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  • 122651.
    Zhang, Silun
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Intrinsic Formation and Macroscopic Intervention in Multi-agent Systems2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this dissertation, we study two problems within the field of the multi-agent systems theory. One is the formation control for multiple reducedattitudes, which are extensively utilized in many pointing applications and under-actuated scenarios for attitude maneuvers. In contrast to most existing methodologies on the formation control, the proposed method does notneed to contain any formation errors in the protocol. Instead, the constructedformation is attributed to geometric properties of the configuration space andthe designed connection topology. We refer to this type of formation controlas intrinsic formation control. Besides, the control protocols proposed in thiswork are designed directly in space S^2 , avoiding to use any attitude parameterizations. Moreover, along the studies, some elementary tools for reducedattitudes control are developed.

    Another problem is a moment-based methodology to modeling and ana-lyzing collective behavior of a group of agents. The theory is applicable fora wide range of applications, such as multi-agent systems with interactionsas well as with leaders and/or control input, and the use of this frameworkcan considerably reduce the computational burden for controlling and ana-lyzing such systems. We therefore propose to develop and use this theory forthe multi-agent applications such as crowd dynamics, opinion dynamics andother macroscopic problems.

    Particularly, in paper A a continuous control law is provided for a reduced attitude system, by which a regular tetrahedron formation can achieveasymptotic stability under a quite large family of gain functions in the con-trol. Then, with a further restriction on the control gain, almost global stability of the tetrahedron formation is also obtained. In this work, we introducea novel coordinates transformation that represents the relative reduced atti-tudes between the agents. The proposed method is an intrinsic formationcontrol that does not need to involve any information of the desired formation beforehand. Another virtue of the method proposed is that only relativeattitude measurement is required.

    Paper B further concerns the formation control of all regular polyhedralconfigurations (also called Platonic solids) for reduced attitudes. Accord-ing to the symmetries possessed by regular polyhedra, a unified frameworkis proposed for their formations. Via using the coordinates transformationpreviously proposed, it is shown that stability of the desired formations canbe provided by stabilizing a constrained nonlinear system. Then, a method-ology to investigate the stability of this type of constrained systems is alsopresented.

    In paper C, we introduce an approach for modeling collective behaviorof a group of agents using moments. We represent the swarming via their dis-tribution and derive a method to estimate the dynamics of the moments. We use this to predict the evolution of the distribution of agents by first computing the moment trajectories and then use this to reconstruct the distributionof the agents. In the latter an inverse problem is solved in order to reconstructa nominal distribution and to recover the macro-scale properties of the groupof agents. The proposed method is applicable for several types of multi-agent systems, including leader-follower systems.

    Paper D considers the problem of tracking and encircling a moving target by agents in the 3-dimensional space. In this work, we show that similardesign techniques proposed for reduced attitudes formations can also be applied to the formation control for point mass systems. Therein, a group ofagents are driven to some desired formation on a spherical surface and simultaneously the center of this spherical formation is kept coinciding withthe target to be tracked. By properly designing communication topology, theagents constitute a cyclic formation along the equator of an encircling sphere.

    In Paper E, a methodology based on differential geometry techniquesis proposed to investigate exponential stability of a formation for reducedattitudes. By such a method, there is no need in finding any relative coordinates, which is typically needed but shown to be difficult when the formationproblem is evolving in a non-Euclidean space. In the paper, the desired formation is treated as an embedding submanifold in (S^2)^N and by using therotation symmetries owned by the attitude dynamics its stability is directlyexamined. Moreover, such a method turns out to be coordinates free, namely,exponential stability of a formation can be completely determined by just investigating any one equilibrium which can result in the formation under anylocal chart of (S^2 )^N . This greatly simplifies the stability analysis for theformation problems.

  • 122652.
    Zhang, Silun
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Relative Information Based Distributed Control for Intrinsic Formations of Reduced Attitudes2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This dissertation concerns the formation problems for multiple reduced attitudes, which are extensively utilized in many pointing applications and under-actuated scenarios for attitude maneuvers. In contrast to most existing methodologies on formation control, the proposed method does not need to contain any formation errors in the protocol. Instead, the constructed formation is attributed to geometric properties of the configuration space and the designed connection topology. We refer to this type of formation control as intrinsic formation control. Besides, the control protocols proposed in this work are designed directly in space S2, avoiding to use any attitude parameterisations. At last but not least, along the studies, some elementary tools for reduced attitudes control are developed.In paper A, a continuous control law is provided for a reduced attitude systems, by which a regular tetrahedron formation can achieve asymptotic stability under a quite large family of gain functions in the control. Then, with a further restriction on the control gain, almost global stability of the tetrahedron formation is also obtained. In this work, we introduce a novel coordinates transformation that represents the relative reduced attitudes be-tween the agents. The proposed method is an intrinsic formation control that does not need to involve any information of the desired formation before-hand. Another virtue of the method proposed is that only relative attitude measurement is required.Paper B further concerns the formation control of all regular polyhedral configurations (also called Platonic solids) for reduced attitudes. According to the symmetries possessed by regular polyhedra, a unified framework is proposed for their formations. Via using the coordinates transformation previously proposed, it is shown that the stability of the desired formations can be provided by stabilizing a constrained nonlinear system. Then, a methodology to investigate the stability of this type of constrained systems is also presented. Paper C considers the problem of tracking and encircling a moving target by agents in 3-dimensional space. By this work, we show that similar design techniques proposed for reduced attitudes formations can also be applied to the formation control for point mass systems. Therein, a group of agents are driven to some desired formation on a spherical surface and simultaneously keep the center of this spherical formation coinciding with the target to be tracked. By properly designing communication topology, the agents constitute a cyclic formation along the equator of an encircling sphere.

  • 122653.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori. Harbin Institute of Technology, China.
    He, F.
    Yao, Y.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Spherical formation of regular tetrahedra2017Ingår i: 2017 36th Chinese Control Conference, CCC, IEEE Computer Society, 2017, s. 1317-1322, artikel-id 8027533Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study the problem of tracking and encircling a moving target by agents in the 3-dimensional space. Specifically, a group of agents are driven to a regular tetrahedron formation on a spherical surface and simultaneously keep the center of this spherical formation coinciding with the target to be tracked. In the proposed method, to avoid the singularity caused by spherical parameterisations in control, we directly consider the spherical formation in space S2. Besides, the protocol proposed does not contain any information of the desired formation beforehand. Rather the constructed formation pattern is attributed to the properties of space S2 and the inter-agent topology.

