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  • 124001.
    Zhang, Wei
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Planning and evaluation of autonomous vehicles in freight and public transport services2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The introduction of automation technology in transport systems brings both opportunities and challenges. The direct benefits of automation technology are obvious, for instance, reduced marginal driving cost, improved energy efficiency and increased safety. However, factors such as additional vehicle acquisition cost might hinder the implementation of autonomous vehicles, especially in the early stages when mass production is not realized yet. Besides, some benefits require large-scale applications or cooperation among multiple vehicles, while the low market penetration rate of autonomous vehicles may make system-specific benefits insignificant. Without proper planning and operation schemes, the advantages of automation technology can be cancelled out by its disadvantages. Given that the advantages of individual autonomous vehicles have been extensively explored, it is necessary to estimate the efficiency of transport systems involving autonomous vehicles. This thesis intends to solve the operation problem of autonomous vehicles in freight and public transport systems, focusing on system cost analysis.

    In freight transport, semi-autonomous truck platooning is a promising way to reduce fuel consumption. By instructing vehicles to form groups and drive together closely, the trailing vehicles experience reduced air resistance from the leading vehicle, and thus less fuel consumption. However, in practice, freight transport companies should also take time windows and transport reliability into consideration. The study answers the questions whether platoons should be formed and how significant can the savings be, considering driving cost, predefined time windows, travel time uncertainty and fuel cost. System optimization techniques, including stochastic optimization and mixed-integer linear programming, are adopted to minimize the total cost.

    In public transport, autonomous buses are assumed to save on-board crew cost, partially or fully. Similar with truck platoons, semi-autonomous buses can also form bus platoons for the purpose of eliminating the drivers from trailing buses. By contrast, fully autonomous buses are completely driverless and operates individually like conventional buses. To investigate the efficiency of autonomous buses, we compare the total cost of autonomous buses with conventional buses, where both passengers’ cost and service provider’s cost are modelled. In a general trunk-and-branches network connecting city center and suburbs, both fully autonomous bus and semi-autonomous bus systems are assessed. On a simple highly demanded corridor where demand varies during peak and off-peak hours, semi-autonomous bus platoons can be used as trains by extending its capacity in peak hours. Application of semi-autonomous vehicles are considered in traditional bus transit and BRT, by comparing with its conventional opponents.

  • 124002.
    Zhang, Wei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Bah, Juho
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wohlfarth, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Franzen, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    A Stereodivergent Strategy for the Preparation of Corynantheine and Ipecac Alkaloids, Their Epimers, and Analogues: Efficient Total Synthesis of ()- Dihydrocorynantheol, ()-Corynantheol, ()-Protoemetinol, ()- Corynantheal, ()-Protoemetine, and Related Natural and Nonnatural Compound2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, no 49, p. 13814-13824Article in journal (Refereed)
    Abstract [en]

    Abstract: Here we present a general and common catalytic asymmetric strategy for the total and formal synthesis of a broad number of optically active natural products from the corynantheine and ipecac alkaloid families, for example, indoloACHTUNGTRENUNG[2,3-a]- and benzo[a]quinolizidines. Construction of the core alkaloid skeletons with the correct absolute and relative stereochemistry relies on an enantioselective and diastereodivergent one-pot cascade sequence followed by an additional diastereodivergent reaction step. This allows for enantio- and diastereoselective synthesis of three out of four possible epimers of the quinolizidine alkaloids that begin from common and easily accessible starting materials by using a common synthetic route. Focus has been made on excluding protecting groups and limiting isolation and purification of synthetic intermediates. This methodology is applied in the total synthesis of the natural products ()-dihydrocorynantheol, ()-hirsutinol, ()-corynantheol, ()-protometinol, ()-dihydrocorynantheal, ()-corynantheal, ()-protoemetine, ()-(15S)-hydroxydihydrocorynantheol, and an array of their nonnatural epimers. The potential of this strategy is also demonstrated in the synthesis of biologically interesting natural product analogues not accessible through synthetic elaboration of alkaloid precursors available from nature, for example, thieno[3,2-a]quinolizidine derivatives. We also report the formal synthesis of (+)-dihydrocorynantheine, ()-emetine, ()-cephaeline, ()-tubulosine, and ()-deoxytubulosine.

  • 124003. Zhang, Wei
    et al.
    Cai, Yixiao
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Department of Engineering Sciences, Ångström Laboratory, Uppsala University, 751 21 Uppsala, Sweden.
    Wang, Baoyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei 430062, China.
    Xia, Chen
    Dong, Wenjing
    Li, Junjiao
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei 430062, China.
    Mixed ionic-electronic conductor membrane based fuel cells by incorporating semiconductor Ni0.8Co0.15Al0.05LiO2-delta into the Ce0.8Sm0.2O2-delta-Na2CO3 electrolyte2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 34, p. 15346-15353Article in journal (Refereed)
    Abstract [en]

    In the present study, a novel composite was fabricated by incorporating the semiconductor Ni0.8Co0.15Al0.05LiO2-delta (NCAL) into the ionic electrolyte Ce0.8Sm0.2O2-delta-Na2CO3 (NSDC), and further developed as a mixed-conducting membrane for single layer fuel cell (SLFC) applications. Experimentally, the crystal structure, morphology, chemical composition and thermo-stability of the composite were characterized by XRD, SEM and TGA. The best cell performance was investigated when the NSDC-NCAL membrane was optimized at a weight ratio of 6:4. On this basis, a number of interesting findings were obtained: i) the mixed conducting membrane did not cause any short circuit; on the contrary, the cell reached a decent open circuit voltage (OCV) of similar to 1.0 V. a high power density of 1072 mW cm(-2) was achieved at 550 degrees C for the NSDC-NCAL membrane based cell, which was much better than that using a pure NSDC electrolyte membrane. Electrochemical impedance spectroscopy (EIS) showed that the NSDC-NCAL composite exhibited significantly improved grain boundary conduction and reduced electrode polarizations, contributing to the resultant performance. To consolidate the usefulness of the device, we also conducted the durability test. The above findings indicate the strategy of introducing mixed NSDC-NCAL membrane is feasible for high-performance SLFCs operating at low temperatures.

  • 124004.
    Zhang, Wei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Franzen, Johan.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Asymmetric catalytic synthesis of corynanthe and ipecac alkaloids2012In: Targets in Heterocyclic Systems: Chemistry and Properties / [ed] Orazio A. Attanasi; Domenico Spinelli, Societa Chimica Italiana , 2012, p. 31-55Chapter in book (Refereed)
    Abstract [en]

    Corynanthe and ipecac alkaloids constitute a large group of natural occurring alkaloids that demonstrate a vast variety of bioactivity and have a long history of usage as herbal drugs. Both the corynanthe and ipecac alkaloids share a common structural unit with a quinolizidine ring fused with a benzo- or indolo-group and three stereocentres wherein one is a ring-junction stereocentre. From synthetic point of view, these natural products represent an intriguing challenge and over the years several strategies toward the asymmetric total synthesis of corynanthe and ipecac alkaloids have been devised and the majority of these are target specific natural-pool based strategies. However, during the last few years, several efficient and diverse strategies based on asymmetric catalysis and one-pot cascade protocols as the key-steps have emerged. In this mini-review the attention is to give an overview of these strategies.

  • 124005.
    Zhang, Wei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Franzén, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Diverse Asymmetric Quinolizidine Synthesis: A Stereodivergent One-Pot Approach2010In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 352, no 2-3, p. 499-518Article in journal (Refereed)
    Abstract [en]

    A diverse stereodivergent organocatalytic one-pot addition/cyclization/annulation sequence to optically active quinolizidine derivatives from easily available starting materials is presented. The one-pot sequence relies on a pyrrolidine-catalyzed enantioselective Conjugate addition of electron-deficient amide alpha-carbons to alpha,beta-unsaturated aldehydes, spontaneous hemiaminal formation and acid-catalyzed/mediated N-acyliminium ion cyclization to give the quinolizidine framework. Simple tuning of the reaction conditions in the N-acyliminuim ion cyclization step provides a diastereomeric switch, which gives access to both of the two bridgehead epimers through kinetic, thermodynamic or chelation control. The methodology display a broad substrate scope that is demonstrated by the stereoselective formation of indolo-, thieno-, benzofuro-, furo- and different benzoquinolizidine derivatives with high atom efficiency, up to >99% ee and up to >95:5 dr. Due to its efficiency, synthetic diversity and operational simplicity, this protocol has the potential to find important use as a key step in natural product Synthesis, biochemistry and pharmaceutical science. The stereochemical Outcome of the one-pot sequence was investigated. and the mechanism and origin of stereoselectivity of the different steps is discussed.

