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  • 3901.
    Yu, Ying
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Improving the Accuracy of 2D On-Road Object Detection Based on Deep Learning Techniques2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta dokument fokuserar p att frbttra noggrannheten nr det gller att upptckaon-road-objekt, inklusive bilar, lastbilar, fotgngare och cyklister. Fr att uppfyllakraven i det inbyggda visionssystemet, och upprtthlla en hg upptckthastighet iADAS-domnen (advanced drive assist system), r den neurala ntverksmodellenutformad baserat p enkanalsbilder som inmatning frn en monokulr kamera.Under de senaste decennierna har systemet fr framtida kollisionsundvikandesystem, ett delsystem fr ADAS, antagits allmnt i fordonsskerhetssystem fr sittstora bidrag till att minska olyckor. Djupa neurala ntverk, som den senastetekniken fr detektering av objekt, kan uppns i detta inbyggda visionssystemmed e↵ektiv berkning p FPGA och hg inferenshastighet. Siktat p att upptckavgar p vgar i hg noggrannhet, tillmpar vi ett avancerat neuralt ntverk, singleshotmulti-box detector (SSD).I det hr avhandlingsarbetet utfrs flera experiment om hur man frbttrar SSDmodellernasnoggrannhet med grtoningng. Genom att lgga till lmpliga extrastandardldor i hglagerskartor och justera hela skalaomrdet har upptckt AP veralla klasser frbttrats e↵ektivt kring 20 %, med mAP av SSD300-modellen kat frn45,1 % till initialt 76,8 % och mAP av SSD512-modellen p KITTI-dataset kadefrn 58,5 % till 78,8 %. Dessutom har det kontrollerats att utan frginformationinte kommer att frsmras i bde prestanda och prestanda. Experimentella resultatutvrderades med hjlp av Nvidia Tesla P100 GPU p KITTI Vision BenchmarkSuite, Udacity annoterade dataset och en kort video inspelad p en gata i Stockholm.

  • 3902.
    Yu, Yiqun
    et al.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Delzanno, Gian Luca
    Los Alamos Natl Lab, Los Alamos, NM USA..
    Jordanova, Vania
    Los Alamos Natl Lab, Los Alamos, NM USA..
    Peng, Ivy Bo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Parallelldatorcentrum, PDC.
    Markidis, Stefano
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST).
    PIC simulations of wave-particle interactions with an initial electron velocity distribution from a kinetic ring current model2018Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 177, s. 169-178Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Whistler wave-particle interactions play an important role in the Earth inner magnetospheric dynamics and have been the subject of numerous investigations. By running a global kinetic ring current model (RAM-SCB) in a storm event occurred on Oct 23-24 2002, we obtain the ring current electron distribution at a selected location at MLT of 9 and L of 6 where the electron distribution is composed of a warm population in the form of a partial ring in the velocity space (with energy around 15 keV) in addition to a cool population with a Maxwellian-like distribution. The warm population is likely from the injected plasma sheet electrons during substorm injections that supply fresh source to the inner magnetosphere. These electron distributions are then used as input in an implicit particle-in-cell code (iPIC3D) to study whistler-wave generation and the subsequent wave-particle interactions. We find that whistler waves are excited and propagate in the quasi-parallel direction along the background magnetic field. Several different wave modes are instantaneously generated with different growth rates and frequencies. The wave mode at the maximum growth rate has a frequency around 0.62 omega(ce), which corresponds to a parallel resonant energy of 2.5 keV. Linear theory analysis of wave growth is in excellent agreement with the simulation results. These waves grow initially due to the injected warm electrons and are later damped due to cyclotron absorption by electrons whose energy is close to the resonant energy and can effectively attenuate waves. The warm electron population overall experiences net energy loss and anisotropy drop while moving along the diffusion surfaces towards regions of lower phase space density, while the cool electron population undergoes heating when the waves grow, suggesting the cross-population interactions.