  • 122654.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori. Harbin Inst Technol, Control & Simulat Ctr, Harbin 150001, Heilongjiang, Peoples R China.
    He, Fenghua
    Hong, Yiguang
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Intrinsic Formation Control of Regular Polyhedra for Reduced Attitudes2017Ingår i: 2017 IEEE 56th Annual Conference on Decision and Control, CDC 2017, IEEE , 2017, s. 1002-1007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper addresses formation control of reduced attitudes in which a continuous protocol is proposed for achieving and stabilizing all regular polyhedra (also known as Platonic solids) under a unified framework. The protocol contains only relative reduced attitude measurements and does not depend on any particular parametrization as is usually used in the literature. A key feature of the control proposed is that it is intrinsic in the sense that it does not need to incorporate any information of the desired formation. Instead, the achieved formation pattern is totally attributed to the geometric properties of the space and the designed inter-agent connection topology. Using a novel coordinates transformation, asymptotic stability of the desired formations is proven by studying stability of a constrained nonlinear system. In addition, a methodology to investigate stability of such constrained systems is also presented.

  • 122655.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    He, Fenghua
    Control and Simulation Center, Harbin Institute of Technology, Harbin, 150001, P. R. China.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Exponential Stability of Formations for Reduced Attitudes: A Coordinates Free Approach2018Ingår i: Proceedings of Chinese Control Conference, 2018, IEEE Computer Society, 2018, s. 7220-, artikel-id 7215Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work, a methodology based on differential geometry techniques is proposed to investigate exponential stability of a formation for reduced attitudes. By the proposed method, there is no need in finding any relative coordinates, which is typically needed but shown to be difficult when the formation problem is evolving in a non-Euclidean space. In this paper, the desired formation is treated as an embedding submanifold in (S-2)(N) and by using the rotation symmetries owned by the attitude dynamics its stability is directly examined. Moreover, such a method turns out to be coordinates free, namely, exponential stability of a formation can be completely determined by just investigating any one equilibrium which can result in the formation under any local chart of (S-2)(N). This greatly simplifies the stability analysis for the formation problems.

  • 122656.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    An Intrinsic Approach to Formation Control of Regular Polyhedra for Reduced AttitudesManuskript (preprint) (Övrigt vetenskapligt)
  • 122657.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Ringh, Axel
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Karlsson, Johan
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    A moment-based approach to modeling collective behaviors2018Ingår i: 2018 IEEE Conference on Decision and Control (CDC), Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 1681-1687, artikel-id 8619389Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work we introduce an approach for modeling and analyzing collective behavior of a group of agents using moments. We represent the occupation measure of the group of agents by their moments and show how the dynamics of the moments can be modeled. Then approximate trajectories of the moments can be computed and an inverse problem is solved to recover macro-scale properties of the group of agents. To illustrate the theory, a numerical example with interactions between the agents is given.

  • 122658.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Ringh, Axel
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Karlsson, Johan
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori. KTH, Skolan för teknikvetenskap (SCI), Centra, Strategiskt centrum för industriell och tillämpad matematik, CIAM.
    Modeling collective behaviors: A moment-based approachManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Abstract—In this work we introduce an approach for modeling and analyzing collective behavior of a group of agents using moments. We represent the group of agents via their distribution and derive a method to estimate the dynamics of the moments. We use this to predict the evolution of the distribution of agents by first computing the moment trajectories and then use this to reconstruct the distribution of the agents. In the latter an inverse problem is solved in order to reconstruct a nominal distribution and to recover the macro-scale properties of the group of agents. The proposed method is applicable for several types of multi-agent systems, e.g., leader-follower systems. We derive error bounds for the moment trajectories and describe how to take these error bounds into account for computing the moment dynamics. The convergence of the moment dynamics is also analyzed for cases with monomial moments. To illustrate the theory, two numerical examples are given. In the first we consider a multi-agent system with interactions and compare the proposed methods for several types of moments. In the second example we apply the framework to a leader-follower problem for modeling pedestrian crowd dynamics.

  • 122659.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Song, Wenjun
    He, Fenghua
    Hong, Yiguang
    Hu, Xiaoming
    Intrinsic Tetrahedron Formation of Reduced AttitudeManuskript (preprint) (Övrigt vetenskapligt)
  • 122660.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori. Harbin Institute of Technology, China.
    Song, Wenjun
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    He, Fenghua
    Control and Simulation Center, Harbin Institute of Technology, 150001 Harbin, China.
    Hong, Yiguang
    Key Laboratory of Systems and Control, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, 100190 Beijing, China.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Intrinsic tetrahedron formation of reduced attitude2018Ingår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 87, s. 375-382Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, formation control for reduced attitude is studied, in which a regular tetrahedron formation can be achieved and shown to be asymptotically stable under a large family of gain functions in the control. Moreover, by further restriction on the control gain, almost global stability of the desired formation is obtained. In addition, the control proposed is an intrinsic protocol that only uses relative information and does not need to contain any information of the desired formation beforehand. The constructed formation pattern is totally attributed to the geometric properties of the space and the designed inter-agent connection topology. Besides, a novel coordinates transformation is proposed to represent the relative reduced attitudes in S2, which is shown to be an efficient approach to reduced attitude formation problems.

  • 122661.
    Zhang, Silun
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Song, Wenjun
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    He, Fenghua
    Control and Simulation Center, Harbin Institute of Technology, 150001, China.
    Yao, Yu
    Control and Simulation Center, Harbin Institute of Technology, 150001, China.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Spherical cyclic formation control2016Ingår i: Proceedings of the 35th Chinese Control Conference 2016, IEEE Computer Society, 2016, Vol. 2016, s. 8207-8212, artikel-id 7554663Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study the problem of tracking and encircling a moving target by agents in 3D. Specifically, a group of agents are driven to some desired formation on a spherical surface and simultaneously keep the center of this spherical formation coinciding with the target to be tracked. In our control design, the desired formation is not used as a reference signal for tracking. Rather by designing communication topology for the agents we can achieve the desired formation using relative positions only. We can also place the desired cyclic formation on the equator if the north pole is specified.

  • 122662.
    Zhang, Sina
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Inter-cell Interference Coordination in Indoor LTE Systems2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Inter-cell interference coordination in 3GPP Long Term Evolution system received much attention in recent years. However, most of the studies are based on ideal system with regular hexagon-shaped cell. The indoor environment has special characteristics that the building shape and BS locations are irregular; the traffic load has great variation compared to urban and rural area. So, conventional ICIC scheme may not be used in indoor situation directly.

    In this thesis, ICIC scheme is employed for indoor environment. Based on different quality of backhaul, static and dynamic schemes will be proposed. The performances of proposed schemes and the performance of system without ICIC will be simulated and compared. At last, how much the improvement of the system can acquire after applying ICIC schemes will be analyzed, and the question about whether it is good to apply ICIC scheme in indoor environment will be answered.