  • 124006. Zhang, Wei
    et al.
    Hu, Youde
    Huan, Yuxiang
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Zou, Zhuo
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Cui, Keji
    Bao, Dongxuan
    Pan, Dashan
    Wang, Lebo
    Zheng, Lirong
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Hierarchical Design of a Low Power Standing Wave Oscillator Based Clock Distribution Network2016In: 2016 2ND IEEE NORDIC CIRCUITS AND SYSTEMS CONFERENCE (NORCAS), IEEE conference proceedings, 2016Conference paper (Refereed)
    Abstract [en]

    This paper introduces a hierarchical clock interconnection network with two-level bufferless standing wave resonant clock distribution to minimize the clock power consumption in a synchronous system. The first level is a serpentine network which consists of many coupled standing wave oscillators to distribute clock signals in the whole chip area. The second level is a group of fishbone architectures connected to the standing wave oscillators to route clock signals in the local areas. A clock synthesis flow for the fishbone architecture is also introduced to enable design automation. This fishbone architecture is studied through a pipelined floating-point fused multiply-add module under 28nm standard CMOS process. Simulation results show that, this architecture can reduce more than 30% clock power consumption compared with a traditional buffered clock network.

  • 124007. Zhang, Wei
    et al.
    Hu, You-de
    Zheng, Li-rong
    KTH, School of Information and Communication Technology (ICT), Industrial and Medical Electronics. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Design and simulation of a standing wave oscillator based PLL2016In: FRONTIERS OF INFORMATION TECHNOLOGY & ELECTRONIC ENGINEERING, ISSN 2095-9184, Vol. 17, no 3, p. 258-264Article in journal (Refereed)
    Abstract [en]

    A standing wave oscillator (SWO) is a perfect clock source which can be used to produce a high frequency clock signal with a low skew and high reliability. However, it is difficult to tune the SWO in a wide range of frequencies. We introduce a frequency tunable SWO which uses an inversion mode metal-oxide-semiconductor (IMOS) field-effect transistor as a varactor, and give the simulation results of the frequency tuning range and power dissipation. Based on the frequency tunable SWO, a new phase locked loop (PLL) architecture is presented. This PLL can be used not only as a clock source, but also as a clock distribution network to provide high quality clock signals. The PLL achieves an approximately 50% frequency tuning range when designed in Global Foundry 65 nm 1P9M complementary metal-oxide-semiconductor (CMOS) technology, and can be used directly in a high performance multi-core microprocessor.

  • 124008.
    Zhang, Wei
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Hua, Yong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Wang, Linqin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Zhang, Biaobiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Liu, Peng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Leandri, Valentina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Guo, Yu
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Chen, Hong
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Gardner, James M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Dalian Univ Technol DUT, DUT KTH Joint Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Kloo, Lars
    The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells2019In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 9, p. 6768-6779Article in journal (Refereed)
    Abstract [en]

    Two zinc-based coordination complexes Y3 and Y4 have been synthesized and characterized, and their performance as hole-transport materials (HTMs) for perovskite solar cells (PSCs) has been investigated. The complex Y3 contains two separate ligands, and the molecular structure can be seen as a disconnected porphyrin ring. On the other hand, Y4 consists of a porphyrin core and therefore is a more extended conjugated system as compared to Y3. The optical and redox properties of the two different molecular complexes are comparable. However, the hole mobility and conductivity of Y4 as macroscopic material are remarkably higher than that of Y3. Furthermore, when employed as hole-transport materials in perovskite solar cells, cells containing Y4 show a power conversion efficiency (PCE) of 16.05%, comparable to the Spiro-OMeTAD-based solar cells with an efficiency around 17.08%. In contrast, solar cells based on Y3 show a negligible efficiency of about 0.01%. The difference in performance of Y3 and Y4 is analyzed and can be attributed to the difference in packing of the nonplanar and planar building blocks in the corresponding materials.

  • 124009.
    Zhang, Wei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Badia, Hugo
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Efficiency of connected semi-autonomous platooning bus services in high-demand transit corridorsManuscript (preprint) (Other academic)
    Abstract [en]

    The paper investigates the efficiency of serving high demand transit corridors with connected semi-autonomous busplatoons in both bus and BRT services. Platooning could make it possible to provide higher capacity than with conventionalbuses by forming virtual long buses out of multiple smaller vehicles, which could be particularly relevant inscenarios with large variation in demand between peak and off-peak hours. The problem is formulated as a constrainedoptimization problem to minimize total system cost, which includes waiting cost, access cost, riding cost, operatingcost and capital cost. For single period with fixed demand, both analytical solutions and numerical examples areprovided. Sensitivity analysis is carried out with regard to demand levels and capacity upper bound. The problemis generalized to a two-period problem considering peak and off-peak demand. Numerical results are provided withsensitivity analysis regarding average demand level and ratio of peak/off-peak demand. Furthermore, the impact of alower bound on service headway is investigated. The result shows that semi-autonomous vehicle platooning is competitivein medium and high demand scenarios, with the potential of reduced users’ cost and operator’s operating costat the expense of additional rolling stock cost. The minimum headway, restricted vehicle size, and higher demandratio all make semi-autonomous platooning more advantageous.

  • 124010.
    Zhang, Wei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Badia, Hugo
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Efficiency of semi-autonomous and fully autonomous bus services in trunk-and-branches networks2019In: Journal of Advanced Transportation, ISSN 0197-6729, E-ISSN 2042-3195, article id 7648735Article in journal (Refereed)
    Abstract [en]

    Automation technology is expected to change the public transport sector radically in the future. One rising issue is whether to embrace the intermediate stage of semi-autonomous buses or to wait until fully autonomous buses are available. This paper proposes a cost model of bus operations considering automation technology. The generalized cost, which is the sum of waiting, riding, operating, and capital cost, is modeled for conventional, semi-autonomous, and fully autonomous bus services on a generic trunk-and-branches network. Semi-autonomous buses achieve reduced unit operating cost through automated platooning on the corridor. The relative efficiency of the different services is studied under a range of scenarios for commercial speed, network structure, and demand distribution. Analytical and numerical results show that fully autonomous buses exhibit great potential through reduced operating and waiting costs even if the additional capital cost is high. The advantages of semi-autonomous buses are weaker and most prominent in networks with low demand along a long corridor such as interurban networks. For both automation levels a commercial speed comparable to conventional vehicles is crucial. The established criteria provide input to planners and operators for understanding the potential of automated bus services.

  • 124011.
    Zhang, Wei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Freight transport platoon coordination and departure time scheduling under travel time uncertainty2017In: Transportation Research Part E: Logistics and Transportation Review, ISSN 1366-5545, E-ISSN 1878-5794, Vol. 98, p. 1-23Article in journal (Refereed)
    Abstract [en]

    The paper formulates and analyzes a freight transport platoon coordination and departure time scheduling problem under travel time uncertainty. The expected cost minimization framework accounts for travel time cost, schedule miss penalties and fuel cost. It is shown that platooning is beneficial only when scheduled arrival times differ less than a certain threshold. Travel time uncertainty typically reduces the threshold schedule difference for platooning to be beneficial. Platooning in networks is less beneficial on converging routes than diverging routes, due to delay at the merging point. The model provides valuable insights regarding platooning benefits for freight transport planning.

  • 124012. Zhang, Wei
    et al.
    Liu, Jianhui
    Jin, Kun
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of some new 4-substituted-3,5-bis(2-pyridyl)-1H-pyrazole2006In: Journal of Heterocyclic Chemistry, ISSN 0022-152X, E-ISSN 1943-5193, Vol. 43, no 6, p. 1669-1672Article in journal (Refereed)
    Abstract [en]

    Several 4-substituted-3, 5-bis(2-pyridyl)-1H-pyrazoles, where the substituent is chloro, bromo, iodo, nitro, diazo, were synthesized under mild reaction conditions in high yields. The structures of the products were characterized by H-1 NMR, C-13 NMR, ESI-MS, IR and elemental analyses.

  • 124013. Zhang, Wei
    et al.
    Liu, Jianhui
    Zhu, Hongjun
    Gao, Weiming
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Practical synthesis of new beta-diketone-connected bipyridine and its conversion to pyrazole-centered bipyridine ligand2007In: Synthetic Communications, ISSN 0039-7911, E-ISSN 1532-2432, Vol. 37, no 19-21, p. 3393-3402Article in journal (Refereed)
    Abstract [en]

    Two new polydentate ligands, 1-(6-hydroxymethyl-2-pyridyl)-3-(2-pyridyl)-propane-1,3-dione (6) and 1,3-bis(6-hydroxymethyl-2-pyridyl)-propane-1, 3-dione (8), have been synthesized starting from 2,6-pyridinedicarboxylic acid by conventional esterification, reduction, and condensation reactions. They were further converted to two new polydentate ligands, 3-(6-hydroxymethyl-2-pyridyl)-5-(2-pyridyl)-1H-pyrazole (7) and 3,5-bis(6-hydroxymethyl-2-pyridyl)-1H-pyrazole (9), by reaction with hydrazine hydrate. These four compounds were characterized by proton nuclear magnetic resonance (H-1 NMR), electrospray ionization-mass spectrum (ESI-MS), infrared spectrum (IR), and elemental analyses. The structure of 9 was also determined by X-ray diffraction.

