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  • 124051. Zhang, Y.
    et al.
    Beskow, Jonas
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Kjellström, Hedvig
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Look but Don’t Stare: Mutual Gaze Interaction in Social Robots2017In: 9th International Conference on Social Robotics, ICSR 2017, Springer, 2017, Vol. 10652, p. 556-566Conference paper (Refereed)
    Abstract [en]

    Mutual gaze is a powerful cue for communicating social attention and intention. A plethora of studies have demonstrated the fundamental roles of mutual gaze in establishing communicative links between humans, and enabling non-verbal communication of social attention and intention. The amount of mutual gaze between two partners regulates human-human interaction and is a sign of social engagement. This paper investigates whether implementing mutual gaze in robotic systems can achieve social effects, thus to improve human robot interaction. Based on insights from existing human face-to-face interaction studies, we implemented an interactive mutual gaze model in an embodied agent, the social robot head Furhat. We evaluated the mutual gaze prototype with 24 participants in three applications. Our results show that our mutual gaze model improves social connectedness between robots and users.

  • 124052. Zhang, Y. C.
    et al.
    Lavraud, B.
    Dai, L.
    Wang, C.
    Marchaudon, A.
    Avanov, L.
    Burch, J.
    Chandler, M.
    Dorelli, J.
    Duan, S. P.
    Ergun, R. E.
    Gershman, D. J.
    Giles, B.
    Khotyaintsev, Y. V.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Paterson, W.
    Russell, C. T.
    Schiff, C.
    Tang, B. B.
    Torbert, R.
    Quantitative analysis of a Hall system in the exhaust of asymmetric magnetic reconnection2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 5, p. 5277-5289Article in journal (Refereed)
    Abstract [en]

    Taking advantage of high-resolution measurements from the MMS mission, we find evidence for a complete Hall system in the exhaust of asymmetric magnetic reconnection 40 Di downstream of the X line. The investigation of the fine structure of the Hall system reveals that it displays features in the exhaust similar to those reported previously in the ion diffusion region by simulations and observations. This finding confirms the importance of particle-scale processes in the reconnection exhaust as well. On the magnetospheric side of the exhaust, electrons are strongly accelerated by parallel electric fields. This process significantly contributes to feed the Hall current system, resulting in a nonnegligible Hall magnetic field signature on this side despite an otherwise lower density. Calculation of the induced out-of-plane magnetic field by in-plane currents (based on Biot-Savart law) provides direct quantitative evidence for the process of Hall magnetic field generation by the Hall current system. A strong normal Hall electric field is present only on the magnetospheric side of the exhaust region, consistent with previous works. Multipoint data analysis shows that the ion pressure gradient in the ion momentum equation produces this Hall electric field. This global pattern of the Hall system can be explained by kinetic Alfvén wave theory.

  • 124053. Zhang, Y. G.
    et al.
    Somesfalean, Gabriel
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Guo, W.
    Wang, H. S.
    Wu, S. H.
    Qin, Y. K.
    Zhang, Z. G.
    An optical system for measuring nitric oxide using spectral separation techniques2012In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 107, no 2, p. 435-440Article in journal (Refereed)
    Abstract [en]

    An optical sensor based on differential absorption spectroscopy for real-time monitoring of industrial nitric oxide (NO) gas emission is described. The influence of gas absorption interference from sulfur dioxide (SO2) in the environment was considered and a spectral separation technique was developed in order to eliminate this interference effect. The absorption spectrum of SO2 around 226 nm was evaluated by the SO2 concentration obtained using the experimentally recorded absorption spectrum around 300 nm. The absorption spectrum of NO around 226 nm was obtained by subtracting the absorption of SO2 from the integral absorption spectrum of SO2 and NO. The concentration measurements were performed at atmospheric pressure. The technique was found to have a lower detection limit of 0.8 ppm for NO per meter path length (SNR=2) and be immune from the influence from SO2 on the NO measurement. The sensor based on this technique was successfully employed for in situ measurement of SO2 and NO concentrations in the flue gas emitted from an industrial coal-fired boiler.

  • 124054. Zhang, Y.
    et al.
    Hu, L.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Tunable dual-broad-band branch-line coupler utilizing composite right/left-handed transmission lines2005In: JZUS-A - Journal of Zhejiang University. Science, ISSN 1009-3095, Vol. 6 A, no 6, p. 483-486Article in journal (Refereed)
    Abstract [en]

    A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broaden the dual bands of the branch-line coupler. Numerical simulation and optimal design of the novel coupler are presented. The dual bands of the novel coupler are tunable and broad. The 1-dB bandwidth of each passband is more than 16% of the central frequency.

  • 124055. Zhang, Y.
    et al.
    Jin, Yi
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Xue, W.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Broad-angle polarization beam splitter using an ultra-low permittivity material2009In: 2008 Asia Optical Fiber Communication and Optoelectronic Exposition and Conference, AOE 2008, 2009Conference paper (Refereed)
    Abstract [en]

    We design a broad-angle polarization beam splitter consisting of alternating layers of dielectric and ultra-low permittivity material. Within wide range of incident angles, it shows high transmissivity for one polarization while high reflectivity for another.

  • 124056. Zhang, Y.
    et al.
    Jin, Yi
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Xue, W.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Polarization-independent 2D omni-directional photonic band gaps in a 1D periodic metal-dielectric (anisotropic) structure2009In: Waves in Random and Complex Media, ISSN 1745-5030, E-ISSN 1745-5049, Vol. 19, no 1, p. 39-48Article in journal (Refereed)
    Abstract [en]

    It is shown that there is no polarization-independent two-dimensionally (2D) omni-directional photonic band gap (PBG) for any conventional one-dimensional (1D) metal-dielectric (isotropic) structure. Through the study of band diagrams and some asymptotic analysis, a 1D periodic metal-dielectric (anisotropic) structure is proposed to achieve a polarization-independent 2D omni-directional PBG. Theoretical predictions for both the lossless and lossy cases are verified with finite element method (FEM) simulation of a point source in such a structure.

  • 124057. Zhang, Y. L.
    et al.
    Wang, Y. Z.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics. Department of Mathematics and Physics, Shijiazhuang Tiedao University, China; Institute of Applied Physics, Shijiazhuang Tiedao University, China; China Institute of Atomic Energy, Beijing 102413, China.
    Systematic study of cluster radioactivity of superheavy nuclei2018In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 97, no 1, article id 014318Article in journal (Refereed)
    Abstract [en]

    The probable cluster radioactivity (CR) of 118294, 120296, and 122298 is studied by using the unified description (UD) formula, universal (UNIV) curve, Horoi formula, and universal decay law (UDL). The predictions by the former three models suggest that the probable emitted clusters are lighter nuclei, and the calculations within the UDL formula give a different prediction: that both the lighter clusters and heavier ones can be emitted from the parent nuclei. A further study on the competition between α decay and CR of Z=104-124 isotopes is performed. The former three models predict that α decay is the dominant decay mode, but the UDL formula suggests that CR dominates over α decay for Z≥118 nuclei and the isotopes of 118292-296,308-318, 120,284-304,308-324 and 122316-322 are the most likely candidates as the cluster emitters. Because the former three formulas are just preformation models, the lighter cluster emissions can be described. However, the UDL formula can predict the lighter and heavier CR owing to the inclusion of the preformation and fissionlike mechanisms. Finally, it is found that the shortest CR half-lives are always obtained when the daughter nuclei are around the double magic Pb208 within the UDL formula, which indicates that shell effect has an important influence on CR. 