  • 3903.
    Yu, Zhongxing
    et al.
    Inria Lille Nord Europe, Ave Halley, F-59650 Villeneuve Dascq, France..
    Martinez, Matias
    Univ Valenciennes, Malvache Bldg,Campus Mont Houy, F-59313 Valenciennes 9, France..
    Danglot, Benjamin
    Inria Lille Nord Europe, Ave Halley, F-59650 Villeneuve Dascq, France..
    Durieux, Thomas
    Inria Lille Nord Europe, Ave Halley, F-59650 Villeneuve Dascq, France..
    Monperrus, Martin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teoretisk datalogi, TCS.
    Alleviating patch overfitting with automatic test generation: a study of feasibility and effectiveness for the Nopol repair system2019Ingår i: Journal of Empirical Software Engineering, ISSN 1382-3256, E-ISSN 1573-7616, Vol. 24, nr 1, s. 33-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Among the many different kinds of program repair techniques, one widely studied family of techniques is called test suite based repair. However, test suites are in essence input-output specifications and are thus typically inadequate for completely specifying the expected behavior of the program under repair. Consequently, the patches generated by test suite based repair techniques can just overfit to the used test suite, and fail to generalize to other tests. We deeply analyze the overfitting problem in program repair and give a classification of this problem. This classification will help the community to better understand and design techniques to defeat the overfitting problem. We further propose and evaluate an approach called UnsatGuided, which aims to alleviate the overfitting problem for synthesis-based repair techniques with automatic test case generation. The approach uses additional automatically generated tests to strengthen the repair constraint used by synthesis-based repair techniques. We analyze the effectiveness of UnsatGuided: 1) analytically with respect to alleviating two different kinds of overfitting issues; 2) empirically based on an experiment over the 224 bugs of the Defects4J repository. The main result is that automatic test generation is effective in alleviating one kind of overfitting, issue-regression introduction, but due to oracle problem, has minimal positive impact on alleviating the other kind of overfitting issue-incomplete fixing.

  • 3904.
    Yuan, Sijian
    et al.
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Wang, Jiao
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Yang, Kunlong
    KTH, Skolan för elektroteknik och datavetenskap (EECS). IPack VINN Excellence Ctr, Royal Inst Technol KTH, S-16440 Stockholm, Sweden..
    Wang, Pengfei
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zhang, Xin
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zhan, Yiqiang
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zheng, Li-rong
    KTH. Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China.;IPack VINN Excellence Ctr, Royal Inst Technol KTH, S-16440 Stockholm, Sweden..
    High efficiency MAPbI(3-x)Cl(x) perovskite solar cell via interfacial passivation2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 40, s. 18909-18914Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The trap states at the interface between perovskite and charge-transport layer have a great influence on the performance of perovskite solar cells. Here, a high efficiency MAPbI(3-x)Cl(x) perovskite solar cell has been demonstrated, by introducing a thin layer of LiF or PbF2 between the SnO2/perovskite. Improved charge collection and reduced interfacial charge recombination are realized, leading to remarkable rises of both open-circuit voltage (V-oc) and short-circuit current (J(sc)). This successful interfacial passivation paved a new way to fabricate high performance perovskite solar cells with large V-oc.

  • 3905.
    Yuan, Weihao
    et al.
    Hong Kong Univ Sci & Technol, ECE, Robot Inst, Hong Kong, Peoples R China..
    Hang, Kaiyu
    Yale Univ, Mech Engn & Mat Sci, New Haven, CT USA..
    Kragic, Danica
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS. KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Wang, Michael Y.
    Hong Kong Univ Sci & Technol, ECE, Robot Inst, Hong Kong, Peoples R China..
    Stork, Johannes A.
    Orebro Univ, Ctr Appl Autonomous Sensor Syst, Orebro, Sweden..
    End-to-end nonprehensile rearrangement with deep reinforcement learning and simulation-to-reality transfer2019Ingår i: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 119, s. 119-134Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nonprehensile rearrangement is the problem of controlling a robot to interact with objects through pushing actions in order to reconfigure the objects into a predefined goal pose. In this work, we rearrange one object at a time in an environment with obstacles using an end-to-end policy that maps raw pixels as visual input to control actions without any form of engineered feature extraction. To reduce the amount of training data that needs to be collected using a real robot, we propose a simulation-to-reality transfer approach. In the first step, we model the nonprehensile rearrangement task in simulation and use deep reinforcement learning to learn a suitable rearrangement policy, which requires in the order of hundreds of thousands of example actions for training. Thereafter, we collect a small dataset of only 70 episodes of real-world actions as supervised examples for adapting the learned rearrangement policy to real-world input data. In this process, we make use of newly proposed strategies for improving the reinforcement learning process, such as heuristic exploration and the curation of a balanced set of experiences. We evaluate our method in both simulation and real setting using a Baxter robot to show that the proposed approach can effectively improve the training process in simulation, as well as efficiently adapt the learned policy to the real world application, even when the camera pose is different from simulation. Additionally, we show that the learned system not only can provide adaptive behavior to handle unforeseen events during executions, such as distraction objects, sudden changes in positions of the objects, and obstacles, but also can deal with obstacle shapes that were not present in the training process.