  • 124014. Zhang, Wei
    et al.
    Liu, Jian-Hul
    Pan, Jing-Xi
    Li, Ping
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis and characterization of some new mononuclear ruthenium complexes containing 4-(un) substituted dipyridylpyrazole ligands2008In: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 27, no 4, p. 1168-1176Article in journal (Refereed)
    Abstract [en]

    A mononuclear ruthenium complex [Ru(bpy)(2)(bpp)](PF6) (1) and its halogenated and nitro derivatives [Ru(bpy)(2)(Xbpp)](PF6) (bpy = 2,2'-bipyridine; bpp = 3,5-bis(2-pyridyl)pyrazole; X = Cl, 2; X = Br, 3; X = I, 4; X = NO2, 5) have been synthesized and characterized by H-1 NMR, C-13 NMR, HRMS, elemental analysis. Complexes 2-5 have been further confirmed by X-ray diffraction. Their UV-Vis and emission spectroscopies, electrochemical measurements and acid-base properties are described. The results presented here reveal that the introduction of Cl, Br, I and NO2 groups to the coordinated bpp(-) ligand makes the absorption and emission maxima of the parent complex 1 blue-shifted, the oxidation potential of the Ru-II/Ru-III couple increased and the pK(a) value decreased obviously. In addition, significant quenching of the emission by these groups is also observed.

  • 124015.
    Zhang, Wei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sadollahkhani, Azar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Li, Yuanyuan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhang, Biaobiao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Fuguo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Safdari, Majid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hao, Yan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hua, Yong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Investigation of Triphenylamine (TPA)-Based Metal Complexes and Their Application in Perovskite Solar Cells2017In: ACS OMEGA, ISSN 2470-1343, Vol. 2, no 12, p. 9231-9240Article in journal (Refereed)
    Abstract [en]

    Triphenylamine-based metal complexes were designed and synthesized via coordination to Ni(II), Cu(II), and Zn(II) using their respective acetate salts as the starting materials. The resulting metal complexes exhibit more negative energy levels (vs vacuum) as compared to 2,2', 7,7'-tetrakis(N, N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD), high hole extraction efficiency, but low hole mobilities and conductivities. Application of dopants typically used for Spiro-OMeTAD was not successful, indicating a more complicated mechanism of partial oxidation besides the redox potential. However, utilization as hole-transport material was successful, giving a highest efficiency of 11.1% under AM 1.5G solar illumination.

  • 124016.
    Zhang, Wei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Planning of heavy-duty vehicle platoon formulation: basic scheduling problem considering travel time variance2016Conference paper (Refereed)
  • 124017.
    Zhang, Wei
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Sadollahkhani, Azar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Leandri, Valentina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Gardner, James M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Mechanistic Insights from Functional Group Exchange Surface Passivation: A Combined Theoretical and Experimental Study2019In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 4, p. 2723-2733Article in journal (Refereed)
    Abstract [en]

    Four different functional groups including amino (-NH2), phosphine (-PH2), hydroxyl (-OH), and thiol (-SH) were combined with POSS (polyhedral oligomeric silsesquioxane) molecules to investigate how functional groups affect the surface passivation of POSS systems. Results from density-functional theory (DFT) calculations indicate that functional group amino (-NH2) with adsorption energy 86 (56) kJ mol(-1) is consistently better than that of thiol (-SH) with adsorption energy 68 (43) kJ mor(-1) for different passivation mechanisms. Theoretical studies on the analogous POSS-OH and POSS-PH2 systems show similar adsorption energies. Two of the systems were also investigated experimentally; aminopropyl isobutyl POSS (POSS-NH2) and mercaptopropyl isobutyl POSS (POSS-SH) were applied as passivation materials for MAPbI(3) (MA = methylammonium) perovskite and (FA)(0.85)(MA)(0.15)Pb(I-3)(0.85)(Br-3)(0)(.15)(FA = formamidinium) perovskite films. The same conclusion was drawn based on the results from contact angle studies, X-ray diffraction (XRD), and the stability of solar cells in ambient atmosphere, indicating the vital importance of choice of functional groups for passivation of the perovskite materials.

  • 124018.
    Zhang, Wei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Sundberg, Marcus
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Platoon coordination with time windows: An operational perspective2017In: 20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary, Elsevier, 2017, Vol. 27, p. 357-364Conference paper (Refereed)
    Abstract [en]

    It has been reported that platooning has the potential of saving fuel and increasing traffic throughput. We formulate a platoon coordination problem with soft time windows as a mixed-integer linear programming problem and solve it with exact solutions. The objective function consists of operation costs, schedule miss penalties and fuel costs. In the numerical example, a Swedish highway network model is used and the computation result shows that, for 21 vehicles, the total cost can be reduced by 3.5% when the optimal preferred arrival times are chosen. A random disturbance is then added to the optimal time windows and the optimal result shows great sensitivity with respect to the disturbance. When the mean of the disturbance becomes larger than 10 minutes, more than half of the platooning benefits will be lost. The study also analyzes the change of different cost compositions as disturbance increases.

  • 124019. Zhang, Weichun
    et al.
    Li, Qiang
    Meng, Lijun
    Zhao, Ding
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO. Zhejiang University, China.
    Universal scaling behavior of the temperature increase of a heat nanoparticle on a substrate2015In: JOURNAL OF NANOPHOTONICS, ISSN 1934-2608, Vol. 9, article id 093046Article in journal (Refereed)
    Abstract [en]

    Knowledge of temperatures at the nanoscale is essential for studying and controlling the heat-induced local thermal responses. The temperature rise of a heated nanoparticle (NP) near the interface of two kinds of media with different thermal conductivities is numerically investigated. We find that the temperature rise becomes size independent if it is scaled by the temperature rise in the case where the particle-interface distance is zero and the distance is scaled by the equivalent radius of the NP. This universal scaling behavior can be understood with the principle of dimensional homogeneity. An empirical equation is retrieved to predict the actual particle temperature at a given position. Our results may benefit precise control of heat at the nanoscale with applications in plasmonic absorbers, immunotargeted photothermal cancer cell killing, etc.

  • 124020. Zhang, Weiqing
    et al.
    Møller-Pedersen, Birger
    Biehl, Matthias
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    A light-weight tool integration approach: From a tool integration model to OSLC integration services2012In: ICSOFT 2012 - Proceedings of the 7th International Conference on Software Paradigm Trends, 2012, p. 137-146Conference paper (Refereed)
    Abstract [en]

    Existing tool integration approaches integrate various tools directly through tool proprietary APIs. This kind of integration lacks standardization and are different case by case. Integration based upon common tool metamodels also turns to be too complicated and hard to maintain. In this paper we provide an approach which integrates tools based on a combination of tool metamodels and an integration model. Tool element representatives (Artifacts) are defined to make integrations more standardized and flexible compared to direct tool APIs. The approach links the tool integration model to the various tool metamodels, and provides mechanism by which the common integration properties and the various tool metamodels are related. An industrial case study has been performed to validate the approach with both scenarios of traceability and exchange of data based upon common data definitions.

  • 124021. Zhang, Wei-Wei
    et al.
    Du, Yong
    Xu, Honghui
    Xiong, Wei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Kong, Yi
    Sun, Weihua
    Pan, Fusheng
    Tang, Aitao
    Thermodynamic Assessment of the Cu-B System Supported by Key Experiment and First-Principles Calculations2009In: Journal of Phase Equilibria and Diffusion, ISSN 1547-7037, Vol. 30, no 5, p. 480-486Article in journal (Refereed)
    Abstract [en]

    The Cu-B system was investigated via a hybrid approach of key experiment and thermodynamic modeling. Based on the critically assessed Cu-B phase diagram, seven crucial alloys were selected and prepared by arc melting the pure elements. An inductively coupled plasma-atomic emission spectrometric analysis was conducted to determine the compositions of the prepared alloys. The phase equilibria were determined by using x-ray diffraction, electron probe microanalysis, and differential thermal analysis. The temperature associated with the eutectic reaction, L double left right arrow (B) + (Cu); was measured to be 1028 +/- 2 degrees C. First-principles calculations indicate that the energy of inserting a B atom into the interstitial vacancy (Va) site of the lattice for Cu atoms is marginally lower than that of substituting for a Cu atom with a B atom. Consequently, the sublattice model (Cu)(B, Va) in which B atoms occupy the interstitial sites was employed for the fcc (Cu) phase rather than the model (Cu, B)(Va) in which B atoms substitute for Cu atoms. A thermodynamic modeling of the Cu-B system was then performed by considering the reliable literature data and the present experimental results. A good agreement between modeling and experiment was obtained.