  • 124058. Zhang, Y.
    et al.
    Liu, Sichao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. Northwestern Polytechnical University, Shaanxi, China.
    Liu, Y.
    Yang, H.
    Li, M.
    Huisingh, D.
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    The ‘Internet of Things’ enabled real-time scheduling for remanufacturing of automobile engines2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 185, p. 562-575Article in journal (Refereed)
    Abstract [en]

    Typical challenges that managers of remanufacturing face are composed of the lack of timely, accurate, and consistent information of remanufacturing resources. Therefore, it is difficult to implement real-time production scheduling for the shop floor. To address this problem, the authors applied the concept of the ‘Internet of Things’ to the remanufacturing of automobile engines to form an Internet of Manufacturing Things environment. Under the Internet of Manufacturing Things, an identification technology for disassembled engine parts was designed, and the real-time status of the remanufacturable resources can be monitored. Based on the captured remanufacturing information, a real-time production scheduling method was developed, and a mathematical model was developed to achieve cost reduction, dynamic management of remanufacturable resources, and energy consumption decrease. To obtain an optimal solution, a Pareto-based optimization method was used. Finally, a case study was performed to analyze the effectivity of the proposed method. The results showed that the remanufacturing cost and energy consumption were reduced by 34% and 34% respectively, and the worker load rate was more balanced. These improvements can contribute to more sustainable development and greener production within the remanufacturing industry, especially for remanufacturing of automobile engines.

  • 124059. Zhang, Y.
    et al.
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    Critical evaluation of thermodynamics of complex formation of metal ions in aqueous solutions VI. Hydrolysis and hydroxo-complexes of Zn2+ at 298.15 K2001In: Hydrometallurgy, ISSN 0304-386X, E-ISSN 1879-1158, Vol. 60, no 3, p. 215-236Article in journal (Refereed)
    Abstract [en]

    The standard thermodynamic properties of Zn2+, its hydrolysis reactions and hydroxo-complex formation are critically evaluated on the basis of published experimental studies and specific interaction theory (SIT) for activity coefficient modelling. A set of thermodynamic data and interaction coefficients are recommended.

  • 124060. Zhang, Y.
    et al.
    Su, Yang
    KTH.
    Zhang, H.
    Zhao, G.
    A comparative study of 10 different methods on numerical solving of point reactor neutron kinetics equations2017In: 2017 25th International Conference on Nuclear Engineering: Nuclear Fuel and Material, Reactor Physics and Transport Theory; Innovative Nuclear Power Plant Design and New Technology Application, ASME Press, 2017Conference paper (Refereed)
    Abstract [en]

    Point reactor neutron kinetics equations describe the time dependent neutron density variation in a nuclear reactor core. These equations are widely applied to nuclear system numerical simulation and nuclear power plant operational control. This paper analyses the characteristics of 10 different basic or normal methods to solve the point reactor neutron kinetics equations. These methods are: explicit and implicit Euler method, explicit and implicit four order Runge-Kutta method, Taylor polynomial method, power series method, decoupling method, end point floating method, Hermite method, Gear method. Three different types of step reactivity values are introduced respectively at initial time when point reactor neutron kinetics equations are calculated using different methods, which are positive reactivity, negative reactivity and higher positive reactivity. The calculation results show that (i) minor relative error can be gain after three types of step reactivity are introduced, when explicit or implicit four order Runge-Kutta method, Taylor polynomial method, power series method, end point floating method or Hermite method is taken. These methods which are mentioned above are appropriate for solving point reactor neutron kinetics equations. (ii) the relative error of decoupling method is large, under the calculation condition of this paper. When a higher reactivity is introduced, the calculation of decoupling method cannot be convergence. (iii) after three types of step reactivity are introduced respectively, the relative error of implicit Euler method is higher than any other method except decoupling method. The third highest is Gear method. (iv) when the higher reactivity is introduced, the relative error of explicit and implicit Euler method are almost coincident, and higher than any other methods obviously. (v) 4 methods are suitable for solution on these given conditions, which are implicit Runge-Kutta method, Taylor polynomial method, power series method and end point floating method, considering both the accuracy and stiffness.

  • 124061. Zhang, Y.
    et al.
    Weber, W. J.
    Jiang, W.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Possnert, G.
    Damage evolution and recovery on both Si and C sublattices in Al-implanted 4H-SiC studied by Rutherford backscattering spectroscopy and nuclear reaction analysis2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 10, p. 6388-6395Article in journal (Refereed)
    Abstract [en]

    Damage evolution and subsequent recovery in 4H-SiC epitaxial layers irradiated with 1.1 MeV Al-2(2+) molecular ions at 150 K to ion fluences from 1.5x10(13) to 2.25x10(14) Al cm(-2) were studied by Rutherford backscattering spectroscopy (RBS) and C-12(d,p)C-13 nuclear reaction analysis (NRA) using a 0.94 MeV deuterium (D+) beam in channeling geometry. Disorder on both the Si and C sublattices was measured simultaneously from the RBS scattering and NRA reaction yields. The relative disorder on both sublattices follows a nonlinear dependence on ion fluence that is consistent with a model based on simple defect accumulation and a direct-impact, defect-stimulated process for amorphization. At low ion fluences, the relative disorder on the C sublattice is higher than that on the Si sublattice. Isochronal annealing up to 870 K revealed the existence of three distinct recovery stages at similar to350, 520, and 650 K for low to intermediate damage levels. In highly damaged samples, where a buried amorphous layer is produced, the onset of a fourth recovery stage appears above 800 K. Similar recovery behaviors on both the Si and C sublattices suggests some coupling of recovery processes for Si and C defects.

  • 124062. Zhang, Y.
    et al.
    Weber, W. J.
    Jiang, W. L.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Possnert, G.
    Evolution and recrystallization of buried amorphous layers in A1(2)(2+) implanted 4H-SiC2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 195, no 04-mar, p. 320-328Article in journal (Refereed)
    Abstract [en]

    Epitaxial 4H-SiC has been irradiated at 150 K with 1.1 MeV Al-2(2+) molecular ions to fluences ranging from 1.5 x 10(13) to 8.00 x 10(14) Al+ cm(-2). The evolution and isochronal recovery of the buried amorphous layers at higher fluences were investigated by in situ Rutherford backscattering spectrometry using a 2.0 MeV He+ beam along the <0001> channeling direction. The damage accumulation at the damage peak in the as-implanted samples indicates a sigmoidal dependence on ion fluence, and a buried amorphous layer is formed at 2.00 x 10(14) Al+ cm(-2). The buried amorphous thickness increased rapidly at 2.00 x 10(14) Al+ cm(-2) and eventually saturated at a thickness of similar to500 nm at the highest fluence. The relative amount of recovery at any depth decreased with increasing ion fluence for temperatures up to 870 K, and once a thick buried amorphous layer is produced, recovery is only observed at the crystalline-amorphous interface. Defect annihilation processes are responsible for the slight recrystallization and sharpening of the damage profiles that are observed at these low annealing temperatures.