  • 122663. Zhang, Song Bin
    et al.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University, Russian Federation.
    Rohringer, Nina
    Nonlinear resonant Auger spectroscopy in CO using an x-ray pump-control scheme2016Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 94, nr 6, artikel-id 06413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present paper we propose nonlinear femtosecond x-ray pump-probe spectroscopy to study the vibrational dynamics of a core-excited molecular state and discuss numerical results in CO. A femtosecond pump resonantly excites the carbon core-excited 1s-1π∗ state of the CO molecule. A second strong probe (control) pulse is applied at variable delay and is resonantly coupled to a valence excited state of the molecule. The strong nonlinear coupling of the control pulse induces Rabi flopping between the two electronic states. During this process, a vibrational wave packet in the core-excited state is created, which can be effectively manipulated by changing the time delay between pump and control pulses. We present an analysis of the resonant Auger electron spectrum and the transient absorption or emission spectrum on the pump transition and discuss their information content for reconstruction of the vibrational wave packet.

  • 122664.
    Zhang, T.
    et al.
    Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Brumboiu, I. E.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Grazioli, C.
    Sincrotrone Trieste, CNR, ISM, I-34149 Trieste, Basovizza, Italy..
    Guarnaccio, A.
    CNR, ISM, I-85050 Potenza, Italy..
    Coreno, M.
    Sincrotrone Trieste, CNR, ISM, I-34149 Trieste, Basovizza, Italy..
    de Simone, M.
    Sincrotrone Trieste, Lab TASC, CNR, IOM, I-34149 Trieste, Basovizza, Italy..
    Santagata, A.
    CNR, ISM, I-85050 Potenza, Italy..
    Rensmo, H.
    Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Brena, B.
    Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Lanzilotto, V.
    Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Puglia, C.
    Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Lone-Pair Delocalization Effects within Electron Donor Molecules: The Case of Triphenylamine and Its Thiophene-Analog2018Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, nr 31, s. 17706-17717Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Triphenylamine (TPA) and its thiophene-analog, N,N-diphenyl-2-thiophenamine (DPTA), are both well-known as electron-donating molecules implemented in optoelectronic devices such as organic solar cells and LEDs. Comprehensive valence and core level photoelectron spectroscopy, as well as near edge X-ray absorption spectroscopy (NEXAFS), measurements have been performed on gas phase TPA and DPTA. The experimental results have been compared to density functional theory calculations, providing a detailed description of the molecular electronic structure. Specifically, the C 1s photoelectron lines of both TPA and DPTA were resolved in the different C atom contributions and their binding energies explained as the result of two counter-acting effects: (1) the electronegativity of the nitrogen atom (and sulfur atom in DPTA) and (2) the the N (and S in DPTA) lone-pair electrons. In addition, the C K-edge NEXAFS spectrum of DPTA reveals that the lowest unoccupied molecular orbital (LUMO) energy position is affected differently if the core hole site is on the phenyl compared to the thiophene ring. The electron-donating properties of these two molecules are largely explained by the significant contribution of the N lone-pair electrons (p(z)) to the highest occupied molecular orbital. The contribution to the LUMO and to the empty density of states of the sulfur of the thiophene ring in DPTA explains the better performance of donor-pi-acceptor molecules containing this moiety and implemented in photoenergy conversion devices.

  • 122665. Zhang, T.
    et al.
    Brumboiu, Iulia
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Lanzilotto, V.
    Luder, J.
    Grazioli, C.
    Giangrisostomi, E.
    Ovsyannikov, R.
    Sass, Y.
    Bidermane, I.
    Stupar, M.
    de Simone, M.
    Coreno, M.
    Ressel, B.
    Pedio, M.
    Rudolf, P.
    Brena, B.
    Puglia, C.
    Conclusively Addressing the CoPc Electronic Structure: A Joint Gas-Phase and Solid-State Photoemission and Absorption Spectroscopy Study2017Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, nr 47, s. 26372-26378Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The occupied and empty densities of states of cobalt phthalocyanine (CoPc) were investigated by photoelectron and X-ray absorption spectroscopies in the gas phase and in thin films deposited on a Au(111) surface. The comparison between the gas-phase results and density functional theory single-molecule simulations confirmed that the CoPc ground state is correctly described by the (2)A(1g) electronic configuration. Moreover, photon-energy-dependent valence photoemission spectra of both the gas phase and thin film confirmed the atomic character of the highest occupied molecular orbital as being derived from the organic ligand, with dominant contributions from the carbon atoms. Multiplet ligand-field theory was employed to simulate the Co L-edge X-ray absorption spectroscopy results.

  • 122666. Zhang, T.
    et al.
    Österberg, Patrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Xu, Y.
    Multicast-favorable max-min fairness: A general definition of multicast fairness2005Ingår i: Proceedings - First International Conference on Distributed Frameworks for Multimedia Applications 2005, DFMA '05, 2005, s. 239-244Konferensbidrag (Refereegranskat)
    Abstract [en]

    As video-streaming services are becoming more common the benefit of multicast transmission is growing, because multicast is more bandwidth efficient than unicast in scenarios where many receivers simultaneously are interested in the same data. Of the same reason the concept of multicast fairness is starting to attract attention, it might be sensible to give multicast flows higher priority and thereby create an incentive for the use of multicast transmission. Allocating link bandwidth in proportion to the logarithm of the number of receivers of a flow, which favors multicast flows without totally starving unicast flows, has been proposed in [1]. That was however just as a bandwidth-allocation policy ran on the individual routers and not a definition of multicast fairness. To our knowledge no one has yet come up with a definition of multicast fairness which prioritizes multicast flows. In this paper we present a general multicast fairness definition, named multicast-favorable max-min fairness (MFMF), which can be used together with any multicast-favorable function.

  • 122667.
    Zhang, Tao
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Marina system.
    Analysis of Active Gyro Based Roll-Stabilization of Slender Boat Hulls2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Currently, traffic congestion often happens in big cities every day. People demand a new conceptual vehiclewhich has a slender shape to reduce space, lightweight structure to decrease the fuel consumption andinnovative technology to adapt for multiple transportation conditions. NEWT is such a conceptual amphibious vehicle that satisfies people's requirements. However, everything has two sides. Slender shape and high centre of gravity will result in instability. When NEWT runs in low speed, it easily gets rolled over. In order to make up for its drawback, gyro-stabilizer has been applied to the vehicle. By tilting the rotational gyro, it generates a counter torque counteracting the roll motion to make the vehicle recover to an upright position.Therefore this master thesis analyses the original stability of the vehicle and the possible improvement by adding the gyro system for both land and water-conditions. The model can handle the problem that thevehicle meets periodic disturbance forces, such as wave excitation force and wind force.

