rotation and ion diamagnetic drift on ELM stability in JET-ILW2016In: 33rd Annual meeting of Japan society of plasma science and nuclear fusion research JSPF, Nov 2016. Japan, 2016Conference paper (Other academic)
  • 2920. Aiba, N.
    et al.
    Pamela, S.
    Honda, M.
    Urano, H.
    Giroud, C.
    Delabie, E.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Lupelli, I.
    Hayashi, N.
    Huijsmans, G.
    Analysis of ELM stability with extended MHD models in JET, JT-60U and future JT-60SA tokamak plasmas2018In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 60, no 1, article id 014032Article in journal (Refereed)
    Abstract [en]

    The stability with respect to a peeling-ballooning mode (PBM) was investigated numerically with extended MHD simulation codes in JET, JT-60U and future JT-60SA plasmas. The MINERVA-DI code was used to analyze the linear stability, including the effects of rotation and ion diamagnetic drift (omega(*i)), in JET-ILW and JT-60SA plasmas, and the JOREK code was used to simulate nonlinear dynamics with rotation, viscosity and resistivity in JT-60U plasmas. It was validated quantitatively that the ELM trigger condition in JET-ILW plasmas can be reasonably explained by taking into account both the rotation and omega(*i) effects in the numerical analysis. When deuterium poloidal rotation is evaluated based on neoclassical theory, an increase in the effective charge of plasma destabilizes the PBM because of an acceleration of rotation and a decrease in omega(*i). The difference in the amount of ELM energy loss in JT-60U plasmas rotating in opposite directions was reproduced qualitatively with JOREK. By comparing the ELM affected areas with linear eigenfunctions, it was confirmed that the difference in the linear stability property, due not to the rotation direction but to the plasma density profile, is thought to be responsible for changing the ELM energy loss just after the ELM crash. A predictive study to determine the pedestal profiles in JT-60SA was performed by updating the EPED1 model to include the rotation and w*i effects in the PBM stability analysis. It was shown that the plasma rotation predicted with the neoclassical toroidal viscosity degrades the pedestal performance by about 10% by destabilizing the PBM, but the pressure pedestal height will be high enough to achieve the target parameters required for the ITER-like shape inductive scenario in JT-60SA.

  • 2921.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar Receiver Design and Verification for Small Scale Polygeneration Unit2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Against a backdrop of our world’s changing climate solar thermal power generation shows great potential to move global energy production away from fossil fuels to non-polluting sources. The Department of Energy Technology at the Royal Institute of Technology Stockholm is contributing to the development and research of solar thermal power by building a solar driven small scale polygeneration unit based on an externally fired micro gas turbine.

    This project focused on the design, analysis and verification of a high temperature solar receiver for integration into this planned solar polygeneration unit. Mean irradiance levels at the focal spot of the solar receiver of 5.5 MW/m² and peak levels of 14 MW/m² were identified as major design challenges. A preliminary heat transfer analysis found volumetric receivers to be the only applicable receiver type capable of withstanding these expected high irradiance levels.

    With volumetric receivers selected as the receiver type, a basic volumetric receiver model was evaluated using a multi-objective optimization tool based on advanced evolutionist algorithms and a numerical heat transfer model. The results were a set of Pareto-optimal solutions showing a tradeoff between a pressure drop in the receiver and material temperature especially at the window of the receiver.

    A parameter study was conducted based on the previous analysis to improve specific aspects of the initial design using a value of benefit analysis to evaluate the different designs. Of all the investigated receiver parameters, the absorber properties and shape had the biggest positive influence on material temperature and thermal stresses without significantly increasing the pressure drop. External cooling of the receiver window with ambient air was found to beneficial influence the window temperature without greatly decreasing the thermal efficiency. For non-uniform high irradiance levels ceramic absorber materials were found to be most suitable. Furthermore, mechanically decoupling the window and the absorber from their surrounding parts was found to be very important; enabling them to expand more or less independently with changing temperature minimizing thermal stresses.

    It can be concluded, when properly designed, volumetric solar receivers for small scale solar polygeneration units are feasible as designs with material temperature, thermal stresses and pressure drop below acceptable limit were found within this work.

  • 2922.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar receiver development for gas-turbine based solar dish systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Small-scale concentrating solar power plants such as micro gas-turbine based solar dish systems have the potential to harness solar energy in an effective way and supply electricity to customers in remote areas. In such systems, the solar receiver transfers the power of concentrated solar radiation to the working fluid of the power conversion cycle. It is one of the key components as it needs to operate at high temperatures to ensure a high power cycle efficiency and under high flux densities to ensure a high receiver efficiency. In order to address these challenges and to ensure efficient and reliable operation innovative designs are needed.