  • 124063. Zhang, Y.
    et al.
    Weber, W. J.
    Jiang, W.
    Shutthanandan, V.
    Thevuthasan, S.
    Janson, Martin
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hallén, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Annealing behavior of Al-implantation-induced disorder in 4H-SiC2004In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 219, p. 647-651Article in journal (Refereed)
    Abstract [en]

    Single crystal 4H-SiC films were implanted at 150 K with 1.1 MeV Al-2(2+) and subsequently annealed at elevated 2 temperatures. In addition to the damage peak, an enhancement of the backscattering yield between the surface peak and damage peak is observed. Rutherford backscattering spectrometry results indicate that the relative Si disorder at the damage peak recovers significantly as the annealing temperature increases, and the near-surface peak disappears after annealing at 570 K. However, the residual Si disorder is more resistant to high-temperature annealing in the region of the implanted Al. The maximum concentration of Al profile measured by secondary ion mass spectroscopy is a factor of 1000 lower than the level of the residual Si disorder at the same region. Analysis of these results indicates that the excess residual Si disorder around the implanted Al projected range cannot be accounted for by just the Al interstitials; instead, it appears that implanted Al stabilizes or inhibits recovery Si disorder under the current experimental conditions.

  • 124064. Zhang, Y.
    et al.
    Weber, W. J.
    Jiang, W.
    Wang, C. M.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Possnert, G.
    Effects of implantation temperature and ion flux on damage accumulation in Al-implanted 4H-SiC2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 4, p. 1954-1960Article in journal (Refereed)
    Abstract [en]

    The effects of implantation temperature and ion flux on damage accumulation on both the Si and C sublattices in 4H-SiC have been investigated under 1.1-MeV Al-2(2+) irradiation at temperatures from 150 to 450 K. The rate of damage accumulation decreases dramatically, and the damage profile sharpens due to significant dynamic recovery at temperatures close to the critical temperature for amorphization. At 450 K, the relative disorder and the density of planar defects increase rapidly with the increasing ion flux, exhibiting saturation at high ion fluxes. Planar defects are generated through the agglomeration of excess Si and C interstitials during irradiation and post-irradiation annealing at 450 K. A volume expansion of similar to8% is estimated for the peak damage region.

  • 124065. Zhang, Y.
    et al.
    Weber, W. J.
    Jiang, W.
    Wang, C. M.
    Shutthanandan, V.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Effects of implantation temperature on damage accumulation in Al-implanted 4H-SiC2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 95, no 8, p. 4012-4018Article in journal (Refereed)
    Abstract [en]

    Damage accumulation in 4H-SiC under 1.1 MeV Al-2(2+) irradiation is investigated as a function of dose at temperatures from 150 to 450 K. Based on Rutherford backscattering spectroscopy and nuclear reaction analysis channeling spectra, the damage accumulation on both the Si and C sublattices have been determined, and a disorder accumulation model has been fit to the data. The model fits indicate that defect-stimulated amorphization is the primary amorphization mechanism in SiC over the temperature range investigated. The temperature dependence of the cross section for defect-stimulated amorphization and the critical dose for amorphization indicate that two different dynamic recovery processes are present, which are attributed to short-range recombination and long-range migration of point defects below and above room temperature, respectively. As the irradiation temperature approaches the critical temperature for amorphization, cluster formation has an increasing effect on disorder accumulation, and ion flux plays an important role on the nature and evolution of disorder. Dislocation loops, which are mostly formed under high ion flux, act as sinks for point defects, thereby reducing the disorder accumulation rate.

  • 124066. Zhang, Y.
    et al.
    Xiao, S.
    Yu, Y.
    Chen, C.
    Bi, M.
    Liu, L.
    Zhang, Lu
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). Shanghai Jiao Tong Univ, Peoples R China.
    Hu, W.
    Experimental study of wideband in-band full-duplex communication based on optical self-interference cancellation2016In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 24, no 26, p. 30139-30148Article in journal (Refereed)
    Abstract [en]

    In this paper, we experimentally demonstrate and study a wideband in-band fullduplex (IBFD) wireless communication system based on optical self-interference cancellation (SIC). The optical SIC performances based on antennas for broadband IBFD are firstly evaluated within high frequency bands (&gt; 10GHz). In this system, two electro-absorptionmodulated lasers (EMLs) and a balanced photo-detector (BPD) are employed to remove the wideband self-interference within received wireless signal. By theoretical derivation and experimental verification, the impact factors of SIC are analyzed, especially for non-flatness wireless channel case. Experimental results show more than 30-dB cancellation depth in 100-MHz bandwidth with employment of horn antennas. Besides, IBFD transmission performance based on OFDM signals for different bandwidth with 11.15-GHz center frequency is also demonstrated, and ∼52.2-dB•Hz2/3 spurious-free dynamic range (SFDR) is obtained.

  • 124067.
    Zhang, Yafan
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems. RISE Acreo AB.
    Multiphysics Characterization of SiC Power Modules2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis proposes several novel silicon carbide power module design concepts. The goal has been to address the problems with the present designs. The electrical, thermal, and thermomechanical performances of the demonstrators have been evaluated along with presentations of methodologies of experimental and numerical characterizations.

    Compact high-temperature power modules with adequate cooling systems are attractive to automotive applications. Therefore, a novel thermal design of a double-sided liquid/air cooled silicon carbide power module (1200 V, 200 A) has been proposed. The concept integrates a dc-link capacitor, a gate driver board, and finned cooling channels. The cooling concept has been evaluated for three application scenarios based on a validated computational fluid dynamics model. Moreover, a simulation methodology has been developed to quantify the effect of different materials and thicknesses of the cold plates on the temperature of the silicon carbide power dies.

    For medium- and high-power applications, contemporary research concludes that the reliability of the existing packaging technology needs to be improved. Therefore, this work proposes a novel press-pack silicon carbide power module concept. The concept enables bondless package and allows for an order of magnitude higher clamping force on the heatsinks than what can be applied on the dies. First, experimental and numerical methodologies for thermomechanical performance characterization of a press-pack structure have been investigated. By using digital image correlation technique, the deformation of each stacked material layer has been obtained. The developed experiment has led to an analytical estimation of friction coefficients on the contact interfaces. The co-influence of the design parameters on the thermomechanical performance of the press-pack structure has been analyzed through a parametric study based on a finite element model. Second, the novel double press-pack silicon carbide power module concept has been evaluated in a demonstrator in terms of parasitic inductance, thermal resistance, and thermomechanical stress.