  • 122668.
    Zhang, Tao
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik. Shanghai Jiao Tong Univ, Shanghai Key Lab Intelligent Sensing & Recognit, Shanghai 200240, Peoples R China..
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Xiong, Huilin
    Shanghai Jiao Tong Univ, Shanghai Key Lab Intelligent Sensing & Recognit, Shanghai 200240, Peoples R China..
    Yu, Wenxian
    Shanghai Jiao Tong Univ, Shanghai Key Lab Intelligent Sensing & Recognit, Shanghai 200240, Peoples R China..
    A SHIP DETECTOR BASED ON THE IMPROVED POLARIMETRIC COVARIANCE DIFFERENCE MATRIX2018Ingår i: IGARSS 2018 - 2018 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM, IEEE , 2018, s. 709-712Konferensbidrag (Refereegranskat)
    Abstract [en]

    Polarimetric Synthetic Aperture Radar data has been widely used for ship detection. In our earlier study, based on the differences between ship pixels and their surrounding background pixels, we designed a polarimetric covariance difference matrix (PCDM) to detect ships. Inadequately, the phase information of scattering differences is not included in PCDM. Aiming at this deficiency, here, we present an improved PCDM matrix (IPCDM). Then an IPCDM-based ship detector is further proposed. To demonstrate the effectiveness of the method, two full polarimetric datasets are adopted. In comparing with other methods, we find that the result of our method is better.

  • 122669.
    Zhang, Thomas
    KTH, Skolan för elektro- och systemteknik (EES).
    A statistical investigation of Bursty Bulk Flow event dynamics in the earth magnetotail2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 122670.
    Zhang, Thomas
    KTH, Skolan för teknikvetenskap (SCI).
    A statistical investigation of Bursty Bulk Flow event dynamics in the Earth magnetotail2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A statistical investigation of the relationship between Lorentz force and Bursty Bulk Flow event (BBF) spatial location in the magnetotail is undertaken. Data is obtained in situ by the ESA Cluster II mission during the period July to October 2004. Firstly, a short introduction to BBFs and the Cluster mission is presented. Secondly, the curlometer method for determining Current densities in the Inner Central Plasma Sheet and its approximations are discussed. The curlometer method uses magnetic field density data from the Fluxgate Magnetometer (FGM) instrument and plasma velocities are obtained by the Hot Ion Analyzer (HIA) instrument. The satellite separation at the time of the measurement in the year 2004 was on the order of 1000 km. Results of the investigation are inconclusive. A few possible sources of error and reference material are mentioned.

  • 122671.
    Zhang, Tianfang
    KTH, Skolan för teknikvetenskap (SCI).
    Direct optimization of dose-volume histogram metrics in intensity modulated radiation therapy treatment planning2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Vid optimering av behandlingsplaner i intensitetsmodulerad strålterapi används dosvolym- histogram-funktioner (DVH-funktioner) ofta som målfunktioner för att minimera avståndet till dos-volymkriterier. Varken DVH-funktioner eller dos-volymkriterier är emellertid idealiska för gradientbaserad optimering då de förstnämnda inte är kontinuerligt deriverbara och de sistnämnda är diskontinuerliga funktioner av dos, samtidigt som båda också är ickekonvexa. Speciellt fungerar DVH-funktioner ofta dåligt i bivillkor

    då de är identiskt noll i tillåtna områden och har försvinnande gradienter på randen

    till tillåtenhet.

    I detta arbete presenteras ett generellt matematiskt ramverk som möjliggör direkt optimering på samtliga DVH-baserade mått. Genom att betrakta voxeldoser som stickprovsutfall från en stokastisk hjälpvariabel och använda ickeparametrisk densitetsskattning för att få explicita formler, kan måtten volume-at-dose och dose-at-volume formuleras som oändligt deriverbara funktioner av dos. Detta utökas till DVH-funktioner och så kallade volymbaserade DVH-funktioner, såväl som till mindos- och maxdosfunktioner och medelsvansdos-funktioner. Explicita uttryck för evaluering av funktionsvärden och tillhörande gradienter presenteras. Det föreslagna ramverket har fördelarna av att bero på endast en mjukhetsparameter, av att approximationsfelen till konventionella motsvarigheter är försumbara i praktiska sammanhang, och av en allmän konsistens mellan härledda funktioner.

    Numeriska tester genomförda i illustrativt syfte visar att slät dose-at-volume fungerar bättre än kvadratiska straff i bivillkor och att släta DVH-funktioner i vissa fall har betydlig fördel över konventionella sådana. Resultaten av detta arbete har med framgång applicerats på lexikografisk optimering inom fluensoptimering.

  • 122672.
    Zhang, Tianfang
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematisk statistik.
    Machine learning multicriteria optimization in radiation therapy treatment planning2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Inom strålterapiplanering har den senaste forskningen använt maskininlärning baserat på historiskt levererade planer för att automatisera den process i vilken kliniskt acceptabla planer produceras. Jämfört med traditionella angreppssätt, såsom upprepad optimering av en viktad målfunktion eller flermålsoptimering (MCO), har automatiska planeringsmetoder generellt sett fördelarna av lägre beräkningstider och minimal användarinteraktion, men saknar däremot flexibiliteten hos allmänna ramverk som exempelvis MCO. Maskininlärningsmetoder kan vara speciellt känsliga för avvikelser i dosprediktionssteget på grund av särskilda egenskaper hos de optimeringsfunktioner som vanligtvis används för att återskapa dosfördelningar, och lider dessutom av problemet att det inte finns något allmängiltigt orsakssamband mellan prediktionsnoggrannhet och kvalitet hos optimerad plan. I detta arbete presenterar vi ett sätt att förena idéer från maskininlärningsbaserade planeringsmetoder med det väletablerade MCO-ramverket. Mer precist kan vi, givet förkunskaper i form av antingen en tidigare optimerad plan eller en uppsättning av historiskt levererade kliniska planer, automatiskt generera Paretooptimala planer som täcker en dosregion motsvarande uppnåeliga såväl som kliniskt acceptabla planer. I det förra fallet görs detta genom att introducera dos--volym-bivillkor; i det senare fallet görs detta genom att anpassa en gaussisk blandningsmodell med viktade data med förväntning--maximering-algoritmen, modifiera den med exponentiell lutning och sedan använda speciellt utvecklade optimeringsfunktioner för att ta hänsyn till prediktionsosäkerheter.Numeriska resultat för konceptuell demonstration erhålls för ett fall av prostatacancer varvid behandlingen levererades med volymetriskt modulerad bågterapi, där det visas att metoderna utvecklade i detta arbete är framgångsrika i att automatiskt generera Paretooptimala planer med tillfredsställande kvalitet och variation medan kliniskt irrelevanta dosregioner utesluts. I fallet då historiska planer används som förkunskap är beräkningstiderna markant kortare än för konventionell MCO.