  • 124022.
    Zhang, Weiwei
    et al.
    Univ Sci & Technol China, Dept Astron, CAS Key Lab Res Galaxies & Cosmol, Hefei 230026, Anhui, Peoples R China.;Univ Sci & Technol China, Sch Astron & Space Sci, Hefei 230026, Anhui, Peoples R China.;Penn State Univ, Dept Mech & Nucl Engn, University Pk, PA 16802 USA..
    Si, Yubing
    Huanghe Sci & Technol Coll, Inst Nanostruct Funct Mat, Henan Prov Key Lab Nanocomposites & Applicat, Zhengzhou 450006, Henan, Peoples R China..
    Zhen, Junfeng
    Univ Sci & Technol China, Dept Astron, CAS Key Lab Res Galaxies & Cosmol, Hefei 230026, Anhui, Peoples R China.;Univ Sci & Technol China, Sch Astron & Space Sci, Hefei 230026, Anhui, Peoples R China..
    Chen, Tao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Linnartz, Harold
    Leiden Univ, Leiden Observ, Sackler Lab Astrophys, POB 9513, NL-2300 RA Leiden, Netherlands..
    Tielens, Alexander G. G. M.
    Leiden Univ, Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands..
    Laboratory Photochemistry of Covalently Bonded Fluorene Clusters: Observation of an Interesting PAH Bowl-forming Mechanism2019In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 872, no 1, article id 38Article in journal (Refereed)
    Abstract [en]

    The fullerene C-60, one of the largest molecules identified in the interstellar medium (ISM), has been proposed to form top-down through the photochemical processing of large (more than 60 C atoms) polycyclic aromatic hydrocarbon (PAH) molecules. In this article, we focus on the opposite process, investigating the possibility that fullerenes form from small PAHs, in which bowl-forming plays a central role. We combine laboratory experiments and quantum chemical calculations to study the formation of larger PAHs from charged fluorene clusters. The experiments show that with visible laser irradiation, the fluorene dimer cation-[C13H9-C13H9](+)-and the fluorene trimer cation-[C13H9-C13H8-C13H9](+)-undergo photodehydrogenation and photoisomerization, resulting in bowl-structured aromatic cluster ions, C26H12+ and C39H20+, respectively. To study the details of this chemical process, we employ quantum chemistry that allows us to determine the structures of the newly formed cluster ions, to calculate the dissociation energies for hydrogen loss, and to derive the underlying reaction pathways. These results demonstrate that smaller PAH clusters (with less than 60 C atoms) can convert to larger bowled geometries that might act as building blocks for fullerenes, because the bowl-forming mechanism greatly facilitates the conversion from dehydrogenated PAHs to cages. Moreover, the bowl-forming induces a permanent dipole moment that-in principle-allows one to search for such species using radio astronomy.

  • 124023. Zhang, Wei-Wei
    et al.
    Xu, Hong-Hui
    Liang, Jian-Lie
    Xiong, Wei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Du, Yong
    Phase equilibria of the Fe-Ni-Si system at 850 degrees C2009In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 481, no 1-2, p. 509-514Article in journal (Refereed)
    Abstract [en]

    By means of X-ray diffraction, metallography, scanning electron microscopy with energy dispersive Xray analysis, and electron probe microanalysis, the constitution of the ternary Fe-Ni-Si system at 850 degrees C over the entire composition range was established with 24 alloys. Ten of the three-phase equilibria were well determined at 850 degrees C. The existence of the ternary compound Fe5Ni3Si2 (tau(1)) with a cubic crystal structure at 850 degrees C is confirmed. The homogeneity ranges were measured and the lattice parameters were determined for most observed phases.

  • 124024.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    An add-on filter technique to improve micropollutant removal and water quality in on-site sewage treatment facilities2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Onsite sewage treatment facilities (OSSFs) in Sweden currently release significant amounts of nitrogen (N) and phosphorus (P) into groundwater or/and receiving water bodies. Micropollutants (MPs) have been found in both surface water and groundwater, indicating insufficient removal of MPs by OSSFs. Two laboratory-scale column experiments, followed by a field experiment, were performed to study removal of a set of organic MPs by organic and inorganic sorbents. The set covered different product categories, e.g. an artificial sweetener, organophosphates, parabens, personal care products, perfluoroalkyl substances (PFASs), pesticides, pharmaceuticals, a plasticiser, a polymer impurity, stimulants and surfactants. An experiment using five organic and five inorganic sorbents showed that coal-based organic sorbents performed better than natural fibre and inorganic sorbents in removal of MPs, with 20% higher removal efficiency on average. Five sorbents were selected for a long-term column experiment examining 31 MPs. Physical properties and chemical structure of the sorbents, namely pore structure and surface functional groups, were found to be correlated to their capacity for removal of MPs. Molecular weight, solvent-accessible area, octanol-water partition coefficient and distribution-coefficient of PFASs were found to be strongly positively correlated with their removal by some sorbents. Organic sorbents with good performance in removal of MPs and a conventional sand bed showed limited ability to remove P, while calcium-rich sorbents increased P removal greatly. Two sorbents, granulated activated carbon (GAC) and xyloid lignite (Xylit), were tested for 24 weeks in an add-on filter for effluent from a soil treatment system and found to significantly improve removal of MPs. A replaceable add-on unit for removal of MPs from OSSF effluent is recommended and should contain an organic sorbent such as GAC or Xylit.

  • 124025.
    Zhang, Wen
    KTH, School of Information and Communication Technology (ICT).
     Market Research for RFID Real-time Cold-chain Monitoring System2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the surging of cold-chain logistics industry, people pay more and more attention to the quality of cold-chain control. There emerge many approaches monitoring the dynamic situation along all the phases of the whole cold supply chain including processing, storage, transportation and selling.

    Here in iPack Center, KTH, a RFID real-time cold-chain monitoring system is presented. The system is aiming to track and monitor the situation of goods in-transit in real-time including the position, temperature, relative humidity as basic monitoring issue, gas concentration and shock parameters as optional. To know in which way and toward whom this product can position itself, a deeper investigation and knowledge of the current cold-chain logistics industry is essential.

    Some field interviews are conducted towards companies that are involved in cold-chain logistics industry at different segmentations majorly in pharmaceuticals and foods. The companies are chosen elaborately that they are considered that they can represent the market environment of cold-chain monitoring to some extent. The real thought and expectations from them are valuable as a useful reference to improve iPack’s own RFID tracking system in some detail or specification way as well as identify the real business opportunity, deduce the business model towards different parties that involved in this industry for the future work.

  • 124026.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System analysis and economics.
    Mental map: A reliable definition of choice or a distorted recognition of space?2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mental map is considered as an individual’s mental representation of his/her spatial

    cognition. People learn from the environment and add information to their personal

    mental map. It becomes important when we try to understand the relationships

    between one’s travel decision processes and their choice sets. The aim of this paper

    is to study the relationship between individuals’ activity travel patterns and their

    mental map by exploring people’s spatial cognition, their activity space and related

    factors. Two-week travel diary and mental maps were collected for the same 57

    individuals in Stockholm. Respondents were asked to report their recent trip

    information in the travel diary and draw their familiar areas in specified maps. The

    specified maps, to some extent, reflect respondents’ mental maps by transferring this

    abstract concept from one’s mind to a visual representation. The derived mental maps

    were manually drawn and transferred from graph to ASCII code in ArcGIS. The visited

    activity locations on where people travelled during the observed period were used to

    construct one’s activity space. The key determinants that construct these activity

    space and mental map will be investigated. Marginal effect of each key variable will be

    calculated to understand the magnitude of influence of each variable into the spatial

    distribution of the given individual’s activity space and mental map.

    The result shows that individual’s activity space is not necessarily within individual

    mental map. Both activity space and mental map are correlated with individual’s

    travel pattern factors. Mental map has positive influence to the formation of activity

    space. The inference of marginal effect is useful for urban planning, promoting

    transport policies and analyzing the effect of transport infrastructure since it can help

    to locate the places that constitute individual’s activity space and mental map areas.

  • 124027.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Removal of micropollutants and nutrients using filter beds for on-site sewage treatment – column and field experiments2017Conference paper (Other academic)
    Abstract [en]

    On-site sewage treatment facilities (OSSFs) are widely applied in rural areas in the Nordic countries. A potential amount of phosphorus (P) and nitrogen (N) are released from these systems every year. The concerns are also about micropollutants (MPs), i.e. pharmaceuticals and synthetic organic compounds which are contaminating the environment and can affect the ecosystem and human health (Luo, 2014). About 40% of the OSSFs in Sweden use soil-based systems to treat wastewater (Olshammar, 2015) and sand is the most commonly applied media. The aim of this study was to evaluate the removal efficiencies of P, N and a number of MPs in filter beds and to find out the potential additional treatment efficiency which could be achieved by combining sand with other commercial filter materials.

    Two bench-scale column experiments were performed during 2016 (Table 1). The first experiment was operated with saturated flow conditions during two weeks. The second experiment applied unsaturated flow conditions and was operated during twelve weeks.