    Furthermore, many of the power module designs only stay at the stage of proof-of-concept due to the cost of retooling of the manufacturing facility. Embedded power modules which employ advanced printed circuit board processing and die embedding technologies, enable a solution with possibility of low cost and mass production. Therefore, a novel design concept of a three-phase embedded power module (1200 V, 20 A) has been proposed. Simulation-driven design development has been implemented and lead to a fabricated demonstrator. The electromagnetic, thermal, and thermomechanical performances of the concept have been evaluated by simulations and compared to a commercially available power module.

  • 124068.
    Zhang, Yafan
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion. Jönköping University, Sweden.
    Belov, Ilja
    Bakowski, Mietek
    Lim, Jang-Kwon
    Leisner, Peter
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Investigation of a Finned Baseplate Material and Thickness Variation for Thermal Performance of a SiC Power Module2014In: 2014 15th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2014, IEEE Computer Society, 2014, article id 6813817Conference paper (Refereed)
    Abstract [en]

    A simplified transient computational fluid dynamics model of an automotive three-phase double-side liquid cooled silicon carbide power inverter, including pin-fin baseplates, has been developed and qualified for parametric studies. Effective heat transfer coefficients have been extracted from the detailed pin-fin baseplate model for two coolant volume flow rates 2 l/min and 6 l/min, at the coolant temperature 105 degrees C. The inverter model includes temperature dependent heat losses of SiC transistors and diodes, calculated for two driving cycles. Baseplate materials such as copper, aluminum-silicon carbide metal matrix composite, aluminium alloy 6061 as well as virtual materials have been evaluated in the parametric studies. Thermal conductivity, specific heat and density have been varied as well as thickness of the finned baseplates (1 to 3 mm). A trade-off between temperature of SiC chips and baseplate weight has been investigated by means of Pareto optimization. The main results of the parametric studies include a weak dependence (1 to 3 degrees C) of the chip temperature on baseplate thickness. Furthermore, switching e.g. between copper and AlSiC results in 5 to 8 degrees C increase of the chip temperature, at 65 to 70 % baseplate weight reduction.

  • 124069.
    Zhang, Yafan
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion. Acreo Swedish ICT AB.
    Belov, Ilja
    Jönköpng University.
    Sarius, Niklas G.
    Sp Technical Research Institute of Sweden.
    Bakowski, Mietek
    Acreo Swedish ICT AB.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leisner, Peter
    Sp Technical Research Institute of Sweden.
    Thermal evaluation of a liquid/air cooled integrated power inverter for hybrid vehicle applications2013In: 2013 14th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2013, New York: IEEE , 2013, p. 6529944-Conference paper (Refereed)
    Abstract [en]

    A thermal design of an integrated double-side cooled SiC 50kW-1200V-200A power inverter for hybrid electric vehicle applications has been proposed to enable cooling in two different automotive operating environments: under-hood and controlled temperature environment of passenger compartment. The power inverter is integrated with air/liquid cooled cold plates equipped with finned channels. Concept evaluation and CFD model calibration have been performed on a simplified thermal prototype. Computational experiments on the detailed model of the inverter, including packaging materials, have been performed for automotive industry defined application scenarios, including two extreme and one typical driving cycles. For the studied application scenarios the case temperature of the SiC transistors and diodes have been found to be below 210°C. The maximum steady-state temperature of the DC-link capacitor has been below 127 °C for the worst-case scenario including liquid cooling, and up to 140 °C for the worst-case scenario with air-cooling.

  • 124070.
    Zhang, Yafan
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems. RISE Acreo AB, Sweden.
    Hammam, Tag
    Belov, Ilja
    Sjögren, Torsten
    Bakowski, Mietek
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Thermomechanical Analysis and Characterization of a Press-Pack Structure for SiC Power Module Packaging Applications2017In: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 7, no 7, p. 1089-1100Article in journal (Refereed)
    Abstract [en]

    This paper presents an experimental methodology for the characterization of thermomechanical displacement and friction properties in a free-floating press-pack structure, and evaluation of the tensile stress on the semiconductor die through simulation of different mechanical and thermal loading conditions. The press-pack structure consists of a single silver-metallized (1 μm) silicon carbide die (400 μm) in contact with rhodium-coated (0.4 μm) molybdenum square plates. The thermomechanical displacements in the press-pack structure have been obtained using the digital image correlation technique, and the mean random error has been $± $0.1 μm, which is approximately 10 ppm of the measured length (10.5 mm). The developed experimental method has led to an analytical estimation of friction coefficients on the interfaces' silicon carbide-molybdenum and molybdenum-copper. The results demonstrate that the thin silver layer behaves as a solid film lubricant. A 2-D finite-element model representing the experimental setup has been implemented. The difference in displacement between measurement and simulation is less than 8%. Furthermore, the coinfluence of the design parameters on the thermomechanical performance of the stacked structure has been analyzed through simulations. Finally, design guidelines to reduce the tensile stress on the silicon carbide die have been proposed regarding free-floating press-pack power electronics packaging.

  • 124071.
    Zhang, Yafan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems. Department of Netlab, RISE Acreo AB, Kista, Sweden.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Hammam, Tag
    Belov, Ilja
    Ranstad, Per
    Bakowski, Mietek
    Multiphysics Characterization of a Novel SiC Power Module2019In: IEEE transactions on components, packaging, and manufacturing technology. Part A (Print), ISSN 1070-9886, E-ISSN 1558-3678, Vol. 9, no 3, p. 489-501Article in journal (Refereed)
    Abstract [en]

    This paper proposes a novel power module concept specially designed for highly reliable silicon carbide (SiC) power devices for medium- and high-power applications. The concept consists of two clamped structures: 1) a press-pack power stage accommodating SiC power switch dies and 2) perpendicularly clamped press-pack heatsinks, in which the heatsinks are in contact with electrically insulated case plates of the power stage. The concept enables bondless package with symmetric double-sided cooling of the dies and allows for an order of magnitude higher clamping force on the heatsinks than what can be applied on the dies. The concept has been evaluated in a first demonstrator (half-bridge configuration with 10 paralleled SiC dies in each position). The experimental methodologies, setups, and procedures have been presented. The commutation loop inductance is approximately 9 nH at 78 kHz. The junction-to-case thermal resistance is approximately 0.028 K/W. Furthermore, a simplified 3-D finite-element thermomechanical model representing the center unit of the demonstrator has been established for the purpose of future optimization. The accuracy of the simulated temperatures is within 4% compared to the measurements. Finally, a 3-D thermomechanical stress distribution map has been obtained for the simplified model of the demonstrator.