  • 122673.
    Zhang, Tianzi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), VA-teknik, Vatten, Avlopp och Avfall.
    The possibility of using BOD on-line measurement.2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    BOD (Biochemical Oxygen Demand) is one of the important parameters in wastewater treatment technology,  it normally takes five days to get the result. Using MFC (Microbial Fuel Cell) to build up a small on-line system to measure BOD will reduce to operating time to 20 minutes. In this report, the MFC BOD on-line measurement was processed in order to test if this rapid way would work in practical usage.

    The experiment used secondary sedimentation sludge as the bacteria source on the MFC anode pattern with GGA (Glucose and Glutamic Acid solution) as an electron producer, and the 30 minutes voltage value changing curves was gotten by measuring the voltage. At the end the curve was analyzed and compared with the real BOD value in order to get the conclusion.

    The BOD on-line measurement is quite promising and efficient when multi-samples are needed to be tested.

  • 122674. Zhang, Ting-Ting
    et al.
    Wang, Mei
    Wang, Ning
    Li, Ping
    Li, Zheng-Yi
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Protophilicity, electrochemical property, and desulfurization of diiron dithiolate complexes containing a functionalized C-2 bridge with two vicinal basic sites2009Ingår i: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 28, nr 6, s. 1138-1144Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two chiron dithiolate complexes [{mu-SC(NBn)CH(NHBn)S-mu)Fe-2(CO)(5)L] (L = PPh3, 2; P(Pyr)(3), 3) containing a functionlized C-2 bridge with two vicinal basic sites were prepared and characterized as models of the FeFe-hydrogenase active site. The molecular structures of 2 and its N-protonated form [(2H(N))(OTf)] were determined by X-ray analyses of single crystals. In the solid state of [(2HN)(OTf)]. Each asymmetric unit contains a molecule of [(2H(N))(OTf)] and a molecule of water. The molecule of water is close to the iron atom of the [Fe(CO)(3)] unit (Fe center dot center dot center dot O(H2O), 4J 99 angstrom). The complexes 2 and 3 are relatively protophilic. P-31 NMR spectra and cyclic voltammograms show that they can be protonated by the mild acids CCl3COOH and CF3COOH. Electrochemical studies show that the first reduction peak of 3 at - 1.51 V versus Fc(+)/Fc is 110 mV more positive than that (-1.62V) found for the analogous diiron azadithiolate complex [{(mu-SCH2)N(CH2C6H5)}Fe-2(CO)(5)P(Pyr)(3)] (7). Protonation of 2 and 3 leads to the anodic shifts of 610-650 mV for the (FeFe1)-Fe-1/(FeFe0)-Fe-1 reduction potentials. The shifts are apparently larger than that (450 mV) for protonation of 7. The reaction of the all-carbonyl complex [{(mu-SC(NBn)CH(NHBn)S-mu}Fe-2(CO)(5)L] with two equivalents of bis(diphenylphosphino)methane (dppm) in refluxing toluene affords a desulfurized complex 1(mu-S)(mu-dppm)(2)Fe-2(CO)(4)] (6). The reaction process was studied. A dppm mono-dentate intermediate [{mu-SC(NBn)CH(NHBn)S-mu)Fe-2(CO)(5)(kappa(1)-dppm)] (4) and a dppm mu-bridging species [{mu-SC(NBn)CH(NHBn)S-mu)Fe-2(CO)(4)(mu-dppm)] (5) have been isolated and spectroscopically characterized.

  • 122675. Zhang, Tong
    et al.
    Jin, Junchen
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Yang, Hui
    Ma, Xiaoliang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Link speed prediction for signalized urban traffic network using a hybrid deep learning approach2019Konferensbidrag (Refereegranskat)
  • 122676. Zhang, Tongyan
    et al.
    Sun, Shiguo
    Liu, Fengyu
    Fan, Jiangli
    Pang, Yi
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Peng, Xiaojun
    Redox-induced partner radical formation and its dynamic balance with radical dimer in cucurbit 8 uril2009Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 11, nr 47, s. 11134-11139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    N-(4-Hydroxy-phenoxyethyl)-N'-ethyl-4,4'-bipyridium (1) can form a stable 1 : 1 inclusion complex with CB[8] in aqueous solution, in which the hydroxyphenol (HP) moiety is back-folded and inserted together with the viologen moiety into the cavity of CB[8]. When the ethyl viologen dication (EV2+) in 1 is reduced, chemically or electrochemically, an intramolecular partner radical (EV+center dot-HP)/CB[8] can be detected, meanwhile, a dynamic balance between the partner radical and the intermolecular radical dimer (EV+center dot-HP)(2)/CB[8] can be observed.

  • 122677.
    Zhang, Tony
    KTH, Skolan för industriell teknik och management (ITM), Tillämpad maskinteknik (KTH Södertälje).
    Taktningsanalys på en monteringsbana2018Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 122678. Zhang, W
    et al.
    Bergholm, Fredrik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Multiscale blur estimation and edge type classification for scene analysis1997Ingår i: Int. J. of Computer Vision, Vol. 24, nr 3Artikel i tidskrift (Refereegranskat)
  • 122679. Zhang, W.
    et al.
    Cai, Y.
    Wang, Baoyuan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Deng, H.
    Feng, C.
    Dong, W.
    Li, J.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    The fuel cells studies from ionic electrolyte Ce0.8Sm0.05Ca0.15O2-δ to the mixture layers with semiconductor Ni0.8Co0.15Al0.05LiO2-δ2015Ingår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487Artikel i tidskrift (Refereegranskat)
  • 122680. Zhang, W.
    et al.
    Li, Q.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    A plasmon ruler based on nanoscale photothermal effect2013Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, nr 1, s. 172-181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The determination of nanoscale distances or distance changes necessitates a nanoscale ruler. In the present paper, distance dependence of particle temperature in an optically heated gold nanoparticle pair is quantitatively investigated to explore the possibility of creating a Plasmon ruler based on this effect. The two origins of the distance-dependence, i.e., electromagnetic coupling and thermal accumulative effect, are studied. For the particle temperature, a scaling behavior is found, and it suggests that the decay of particle temperature with the interparticle gap for different particle sizes follows a common exponential decay equation. This scaling behavior is qualitatively explained with a simple dipolar-coupling model combined with a point heat source interaction model. On the basis of this scaling behavior of absorption power, we further establish a plasmon ruler equation relating the particle temperature and the interparticle distance. Our findings can serve as an excellent guideline for designing and optimizing temperature-based plasmon rulers.