    The wastewater used in the experiment was spiked with a number of MPs to investigate their removal by the sand filtration. The MPs included pharmaceuticals, pesticides, biocides, plasticizers, fragrances, surfactants, UV-stabilizers, rubber additives and food additives. Weekly samples were taken for N, P and MPs analysis. Other parameters measured during the experiments included dissolved organic carbon (DOC), pH, turbidity and electric conductivity.

    A field pilot plant was constructed in 2013 (Kholoma, 2016) with three subsurface parallel filter beds. Each bed had a length and depth of 1.5 and 0.8 m, respectively, and an upper surface area of 0.75 m2. The three filter beds were filled with sand, biochar and sand, biochar and Sorbulite® (a product based on gas concrete), respectively. The system was maintained for two and a half years prior the sampling (November 2016), where 24-hour composite water samples were taken from the influent and the effluent.

    The average removal efficiencies of DOC, NH4-N and Ptot in column and field samples are presented in table 2. Compared with the sand filter, the added biochar layer improved the removal of DOC by 18% and the added Sorbulite layer increased both the DOC and total phosphorus removal efficiencies by 7%.

    The MPs in the column experiment showed different removal efficiencies: Firstly, biocides (hexachlorobenzene and triclosan), pharmaceuticals (acetaminophen and caffeine), fragrance (musk xylene) and preservative (propylparaben) have been efficiently removed with an average removal above 90%. Secondly, a few organophosphorus flame retardants such as tributylphosphate and triphenylphosphate, perfluoroaklyl substances, UV stabilizer (benzophenone) and fragrances (musk ketone and galaxolide) had lower removal efficiencies in the range 51% and 81%. The sand did not remove most of pharmaceuticals very efficiently. Seven out of the nine investigated pharmaceuticals had removal efficiencies ranging between 17% and 48%, whereas four of them (diclofenac, oxazepam, losartan and carbamazepine) had an average removal efficiency lower than 30%.

    A number of 47 MPs were identified in the field experiment samples with concentrations ranging from 0.1 ng L-1 to 46285 ng L-1. The removal efficiency varied depending on the type of filter media and MPs. The dual layer filter with biochar and sand provided a better removal of MPs (on average, 68%) than the other two filters (on average, 65% and 56% for sand and biochar + Sorbulite, respectively). In the future, to improve the removal efficiency of nutrients and MPs, the application of new filter materials to optimize the traditional filter bed is needed. The life span of sand and alternative sorbents were not considered in the column experiments, however it is one of the essential research tasks for future work.

  • 124028.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Screening of different types of on-site sewage facilities - treatment function and potential for removing micropollutants2016Conference paper (Other academic)
    Abstract [en]

    On-site sewage facilities (OSSF) in Sweden were investigated to check the treatment function and determine the potential for removing micropollutants (MPs). The 16 OSSFs studied included soil filtration systems (SFS), package treatment systems (PTS) and source separation of sewage (SSS). Two medium-sized municipal wastewater treatment plants were also included for reference. Nitrogen (N), phosphorus (P), dissolved organic carbon (DOC) and MPs were analysed. For SFS, overall removal efficiency of nitrogen and phosphorus was acceptable, but some individual facilities showed poor treatment results. This was generally attributable to lack of maintenance, which affected removal performance for most parameters tested. No-target screening for MPs, carried out in laboratories at Umeå University (UU) and the Swedish University of Agricultural Sciences (SLU), revealed average removal efficiency of 52.4% for SFS and 37.5% for PTS. Thus MPs can be removed by on-site sewage systems, but higher removal efficiency is needed.

  • 124029.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Gago-Ferrero, Pablo
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Box 7050, SE-75007 Uppsala, Sweden..
    Gao, Qiuju
    Umea Univ, Dept Chem, Linnaeus Vag 6, SE-90187 Umea, Sweden..
    Ahrens, Lutz
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Box 7050, SE-75007 Uppsala, Sweden..
    Blum, Kristin
    Umea Univ, Dept Chem, Linnaeus Vag 6, SE-90187 Umea, Sweden..
    Rostvall, Ande
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Box 7050, SE-75007 Uppsala, Sweden..
    Björlenius, Berndt
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Industrial Biotechnology.
    Andersson, Patrik L.
    Umea Univ, Dept Chem, Linnaeus Vag 6, SE-90187 Umea, Sweden..
    Wiberg, Karin
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Box 7050, SE-75007 Uppsala, Sweden..
    Haglund, Peter
    Umea Univ, Dept Chem, Linnaeus Vag 6, SE-90187 Umea, Sweden..
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Evaluation of five filter media in column experiment on the removal of selected organic micropollutants and phosphorus from household wastewater2019In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 246, p. 920-928Article in journal (Refereed)
    Abstract [en]

    A bench-scale column experiment was performed to study the removal of 31 selected organic micropollutants (MPs) and phosphorus by lignite, xyloid lignite (Xylit), granular activated carbon (GAC), Polonite (R) and sand over a period of 12 weeks. In total 29 out of the 31 MPs showed removal efficiency > 90% by GAC with an average removal of 97 +/- 6%. Xylit and lignite were less efficient with an average removal of 80 +/- 28% and 68 +/- 29%, respectively. The removal efficiency was found to be impacted by the characterization of the sorbents and physicochemical properties of the compounds, as well as the interaction between the sorbents and compounds. For instance, Xylit and lignite performed well for relatively hydrophobic (log octanol/water partition coefficient (K-ow) >= 3) MPs, while the removal efficiency of moderately hydrophilic, highly hydrophilic and negatively charged MPs were lower. The organic sorbents were found to have more functional groups at their surfaces, which might explain the higher adsorption of MPs to these sorbents. The removal of several MPs improved after four weeks in sand, Xylit, GAC and lignite which may be related to increased biological activity and biofilm development. GAC and sand had limited ability to remove phosphorus (12 +/- 27% and 14 +/- 2%, respectively), while the calcium-silicate material Polonite (R) precipitated phosphorus efficiently and increased the total phosphorus removal from 12% to 96% after the GAC filter.

  • 124030.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Removal of 31 organic micropollutants and phosphorus by filter media in a column experiment using household wastewaterManuscript (preprint) (Other academic)
    Abstract [en]

    A bench-scale column experiment was performed to study the removal of 31 selected organic micropollutants (MPs) by lignite, xyloid lignite (Xylit), granular activated carbon (GAC), Polonite® and sand over a period of 12 weeks. The MPs analysed included an artificial sweetener, biocides, fragrances, organophosphates, perfluoroalkyl substances (PFASs), pesticides, pharmaceuticals, a plasticiser, a polymer impurity, a preservative, a rubber additive, a surfactant and UV stabilisers. The removal of several MPs improved after four weeks in sand, Xylit, GAC and lignite which may be related to increased biological activity and biofilm development. In total 29 out of the 31 MPs showed a removal efficiency of >90% by GAC with an average removal of 97 ± 6%. Xylit and lignite were less efficient with an average removal of 80 ± 28% and 68 ± 29%, respectively. However, Xylit and lignite performed well for relatively hydrophobic (log Kow ≥3) MPs (i.e. hexachlorobenzene, galaxolide and tributylphosphate) with an average removal efficiency of 90 ± 5 % and 95 ± 4 %, respectively. The removal efficiency obtained with Xylit and lignite of moderately hydrophilic MPs (i.e. tris-(2-chloroethyl)phosphate), highly hydrophilic (i.e. sucralose) and negatively charged (i.e. PFOS and diclofenac) were lower (67 ± 35% for Xylit and 49 ± 26% for lignite). The organic sorbents were found to have more functional groups at their surfaces, which might explain the higher adsorption of MPs to these sorbents. GAC and sand had limited ability to remove phosphorus (12 ± 27% and 14 ± 2%, respectively), while the calcium-silicate material Polonite® precipitated phosphorus efficiently and increased the total phosphorus removal from 12% to 96% after the GAC filter.

  • 124031.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Removal of micropollutants and nutrients in household wastewater using organic and inorganic sorbentsIn: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986Article in journal (Refereed)
    Abstract [en]

    The efficiency of five organic and five inorganic sorbents in removing 19 organic micropollutants (MPs), phosphorus, nitrogen, and dissolved organic carbon (DOC) was tested in a two-week column experiment using household wastewater spiked with pharmaceuticals (n = 6), biocides/pesticides (n = 4), organophosphates (n = 3), a fragrance, a UV-stablizer, a food additive,a rubber additive, a plasticizer and a surfactant. Two types of granular activated carbon (GAC), two types of lignite, a pine bark product, and five mineral-based sorbents were tested. All the organic sorbents except pine bark achieved better removal efficiencies of DOC (on average, 70 ± 27%) and MPs (93 ± 11%) than the inorganic materials (DOC: 44 ± 7% and MPs: 66 ± 38%). However, the organic sorbents (i.e. GAC and xyloid lignite) removed less phosphorus (46 ± 18%), while sorbents with a high calcium or iron content (i.e. Polonite® and lignite) generally removed phosphorus more efficiently (93 ± 3%). Ammonium-nitrogen was well removed by sorbents with a pH between 7 and 9, with an average removal of 87%, whereas lignite (pH 4) showed the lowest removal efficiency (50%). Some MPs were well removed by all sorbents (≥97%) including biocides (hexachlorobenzene, triclosan and terbutryn), organophosphates (tributylphosphate, tris-(1,3-dichloro-2-propyl)phosphate and triphenylphosphate) and one fragrance (galaxolide). The pesticide 2,6-dichlorobenzamide and the pharmaceutical diclofenac were poorly removed by the pine bark and inorganic sorbents (on average, 4%), while organic sorbents achieved high removal of these chemicals (87%).