    This research work focuses on the complete development of a novel solar receiver applying a new systematic design and analysis methodology. Therefore, a comprehensive receiver design and experimental evaluation process were developed and implemented. The design process includes the identification of technical specifications and requirements, the development of receiver design tools of different investigation levels coupled with multi-objective optimization tools, the evaluation of scaling effects between tests in the KTH high-flux solar simulator and the full-scale solar dish system. As a result of the design process a representative final receiver was established with material temperatures and stresses below critical limits while respecting the design specification.

    The experimental evaluation includes the enhancement of the KTH high-flux solar simulator to provide stable and reliable operating conditions, the precise characterization of the radiative boundary conditions, the design of a receiver test bed recreating the operating behavior of a gas-turbine, and the final receiver testing for multiple operating points. It was shown that the prototype reaches an efficiency of 69.3% for an air outlet temperature of 800°C and a mass flow of 29.5 g/s. For a larger mass flow of 38.4 g/s a receiver efficiency of 84.8% was achieved with an air outlet temperature of 749°C.

    The measurement results obtained were then used for a multi-point validation of the receiver design tools, resulting in a high level of confidence in the accuracy of the tools. The validated models were then harnessed to calculate the performance of a full-scale solar receiver integrated into the OMSoP solar dish system. It was shown that a solar receiver can be designed, which delivers air at 800°C with a receiver efficiency of 82.2%.

    Finally, the economic potential of micro gas-turbine based solar systems was investigated and it was shown that they are ideally suited for small-scale stand-alone and off-grid applications.

    The results of the receiver development highlight the feasibility of using volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems and no major hurdles were found.

  • 2923.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Performance Improvements of the KTH High-Flux Solar Simulator2017In: AIP Conference Proceedings 1850, American Institute of Physics (AIP), 2017, Vol. 1850, article id 150001Conference paper (Refereed)
    Abstract [en]

    This paper presents the performance improvements implemented in the KTH high-flux solar simulator to deliver a total power on target closer to the working conditions of real CSP systems. Therefore, additional rectifiers were installed in the power conversion unit of the high-power lamps as well as the back reflector was coated providing more favorable spectral reflectance properties. The results of a single lamp/lens-combination show that the power on target in an aperture of 280mm in diameter was increased from 831W to 1446W while the peak flux was increased from 675kW/m² to 905kW/m².

  • 2924.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Scaling effects of a novel solar receiver for a micro gas-turbine based solar dish system2018In: International Journal of Solar Energy, ISSN 0142-5919, E-ISSN 1477-2752, Vol. 162, p. 248-264Article in journal (Refereed)
    Abstract [en]

    Laboratory-scale component testing in dedicated high-flux solar simulators is a crucial step in the developmentand scale-up of concentrating solar power plants. Due to different radiative boundary conditions available inhigh-flux solar simulators and full-scale power plants the temperature and stress profiles inside the investigatedreceivers differ between these two testing platforms. The main objective of this work is to present a systematicscaling methodology for solar receivers to guarantee that experiments performed in the controlled environmentof high-flux solar simulators yield representative results when compared to full-scale tests. In this work theeffects of scaling a solar air receiver from the integration into the OMSoP full-scale micro gas-turbine based solardish system to the KTH high-flux solar simulator are investigated. Therefore, Monte Carlo ray-tracing routines ofthe solar dish concentrator and the solar simulator are developed and validated against experimental characterizationresults. The thermo-mechanical analysis of the solar receiver is based around a coupled CFD/FEManalysislinked with stochastic heat source calculations in combination with ray-tracing routines. A geneticmulti-objective optimization is performed to identify suitable receiver configurations for testing in the solarsimulator which yield representative results compared to full-scale tests. The scaling quality is evaluated using aset of performance and scaling indicators. Based on the results a suitable receiver configuration is selected forfurther investigation and experimental evaluation in the KTH high-flux solar simulator.