  • 124072.
    Zhang, Yafan
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems. RISE Acreo AB, Sweden.
    Neumaier, K.
    Zschieschang, O.
    Weis, G.
    Schmid, G.
    Bakowski, M.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Simulation-driven development of a novel SiC embedded power module design concept2017In: 2017 18th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7926252Conference paper (Refereed)
    Abstract [en]

    Silicon carbide embedded power modules enable a compact and cost competitive packaging solution for high-switching frequency and high-temperature operation applications. Power module packaging technologies span several engineering domains. At the early design stage, simulation-driven development is necessary to shorten the design period and reduce the design cost. This paper presents a novel design concept of a three-phase embedded power module (1200 V, 20 A, 55 mm × 36 mm × 0.808 mm) including silicon carbide metal-oxide-semiconductor field-effect transistor and antiparallel diode dies. Based on the E/CAD design data different layer built-up designs have been tested against thermal, mechanical, and electrical behavior. The obtained simulation data then have been evaluated against a commercial available power module (Motion Smart Power Module SMP33) which utilizes over mold direct bonded copper substrates with soldered semiconductor dies and bond wire contacts. Compared to the conventional module, the loop conductive interconnection parasitic inductance and resistance of the design concept (Vdc+ to Vdc-) reduces approximately by 88 % and 72 %, respectively. The average junction to case thermal resistance has been improved by approximately more than 10 % even though the total package size reduces by approximately 88 %. Furthermore, the contours of deformation and stresses have been investigated for the design concept in the thermomechanical simulation.

  • 124073.
    Zhang, Yan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chemoenzymatic Resolution in Dynamic Systems: Screening, Classification and Asymmetric Synthesis2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This  thesis  is  divided  into  four  parts,  all  centered  around  Constitutional Dynamic  Chemistry  (CDC)  and  Dynamic  Kinetic  Resolution  (DKR)  using biocatalysts for selective transformations, and their applications in screening of bioactive compounds, organic synthesis, and enzyme classification.   

    In  part  one,  an  introduction  to  CDC  and  DKR  is  presented,  illustrating  the basic  concepts,  practical  considerations  and  potential  applications  of  such dynamic systems, thus providing the background information for the studies in the following chapters.  

    In part two, Dynamic Systemic Resolution (DSR), a concept based on CDC is exemplified.  With  enzyme-catalyzed  transformations  as  external  selection pressure,  optimal  structures  can  be  selected  and  amplified  from  the  system. This  concept  is  expanded  to  various  types  of  dynamic  systems  containing single, double cascade/parallel, and multiple reversible reactions. In addition, the  substrate  selectivity  and  catalytic  promiscuity  of  target  enzymes  are  also investigated.  

    In   part   three,   DKR   protocols   using   reversible   reactions   for   substrate racemizations  are  illustrated.  Biocatalysts  are  here  employed  for  asymmetric transformations,  resulting  in  efficient  synthetic  pathways  for  enantioenriched organic compounds.  

    Part  four  demonstrates  two  unique  applications  of  CDC:  one  resulting  in enzyme  classification  by  use  of  pattern  recognition  methodology;  the  other involving  enzyme  self-inhibition  through  in  situ  transformation  of  stealth inhibitors employing the catalytic activity of the target enzyme.

  • 124074.
    Zhang, Yan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Wireless sensor network for volcano monitoring2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The monitoring of volcanoes for risk assessment has deployed single sensors for years. This kind of system requires manual supervision to monitor each sensor, which makes the monitoring work not flexible and efficient enough to adapt to variable volcano environments. With the development of wireless sensor networks, the accuracy and coverage of volcano observations can be improved by deploying networked sensors. This paper proposes a wireless sensor network prototype for volcano remote monitoring, which was built and tested in a field campaign in volcano Etna, Italy in September of 2004.Hardware design of sensors, in-depth sensor network design and software module architecture will be introduced in this paper. The experience gained from the practical work in volcano Etna will be used in an upcoming volcano monitoring project.

  • 124075.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Angelin, Marcus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Larsson, Rikard
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Albers, Antonia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Simons, Adrian
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tandem driven dynamic self-inhibition of acetylcholinesterase2010In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 46, no 44, p. 8457-8459Article in journal (Refereed)
    Abstract [en]

    A concept of tandem driven dynamic self-inhibition is demonstrated through dynamic inhibitors of acetylcholinesterase (AChE) using reversible transthiolesterification.

  • 124076.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hu, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Double parallel dynamic resolution through lipase-catalyzed asymmetric transformation2013In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, no 18, p. 1805-1807Article in journal (Refereed)
    Abstract [en]

    Dynamic systems based on double parallel reactions have been generated and resolved in situ by secondary lipase-catalyzed asymmetric transformation, resulting in high chemo- and enantioselectivities.

  • 124077.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Jayawardena, H. Surangi N.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts Lowell, MA, United States.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Enzyme classification using complex dynamic hemithioacetal systems2016In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 52, no 28, p. 5053-5056Article in journal (Refereed)
    Abstract [en]

    A complex dynamic hemithioacetal system was generated for the evaluation of lipase reactivities in organic media. In combination with pattern recognition methodology, twelve different lipases were successfully classified into four distinct groups following their reaction selectivities and reactivities. A probe lipase was further categorized using the training matrix with predicted reactivity.

  • 124078.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Jayawardena, Surangi
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Classification of Lipases Using Pattern Recognition through Transformation of Dynamic Hemithioacetal SystemsArticle in journal (Other academic)
    Abstract [en]

    A complex dynamic hemithioacetal system was generated for the evaluation of lipase reactivities. In combination with pattern recognition methodology, twelve different lipases were successfully classified into three distinct groups following their reaction selectivities and reactivities. A probe lipase was further categorized using the training matrix with predicted reactivity.

  • 124079.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lipase-Catalyzed Dynamic Systemic Resolution from Reversible Reaction NetworksArticle in journal (Other academic)
    Abstract [en]

    A dynamic system based on a network of multiple reversible reactions has been established. The network was applied to a dynamic systemic resolution protocol based on two kinetically controlled lipase-catalyzed transformations, where two compounds were efficiently selected from a pool of potential products.

  • 124080.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Thiazolidinones Derived from Dynamic Systemic Resolution of Complex Reversible-Reaction Networks2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 12, p. 3288-3291Article in journal (Refereed)
    Abstract [en]

    A complex dynamic system based on a network of multiple reversible reactions has been established. The network was applied to a dynamic systemic resolution protocol based on kinetically controlled lipase-catalyzed transformations. This resulted in the formation of cyclized products, where two thiazolidinone compounds were efficiently produced from a range of potential transformations.

  • 124081. Zhang, Yan
    et al.
    Sakulsombat, Morakot
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Vongvilai, Pornrapee
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hu, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lipase-mediated dynamic systemic resolution based on single or double reversible reactions2012In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 244Article in journal (Other academic)
  • 124082.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Schaufelberger, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sakulsombat, Morakot
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Liu, Chelsea
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Asymmetric Dynamic Kinetic Resolution for the Synthesis of 1,3-Oxathiolan-5-one DerivativesArticle in journal (Other academic)
    Abstract [en]

    Synthesis of 1,3-oxathiolan-5-one derivatives through dynamic kinetic resolution strategy has been illustrated, resulting in moderate to good enantioselectivities of the final products. In addition, the substrate scope and potential access to lamivudine (3TC) have also been explored.