  • 124032.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Wastewater purification and removal of micropollutants in a soiltreatment system and by subsequent filtration through activatedcarbon and xyloid lignite – a field experimentManuscript (preprint) (Other academic)
    Abstract [en]

    Soil treatment systems (STS) are often used in rural areas to remove nutrients and microorganisms from wastewater. These and other facilities designed for on-site sewage treatment should also have the capacity to remove micropollutants (MPs), i.e. pharmaceuticals, personal care products, detergents, polymer additives, and other synthetic organic compounds. In a six-month study on a medium-scale STS with two add-on filters installed to purify the effluent, possible removal enhancement of MPs, phosphorus (Ptot) and ammonium-nitrogen (NH4-N) was examined. The filters contained granular activated carbon (GAC) and xyloid lignite (Xylit). A total of 58 compounds were detected, comprising artificial sweeteners (n = 2), organophosphates (n = 7), parabens (n = 3), personal care products (n = 7), pesticides (n = 2), perfluoroalkyl substances (PFAS) (n = 3), pharmaceuticals (n = 27), a plasticiser, a polymer impurity, a rubber additive, stimulants (n = 3) and a surfactant. The concentrations in influent water to the STS ranged from 1.3 ng L-1 (ranitidine) to 110 μg L-1 (acetaminophen). Mean removal rate of MPs by the STS was 49 ± 56 %. The add-on filters significantly improved (ANOVA, p<0.001) removal of MPs, despite treating a high hydraulic load (2350 L m-2 day-1). The GAC and Xylit filters removed 98 ± 6 % and 87 ± 28 %, respectively, demonstrating the potential of these materials to reduce MPs in STS effluent to very low concentrations. The add-on filters did not improve removal of P and NH4-N from STS effluent, but the GAC-based filter improved removal of organics (COD) by 5%. 

  • 124033.
    Zhang, Wen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Termida, Nursitihazlin Ahmad
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    What construct one's familiar area?: A quantitative and longitudinal study2019In: Environment and Planning B: Urban Analytics and City Science, ISSN 2399-8083, Vol. 46, no 2, p. 322-340Article in journal (Refereed)
    Abstract [en]

    There is a lack of understanding of how certain characteristics of the urban environment influence an individual's spatial cognition and familiarity with surrounding areas, and, subsequently, their travel behaviours and how these change over time. This paper aims to address this research gap in exploring the dynamics of individuals' spatial cognitions by observing the changes of respondents' familiar areas over time, and investigating the possible determinants that constitute respondents' familiar areas. Panel data, containing two-week travel diaries and maps of familiar areas, were collected in four different waves over a seven-month period for 55 individuals in Stockholm, Sweden. The reported familiar areas for each individual were digitised into quantifiable variable form and further analysed by applying dynamic binary probit and linear regression models. The results show that, while familiar area is largely influenced by one's previous knowledge of the area, it is also continuously corrected by events in between. Different land use characteristics have different impacts on different social groups' travel patterns, thus contributing to the variability in the size of one's familiar areas.

  • 124034.
    Zhang, Wenhua
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    First Principles Studies on Chemical and Electronic Structures of Adsorbates2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, we focus on theoretical study of adsorbates on metal and oxide surfaces that are important for surface chemistry and catalysis. Based on first principles calculations, the adsorption ofCO, NO, NO2, C4H6S2, C22H27SH and other molecules or radicals on nobel metal surfaces (gold and silver) are investigated. Also, NO oxidation on oxygen pre-covered Au(111)surface and CO oxidation on water-oxygen covered Au(111)surface aretheoretically studied. A new mechanism of water-enhanced COoxidation is proposed. As for oxide surfaces, we first investigatethe geometric, electronic and magnetic structures of FeO ultrathin film on Pt(111) surface. The experimentally observed scanning tunneling microscopy images are well reproduced for the first timewith our model. The adsorption and dissociation of water on rutileTiO2(110) surface are investigated by quantum molecular dynamics.By theoretical X-ray photoemission spectroscopy (XPS) calculations,the surface species are properly assigned. The same strategy has applied to the study of the phase transition of water covered reconstructed anatase TiO2(001) surface, from which two different phases are theoretically identified. The structure of graphene oxideis also studied by comparing experimental and theoretical XPS spectra. Based on the novel structures identified, a new cutmechanism of graphene oxide is proposed.

  • 124035.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Carravetta, Vincenzo
    Li, Zhenyu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Yang, Jinlong
    Oxidation states of graphene: Insights from computational spectroscopy2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, no 24Article in journal (Refereed)
    Abstract [en]

    When it is oxidized, graphite can be easily exfoliated forming graphene oxide (GO). GO is a critical intermediate for massive production of graphene, and it is also an important material with various application potentials. With many different oxidation species randomly distributed on the basal plane, GO has a complicated nonstoichiometric atomic structure that is still not well understood in spite of intensive studies involving many experimental techniques. Controversies often exist in experimental data interpretation. We report here a first principles study on binding energy of carbon 1s orbital in GO. The calculated results can be well used to interpret experimental x-ray photoelectron spectroscopy (XPS) data and provide a unified spectral assignment. Based on the first principles understanding of XPS, a GO structure model containing new oxidation species epoxy pair and epoxy-hydroxy pair is proposed. Our results demonstrate that first principles computational spectroscopy provides a powerful means to investigate GO structure.

  • 124036.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Carravetta, Vincenzo
    Monti, Susanna
    Interaction of biomolecular systems with titanium-based materials: computational investigations2009In: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 123, no 3-4, p. 299-309Article in journal (Refereed)
    Abstract [en]

    Ab initio calculations and molecular dynamics simulations were performed to investigate the adsorption mode of various oligopeptides on titanium dioxide surfaces and to characterize their conformational behavior upon adsorption. The models were progressively improved obtaining a description compatible with the experimental observations.

  • 124037.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Carravetta, Vincenzo
    Plekan, Oksana
    Feyer, Vitaliy
    Richter, Robert
    Coreno, Marcello
    Prince, Kevin C.
    Electronic structure of aromatic amino acids studied by soft x-ray spectroscopy2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, no 3, p. 035103-Article in journal (Refereed)
    Abstract [en]

    The electronic structure of phenylalanine, tyrosine, tryptophan, and 3-methylindole in the gas phase was investigated by x-ray photoemission spectroscopy (XPS) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the C, N, and O K-edges. The XPS spectra have been calculated for the four principal conformers of each amino acid, and the spectra weighted by the Boltzmann population ratios calculated from published free energies. Instead of the single peaks expected from the stoichiometry of the compounds, the N 1s core level spectra of phenylalanine and tryptophan show features indicating that more than one conformer is present. The calculations reproduce the experimental features. The C and O 1s spectra do not show evident effects due to conformational isomerism. The calculations predict that such effects are small for carbon, and for oxygen it appears that only broadening occurs. The carbon K-edge NEXAFS spectra of these aromatic amino acids are similar to the published data of the corresponding molecules in the solid state, but show more structure due to the higher resolution in the present study. The N K-edge spectra of tryptophan and 3-methylindole differ from phenylalanine and tyrosine, as the first two both contain a nitrogen atom located in a pyrrole ring. The nitrogen K-edge NEXAFS spectra of aromatic amino acids do not show any measurable effects due to conformational isomerism, in contrast to the photoemission results. Calculations support this result and show that variations of the vertical excitation energies of different conformers are small, and cannot be resolved in the present experiment. The O NEXAFS spectra of these three aromatic compounds are very similar to other, simpler amino acids, which have been studied previously.

  • 124038.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Gao, Bin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Yang, Jinlong
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Caravetta, V.
    Wu, Z.
    Electronic structure of [121]tetramantane-6-thiol on gold and silver surfaces2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 130, no 054705Article in journal (Refereed)
    Abstract [en]

    The mechanism for electron photoemission of [121]tetramantane and its functionalized compound [121]tetramantane-6-thiol adsorbed on different noble metal surfaces has been investigated by density functional theory calculations. It is found that good chemical bonding between molecules and metal surfaces is a helpful but not a necessary condition for electron photoemission. A lower work function and weaker hybridization between the molecule and the metal could lead to much more efficient electron photoemission. It is observed that, neglecting final state effect, a simple ground state picture cannot result in negative electron affinity for the systems under investigation. Calculations have shown that by exciting an electron in the lowest unoccupied molecular orbital, the highest singly occupied molecular orbital of the molecule can be shifted above the vacuum level, resulting in negative electron affinity and emission of the accumulated electrons.