  • 2925.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Preliminary design and analysis of a novel solar receiver for a micro gas-turbine based solar dish system2015In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 114, no 4, p. 378-396Article in journal (Refereed)
    Abstract [en]

    The solar receiver is one of the key components of hybrid solar micro gas-turbine systems, which would seem to present a number of advantages when compared with Stirling engine based systems and photovoltaic panels. In this study a solar receiver meeting the specific requirements for integration into a small-scale (10 kWel) dish-mounted hybrid solar micro gas-turbine system has been designed with a special focus on the trade-offs between efficiency, pressure drop, material utilization and economic design. A situation analysis, performed using a multi-objective optimizer, has shown that a pressurized configuration, where the solar receiver is placed before the turbine, is superior to an atmospheric configuration with the solar receiver placed after the turbine. Based on these initial design results, coupled CFD/FEM simulations have been performed, allowing detailed analysis of the designs under the expected operating conditions. The results show that the use of volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems appears to be a promising solution; with material temperatures and material stresses well below permissible limits.

  • 2926.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Small Scale Hybrid Solar Power Plants for Polygeneration in Rural Areas2014In: Energy Procedia 57, Elsevier, 2014, Vol. 57, p. 1536-1545Conference paper (Refereed)
    Abstract [en]

    Small scale micro gas-turbine based hybrid solar power plants are a promising technology for supplying multiple energy services in a controllable and sustainable manner using polygeneration technologies. Compared to a conventional diesel generator based system where electricity is used as the main energy carrier, these systems show great potential to reduce costs and carbon dioxide emissions. Depending on the design, carbon dioxide emissions are reduced by around 9% and equivalent annual costs are reduced by 21% - 26%, as compared to a base polygeneration configuration where cooling services are provided centrally by an absorption chiller without integrating a solar micro gas-turbine. Compared to the system where electricity is used as the main energy carrier a reduction of equivalent annual costs of up to 20% and a reduction of carbon dioxide emissions of up to 33.5% was achieved.

  • 2927.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    IMDEA Energy Institute, Spain.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermoeconomic Analysis of a Solar Dish Micro Gas-Turbine Combined-Cycle Power Plant2015In: Energy Procedia 69, Elsevier, 2015, Vol. 69, p. 1089-1099Conference paper (Refereed)
    Abstract [en]

    A novel solar power plant concept is presented, based on the use of a coupled network of hybrid solar-dish micro gas-turbines, driving a centralized heat recovery steam generator and steam-cycle, thereby seeking to combine the high efficiency of the solar dish collector with a combined-cycle power block. A 150 MWe solar power plant was designed based on this concept and compared with both a conventional combined-cycle power plant and a hybrid solar-tower combined-cycle. The solar dish combined-cycle power plant could reach higher levels of solar integration than other concepts but was shown to be more expensive with current technology; solar electricity costs are double those of the hybrid solar-tower combined cycle.

  • 2928.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013In: Proceedings of the ASME Turbo Expo 2013. San Antonio, USA. June 3-7, ASME , 2013Conference paper (Refereed)
    Abstract [en]

    Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts the combined pressure drop of the recuperator and receiver is more important. The internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated, in terms of both electricity costs and carbon emissions. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20 – 35%.

  • 2929.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, no 11, p. 113001-Article in journal (Refereed)
    Abstract [en]

    Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts, the combined pressure drop of the recuperator and receiver is more important. In terms of both electricity costs and carbon emissions, the internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20–35%.

  • 2930.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Design and Analysis of a Solar Receiver for Micro Gas Turbine based Solar Dish Systems2012In: Proceedings of the International SolarPACES Conference 2012. Marrakesh, Morocco. September 11-14, 2012, 2012Conference paper (Refereed)
    Abstract [en]

    The solar receiver is one of the key components of hybrid solar micro gas turbine systems which would seem to present a number of advantages when compared with Stirling engine systems. A solar receiver meeting the specific requirements for integration into the power conversion system of the solar laboratory of the Royal Institute of Technology - which will emulate a solar dish system and is currently under construction - was designed. The simulations that have been performed utilize a heat transfer and pressure drop model coupled with a multi-objective optimizer as well as a coupled-CFD/FEM tool, allowing determination of the ideal receiver design for the expected conditions. The analysis has shown that the use of volumetric solar receivers to provide heat input to micro gas turbine based solar dish systems appears to be a promising solution; with pressurized receiver configurations as the preferred choice due to significant lower pressure drops as compared to atmospheric configurations.