  • 124083.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Schaufelberger, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sakulsombat, Morakot
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Liu, Chelsea
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Asymmetric synthesis of 1,3-oxathiolan-5-one derivatives through dynamic covalent kinetic resolution2014In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 70, no 24, p. 3826-3831Article in journal (Refereed)
    Abstract [en]

    The asymmetric synthesis of 1,3-oxathiolan-5-one derivatives through an enzyme-catalyzed, dynamic covalent kinetic resolution strategy is presented. Dynamic hemithioacetal formation combined with intramolecular, lipase-catalyzed lactonization resulted in good conversions with moderate to good enantiomeric excess (ee) for the final products. The process was evaluated for different lipase preparations, solvents, bases, and reaction temperatures, where lipase B from Candida antarctica (CAL-B) proved most efficient. The substrate scope was furthermore explored for a range of aldehyde structures, together with the potential access to nucleoside analog inhibitor core structures.

  • 124084.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Vongvilai, Pornrapee
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sakulsombat, Morakot
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Asymmetric Synthesis of Substituted Thiolanes through Domino Thia-Michael-Henry Dynamic Covalent Systemic Resolution using Lipase Catalysis2014In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 356, no 5, p. 987-992Article in journal (Refereed)
    Abstract [en]

    Dynamic systems based on consecutive thia-Michael and Henry reactions were generated and transformed using lipase-catalyzed asymmetric transformation. Substituted thiolane structures with three contiguous stereocenters were resolved in the process in high yields and high enantiomeric excesses.

  • 124085.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Vongvilai, Pornrapee
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sakulsombat, Morakot
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Biocatalyzed Dynamic Systemic Domino Thia-Michael--Henry Resolution to Substituted Asymmetric ThiolanesArticle in journal (Other academic)
    Abstract [en]

    Dynamic systems based on consecutive thia-Michael and Henry reactions were generated and transformed using lipase-catalyzed asymmetric transformation. Substituted thiolane structures with three contiguous stereocenters were resolved in the process in high yields and high enantiomeric excesses.

  • 124086.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Zhang, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Asymmetric synthesis of oxazolidin-2-one derivatives through lipase-catalyzed kinetic resolution2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247Article in journal (Other academic)
  • 124087.
    Zhang, Yan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ren, Yansong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of chiral oxazolidinone derivatives through lipase-catalyzed kinetic resolution2015In: Journal of Molecular Catalysis B: Enzymatic, ISSN 1381-1177, E-ISSN 1873-3158, Vol. 122, p. 29-34Article in journal (Refereed)
    Abstract [en]

    The synthesis of enantioenriched oxazolidinone derivatives through lipase-catalyzed kinetic resolution is described. The synthesis comprised a two-step, cascade acylation in one pot, resulting in a range of oxazolidinone derivatives in good yields and excellent enantiopurities.

  • 124088.
    Zhang, Yang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    A visualization interface for spatial pathway regulation data2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Data visualization is an essential methodology for bioinformatics studies. Spatial Transcriptomics(ST) is a method that aims at measuring the transcriptome of tissue sections while maintaining its spacial information. Finally, the study of biological pathway focuses on a series of biochemical reactions that take place in organisms. As these studies generate a large number of datasets, this thesis attempts to combine the ST’s data with pathwayinformation and visualize it in an intuitive way to assist user comprehension and insight.In this thesis, Python was used for integrating the dataset and JavaScript libraries wereused for building the visualization. The processing of ST pathway data together with the data visualization interface are the outcomes of this thesis. The data visualization can show the regulation of pathways in the ST data and can be accessed by modern browsers. These outcomes can help users navigate the ST and pathway datasets more effectively.

  • 124089.
    Zhang, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dynamic Systems: Enzymatic Synthesis, Exchange Reactions and Applications in Materials Science2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is divided into three parts, revolving around the developments of dynamic systems utilized in dynamic kinetic resolution (DKR) and constitutional dynamic chemistry (CDC).

    The first section gives an introduction to constitutional dynamics, the core concept of this thesis. Constitutional dynamics can be tuned through reversible interactions. Then, the basic principles of constitutional dynamics in DKR and CDC are discussed, along with their applications.

    The second section explores the asymmetric synthesis of oxazolidinone derivatives using lipase catalysis through kinetic resolution (KR) and dynamic kinetic resolution. In the first example, synthetic protocol to enantioenriched 5-phenyloxazolidin-2-ones is described, where a kinetically controlled carbamation is followed by lipase-catalyzed cyclization. In contrast to the 5-substituted species, the synthesis of 3-phenyloxazolidin-2-one derivatives could be achieved through lipase-catalyzed cascade O- and N- alkoxycarbonylations in one pot. Furthermore, this KR system could be coupled to a ruthenium-catalyzed racemization process of 1,2-aminoalcohols, thus providing an efficient DKR methodology for asymmetric transformations.

    The third section focuses on dynamic systems built through reversible covalent reactions. In the first example, a selective gelation process is described, and employed to resolve dynamic imine systems consisting of gelator candidates.  In the second example, reversible reactions with aldehyde enamines are presented, including enamine formation and exchange reactions. In particular, Bi(III) and Sc(III) were discovered to accelerate the enamine exchange reactions by 50-400 times, in which the equilibria could be reached within hours. The last example describes reversible nitroaldol reactions in aqueous media, where rapid and efficient equilibration was identified for selected structures in neutral phosphate buffer.

  • 124090.
    Zhang, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Integration of Battery and Hydrogen Storage with a Grid-Connected Photovoltaic System in Buildings2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

        The integration of Photovoltaic (PV) with buildings changes the previous electricity consumers into prosumers. The reduced PV subsidies and the grid stable operation requirements are pushing prosumers from direct exportation to self-consumption of the produced electricity. Electricity storage increases the self-consumption, while comes with higher investment. During the system planning stage, the benefits of storage should be clarified to prosumers. The storage type, the storage capacity and the system operation strategy should be determined at the same time.

        This thesis dealt with a grid-connected PV-storage system and proposed an optimization method, which simultaneously determined the storage capacity and rule-based operation strategy parameters. This method eliminated the necessity of forecasting and could be easily implemented. A typical residential building in Sweden was taken as a case study. Different operation strategies as well as two storage technologies – battery storage and hydrogen storage – were compared.

        For the battery storage system, the proposed battery hybrid operation strategy, which carries out the conventional operation strategy during warm months and the peak shaving strategy during cold months, provides the best performance in Self Sufficiency Ratio (SSR) and Net Present Value (NPV). For the hydrogen storage system, the hydrogen hybrid operation strategy outperforms other studied operation strategies under different scenarios, which have optimistic or pessimistic cost assumptions of the hydrogen storage system.