  • 124039.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Li, Zhenyu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Theoretical Study of X-ray PhotoemissionSpectra of Graphene OxideManuscript (Other academic)
    Abstract [en]

    Chemical structure of graphene oxide is complicated by the presence of many different oxidation species. We report here a density functional theory study on binding energy of carbon 1s at different oxidation environments on a graphene oxide sheet. It is shown that the calculated results can be wellused to interpret experimental X-ray photoemission spectra of different research groups and provide united spectral assignments. New species that are important for understanding cut mechanisms of graphene oxide have been identified.

  • 124040.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Li, Zhenyu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Yang, A
    A first-principles study of NO adsorption and oxidation on Au(111) surface2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 129, no 13, p. 134708-Article in journal (Refereed)
    Abstract [en]

    Density functional theory and slab models are employed to study NO molecule adsorption and reaction on clean and atomic oxygen precovered Au(111) surfaces. While clean Au(111) surface is catalytically inert and can only weakly adsorb NO, an atomic oxygen precovered Au(111) surface is found to be very active to NO. On the clean surface, NO prefers to bond at the onefold on-top surface site with a tilted geometry. On 0.33 ML (monolayer) oxygen precovered surface NO reacts with chemisorbed oxygen to form chemisorbed NO2 by conquering a small energy barrier about 0.18 eV, and the desorption energy of NO 2 is 0.64 eV. On 1.0 ML oxygen coverage surface, no barrier is found while NO reacts with precovered oxygen. The desorption energy of NO2 is 0.03 eV. The desorption of NO2 is the rate determining step on both surfaces and the overall reaction barriers are 0.64 and 0.03 eV, respectively. The activation energies depend on the initial coverage of oxygen, which compare favorably with experiments on Au surface with different oxygen coverages.

  • 124041.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Li, Zhenyu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Yang, J.
    Density Functional Study on the Mechanism of CO Oxidation with Activated Water on O/Au(111) Surface2009In: Chinese Science Bulletin, ISSN 1001-6538, E-ISSN 1861-9541, Vol. 54, no 11, p. 1973-1977Article in journal (Refereed)
    Abstract [en]

    With density functional theory, the mechanism of water-enhanced CO oxidation on oxygen pre-covered Au (111) surface is theoretically studied. First, water is activated by the pre-covered oxygen atom and dissociates to OHads group. Then, OHads reacts with COads to form chemisorbed HOCOads. Finally, with the aid of water, HOCO ads dissociates to CO2. The whole process can be described as 1/2H2O ads + H2Oads + 1/2O ads + COads → H3Oads + CO 2, gas. One CO2 is formed with only 1/2 pre-covered oxygen atom. That is why more CO2 is observed when water is present on oxygen pre-covered Au (111) surface. Activation energy of each elementary step is low enough to allow the reaction to proceed at low temperature

  • 124042.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Li, Zhenyu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Yang, Jinlong
    First Principles Study on the Geometric and Electronic Structures of the FeO/Pt(111) Surface2009In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 113, no 19, p. 8302-8305Article in journal (Refereed)
    Abstract [en]

    The geometric, electronic, and magnetic properties of the FeO monolayer on a Pt(111) surface are investigated by first principles calculations. Generally, antiferromagnetic (AFM) structures are more stable than that of the ferromagnetic one. On the basis of a specific AFM structure, the long puzzling scanning tunneling microscopy (STM) experimental observations can be well explained. In this AFM model, the Fe-O layer distance at the fee region is larger than the hcp region, in contrast to previous theoretical results. The STM images at the field-emission regime are explained by local surface potential.

  • 124043.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    First-Principles Study on Different BDT-gold Contact StructuresManuscript (Other academic)
    Abstract [en]

    Density functional theory calculations have been carried out for a benzene-1,4-dithiol (BDT)molecule adsorbed on a perfect Au (111) surface, a gold nanowire of 1 nm in diameter and alsosurface supported gold cluster (point). It is indicated that a BDT molecule prefers to adsorbon irregular surface sites. The Simulated S K-edge x-ray absorption spectra (XAS) and ultra-violet photoemission spectra (UPS) are presented. The predicted XAS spectra show that x-rayspectroscopy could be a powerful method to study the structure of molecule-metal contact.

  • 124044.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Theoretical study on phase transition of watercovered anatase TiO2 (001) surfaceManuscript (Other academic)
    Abstract [en]

    With the (4x1) ADM structural model proposed by Lazzeri and Selloni, the behavior of wateron reconstructed anatase TiO2 (001) surface is studied by quantum molecular dynamics simulationsand an interpretation of the x-ray photoemission spectra, recently collected for such systems, with different water coverage, is provided. The spectrum of the low coverage phase is assigned to oxygencore ionization of only acceptor hydrogen bonded hydroxyl species, while the spectrum of the highcoverage phase is due to contributions from both donor and acceptor hydrogen bonded hydrox-yls. The experimental spectral evolution with temperature and dosing is also well interpreted bytheoretical simulations.

  • 124045.
    Zhang, Wenhua
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Caravetta, V.
    Monti, Susanna
    Yang, Jinlong
    Quantum molecular dynamics study of water onTiO2(110) surface2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 129, no 064703Article in journal (Refereed)
    Abstract [en]

    The adsorption of water on perfect TiO2(110) surface is studied by quantum molecular dynamics simulation adopting a periodic model formed by five water molecules on a (5 x 1) surface unit cell of a five layer slab of TiO2. The total simulation time is 3.2 ps. At about 1.3 ps, one water molecule dissociates with the help of other adsorbed waters and surface bridging oxygens. During the remaining 1.9 ps, the waters and OH groups vibrate, but no more dissociation or recombination is observed. By comparing recent experimental O1s photoemission (x-ray photoelectron spectroscopy) spectra of H2O/TiO2(110) to the computed spectrum of the adsorbate in the configurations supplied by the molecular dynamics simulation, the observed peaks can be attributed to different oxygen species. The proposed assignment of the main spectral features supports the occurrence of partial water dissociation (similar to 20%) also on a perfect TiO2 surface.

  • 124046.
    Zhang, Wenhui
    et al.
    Huazhong Univ Sci & Technol, Sch Comp Sci & Technol, Wuhan Natl Lab Optoelect, Key Lab Informat Storage Syst,Minist Educ, Wuhan 430074, Hubei, Peoples R China..
    Cao, Qiang
    Huazhong Univ Sci & Technol, Sch Comp Sci & Technol, Wuhan Natl Lab Optoelect, Key Lab Informat Storage Syst,Minist Educ, Wuhan 430074, Hubei, Peoples R China..
    Lu, Zhonghai
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
    Bit-Flipping Schemes Upon MLC Flash: Investigation, Implementation, and Evaluation2019In: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, ISSN 0278-0070, E-ISSN 1937-4151, Vol. 38, no 4, p. 780-784Article in journal (Refereed)
    Abstract [en]

    Multilevel cell (MLC) stales with lower threshold voltage endure less cell damage, lower retention error, and less current consumption. Based on these characteristics, it is opportunistic to strengthen MLC flash by introducing hit-flipping that reshapes state proportions on MLC pages. In this paper. we present a holistic study of bit-flipping schemes upon MLC flash in theory and practice. Specifically, we systematically investigate effective bit-flipping schemes and propose four new schemes on manipulating MLC states. We further design a generic implementation framework, named MLC bit-flipping framework, to implement bit-flipping schemes within solid state drives controllers, nicely integrating with existing system-level optimizations to further improve overall performance. The experimental results demonstrate that our proposed bit-flipping schemes standalone can reduce up to 28% cell damages and 53% retention errors. Our circuit-level simulation manifests that the bit-flipping latency on a page is less than 4 mu s when using 8K logic gates.

  • 124047.
    Zhang, Wenjie
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Gap Analysis of ISO 26000 in Two Atlas Copco Companies in China:: Atlas Copco (Nanjing) Construction and Mining Equipment Co., Ltd. and Wuxi Pneumatech Air/ Gas Purity Equipment Co., Ltd. 2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Social Responsibility(SR)is gathering accumulative attentionrecently.It has become a key criterion of business campaign among companies.This thesis studiesthe current SR performancein two branch companies inAtlas Copco (China), Atlas Copco (Nanjing) Construction and Mining Equipment Ltd. andWuxi Pneumatech Air/Gas Purity Equipment Ltd.Interviews were made separately with company staff, including employees from management level and staff from workshop. ISO 26000 was adoptedas aguiding standard when conducting SR investigation and following analysing work.Core subjects of ‘Labour Practices’, ‘the Environment’ and ‘Community involvement and development’ in ISO 26000 were thethreeresearching aspects in the work. For each detailed actions and expectations in the subject, particular comments and acorresponding rating score aregiven according to its status quo. These rating scoresare utilized in the gap analysing process to illustrate the differences between the current SR situation and theexpectations illustrated in ISO 26000.Moreover, the disparity between twoselected companies is alsodefined by illustrating theirfinal scores on each issueina radar chart.As a result from the assessment,bothcompanies have a far way to go to entirely accomplish ISO 26000’s requirements. For the core subject which is strong at, their current measures need to be kept and finely turned; for the weak core subjects, more attentions should be attracted and concrete actions should be conducted.