  • 2931.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 159, p. 184-195Article in journal (Refereed)
    Abstract [en]

    This work presents the experimental evaluation of a novel pressurized high-temperature solar air receiver for the integration into a micro gas-turbine solar dish system reaching an air outlet temperature of 800°C. The experiments are conducted in the controlled environment of the KTH high-flux solar simulator with well-defined radiative boundary conditions. Special focus is placed on providing detailed information to enable the validation of numerical models. The solar receiver performance is evaluated for a range of operating points and monitored using multiple point measurements. The porous absorber front surface temperature is measured continuously as it is one of the most critical components for the receiver performance and model validation. Additionally, pyrometer line measurements of the absorber and glass window are taken for each operating point. The experiments highlight the feasibility of volumetric solar receivers for micro gas-turbine based solar dish systems and no major hurdles were found. A receiver efficiency of 84.8% was reached for an air outlet temperature of 749°C. When using a lower mass flow, an air outlet temperature of 800°C is achieved with a receiver efficiency of 69.3%. At the same time, all material temperatures remain below permissible limits and no deterioration of the porous absorber is found.

  • 2932.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Flux Measurement of a High-Flux Solar Simulator using a Lambertian Target and a Thermopile Flux Sensor2016In: AIP Conference Proceedings 1734, American Institute of Physics (AIP), 2016, Vol. 1734, article id 130001Conference paper (Refereed)
    Abstract [en]

    A measurement system for the experimental determination of the flux distribution at the focal plane of the KTH high-flux solar simulator was designed and implemented. It is based on a water-cooled Lambertian target and a thermopile flux sensor placed close to the focal point of the solar simulator. Correction factors to account for systematic effects were determined and an uncertainty analysis was performed. The measurement system was successfully used to evaluate the flux distribution of a single lamp/lens-arrangement with a peak flux of 675kW/m².

  • 2933.
    Aid, Graham
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Industrial Ecology Methods within Engagement Processes for Industrial Resource Management2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The global use of resources such as materials, energy, and water has surpassed sustainable levels by many accounts.  The research presented here was explicitly normative in its aim to improve the understanding of, and make sustainable change toward highly systemic issues of resource management.  The core methods chosen to work toward this aim were bottom up action research procedures (including stakeholder engagement processes) and industrial ecology analysis tools.  These methods were employed and tested in pragmatic combination through two of the author’s case study projects. The first case study, performed between 2009 and 2012, employed a multi-stakeholder process aimed at improving the cycling of construction and demolition waste in the Stockholm region.  The second case study produced a strategic tool (Looplocal) built for facilitating more efficient regional industrial resource networks. While the highly participative aim of the cases required a larger contribution of resources than that of more closed studies, it is arguable that the efficacy of approaching the project aims is improved through their employment. 

  • 2934.
    Aid, Graham
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Potential technology for the advanced utilization of construction, demolition, and industrial waste2008Conference paper (Refereed)
  • 2935.
    Aid, Graham
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Brandt, Nils
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Action Research In Waste Management: Application to construction and demolition waste in the Stockholm region2010In: Linnaeus ECO-TECH ´10 / [ed] Fabio Kaczala, Linnaeus University , 2010, p. 1009-1019Conference paper (Refereed)
    Abstract [en]

    The action research methodology and several of its methods have previously been highlighted and described by the authors as a fitting and rigorous framework approach for complex waste management systems.  This was in response to criticism of the ex ante selection of traditional empiric systems analysis tools to provide decision support and ‘sustainable improvement’ in such complex systems which often involve strong human and political factors.   Several of the action research methods described have recently been utilized in a case study around mineral (aggregate) construction and demolition waste in the Stockholm region.  These methods were integrated through a series of workshops and work areas undergone together with project members from several private and public sectors.  Leaving the problem fuzzy (loosely defined) in the beginning; utilizing convergent interviewing, rich pictures and focus groups allowed the researchers and partner stakeholders to identify not one but several problem areas within the system of focus.  Indicator creation and a dialectic processes were then used to identify qualitative and quantitative aspects of salience around these problem areas.  These resulting indicators were strengthened through a process of verification.  Each indicator was then analyzed by what was deemed to be appropriate and transparent means.  It is argued that this approach may create better communication, transparency, and understanding by the stakeholders.  These factors in turn allowing stronger stakeholder ownership of the process and assisting in more informed decisions and help to provide stability for desired change. However the process was not without its drawbacks such as intense communication and time requirements.