        The comparison between hydrogen storage and battery storage suggests that battery storage has much better performance in SSR and NPV under the pessimistic cost scenario. Under the optimistic cost scenario, battery storage and hydrogen storage achieve comparable performance in SSR and NPV. However, hydrogen storage is more favorable when considering reducing the prosumer’s negative impact on the grid.

  • 124091.
    Zhang, Yang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Integration of Distributed Renewable Energy and Energy Storages in Buildings2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Photovoltaic (PV) is a distributed renewable energy technology that is suitable for integration in buildings. PV reduces the electricity demands as well as the greenhouse gas emissions of buildings. However, the surplus electricity from PV is exported to the electricity grid, which not only lowers the economic performance of the PV but also creates operational problems in the grid. Efficient approaches should be identified to improve PV’s economic and environmental performance.

    Buildings differ by their connections to energy networks. In buildings that are only connected to the electricity grid, electrical energy storages— including battery and hydrogen storage—can mitigate the mismatch between production and consumption. When a grid-connected PV system follows the conventional operation strategy, its economic performance worsens with storage. Two new operation strategies are developed. With a developed optimization framework, operation strategies and storage capacities are optimized simultaneously. Optimization results indicate that both net present value and self-sufficiency ratio are increased by storages. A comparison between battery storages and hydrogen storages shows that the hydrogen storage can compete with the battery counterpart under an optimistic hydrogen storage cost scenario. In addition, the hydrogen storage can better decrease the exported electricity.

    In buildings that are connected to the electricity grid and the district heating network, additional energy conversion and storage equipment— including heat pumps, electrical heaters, and hot water tanks—can be installed to form an integrated energy system (IES). After optimal system sizing, the IES decreases the net present cost by 22%, and the self-consumption ratio increases from 43% to 61%. Moreover, the IES serves as a new flexibility measure, and the provided flexibility energy is over 36% of its electricity consumption. During system planning, the system configuration and operation cost are obtained without considering forecast errors. Through the year-round simulation of system operation that considers forecast errors, a corrected operation cost is obtained. The yearly operation cost difference between system operation and system planning is less than 4% and 6% under the high and low forecast accuracy scenarios.

    The full text will be freely available from 2019-12-31 12:46
  • 124092.
    Zhang, Yang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Campana, Pietro Elia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Lundblad, Anders
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Wandong, Zheng
    Yan, Jinyue
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Planning and Operation of an Integrated Energy System in a Swedish BuildingManuscript (preprint) (Other academic)
    Abstract [en]

    The increasing capacities of variable renewable energies (VRE) require more flexibility measures. The integration of energy supplies in buildings forms integrated energy systems (IES). IESs can provide flexibility and help increase the VRE penetration level. To upgrade a current building energy system into an IES, several energy conversion and storage components need to be installed. How to decide the component capacities and operate the IES were investigated separately in studies on system planning and system operation. However, a research gap exists that the system configuration from system planning is not validated by real operation conditions in system operation. Meanwhile, studies on system operation assume that the IES configuration is predetermined. This work combines system planning and system operation. The IES configuration is determined by mixed integer linear programming in system planning. Real operation conditions and forecast errors are considered in the system operation. The operation profiles are obtained through different energy management systems. The results indicate that the system configuration from system planning can meet energy demands in real operation conditions. Among different energy management systems, the combination of robust optimization and receding horizon optimization achieves the lowest yearly operation cost. Meanwhile, two scenarios that represent high and low forecast accuracies are employed. Under the high and low forecast accuracy scenarios, the yearly operation costs are about 4% and 6% higher than those obtained from system planning.

  • 124093.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Campana, Pietro Elia
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Wang, Lei
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    The Influence of Photovoltaic Models and Battery Models in System Simulation and Optimization2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105C, p. 1185-1192Article in journal (Refereed)
    Abstract [en]

    Selecting accurate and robust models is important for simulation and optimization of a clean energysystem. This paper compares two photovoltaic (PV) models and two battery models in an open-sourcecode, Opti-CE. The PV models are single diode model and its simplified model. The battery models areImproved Shepherd model and energy balance model. The models are compared from a perspective ofoverall system simulation and optimization in particular on both accuracy and computational time. Theresults indicate that simplified PV model causes 0.86% normalized root mean square error (nRMSE)compared with the single diode model, while decreases the simulation time from more than 800s to lessthan 0.01s. The energy balance battery model reduces simulation time from more than 5s to less than0.03s. The energy balance model tends to underestimate the battery State of Charge (SOC) compared withthe Improved Shepherd model. However, the error is not accumulative during the simulation. Comparedto the Pareto front with single diode model and Improved Shepherd model, the simplified PV modelincreases the Pareto front values and result in both higher Self Sufficiency Ratio (SSR) and Net PresentValue (NPV), while the energy balance battery model decreases the part of Pareto front, whereindividuals have low NPV.

  • 124094.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Campana, Pietro Elia
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Comparative study of hydrogen storage and battery storage in gridconnected photovoltaic system: Storage sizing and rule-basedoperation2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118Article in journal (Refereed)
    Abstract [en]

    The paper studies grid-connected photovoltaic (PV)-hydrogen/battery systems. The storage componentcapacities and the rule-based operation strategy parameters are simultaneously optimized by theGenetic Algorithm. Three operation strategies for the hydrogen storage, namely conventional operationstrategy, peak shaving strategy and hybrid operation strategy, are compared under two scenarios basedon the pessimistic and optimistic costs. The results indicate that the hybrid operation strategy, whichcombines the conventional operation strategy and the peak shaving strategy, is advantageous in achievinghigher Net Present Value (NPV) and Self Sufficiency Ratio (SSR). Hydrogen storage is further comparedwith battery storage. Under the pessimistic cost scenario, hydrogen storage results in poorer performancein both SSR and NPV. While under the optimistic cost scenario, hydrogen storage achieves higher NPV.Moreover, when taking into account the grid power fluctuation, hydrogen storage achieves better performancein all three optimization objectives, which are NPV, SSR and GI (Grid Indicator).

  • 124095.
    Zhang, Yang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Campana, Pietro Elia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes. Mälardalen Univ, Sch Business Soc & Engn, SE-72123 Västerås, Sweden..
    Yang, Ying
    Mälardalen Univ, Sch Business Soc & Engn, SE-72123 Västerås, Sweden..
    Lundblad, Anders
    RISE Res Inst Sweden, Div Safety & Transport Elect, SE-50462 Borås, Sweden..
    Yan, Jerry
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes. Mälardalen Univ, Sch Business Soc & Engn, SE-72123 Västerås, Sweden..
    Energy Flexibility through the Integrated Energy Supply System in Buildings: A Case Study in Sweden2018In: RENEWABLE ENERGY INTEGRATION WITH MINI/MICROGRID / [ed] Yan, J Wang, C Yu, J Jia, H Wu, J Xu, T Zhang, Y, ELSEVIER SCIENCE BV , 2018, p. 564-569Conference paper (Refereed)
    Abstract [en]

    The increasing penetration level of renewable energies requires more flexibility measures at the consumption side. Flexible energy prices have been placed by energy providers to promote flexibility measures from energy users. However, because of the current energy supply system in buildings, these flexible energy prices haven't been fully taken advantage of This study focuses on the integrated energy supply system in buildings. A Swedish office building is used as the case study. The integrated energy supply system is built by installing new components, including battery, heat pump and electrical heater, and hot water tank. Mixed Integer Linear Programming (MILP) problems are solved to determine the optimal component capacities and operation profiles. The results indicate that all the studied system configurations achieve lower net present cost (NPC) than the current system. It suggests that the integrated energy supply system can take advantage of the flexible energy prices and lower the overall energy cost in the building. Among the studied configurations, the combination of air source heat pump (ASHP) and electrical heater (EH) has the lowest investment cost. This combination also has the lowest NPC except in the scenario with low borehole cost.