  • 3906.
    Yuan, Weihao
    et al.
    Hong Kong Univ Sci & Technol, Hong Kong, Hong Kong, Peoples R China.;HKUST Robot Inst, Hong Kong, Hong Kong, Peoples R China.;Dept Elect & Comp Engn, Hong Kong, Hong Kong, Peoples R China..
    Stork, Johannes A.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS.
    Kragic, Danica
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS.
    Wang, Michael Y.
    Hong Kong Univ Sci & Technol, Hong Kong, Hong Kong, Peoples R China.;HKUST Robot Inst, Hong Kong, Hong Kong, Peoples R China.;Dept Mech & Aerosp Engn, Hong Kong, Hong Kong, Peoples R China..
    Hang, Kaiyu
    Hong Kong Univ Sci & Technol, Hong Kong, Hong Kong, Peoples R China.;HKUST Robot Inst, Hong Kong, Hong Kong, Peoples R China.;Dept Comp Sci & Engn, Hong Kong, Hong Kong, Peoples R China.;HKUST Inst Adv Study, Hong Kong, Hong Kong, Peoples R China..
    Rearrangement with Nonprehensile Manipulation Using Deep Reinforcement Learning2018Ingår i: 2018 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION (ICRA), IEEE Computer Society, 2018, s. 270-277Konferensbidrag (Refereegranskat)
    Abstract [en]

    Rearranging objects on a tabletop surface by means of nonprehensile manipulation is a task which requires skillful interaction with the physical world. Usually, this is achieved by precisely modeling physical properties of the objects, robot, and the environment for explicit planning. In contrast, as explicitly modeling the physical environment is not always feasible and involves various uncertainties, we learn a nonprehensile rearrangement strategy with deep reinforcement learning based on only visual feedback. For this, we model the task with rewards and train a deep Q-network. Our potential field-based heuristic exploration strategy reduces the amount of collisions which lead to suboptimal outcomes and we actively balance the training set to avoid bias towards poor examples. Our training process leads to quicker learning and better performance on the task as compared to uniform exploration and standard experience replay. We demonstrate empirical evidence from simulation that our method leads to a success rate of 85%, show that our system can cope with sudden changes of the environment, and compare our performance with human level performance.

  • 3907.
    Yuan, Zhao
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Convex Optimal Power Flow Based on Second-Order Cone Programming: Models, Algorithms and Applications2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Optimal power flow (OPF) is the fundamental mathematical model to optimally operate the power system. Improving the solution quality of OPF can help the power industry save billions of dollars annually. Past decades have witnessed enormous research efforts on OPF since J. Carpentier proposed the fully formulated alternating current OPF (ACOPF) model which is nonconvex. This thesis proposes three convex OPF models (SOC-ACOPF) based on second-order cone programming (SOCP) and McCormick envelope. The underlying idea of the proposed SOC-ACOPF models is to drop assumptions of the original SOC-ACOPF model by convex relaxation and approximation methods. A heuristic algorithm to recover feasible OPF solution from the relaxed solution of the proposed SOC-ACOPF models is developed. The quality of solutions with respect to global optimum is evaluated using MATPOWER and LINDOGLOBAL. A computational comparison with other SOC-ACOPF models in the literature is also conducted. The numerical results show robust performance of the proposed SOC-ACOPF models and the feasible solution recovery algorithm. We then propose to speed up solving large-scale SOC-ACOPF problem by decomposition and parallelization. We use spectral factorization to partition large power network to multiple subnetworks connected by tie-lines. A modified Benders decomposition algorithm (M-BDA) is proposed to solve the SOC-ACOPF problem iteratively. Taking the total power output of each subnetwork as the complicating variable, we formulate the SOC-ACOPF problem of tie-lines as the master problem and the SOC-ACOPF problems of the subnetworks as the subproblems in the proposed M-BDA. The feasibility of the proposed M-BDA is analytically proved. A GAMS grid computing framework is designed to compute the formulated subproblems in parallel. The numerical results show that the proposed M-BDA can solve large-scale SOC-ACOPF problem efficiently. Accelerated M-BDA by parallel computing converges within few iterations.Finally, various applications of our SOC-ACOPF models and M-BDA including distribution locational marginal pricing (DLMP), wind power integration and ultra-large-scale power network or super grid operation are demonstrated.

  • 3908.
    Yuan, Zhao
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Hesamzadeh, Mohammad Reza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    A Distributed Economic Dispatch Mechanism to Implement Distribution Locational Marginal Pricing2018Ingår i: 2018 POWER SYSTEMS COMPUTATION CONFERENCE (PSCC), IEEE , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    We address the challenges of power flow computation and network operator coordination to implement distribution locational marginal pricing (DLMP) in this paper. Compared with other dynamic pricing schemes, DLMP can give clearer economic signals regarding distributed energy resources (DERs) investment, demand side response, congestion management and network reinforcement. Without neglecting the power loss of distribution network, the second-order cone AC optimal power flow (SOPF) model is used here to calculate DLMP. A distributed economic dispatch mechanism based on the modified Benders decomposition and distributed generation cost (DGC) is proposed to reduce the dispatch complexity in facing high penetration of DERs. The key contribution is that we take the tie-line power flow as the complicating variable to formulate the modified Benders decomposition algorithm. The concept of DGC is proposed to reallocate the global dispatch cost to economically incentivize the regional network operators for coordination. The distributed economic dispatch mechanism is implemented in GAMS grid computing platform. Numerical results show that SOPF can give accurate power flow and DLMP results. The fast convergence of the proposed distributed dispatch is guaranteed by the convexity of the SOPF model and efficient grid computing technique.