  • 2936.
    Aid, Graham
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Brandt, Nils
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Bygg- och rivningsavfall: Action Research vid KTH2010In: Återvinnare För Industrin / [ed] Kjell-Arne Larsson, Stockholm: Rekord Media och Produktion AB , 2010Chapter in book (Other academic)
  • 2937.
    Aid, Graham
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Brandt, Nils
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Improvement of aggregate cycles in Stockholm and the Baltic Region: Activities and results of the BRA initiative2012In: WASCON 2012 Conference proceedings / [ed] M. Arm, C. Vandecasteele, J. Heynen, P. Suer and B. Lind, 2012, p. 1-9Conference paper (Refereed)
    Abstract [en]

    From 2009 until 2011 project BRA (Bygg-och Rivningsavfall i Stockholms Län) “Construction and Demolition (C&D) waste in Stockholm County” was coordinated from the division of Industrial Ecology, KTH. This project was focused on actively improving (from plural perspectives) the cycles of C&D (specifically non-metallic inert) materials in the region. In response to the normative aim and inter-systems complexity, a highly participative action research procedure was adopted. Through processes of network communication, workshops, a course, and an international symposium - a number of issues (such as market development, recycled product quality, greenhouse gas impacts, collaborative planning, and statistics) were prioritized, researched, and acted upon. Indicators for measuring progress in selected areas were developed and preliminary action plans created. At a final co-organized symposium Swedish delegates laid the groundwork for the establishment of a Swedish C&D recycling b ranch organization. This initiative of continued collaboration between and within sectors is seen as a vehicle for the priorities and action requirements identified in BRA to be further enabled and held in focus. Furthermore, these actors taking ownership of the process is seen as a success in accordance to the original aims and the need for further cycles of evaluation, planning, and action.

  • 2938.
    Aid, Graham
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Brandt, Nils
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Lysenkova, Mariya
    Smedberg, Niklas
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Looplocal - a heuristic visualization tool to support the strategic facilitation of industrial symbiosis2015In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 98, p. 328-335Article in journal (Refereed)
    Abstract [en]

    Industrial symbiosis (IS) developments have been differentiated as self-organized, facilitated, and planned. This article introduces a tool, Looplocal, which has been built with objectives to support the strategic facilitation of IS. Looplocal is a visualization tool built to assist in 1) Simplifying the identification of regions susceptible to new industrial symbiosis facilitation activities 2) Enabling proactive and targeted marketing of potential exchanges to key actors in specific regions and 3) Assisting facilitators to assess the various strategies and consequential engagement and analysis methodologies suitable for additional IS development in specific regions. The tool compares industrial symbiosis data and estimated regional material and energy flows (on a facility level) to identify potential IS transfer information along with key stakeholder and network data. The authors have performed a proof of concept run of this tool on Sweden. In its early stages of application the method has given results seen as useful for identifying regions susceptible to the investment of symbiosis facilitators' time and resources. The material focus and customization possibilities for the tool show potential for a spectrum of potential facilitators: from waste management companies to national or regional authorities. In conjunction with long term business models, such a tool might be utilized throughout an adaptive chain of facilitation activities and aims.

  • 2939.
    Aid, Graham
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Brandt, Nils
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Lysenkovac, Mariya
    Smedberg, Niklas
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Looplocal: a Heuristic Visualization Tool for the Strategic Facilitation of Industrial Symbiosis2012In: Greening of Industry Netowrk Proceedings / [ed] Leo Baas, 2012Conference paper (Refereed)
    Abstract [en]

    Industrial symbiosis (IS) developments have been differentiated as ‘self organized’, ‘facilitated’, and ‘planned’. This article introduces a tool that has been built with objectives to support the strategic facilitation of IS. ‘Looplocal’ is a visualization tool built to assist in 1) the identification of regions prone to new industrial symbiosis activities 2) market potential exchanges to key actors and 3) assist aspiring facilitators to assess the various strategies and social methodologies available for the initial phases of a facilitated industrial symbiosis venture. This tool combines life cycle inventory (LCI) data, waste statistics, and national industrial data (including geographic, activity, economic, and contact information) to perform a heuristic analysis of raw material and energy inputs and outputs (wastes). Along with an extensive list of ‘waste to raw material’ substitutions (which may be direct, combined, or upgraded) gathered from IS uncovering studies, IS organizations, and waste and energy professionals; heuristic regional output to input ‘matching’ can be visualized. On a national or regional scale the tool gives a quick overview of what could be the most interesting regions to prioritize resources for IS facilitation. Focusing in on a regional level, the tool visualizes the potential structure of the network in that region (centralized, decentralized, or distributed), allowing a facilitator to adapt the networking approach correspondingly. The tool also visualizes potential IS transfer information, along with key stakeholder data. The authors have performed a proof of concept run of this tool in the ‘industrial disperse’ context of Sweden. In its early stages of application, the method has proven capable of identifying regions prone to the investment of facilitators’ resources. The material focus and custom possibilities for the tool show potential for a wide spectrum of potential facilitators: from waste management companies (using the tool as a strategic market analysis tool) to national or regional authorities looking to lower negative environmental impacts, to ‘sustainable’ industry sectors looking to strengthen market positioning. In conjunction with proper long term business models, such a tool could be reusable itself over the evolution of facilitation activities and aims.