  • 122681. Zhang, W.
    et al.
    Wu, Y.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Li, E.
    Song, X.
    Jiang, H.
    Shen, C.
    Zhang, H.
    Tian, H.
    Zhu, W. -H
    Molecular engineering and sequential cosensitization for preventing the “trade-off” effect with photovoltaic enhancement2017Ingår i: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 8, nr 3, s. 2115-2124Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In dye-sensitized solar cells (DSSCs), it is essential to use rational molecular design to obtain promising photosensitizers with well-matched energy levels and narrow optical band gaps. However, the “trade-off” effect between the photocurrent and photovoltage is still a challenge. Here we report four benzoxidazole based D-A-π-A metal-free organic dyes (WS-66, WS-67, WS-68 and WS-69) with different combinations of π-spacer units and anchoring-acceptor groups. Either extending the π-spacer or enhancing the electron acceptor can efficiently modulate the molecular energy levels, leading to a red-shift in the absorption spectra. The optimal dye, WS-69, containing a cyclopentadithiophene (CPDT) spacer and cyanoacetic acid acceptor, shows the narrowest energy band gap, which displays a very high photocurrent density of 19.39 mA cm−2, but suffers from a relatively low photovoltage of 696 mV, along with the so-called deleterious “trade-off” effect. A cosensitization strategy is further adopted for enhancing the device performance. Optimization of the dye loading sequence is found to be capable of simultaneously improving the photocurrent and photovoltage, and distinctly preventing the “trade-off” effect. The superior cosensitized cell exhibits an excellent power-conversion efficiency (PCE) of 10.09% under one-sun irradiation, and 11.12% under 0.3 sun irradiation, which constitutes a great achievement in that the efficiency of a pure metal-free organic dye with iodine electrolyte can exceed 11% even under relatively weak light irradiation. In contrast with the previous cosensitization strategy which mostly focused on compensation of light-harvesting, we propose a novel cosensitization architecture, in which the large molecular-sized, high photocurrent dye WS-69 takes charge of broadening the light-harvesting region to generate a high short-circuit current (JSC) while the small molecular-sized, high photovoltage dye WS-5 is responsible for retarding charge recombination to generate a high open-circuit voltage (VOC). In addition, adsorption amount and photo-stability studies suggest that the cyano group in the anchoring acceptor is important for the stability since it is beneficial towards decreasing the LUMO levels and enhancing the binding of dyes onto TiO2 nanocrystals.

  • 122682. Zhang, W.
    et al.
    Zhang, F.
    Wang, Yong-Lei
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Song, B.
    Zhang, R.
    Yuan, J.
    Red-Emitting Ruthenium(II) and Iridium(III) Complexes as Phosphorescent Probes for Methylglyoxal in Vitro and in Vivo2017Ingår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, nr 3, s. 1309-1318Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transition-metal complexes, ruthenium(II) and iridium(III) complexes in particular, with fascinating triplet emissions are rapidly emerging as important phosphorescent dyes for application in the sensing and imaging of biological makers in live cells and organisms. In this contribution, two red-emitting transition-metal complexes, [Ru(bpy)2(DA-phen)](PF6)2 and [Ir(ppy)2(DA-phen)](PF6) (bpy = 2,2′-bipyridine, DA-phen = 4,5-diamino-1,10-phenanthroline, and ppy = 2-phenylpyridine), were designed and synthesized as phosphorescent probes for the highly sensitive and selective detection of methylglyoxal (MGO), an essential biomarker in the etiopathogenesis of several diseases. Both probes showed weak emissions in aqueous media because of the existence of an effective photoinduced-electron-transfer process, while their emissions could be remarkably enhanced upon the addition of MGO. The photophysical and electrochemical properties, as well as phosphorescent responses of the probes toward MGO, were examined. The ground- and excited-state properties of the probes and their reaction products with MGO, [Ru(bpy)2(MP-phen)](PF6)2 and [Ir(ppy)2(MP-phen)](PF6) (MP-phen = 2-methylpyrazino-1,10-phenanthroline), the sensing mechanism, and several important experimental facts were investigated and validated using density functional theory (DFT)/time-dependent DFT computations. The results indicated that the phosphorescence switch-ON is due to the elimination of electron transfer and followed the reestablishment of emissive triplet excited states. To evaluate the feasibility of [Ru(bpy)2(DA-phen)](PF6)2 and [Ir(ppy)2(DA-phen)](PF6) as bioprobes, their cytotoxicity was examined, and their applicability for visualizing intracellular and in vivo MGO was demonstrated.

  • 122683. Zhang, W.
    et al.
    Zhang, Shi-Li
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Huang, X.
    Wang, C.
    3D treatment planning and simulating for craniofacial skeleton2005Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 26, nr 10-sep, s. 1043-1047Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In surgery of the craniofacial skeleton, the current simulation planning systems extrapolate 3D surgical movements and outcomes based on 2D radiographs, which are inadequate for complex surgical movements. This paper presents a 3D treatment-planning system based on computerized tomography (CT) data. Based upon MedGraphics software, a 3D data field is constructed out of the sectional image stack through linear interpolation, and a seeded region-growing algorithm is adopted for the objective tissue segmentation. With the marching cubes algorithm, the triangular mesh model and 3D geometric model of diseased facial skeleton are reconstructed. Then the model is cut, the segments are moved or rotated to their predicted positions, and angles and distances are measured. After the triangular mesh model is decimated, an RP model is manufactured for surgical simulation and a prosthesis is designed. The system has been clinically used for more than 50 cases and technically validated with success.