  • 3909.
    Yuan, Zhao
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Hesamzadeh, Mohammad Reza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    A Max-Affine Approximation Model to Solve Power Flow Problem with Controllable Accuracy2018Ingår i: Proceedings - 2018 IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT-Europe 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, artikel-id 8571864Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper proposes a max-affine power flow (MAPF) model to solve the power flow (PF) problem based on linear approximation. Both active and reactive power loss variables in the original power flow equations are approximated by multiple sets of affine functions. The derivations of the proposed MAPF model are based on the branch flow equations which have been validated in the literature. The problem of solving PF equations is then equivalently reformulated in an linear optimization model. The proposed MAPF model works by minimizing the approximation error in the objective function of the formulated optimization model while satisfying all the power flow equations serving as the constraints of the formulated optimization model. Since the proposed MAPF model is linear, it is advantageous in that the accuracy of the approximation is controllable by the number of affine functions. The fast convergence and accuracy of the proposed MAPF model are proved by numerical results for various IEEE test cases. A comparison with DC power flow (DCPF) results using AC power flow (ACPF) as the benchmark shows that the accuracy of MAPF is better especially in power distribution networks where power loss is un-neglectable due to larger resistance to reactance (R/X) ratio of the power lines. The proposed MAPF model is applicable for both radial and mesh power networks.

  • 3910.
    Yuan, Zhao
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Hesamzadeh, Mohammad Reza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    A Modified Benders Decomposition Algorithm to Solve Second-Order Cone AC Optimal Power Flow2019Ingår i: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 10, nr 2, s. 1713-1724Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper proposes to speed up solving large-scale second-order cone ac optimal power flow (SOC-ACOPF) problem by decomposition and parallelization. First, we use spectral factorization to partition large power network to multiple subnetworks connected by tie-lines. Then a modified Benders decomposition algorithm (M-BDA) is proposed to solve the SOC-ACOPF problem iteratively. Taking the total power output of each subnetwork as the complicating variable, we formulate the SOC-ACOPF problem of tie-lines as the master problem and the SOC-ACOPF problems of the subnetworks as the subproblems in the proposed M-BDA. The feasibility and optimality (preserving the original optimal solution of the SOC-ACOPF model) of the proposed M-BDA are analytically and numerically proved. A GAMS grid computing framework is designed to compute the formulated subproblems of M-BDA in parallel. The numerical results show that the proposed M-BDA can solve large-scale SOC-ACOPF problem efficiently. Accelerated M-BDA by parallel computing converges within few iterations. The computational efficiency (reducing computation CPU time and computer RAM requirement) can be improved by increasing the number of partitioned subnetworks.

  • 3911.
    Yuan, Zhao
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Hesamzadeh, Mohammad Reza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Improving the Accuracy of Second-Order Cone AC Optimal Power Flow by Convex Approximations2018Ingår i: International Conference on Innovative Smart Grid Technologies, ISGT Asia 2018, Institute of Electrical and Electronics Engineers Inc. , 2018, s. 172-177Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose three convex approximation methods to improve the performance of second-order cone AC optimal power flow (SOC-ACOPF) model. These methods are formulated in the proposed SOC-ACOPF models, correspondingly, ConicLA, ConicRe, and ConicTA. The principle is to drop the original assumptions of the SOC-ACOPF model by using improved approximation methods. The nonconvex constraints in ACOPF are expressed by using quadratic equivalence. These quadratic constraints are then approximated in two different ways: ConicLA uses controllable tangent lines as linear approximations; ConicRe uses rotated cones. Furthermore, the assumption of small voltage phase angle difference (along each line) which is used in many power flow models is dropped in the ConicTA model. ConicTA approximates sinusoidal function by its expanded Taylor series and then re-applies approximation methods developed in ConicLA and ConicRe. The advantages of our approximation methods are that the proposed SOC-ACOPF models are convex and more accurate. Using Power System Analysis Toolbox (PSAT) as the benchmark, numerical results from various IEEE test cases show that our models outperform the original SOC-ACOPF model prominently especially for power distribution networks.