  • 2940.
    Aid, Graham
    et al.
    Ragn-Sells AB.
    Lazarevic, David
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology. Finnish Environment Institute SYKE.
    Kihl, Anders
    Ragn-Sells AB.
    Waste to Resources: Moving Toward the 2030 Sustainable Development Goals2016Conference paper (Other academic)
  • 2941.
    AIDANPÄÄ, MATHILDA
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    SJÖBERG, MATHILDA
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    De etiska konsekvenserna av produktutveckling: Oönskade konsekvenser av strävan efter zero-labourfactories2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today’s development of automation happens at an increasing rate driven by innovation and product development. Companies have to keep up with this progress to stay competitive. The question has risen whether we are now facing a new industrial revolution or not. The ethical perspective has now become a concern.

    The purpose of this report is to investigate the following questions:

    • How big of a role has the ethical perspective in decision-making processes with regards to automation?

    • Who is responsible for ethical issues within product development?

    • To what extent should ethics be a part of engineering education?

    The chosen method during the study was extensive literature studies and semi structured interviews with employees and managers from the affected area.

    The result of the report is that the ethical perspective has a smaller impact in the decisionmaking processes compared to other factors. The responsibility of the ethical consequences lies in both product development companies and producing companies. Finally, ethical perspectives should be integrated into engineering education.

  • 2942.
    Aidanpää, Sandra
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Nordmark, Elin MK
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Flexible Updates of Embedded Systems Using Containers2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis the operating-system-level virtualization solution Docker is investigated in the context of updating an embedded system on application level. An updating sequence is designed, modelled and implemented, on which experiments are conducted to measure uptime and current. Within the popular notion of the Internet of Things, more and more things are being connected to the Internet and there by the possibility of dynamic updates over the Internet is created. Being able to update remotely can be very benecial, as systems may be costly or unpractical to reach physically for software updates. Operating-system-level virtualization, software containers, are a lightweight virtualization solution that can be used for dynamic updating purposes. Virtualization properties, like resource isolation and letting software share hardware capabilities are used in determining the architecture. The container architecture used is a microservice architecture, where systems are composed from many smaller, loosely coupled services. The application area for the results of this thesis are start-ups in the Internet of Things eld, delimited to low complexity systems such as consumer products. The update regime is created with the properties of microservice architectures in mind, creating a self-propelling, self-testing, scalable and seamless dynamic updating process that can be used for systems of dierent complexity. The update regime is modeled to give proof of concept and to help design the implementation. The implemented update regime was made on an ARM based single board computer with a Linux-kernel based operating system running Docker. Experiments were then conducted in order to give a clear indication of the behavior of a dynamically updated embedded system. The experiments showed that the update regime can be seamless, meaning that the uptime properties are not aected by this kind of updating. The experiments also showed that no signicant changes in current can be noted for container limitations during this kind of update.

  • 2943. Aidas, Kestutis
    et al.
    Angeli, Celestino
    Bak, Keld L.
    Bakken, Vebjorn
    Bast, Radovan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Boman, Linus
    Christiansen, Ove
    Cimiraglia, Renzo
    Coriani, Sonia
    Dahle, Pal
    Dalskov, Erik K.
    Ekstrom, Ulf
    Enevoldsen, Thomas
    Eriksen, Janus J.
    Ettenhuber, Patrick
    Fernandez, Berta
    Ferrighi, Lara
    Fliegl, Heike
    Frediani, Luca
    Hald, Kasper
    Halkier, Asger
    Hattig, Christof
    Heiberg, Hanne
    Helgaker, Trygve
    Hennum, Alf Christian
    Hettema, Hinne
    Hjertenaes, Eirik
    Host, Stinne
    Hoyvik, Ida-Marie
    Iozzi, Maria Francesca
    Jansik, Branislav
    Jensen, Hans Jorgen Aa.
    Jonsson, Dan
    Jorgensen, Poul
    Kauczor, Joanna
    Kirpekar, Sheela
    Kjrgaard, Thomas
    Klopper, Wim
    Knecht, Stefan
    Kobayashi, Rika
    Koch, Henrik
    Kongsted, Jacob
    Krapp, Andreas
    Kristensen, Kasper
    Ligabue, Andrea
    Lutnaes, Ola B.
    Melo, Juan I.
    Mikkelsen, Kurt V.
    Myhre, Rolf H.
    Neiss, Christian
    Nielsen, Christian B.
    Norman, Patrick
    Olsen, Jeppe
    Olsen, Jogvan Magnus H.
    Osted, Anders
    Packer, Martin J.
    Pawlowski, Filip
    Pedersen, Thomas B.
    Provasi, Patricio F.
    Reine, Simen
    Rinkevicius, Zilvinas
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Ruden, Torgeir A.
    Ruud, Kenneth
    Rybkin, Vladimir V.
    Salek, Pawel
    Samson, Claire C. M.
    de Meras, Alfredo Sanchez
    Saue, Trond
    Sauer, Stephan P. A.
    Schimmelpfennig, Bernd
    Sneskov, Kristian
    Steindal, Arnfinn H.
    Sylvester-Hvid, Kristian O.
    Taylor, Peter R.
    Teale, Andrew M.
    Tellgren, Erik I.
    Tew, David P.
    Thorvaldsen, Andreas J.
    Thogersen, Lea
    Vahtras, Olav
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Watson, Mark A.
    Wilson, David J. D.
    Ziolkowski, Marcin
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    The Dalton quantum chemistry program system2014In: Wiley Interdisciplinary Reviews. Computational Molecular Science, ISSN 1759-0876, Vol. 4, no 3, p. 269-284Article in journal (Refereed)
    Abstract [en]

    Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from for a number of UNIX platforms.

  • 2944. Aidas, Kestutis
    et al.
    Olsen, Jogvan Magnus H.
    Kongsted, Jacob
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Photoabsorption of Acridine Yellow and Proflavin Bound to Human Serum Albumin Studied by Means of Quantum Mechanics/Molecular Dynamics2013In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 117, no 7, p. 2069-2080Article in journal (Refereed)
    Abstract [en]

    Attempting to unravel mechanisms in optical probing of proteins, we have performed pilot calculations of two cationic chromophores-acridine yellow and proflavin-located at different binding sites within human serum albumin, including the two primary drug binding sites as well as a heme binding site. The computational scheme adopted involves classical molecular dynamics simulations of the ligands bound to the protein and subsequent linear response polarizable embedding density functional theory calculations of the excitation energies. A polarizable embedding potential consisting of point charges fitted to reproduce the electrostatic potential and isotropic atomic polarizabilities computed individually for every residue of the protein was used in the linear response calculations. Comparing the calculated aqueous solution-to-protein shifts of maximum absorption energies to available experimental data, we concluded that the cationic proflavin chromophore is likely not to bind albumin at its drug binding site I nor at its heme binding site. Although agreement with experimental data could only be obtained in qualitative terms, our results clearly indicate that the difference in optical response of the two probes is due to deprotonation, and not, as earlier suggested, to different binding sites. The ramifications of this finding for design of molecular probes targeting albumin or other proteins is briefly discussed.

  • 2945.
    Aidas, Kestutis
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Kongsted, Jacob
    Laaksonen, Aatto
    Mocci, Francesca
    A quantum mechanics/molecular dynamics study of electric field gradient fluctuations in the liquid phase. The case of Na+ in aqueous solution2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 5, p. 1621-1631Article in journal (Refereed)
    Abstract [en]

    The Na-23 quadrupolar coupling constant of the Na+ ion in aqueous solution has been predicted using molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics methods for the calculation of electric field gradients. The developed computational approach is generally expected to provide reliable estimates of the quadrupolar coupling constants of monoatomic species in condensed phases, and we show here that intermolecular polarization and non-electrostatic interactions are of crucial importance as they result in a 100% increased quadrupolar coupling constant of the ion as compared to a simpler pure electrostatic picture. These findings question the reliability of the commonly applied classical Sternheimer approximation for the calculations of the electric field gradient. As it can be expected from symmetry considerations, the quadrupolar coupling constants of the 5- and 6-coordinated Na+ ions in solution are found to differ significantly.

  • 2946.
    Aidas, Nina
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Responsive Textile Geometries: Vanadisbadet Revised2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    How can principles found in textile behaviour be translated into architectural expression? With water as a program in context of a new bath in Vanadislunden, Stockholm, this project studies how a rigid material can be percieved as soft and flexible.