  • 122684.
    Zhang, Wang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH). Karolinska institutet.
    Development of novel molecular and microfluidics tools for identification and characterization of latent HIV-1 reservoir2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The existence of latent HIV-1 reservoir (LR) in all HIV-1 infected patients serves as a major obstacle to completely cure HIV-1 infection. However, up to now there is still no available assay that provides an accurate measurement of the reservoir size. This thesis aims to address this challenge from different aspects with several novel technologies, using both molecular and microfluidics-based tools. To find a proper tool to identify the latent HIV-1 reservoir, in Paper I and II, LIPS assay, RNAflow, and RNAscope assay were optimized and evaluated for indirect and direct detection of latent HIV-1 reservoir. The results indicated the LIPS method might not be sufficient for latent HIV-1 reservoir detection, although it has been proposed to quantify the latent HIV-1 reservoir indirectly. Furthermore, the optimized RNAscope technique performed better than RNAflow for transcription and translation competent latent HIV-1 reservoir identification. The RNAscope was also found to be independent of the HIV-1 subtype and can be applied to patient samples at single cell level. As there are currently no available surface biomarkers for latent HIV-1 reservoir, in Paper III, transcriptomics and proteomics-based analysis method for high-throughput selection of potential biomarker were established and applied to different patient groups. Twelve membrane protein-coding genes were identified as downregulated in the patient group who were hypothesized to have lower latent reservoir. These proteins might have the potential to be used as surface biomarkers for latent HIV-1 reservoir. CD4+ T cells, monocyte/macrophages, and natural killer cells are believed to be the primary source for HIV-1 reservoirs in peripheral blood. In paper IV, a microfluidic chip was developed to simultaneously isolate these three mononuclear leukocyte cell types directly from whole blood. The microfluidic method reduces the sample volume requirement and is a promising tool for latent HIV-1 reservoir study. Together, though further improvement and clinical verification are necessary, the work in this thesis has contributed to the advancement of latent HIV-1 reservoir characterization and may facilitate future development of the latent HIV-1 reservoir targeting and clearance methods with the ultimate goal – to cure HIV-1 infection.

  • 122685.
    Zhang, Wang
    et al.
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.
    Akusjarvi, Sara Svensson
    Karolinska Inst, Div Clin Microbiol, Dept Lab Med, Solna, Sweden..
    Sonnerborg, Anders
    Karolinska Inst, Div Clin Microbiol, Dept Lab Med, Solna, Sweden.;Karolinska Univ Hosp, Karolinska Inst, Unit Infect Dis, Dept Med Huddinge, Solna, Sweden..
    Neogi, Ujjwal
    Karolinska Inst, Div Clin Microbiol, Dept Lab Med, Solna, Sweden..
    Characterization of Inducible Transcription and Translation-Competent HIV-1 Using the RNAscope ISH Technology at a Single-Cell Resolution2018Ingår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, artikel-id 2358Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Identifying the source and dynamics of persistent HIV-1 at single-cell resolution during cART is crucial for the design of strategies to eliminate the latent HIV-1 reservoir. An assay to measure latent HIV-1 that can distinguish inducible from defective proviruses with high precision is essential to evaluate the efficacy of HIV-1 cure efforts but is presently lacking. The primary aim of this study was therefore to identify transcription and translation competent latently infected cells through detection of biomolecules that are dependent on transcriptional activation of the provirus. We investigated the applicability of two commercially available assays; PrimeFlow (TM) RNA Assay (RNAflow) and RNAscope (R) ISH (RNAscope) for evaluation of the efficacy of latency reversal agents (LRAs) to reactivate the HIV-1 latent reservoir. The J-Lat cell model (clones 6.3, 9.3, and 10.6) and four LRAs was used to evaluate the sensitivity, specificity, and lower detection limit of the RNAflow and RNAscope assays for the detection and description of the translation-competent HIV-1 reservoir. We also checked for HIV-1 subtype specificity of the RNAscope assay using patient-derived subtype A1, B, C, and CRFOLAE recombinant plasmids following transfection in 293T cells and the applicability of the method in patient-derived peripheral blood mononuclear cells (PBMCs). The lower detection limit of RNAflow was 575 HIV-1 infected cells/million and 45 cells/million for RNAscope. The RNAscope probes, designed for HIV-1B, also detected other subtypes (A1, B, C, and CRF<b>01 _AE). RNAscope was applicable for the detection of in patient-derived PBMCs following LRA activation. In conclusion, our study showed that RNAscope can be used to quantify the number of directly observed individual cells expressing HIV-1 mRNA following LRA activation. Therefore, it can be a useful tool for characterization of translation-competent HIV-1 in latently infected cell at single-cell resolution in the fields of HIV-1 pathogenesis and viral persistence.

  • 122686.
    Zhang, Wang
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Nanobioteknologi. karolinska institutet.
    Aljadi, Zenib
    Neogi, Ujjwal
    Russom, Aman
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Nanobioteknologi.
    Microfluidic based immunoaffinity mononuclear leukocytes isolation from whole bloodManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    CD4+ T cells, monocyte/macrophages and natural killer cells are believed to be the main source for HIV-1 reservoirs in peripheral blood. However, despite the potential these subsets of providing a wealth of new information about immune function and host pathology, current HIV latency studies are often based on PBMCs or only CD4+ T cells, mainly due to the lack of appropriate cell subset isolation methods. We present here a microfluidic chip-based method to capture and enrich the three mononuclear cells sub-population peripheral leukocyte sub-populations: CD4+ lymphocytes, natural killer cells and monocytes; using a single source of whole blood (volume < 200 μL) on a single integrated platform, within a time frame of 20 min. The single step isolation method can be used for downstream proteomics and genomics analysis to study the aberrations in these cell types’ functions in critical diseases such as HIV.

  • 122687.
    Zhang, Wang
    et al.
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.
    Ambikan, Anoop T.
    Sperk, Maike
    van Domselaar, Robert
    Nowak, Piotr
    Noyan, Kajsa
    Russom, Aman
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.
    Sonnerborg, Anders
    Neogi, Ujjwal
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.
    Transcriptomics and Targeted Proteomics Analysis to Gain Insights Into the Immune-control Mechanisms of HIV-1 Infected Elite Controllers2018Ingår i: EBioMedicine, E-ISSN 2352-3964, Vol. 27, s. 40-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A small subset of HIV-1 infected individuals, the "Elite Controllers" (EC), can control viral replication and restrain progression to immunodeficiency without antiretroviral therapy (ART). In this study, a cross-sectional transcriptomics and targeted proteomics analysis were performed in a well-defined Swedish cohort of untreated EC (n = 19), treatment naive patients with viremia (VP, n = 32) and HIV-1-negative healthy controls (HC, n = 23). The blood transcriptome identified 151 protein-coding genes that were differentially expressed (DE) in VP compared to EC. Genes like CXCR6 and SIGLEC1were downregulated in EC compared to VP. A definite distinction in gene expression between males and females among all patient-groups were observed. The gene expression profile between female EC and the healthy females was similar but did differ between male EC and healthy males. At targeted proteomics analysis, 90% (29/32) of VPs clustered together while EC and HC clustered separately from VP. Among the soluble factors, 33 were distinctive to be statistically significant (False discovery rate = 0.02). Cell surface receptor signaling pathway, programmed cell death, response to cytokine and cytokine-mediated signaling seem to synergistically play an essential role in HIV-1 control in EC.