  • 3912.
    Yuan, Zhao
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Hesamzadeh, Mohammad Reza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Second-Order Cone AC Optimal Power Flow:Convex Relaxations and Feasible Solutions2018Manuskript (preprint) (Övrigt vetenskapligt)
  • 3913.
    Yuan, Zhao
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Hesamzadeh, Mohammad Reza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Second-order cone AC optimal power flow: convex relaxations and feasible solutions2019Ingår i: Journal of Modern Power Systems and Clean Energy, ISSN 2196-5625, E-ISSN 2196-5420, Vol. 7, nr 2, s. 268-280Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Optimal power flow (OPF) is the fundamental mathematical model to optimize power system operations. Based on conic relaxation, Taylor series expansion and McCormick envelope, we propose three convex OPF models to improve the performance of the second-order cone alternating current OPF (SOC-ACOPF) model. The underlying idea of the proposed SOC-ACOPF models is to drop assumptions of the original SOC-ACOPF model by convex relaxation and approximation methods. A heuristic algorithm to recover feasible ACOPF solution from the relaxed solution of the proposed SOC-ACOPF models is developed. The proposed SOC-ACOPF models are examined through IEEE case studies under various load scenarios and power network congestions. The quality of solutions from the proposed SOC-ACOPF models is evaluated using MATPOWER (local optimality) and LINDOGLOBAL (global optimality). We also compare numerically the proposed SOC-ACOPF models with other two convex ACOPF models in the literature. The numerical results show robust performance of the proposed SOC-ACOPF models and the feasible solution recovery algorithm.

  • 3914.
    Yuan, Zhao
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Hesamzadeh, Mohammad Reza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Wogrin, Sonja
    Comillas Pontifical University.
    Baradar, Mohamadreza
    Stochastic Optimal Operationof VSC-MTDC System and FACTS Considering Large-Scale Integration of Wind Power2017Manuskript (preprint) (Övrigt vetenskapligt)
  • 3915.
    Yuan, Zhao
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Reza Hesamzadeh, Mohammad
    A Modified Benders Decomposition Algorithm to Solve Second-Order Cone AC Optimal Power FlowIngår i: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper proposes to speed up solving large-scale second-order cone AC optimal power flow (SOC-ACOPF) problem by decomposition and parallelization. Firstly, we use spectral factorization to partition large power network to multiple subnetworks connected by tie-lines. Then a modified Benders decomposition algorithm (M-BDA) is proposed to solve the SOC-ACOPF problem iteratively. Taking the total power output of each subnetwork as the complicating variable, we formulate the SOC-ACOPF problem of tie-lines as the master problem and the SOC-ACOPF problems of the subnetworks as the subproblems in the proposed M-BDA. The feasibility and optimality (preserving the original optimal solution of the SOC-ACOPF model) of the proposed M-BDA are analytically and numerically proved. A GAMS grid computing framework is designed to compute the formulated subproblems of M-BDA in parallel. The numerical results show that the proposed M-BDA can solve large-scale SOC-ACOPF problem efficiently. Accelerated M-BDA by parallel computing converges within few iterations. The computational efficiency (reducing computation CPU time and computer RAM requirement) can be improved by increasing the number of partitioned subnetworks.

  • 3916.
    Yudhanira, Ela
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Medieteknik och interaktionsdesign, MID.
    Optimize the user experience of Linked Data visualization2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Användningen av Linked Data i syfte att modellera och visualisera komplex information medför både utmaningar och möjligheter för förbättringar när det kommer till användarupplevelsen. Denna studie strävar efter att förbättra användarupplevelsen av ett produktinformationsverktyg som utvecklats med Linked Data-tekniker. Studien är en fallstudie som genomfördes i en industriell miljö och består av: 1) användarundersökning och litteraturöversikt för att definiera designkrav, 2) prototyputveckling, och 3) användbarhetstester. Användarundersökningen resulterade i en lista av problem relaterade till användarupplevelsen, vilken i sin tur översattes till designkrav genom reflektioner kring både tidigare forskning och användarnas behov och mål. De identifierade designkraven utgjorde sedan grunden för de designelement som inkluderades i utvecklingen av High and Low-fidelity-prototyper. Därefter utvärderades i vilken utsträckning de nya designelementen i den slutgiltiga High-fidelity-prototypen kunde förbättra datavisualiseringen. Resultaten visar att designbeslut som att inkludera interaktionsdynamik och rik färgrepresentation kan förbättra användarvänligheten av systemet. Även om både tillvägagångssätt som UML-diagram och Node-Link-diagram fick likartade resultat när det kom till effektivitet, gav skiftet från UML-diagram till Node-Link-diagram en mer positiv respons från användarna när det kom till generell information och visuell notation.

  • 3917.
    Yue, Jing
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Xiao, Ming
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Lin, Zihuai
    Univ Sydney, Sch Elect & Informat Engn, Sydney, NSW 2007, Australia..
    Vucetic, Branka
    Univ Sydney, Sch Elect & Informat Engn, Sydney, NSW 2007, Australia..
    An Expanded Network Coding with Finite Buffer Size Information Dissemination Approach in Social Networks2018Ingår i: 2018 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    A social network is a social structure made up of a set of social actors and a set of dyadic ties between these actors. The actors form a number of communities. In communities, some actors want to transmit their information to all other actors. Each actor corresponds to a user equipment (UE). The UE of the actor which has information to be transmitted is also called the source, and the UEs of all other actors are called destinations. The information is transmitted from the source to destinations with the assistance of helpers, which can be small cell base stations (SCBSs). A novel information dissemination approach, namely expanded network coding with a finite buffer size (ENCFB), is proposed for the case when the buffer size of helpers is limited. The performance comparison of the uncoded information dissemination approach, the network coded approach and the ENCFB approach is conducted. Comparison results show that the ENCFB approach can significantly improve the performance of information dissemination when the buffer size is limited.