  • 124096.
    Zhang, Yang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Campana, Pietro Elia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes. Mälardalen University, Västerås, Sweden.
    Yang, Ying
    Stridh, Bengt
    Lundblad, Anders
    Yan, Jinyue
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes. Mälardalen University, Västerås, Sweden.
    Energy flexibility from the consumer: Integrating local electricity and heat supplies in a building2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 223, p. 430-442Article in journal (Refereed)
    Abstract [en]

    The increasing penetration level of renewable energy requires more flexibility measures to be implemented in future energy systems. Integrating an energy consumer's local energy supplies connects multiple energy networks (i.e., the electrical grid, the district heating network, and gas network) in a decentralized way. Such integration enhances the flexibility of energy systems. In this work, a Swedish office building is investigated as a case study. Different components, including heat pump, electrical heater, battery and hot water storage tank are integrated into the electricity and heat supply system of the building. Special focus is placed on the flexibility that the studied building can provide to the electrical grid (i.e., the building modulates the electricity consumption in response to the grid operator's requirements). The flexibility is described by two metrics including the flexibility hours and the flexibility energy. Optimization of the component capacities and the operation profiles is carried out by using Mixed Integer Linear Programming (MILP). The results show that the system fully relies on electricity for the heat demand when not considering the flexibility requirements of the electrical grid. This suggests that district heating is economically unfavorable compared with using electricity for the heat demand in the studied case. However, when flexibility requirements are added, the system turns to the district heating network for part of the heat demand. The system provides great flexibility to the electrical grid through such integration. The flexibility hours can be over 5200 h in a year, and the flexibility energy reaches more than 15.7 MWh (36% of the yearly electricity consumption). The yearly operation cost of the system slightly increases from 62,273 to 65,178 SEK when the flexibility hours increase from 304 to 5209 h. The results revealed that flexibility can be provided from the district heating network to the electrical grid via the building.

  • 124097.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Karalius, Antanas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kinetics and Thermodynamics of Dynamic Nitroaldol Systems in Neutral Aqueous MediaManuscript (preprint) (Other academic)
  • 124098.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Ningbo RK Solar Tech. Ltd., China.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Västerås, Sweden.
    Campana, P. E.
    Benavente, F.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Sweden.
    Battery sizing and rule-based operation of grid-connected photovoltaic-battery system: A case study in Sweden2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 133, p. 249-263Article in journal (Refereed)
    Abstract [en]

    The optimal components design for grid-connected photovoltaic-battery systems should be determined with consideration of system operation. This study proposes a method to simultaneously optimize the battery capacity and rule-based operation strategy. The investigated photovoltaic-battery system is modeled using single diode photovoltaic model and Improved Shepherd battery model. Three rule-based operation strategies—including the conventional operation strategy, the dynamic price load shifting strategy, and the hybrid operation strategy—are designed and evaluated. The rule-based operation strategies introduce different operation parameters to run the system operation. multi-objective Genetic Algorithm is employed to optimize the decisional variables, including battery capacity and operation parameters, towards maximizing the system's Self Sufficiency Ratio and Net Present Value. The results indicate that employing battery with the conventional operation strategy is not profitable, although it increases Self Sufficiency Ratio. The dynamic price load shifting strategy has similar performance with the conventional operation strategy because the electricity price variation is not large enough. The proposed hybrid operation strategy outperforms other investigated strategies. When the battery capacity is lower than 72 kW h, Self Sufficiency Ratio and Net Present Value increase simultaneously with the battery capacity.

  • 124099.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Ningbo RK Solar Tech. Ltd., China.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Sweden.
    Campana, Pietro Elia
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. Mälardalen University, Sweden.
    Comparative Study of Battery Storage and Hydrogen Storage to Increase Photovoltaic Self-sufficiency in a Residential Building of Sweden2016In: PROCEEDINGS OF RENEWABLE ENERGY INTEGRATION WITH MINI/MICROGRID (REM2016) / [ed] Yan, J Zhai, Y Wijayatunga, P Mohamed, AM Campana, PE, ELSEVIER SCIENCE BV , 2016, p. 268-273Conference paper (Refereed)
    Abstract [en]

    Photovoltaic (PV) is promising to supply power for residential buildings. Battery is the most widely employed storage method to mitigate the intermittence of PV and to overcome the mismatch between production and load. Hydrogen storage is another promising method that it is suitable for long-term storage. This study focuses on the comparison of self-sufficiency ratio and cost performance between battery storage and hydrogen storage for a residential building in Sweden. The results show that battery storage is superior to the hydrogen storage in the studied case. Sensitivity study of the component cost within the hydrogen storage system is also carried out. Electrolyzer cost is the most sensitive factor for improving system performance. A hybrid battery and hydrogen storage system, which can harness the advantages of both battery and hydrogen storages, is proposed in the last place.

  • 124100.
    Zhang, Yang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Campana, Pietro Elia
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Employing Battery Storage to Increase Photovoltaic Self-sufficiency in a Residential Building of Sweden2016In: CUE 2015 - APPLIED ENERGY SYMPOSIUM AND SUMMIT 2015: LOW CARBON CITIES AND URBAN ENERGY SYSTEMS, Elsevier, 2016, p. 455-461Conference paper (Refereed)
    Abstract [en]

    Photovoltaic (PV) or hybrid PV-battery systems are promising to supply power for residential buildings. In this study, the load profile of a multi apartment building in Gothenburg and the PV production profile under local weather conditions are compared and analyzed. Three different types of batteries, including lead acid, NaNiCl (Sodium-Nickel-Chloride) and Lithium ion, are studied in combination with the PV systems. It is found that Lithium ion battery system is superior in achieving higher Self-Sufficiency Ratio (SSR) with the same Life Cycle Cost (LCC). Achieving high SSR with the hybrid PV-battery system is unrealistic because of the seasonal mismatch between the load and electricity production profile. The capacity match between the PV and battery to maximize SSR was investigated, showing different trends under system LCC range of 0.1-40 Million SEK (1SEK approximate to 0.12USD). The system LCC should be lower than 10.6 Million SEK (at the SSR of 36%) in order to keep the payback time positive.

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