  • 122688.
    Zhang, Wang
    et al.
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab. Karolinska Inst, Sweden.
    Morshed, Mohammed M.
    Noyan, Kajsa
    Russom, Aman
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Sonnerborg, Anders
    Neogi, Ujjwal
    Quantitative humoral profiling of the HIV-1 proteome in elite controllers and patients with very long-term efficient antiretroviral therapy2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 666Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A major challenge in evaluating the success of HIV eradication approaches is the need for accurate measurement of persistent HIV during effective antiretroviral therapy (ART). Previous studies have reported that the anti-HIV antibody assay "luciferase immuno-precipitation systems (LIPS)"can distinguish HIV-infected individuals harboring different sizes of the viral reservoirs. We performed antibody profiling of HIV-1 proteomes using LIPS in viremic progressors (n = 38), elite controllers (ECs; n = 19) and patients with fully suppressive long-term antiretroviral therapy (ART) (n = 19) (mean 17 years). IgG was quantified against six HIV-1 fusion proteins: p24, gp41, RT, Tat, integrase and protease. Lower antibody levels to all six-fusion proteins were observed in long-term ART patients compared to viremics (p < 0.05). In contrast ECs had lower antibody levels only against Tat and Integrase (p < 0.05). Principal component analysis and cluster-network analysis identified that 68% (13/19) of the long-term ART patients clustered together with 26% (5/19) ECs. The remaining ECs clustered together with the viremics indicating non-homogeneity among the ECs. The low anti-HIV levels in the long-term treated patients may indicate a restricted remaining viral replication. In contrast, the higher levels in ECs suggest a continuous viral expression with a limited concomitant release of extracellular virus.

  • 122689.
    Zhang, Wei
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Design and Implementation of Multi-core Support for an Embedded Real-time Operating System for Space Applications2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Nowadays, multi-core processors are widely used in embedded applications due to the advantages of higher performance and lower power consumption. However, the complexity of multi-core architectures makes it a considerably challenging task to extend a single-core version of a real-time operating system to support multi-core platform. This thesis documents the process of design and implementation of a multi-core version of RODOS - an embedded real-time operating system developed by German Aerospace Center and the University of Würzburg - on a dual-core platform. Two possible models are proposed: Symmetric Multiprocessing and Asymmetric Multiprocessing. In order to prevent the collision of the global components initialization, a new multi-core boot loader is created to allow that each core boots up in a proper manner. A working version of multi-core RODOS is implemented that has an ability to run tasks on a multi-core platform. Several test cases are applied and verified that the performance on the multi-core version of RODOS achieves around 180% improved than the same tasks running on the original RODOS. Deadlock free communication and synchronization APIs are provided to let parallel applications share data and messages in a safe manner.

  • 122690.
    Zhang, Wei
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Transportplanering.
    Planning and evaluation of autonomous vehicles in freight and public transport services2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

  • 122691.
    Zhang, Wei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Bah, Juho
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Wohlfarth, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Franzen, Johan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    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 Compound2011Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, nr 49, s. 13814-13824Artikel i tidskrift (Refereegranskat)
    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.

  • 122692. Zhang, Wei
    et al.
    Cai, Yixiao
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. Department of Engineering Sciences, Ångström Laboratory, Uppsala University, 751 21 Uppsala, Sweden.
    Wang, Baoyuan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. 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, Skolan för industriell teknik och management (ITM), Energiteknik. 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 electrolyte2016Ingår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, nr 34, s. 15346-15353Artikel i tidskrift (Refereegranskat)
    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.

  • 122693.
    Zhang, Wei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Franzen, Johan.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Asymmetric catalytic synthesis of corynanthe and ipecac alkaloids2012Ingår i: Targets in Heterocyclic Systems: Chemistry and Properties / [ed] Orazio A. Attanasi; Domenico Spinelli, Societa Chimica Italiana , 2012, s. 31-55Kapitel i bok, del av antologi (Refereegranskat)
    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.

  • 122694.
    Zhang, Wei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Franzén, Johan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Diverse Asymmetric Quinolizidine Synthesis: A Stereodivergent One-Pot Approach2010Ingår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 352, nr 2-3, s. 499-518Artikel i tidskrift (Refereegranskat)
    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.

  • 122695. Zhang, Wei
    et al.
    Hu, Youde
    Huan, Yuxiang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Zou, Zhuo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Cui, Keji
    Bao, Dongxuan
    Pan, Dashan
    Wang, Lebo
    Zheng, Lirong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Hierarchical Design of a Low Power Standing Wave Oscillator Based Clock Distribution Network2016Ingår i: 2016 2ND IEEE NORDIC CIRCUITS AND SYSTEMS CONFERENCE (NORCAS), IEEE conference proceedings, 2016Konferensbidrag (Refereegranskat)
    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.

  • 122696. Zhang, Wei
    et al.
    Hu, You-de
    Zheng, Li-rong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Industriell och Medicinsk Elektronik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Design and simulation of a standing wave oscillator based PLL2016Ingår i: FRONTIERS OF INFORMATION TECHNOLOGY & ELECTRONIC ENGINEERING, ISSN 2095-9184, Vol. 17, nr 3, s. 258-264Artikel i tidskrift (Refereegranskat)
    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.

  • 122697.
    Zhang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Transportplanering.
    Jenelius, Erik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Transportplanering.
    Badia, Hugo
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Transportplanering.
    Efficiency of connected semi-autonomous platooning bus services in high-demand transit corridorsManuskript (preprint) (Övrigt vetenskapligt)
    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.

  • 122698.
    Zhang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Jenelius, Erik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Badia, Hugo
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Efficiency of semi-autonomous and fully autonomous bus services in trunk-and-branches networks2019Ingår i: Journal of Advanced Transportation, ISSN 0197-6729, E-ISSN 2042-3195, artikel-id 7648735Artikel i tidskrift (Refereegranskat)
    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.

  • 122699.
    Zhang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transportplanering, ekonomi och teknik.
    Jenelius, Erik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transportplanering, ekonomi och teknik.
    Ma, Xiaoliang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transportplanering, ekonomi och teknik.
    Freight transport platoon coordination and departure time scheduling under travel time uncertainty2017Ingår i: Transportation Research Part E: Logistics and Transportation Review, ISSN 1366-5545, E-ISSN 1878-5794, Vol. 98, s. 1-23Artikel i tidskrift (Refereegranskat)
    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.

  • 122700. Zhang, Wei
    et al.
    Liu, Jianhui
    Jin, Kun
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Synthesis of some new 4-substituted-3,5-bis(2-pyridyl)-1H-pyrazole2006Ingår i: Journal of Heterocyclic Chemistry, ISSN 0022-152X, E-ISSN 1943-5193, Vol. 43, nr 6, s. 1669-1672Artikel i tidskrift (Refereegranskat)
    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.

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