  • 3918.
    Yue, Jing
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Xiao, Ming
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Pang, Z.
    Distributed BATS-Based Schemes for Uplink of Industrial Internet of Things2019Ingår i: ICC 2019 - 2019 IEEE International Conference on Communications (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2019, Vol. 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    In Industrial Internet of Things (IIoTs), data generated during manufacturing are collected by sensors and need be processed timely. The direction of data transmissions from sensors to processing centers (fog nodes) is often called uplink transmission. In this paper, the cases with single and multiple distributed fog nodes, which are also referred to as centralized and distributed models, are studied. Two distributed schemes based on batched sparse (BATS) codes are proposed separately for the uplink of these two models. The expected rank and the recovery probability of the information from sensors at fog node(s) are derived. Comparison results show that by using the proposed BATS-based schemes, improved transmission reliability can be achieved compared to the XOR-based network coding (NC) scheme.

  • 3919.
    Yue, Jing
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Xiao, Ming
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Pang, Zhibo
    ABB Corp Res, Wireless Commun, S-72178 Vasteras, Sweden..
    Distributed Fog Computing Based on Batched Sparse Codes for Industrial Control2018Ingår i: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 14, nr 10, s. 4683-4691Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In an industrial automation system, one of the most important parts is control loop. Fog computing is a potential solution for industrial control in time-critical applications as it provides distributed computing services closer to the connected devices. However, a huge amount of data exchanging among fog nodes causes high communication load, which constrains the overall response time from fog nodes to actuators. In this paper, we consider the erasure environment, batched sparse (BATS) codes are applied to the Map and the Data Shuffling stages of distributed fog computing process to reduce both the communication and the computation loads. The communication loads of the uncoded, the coded, and the proposed BATS-based schemes over erasure channels are calculated, respectively. Numerical results show that the BATS-based scheme can reduce the communication and the computation loads simultaneously, and furthermore reduce the overall response time from fog nodes to the actuators.

  • 3920.
    Yus, Diego
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Long-term vehicle movement prediction using Machine Learning methods2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Lokaliserings- eller rörelseprognosering kan beskrivas som uppgiften att förutsäga ett objekts framtida placering med hjälp av de tidigare platserna för objektet. Intresset för problemet ökar i och med införandet av platsbaserade tjänster och autonoma fordon. Även om det är vanligare att studera kortsiktiga förutsägelser, särskilt när det gäller fordon, kan långsiktiga förutsägelser vara användbara i många applikationer som schemaläggning, resurshantering eller trafikprognoser.

    I detta masterprojekt presenterar jag en feature-representation av rörelse som kan användas för att lära in långsiktiga rörelsemönster och för långsiktig rörelseprediktion både i rymden och tiden. Representationen bygger på periodicitet i data och är baserad på att dela upp banan i fönster och sedan beräkna viktade n-grams av banorna från de olika fönstren.

    Algoritmen utvärderas på transportdata för tunga transportfordon för att bedöma dess förmåga att från ett sökindex hämta fordon som med stor sannolikhet kommer att röra sig längs en rutt som matchar ett önskat transportuppdrag. Experimentella resultat visar att algoritmen kan uppnå ett konsekvent lågt fel i relativt predikterat avstånd över olika transportlängder i ett begränsat geografiskt område under verkliga förhållanden. Resultaten indikerar även att den totala populationen av fordon i indexet är en kritisk faktor för algoritmens prestanda och därmed även för dess applicerbarhet för verklig användning.

  • 3921.
    Zabetian, Negar
    et al.
    Amirkabir Univ Technol, Dept Elect Engn, Microwave & Wireless Commun Res Lab, Tehran Polytech, Tehran 1591634311, Iran..
    Mohammadi, Abbas
    Amirkabir Univ Technol, Dept Elect Engn, Microwave & Wireless Commun Res Lab, Tehran Polytech, Tehran 1591634311, Iran..
    Masoudi, Meysam
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Energy-efficient power allocation for device-to-device communications underlaid cellular networks using stochastic geometry2019Ingår i: European transactions on telecommunications, ISSN 1124-318X, E-ISSN 2161-3915, artikel-id e3768Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we study an energy efficiency maximization problem in uplink for device-to-device (D2D) communications underlaid with cellular networks on multiple bands. Utilizing stochastic geometry, we derive closed-form expressions for the average sum rate, successful transmission probability, and energy efficiency of cellular and D2D users. Then, we formulate an optimization problem to jointly maximize the energy efficiency of D2D and cellular users and obtain optimum transmission power of both D2D and cellular users. In the optimization problem, we guarantee the quality-of-service of users by taking into account the success transmission probability on each link. To solve the problem, first we convert the problem into canonical convex form. Afterwards, we solve the problem in two phases: energy efficiency maximization of devices and energy efficiency maximization of cellular users. In the first phase, we maximize the energy efficiency of D2D users and feed the solution to the second phase where we maximize the energy efficiency of cellular users. Simulation results reveal that significant energy efficiency can be attained, eg, 10% energy efficiency improvement compared to fix transmission power in a high-density scenario.