  • 2947.
    Aidi, Laili
    KTH, School of Information and Communication Technology (ICT).
    Business Modelsfor Mobile Broadband Media Services: Case Study Indonesia Telecom Market2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increase mobile data traffic from the emerging Internet services, especially multimedia, has posed considerable challenges for the telecom industry. Their initial mobile data services business models are generally not compatible with these emerging Internet services. Thus, there is a substantial need to investigate the suitable options to make media as a profitable telecom business sector. However, there are different challenges and opportunity factors in developing sustainable mobile media business in each market, due to the unique circumstances applied as the result of customer characteristics, mobile market situation and regulatory/law enforcement.</p><p>The first purpose of this thesis is to explore the business model options to deliver media services on top of mobile broadband. Although, we limit our focus to Indonesia, we first analyzed the worldwide patterns toward the media services in order to get a broader view of the current trend. We mapped multitudes of actor involved in digital online / on the top (OTT)media service, which together they form different types of constellation in the value network,as well as service, delivery and revenue model. We also put our focus to get the lessons learned from Spotify's business model, by framing it using Chesbrough and Rosenbloom's model.</p><p>The second purpose is to understand the Indonesian mobile user's characteristic toward the mobile media services. We conducted survey to 119 Indonesians, analyzed the result with one sample T-tests and validated it with the correlation tests (Cronbach Alpha and Pearson correlation), within the Unified theory of acceptance and use of technology (UTAUT)framework. Our findings confirm the low willingness to pay, but an open attitude for the services. The mobile device and network quality are not the barriers for them to adopt the services, and there is a tight connection between the decisions to adopt the services with the perception that the service is popular.</p><p>Through those findings, we assessed the feasibility of the identified options and formulated the recommendations. We used our understanding about Indonesian market structure (telecom and media), regulation, and mobile user, as well as the lesson that we got from media services provisioning in Sweden and worldwide trend. We found that the pricing tiers, adjustable pricing, and differentiated features are some of the key success factors.Meanwhile, being part in the point-to-multipoint partnership with the well-known OTT player is the potential position that the Mobile network operators (MNOs) in Indonesia should take in provisioning OTT media services, rather than deliver the services by their own.

  • 2948.
    Aidi, Laili
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Huang, Jin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Selvakumar, Ekambar
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    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.
    Tollmar, Konrad
    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.
    Blennerud, Greger
    Ericsson.
    How can Mobile Music Streaming Service Take off in India, China and Indonesia?: Analysis of Drivers and Obstacles2012In: , 2012Conference paper (Refereed)
  • 2949.
    Aidi, Laili
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Tollmar, Konrad
    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.
    Blennerud, Greger
    Ericsson.
    Competing or Aligning? Assessment for Telecom Operator's strategy to address OTT TV/Video services2012Conference paper (Refereed)
    Abstract [en]

    Up until recently, it was rarely direct competition between telecom operators, cable and satellite Pay-TV providers in digital TV/Video, as their business area were different and value chain was well established. However, technology advance has altered digital TV/Video landscape, made these Communication Service Providers (CSPs) cross other’s area and opened door for new actor (OTT player) to enter the market. This triggers second change in the landscape, as it potentially bypasses CSP’s role in digital media value chain.

    There are generic potential options for telecom operator to address OTT service‘s treat, where the trend shows gradual shifts toward allowing or promoting. This study assesses telecom operator’s reaction strategies to react to this digital TV/Video convergence trend. Our analysis reveals two typical relation patterns in the value network, used by telecom operators based on strategy options above, which are ”point-to-point” and ”point-to-multipoint” relation model. We explore the underlining motivations that based these strategies, as well as analysis of the eco-systems: actors identification, business roles and distributed responsibilities among them, where we use ARA (Actors, Resource, Activities) point of view to model these value networks.

  • 2950. Aiempanakit, Montri
    et al.
    Aijaz, Asim
    Lundin, Daniel
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Helmersson, Ulf
    Kubart, Tomas
    Understanding the discharge current behavior in reactive high power impulse magnetron sputtering of oxides2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 13, p. 133302-Article in journal (Refereed)
    Abstract [en]

    The discharge current behavior in reactive high power impulse magnetron sputtering (HiPIMS) of Ti-O and Al-O is investigated. It is found that for both metals, the discharge peak current significantly increases in the oxide mode in contrast to the behavior in reactive direct current magnetron sputtering where the discharge current increases for Al but decreases for Ti when oxygen is introduced. In order to investigate the increase in the discharge current in HiPIMS-mode, the ionic contribution of the discharge in the oxide and metal mode is measured using time-resolved mass spectrometry. The energy distributions and time evolution are investigated during the pulse-on time as well as in the post-discharge. In the oxide mode, the discharge is dominated by ionized oxygen, which has been preferentially sputtered from the target surface. The ionized oxygen determines the discharge behavior in reactive HiPIMS.

56575859606162 2901 - 2950 of 124192
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