    Social Responsibility(SR)is gathering accumulative attentionrecently.It has become a key criterion of business campaign among companies.This thesis studiesthe current SR performancein two branch companies inAtlas Copco (China), Atlas Copco (Nanjing) Construction and Mining Equipment Ltd. andWuxi Pneumatech Air/Gas Purity Equipment Ltd.Interviews were made separately with company staff, including employees from management level and staff from workshop. ISO 26000 was adoptedas aguiding standard when conducting SR investigation and following analysing work.Core subjects of ‘Labour Practices’, ‘the Environment’ and ‘Community involvement and development’ in ISO 26000 were thethreeresearching aspects in the work. For each detailed actions and expectations in the subject, particular comments and acorresponding rating score aregiven according to its status quo. These rating scoresare utilized in the gap analysing process to illustrate the differences between the current SR situation and theexpectations illustrated in ISO 26000.Moreover, the disparity between twoselected companies is alsodefined by illustrating theirfinal scores on each issueina radar chart.As a result from the assessment,bothcompanies have a far way to go to entirely accomplish ISO 26000’s requirements. For the core subject which is strong at, their current measures need to be kept and finely turned; for the weak core subjects, more attentions should be attracted and concrete actions should be conducted.

     

  • 124048.
    Zhang, Wenliang
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. National Engineering Laboratory for Electric Vehicles and the Collaborative Innovation Centre for Electric Vehicles in Beijing.
    Wang, Zhenpo
    School of Mechnical Engineering, Beijing Institute of Technology.
    Zou, Changfu
    Department of Electrical Engineering, Chalmers University of Technology.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Advanced Vehicle State Monitoring:: Evaluating Moving Horizon Estimators and Unscented Kalman Filter2019In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, no 6, p. 5430-5442, article id 8682143Article in journal (Refereed)
    Abstract [en]

    Active safety systems must be used to manipulate the dynamics of autonomous vehicles to ensure safety. To this end, accurate vehicle information, such as the longitudinal and lateral velocities, is crucial. Measuring these states, however, can be expensive, and the measurements can be polluted by noise. The available solutions often resort to Bayesian filters such as the Kalman filter, but can be vulnerable and erroneous when the underlying assumptions do not hold. With its clear merits in handling nonlinearities and uncertainties, moving horizon estimation (MHE) can potentially solve the problem and is thus studied for vehicle state estimation. This paper designs an unscented Kalman filter, standard MHE, modified MHE and recursive least squares MHE to estimate critical vehicle states, respectively. All the estimators are formulated based upon a highly nonlinear vehicle model that is shown to be locally observable. The convergence rate, accuracy and robustness of the four estimation algorithms are comprehensively characterised and compared under three different driving manoeuvres. For MHE-based algorithms, the effects of horizon length and optimisation techniques on the computational efficiency and accuracy are also investigated.

  • 124049.
    Zhang, Wensheng
    et al.
    Soochow Univ, Cam Su Genom Resource Ctr, Suzhou 215123, Peoples R China.;Wellcome Sanger Inst, Hinxton CB10 1SA, England..
    Chronis, Constantinos
    Univ Calif Los Angeles, David Geffen Sch Med, Dept Biol & Chem, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Eli & Edythe Broad Ctr Regenerat Med & Stem Cell, Los Angeles, CA USA.;Univ Calif Los Angeles, Jonsson Comprehens Canc Ctr, Bioinformat Program, Los Angeles, CA 90024 USA.;Univ Calif Los Angeles, Mol Biol Inst, Los Angeles, CA 90095 USA..
    Chen, Xi
    Wellcome Sanger Inst, Hinxton CB10 1SA, England..
    Zhang, Heyao
    Soochow Univ, Cam Su Genom Resource Ctr, Suzhou 215123, Peoples R China..
    Spalinskas, Rapolas
    KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Pardo, Mercedes
    Chester Beatty Labs, Inst Canc Res, London, England..
    Chen, Liangliang
    Soochow Univ, Cam Su Genom Resource Ctr, Suzhou 215123, Peoples R China..
    Wu, Guangming
    Max Planck Inst Mol Biomed, Dept Cell & Dev Biol, Rontgenstr 20, D-48149 Munster, Germany..
    Zhu, Zhexin
    Wellcome Sanger Inst, Hinxton CB10 1SA, England..
    Yu, Yong
    Wellcome Sanger Inst, Hinxton CB10 1SA, England..
    Yu, Lu
    Chester Beatty Labs, Inst Canc Res, London, England..
    Choudhary, Jyoti
    Chester Beatty Labs, Inst Canc Res, London, England..
    Nichols, Jennifer
    Univ Cambridge, Wellcome Trust Med Res Council, Stem Cell Inst, Tennis Court Rd, Cambridge CB2 1QR, England..
    Parast, Mana M.
    Univ Calif San Diego, Dept Pathol, La Jolla, CA 92093 USA.;Univ Calif San Diego, Sanford Consortium Regenerat Med, La Jolla, CA 92093 USA..
    Greber, Boris
    Max Planck Inst Mol Biomed, Dept Cell & Dev Biol, Rontgenstr 20, D-48149 Munster, Germany..
    Sahlén, Pelin
    KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Plath, Kathrin
    Univ Calif Los Angeles, David Geffen Sch Med, Dept Biol & Chem, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Eli & Edythe Broad Ctr Regenerat Med & Stem Cell, Los Angeles, CA USA.;Univ Calif Los Angeles, Jonsson Comprehens Canc Ctr, Bioinformat Program, Los Angeles, CA 90024 USA.;Univ Calif Los Angeles, Mol Biol Inst, Los Angeles, CA 90095 USA..
    The BAF and PRC2 Complex Subunits Dpf2 and Eed Antagonistically Converge on Tbx3 to Control ESC Differentiation2019In: Cell Stem Cell, ISSN 1934-5909, E-ISSN 1875-9777, Vol. 24, no 1, p. 138-+Article in journal (Refereed)
    Abstract [en]

    BAF complexes are composed of different subunits with varying functional and developmental roles, although many subunits have not been examined in depth. Here we show that the Baf45 subunit Dpf2 maintains pluripotency and ESC differentiation potential. Dpf2 co-occupies enhancers with Oct4, Sox2, p300, and the BAF subunit Brg1, and deleting Dpf2 perturbs ESC self-renewal, induces repression of Tbx3, and impairs mesendodermal differentiation without dramatically altering Brg1 localization. Mesendodermal differentiation can be rescued by restoring Tbx3 expression, whose distal enhancer is positively regulated by Dpf2-dependent H3K27ac maintenance and recruitment of pluripotency TFs and Brg1. In contrast, the PRC2 subunit Eed binds an intragenic Tbx3 enhancer to oppose Dpf2-dependent Tbx3 expression and mesendodermal differentiation. The PRC2 subunit Ezh2 likewise opposes Dpf2-dependent differentiation through a distinct mechanism involving Nanog repression. Together, these findings delineate distinct mechanistic roles for specific BAF and PRC2 subunits during ESC differentiation.

  • 124050.
    Zhang, Wenxin
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Long-term Trend of Evapotranspiration in Sweden Affected by Climate Change or Land-use Change.2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Evapotranspiration (ET) is an essential component of water cycle as it is an interlinkage between atmosphere, vegetation and soil surface in terms of energy and water balance. However, whether potential ET has the same tendency to change as actual ET and how ET trend (based on the difference between precipitation and runoff) is directly driven by dominant meteorological factors alone or combined with ecosystem‘s feedbacks to climate change (like land-use change) is still under the discussion. In this report, five ET parameterizations within two rainfall-runoff models [Coupled Heat and Mass Transfer Model (CoupModel) and Hydrologiska Byråns Vattenbalansavdelning (HBV)] have been set up based on six subcatchments of Sweden. The scenario derived from CoupModel shows that the trend of ET is affected by the change of land-use, where soil evaporation tends to shift to transpiration and interception evaporation. However, HBV model produces the other scenario: the trend of ET is merely the consequence of meteorological factors. Increased ET is contributed by increased interception evaporation due to the increased precipitation. After identifying the time split of changing ET trends, a dynamic simulation constructed both from HBV and CoupModel indicate that the increased total ET is primarily from increased ET in winter time. More and more interceptive water loss and transpiration resulted from land-use change due to more vegetation. On the other hand, land-use change is also a feed back to climate change. Transpiration controlled by the mechanism of stomata and water uptake controlled by reduction of soil moisture is highly related to variations of climatic conditions.

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