  • 3922.
    Zaki, Ahmed
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Cooperative Compressive Sampling2018Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Compressed Sampling (CS) is a promising technique capable of acquiring and processing data of large sizes efficiently. The CS technique exploits the inherent sparsity present in most real-world signals to achieve this feat. Most real-world signals, for example, sound, image, physical phenomenon etc., are compressible or sparse in nature. This means that a few data samples are sufficient to accurately or closely describe the signal under a suitable representation. The CS technique banks on reconstruction algorithms to recover the original signal upto a desired level of distortion, when required . In this thesis, we design practical CS reconstruction algorithms motivated by cooperation to efficiently recover the original signal.

    We first consider the case of CS reconstruction at a single node. This problem has been extensively studied in literature. It is observed that for such a scenario there is no single strategy that works best in all problem settings. The performance of CS reconstruction algorithms is heavily influenced by different factors such as sparsity level, signal statistics and the level of undersampling; among others. With this intuition, we propose a general strategy for designing greedy CS reconstruction algorithms. This strategy involves cooperation among several participating CS algorithms in order to achieve better performance. In addition, the general strategy enables the use of off-the-shelf CS reconstruction algorithms and still guarantee theoretical tractability.

    We next consider the case where CS data samples are available across the nodes of a network. The goal is to estimate a common signal in a distributed setting at the individual nodes. We solve this problem, referred to as distributed sparse learning, through greedy pursuit as well as convex optimization based strategies. Our strategies involve exchange of intermediate estimates among the neighboring nodes in the network. The nodes then refine their estimates over the subsequent iterations to reflect the side information from the neighbors. It is shown that these cooperative strategies lead to fast convergence of the local estimates while achieving better performance results compared to other state-of-the-art distributed sparse learning algorithms.

    All cooperative CS strategies studied in this thesis are shown to have restricted isometry property (RIP) based reconstruction guarantees. The use of RIP based tools leads to a worst case performance analysis. Hence, we use simulation results to demonstrate the superior performance of the proposed algorithms in typical CS settings. 

  • 3923.
    Zaki, Ahmed
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Mitra, Partha P.
    Cold Spring Harbor Lab, 1 Bungtown Rd, New York, NY USA..
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Chatterjee, Saikat
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Estimate exchange over network is good for distributed hard thresholding pursuit2019Ingår i: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 156, s. 1-11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate an existing distributed algorithm for learning sparse signals or data over networks. The algorithm is iterative and exchanges intermediate estimates of a sparse signal over a network. This learning strategy using exchange of intermediate estimates over the network requires a limited communication overhead for information transmission. Our objective in this article is to show that the strategy is good for learning in spite of limited communication. In pursuit of this objective, we first provide a restricted isometry property (RIP)-based theoretical analysis on convergence of the iterative algorithm. Then, using simulations, we show that the algorithm provides competitive performance in learning sparse signals vis-a-vis an existing alternate distributed algorithm. The alternate distributed algorithm exchanges more information including observations and system parameters.

  • 3924.
    Zaki, Ahmed
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Venkitaraman, Arun
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Chatterjee, Saikat
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehoj
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Greedy Sparse Learning Over Network2018Ingår i: IEEE TRANSACTIONS ON SIGNAL AND INFORMATION PROCESSING OVER NETWORKS, ISSN 2373-776X, Vol. 4, nr 3, s. 424-435Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we develop a greedy algorithm for solving the problem of sparse learning over a right stochastic network in a distributed manner. The nodes iteratively estimate the sparse signal by exchanging a weighted version of their individual intermediate estimates over the network. We provide a restricted-isometry-property (RIP)-based theoretical performance guarantee in the presence of additive noise. In the absence of noise, we show that under certain conditions on the RIP-constant of measurement matrix at each node of the network, the individual node estimates collectively converge to the true sparse signal. Furthermore, we provide an upper bound on the number of iterations required by the greedy algorithm to converge. Through simulations, we also show that the practical performance of the proposed algorithm is better than other state-of-the-art distributed greedy algorithms found in the literature.

  • 3925.
    Zaki, Ahmed
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Venkitaraman, Arun
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Chatterjee, Saikat
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehöj
    Distributed Greedy Sparse Learning over Doubly Stochastic Networks2017Ingår i: 2017 25TH EUROPEAN SIGNAL PROCESSING CONFERENCE (EUSIPCO), IEEE , 2017, s. 361-364Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we develop a greedy algorithm for sparse learning over a doubly stochastic network. In the proposed algorithm, nodes of the network perform sparse learning by exchanging their individual intermediate variables. The algorithm is iterative in nature. We provide a restricted isometry property (RIP)-based theoretical guarantee both on the performance of the algorithm and the number of iterations required for convergence. Using simulations, we show that the proposed algorithm provides good performance.

  • 3926.
    Zakipour Mahmoudi, Anna
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Englund, Leila
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Användarupplevelsen av en mobilapplikation - En utvärdering av företaget Amazing Leaders' prototyp2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Under de senaste decenniet har användandet av smarta mobiltelefoner ökat kraftigt. Som ett resultat av detta har mycket forskning drivits inom området MDI (människa datorinteraktion). Ur MDI, som studerar interaktionen mellan människa och dator, har forskningsområdet User Experience (UX) fötts. På ett generellt plan så handlar UX-området om den helhetsbild som fås av en tjänst eller produkt samt huruvida människor kommer att använda den och vad som attraherar användaren till att nyttja en produkt eller tjänst.

    Organisationen Amazing Leaders har utvecklat en prototyp för en framtida mobilapplikation som ska utvecklas av IT-firman VNTRS. VNTRS och författarna har tagit sig an kandidatexamensarbetet för att, med hjälp av UX som forskningsområde, studera de egenskaper hos prototypen som Amazing Leaders’ slutanvändare har tyckt varit viktigast för användarupplevelsen. Utefter Hassenzahls UX-ramverk och Laugwitz et al. egenskaper hos användarupplevelsen undersöktes prototypen med hjälp av enkätundersökningar och fokusgrupper. 

    Med hjälp av insamlad data från enkäterna och fokusgrupperna kunde de viktigaste kategorierna för prototypen fastställas och en rekommendation om fortsatt arbete göras.

  • 3927.
    Zaklouta, Ahmadmunthar
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    High-Speed Communication Scheme in OSI Layer 2 Research and Implementation2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna avhandling är en del av ett projekt på Bombardiers Object Controller System. Detta system fungerar som ett kommunikationsgränssnitt för flera delsystem som styr järnvägstrafiken. Därför är en del av säkerheten och tillgängligheten av järnvägstransporten beroende av systemets prestanda och tillförlitlighet, särskilt det digitala kommunikationssystemet som hanterar kommunikationen ombord. Bombardier har sålunda implementerat nya höghastighets LVDS-kanaler för att använda istället för de implementerade RS-485-kanalerna för att förbättra kommunikationsprestandan ombord i objektkontrollen, men de saknar en transceiver. Denna avhandling arbetar med att undersöka möjliga transceiverlösningar som uppnår Bombardier-krav. Återanvändbarhet är mycket viktigt för Bombardier för säkerhetsöverensstämmelse och certifiering. Undersökningen genomfördes därför genom att undersöka vad som för närvarande implementeras och sedan genomföras genom att titta på transceivers som används i höghastighetskommunikation och kontrollera deras lämplighet och överensstämmelse för FPGA och kraven. Denna undersökning resulterar i tre experiment för olika transceiverarkitektur. Det första experimentet utnyttjar den nuvarande implementerade transceiverarkitekturen. Den är inte lämplig för höghastighetsdatakommunikation på grund av en begränsning i bufferten. Det andra experimentet övervinns buffertbegränsningen genom att använda en klockdomänöverföringsbuffert vilket resulterar i ett 100-timmars snabbare system. Det tredje experimentet syftade till att uppnå en högre datahastighet genom att använda en klockoch dataåterställningstransceiver vilket resulterar i en lovande lösning men behöver vissa förbättringar. För testning har en verifieringsmetod som följer envägsstresstestarkitekturen utvecklats med hjälp av VHDL för simulering och för inchip-testning. Resultaten verifierades med hjälp av ChipScope logic analyzer från Xilinx. Dessutom har ett termiskt test för lösningen från det andra experimentet utförts.

  • 3928.
    Zamovaro, A. M.
    et al.
    Research Institute on Health Sciences, University of Balearic Islands, Palma de Mallorca, Spain;Institute for Medical Psychology and Behavioral Neurobiology, University of Tübingen, Germany.
    Zatorre, R. J.
    International Laboratory for Brain, Music and Sound research (BRAMS), Montreal, Canada;McGill University–Montreal Neurological Institute, Neuropsychology and Cognitive Neuroscience, Montreal, Canada.
    Vuust, Peter
    Center for Music in the Brain, Department of Clinical Medicine, Aarhus University;The Royal Academy of Music Aarhus/Aalborg, Denmark.
    Friberg, Anders
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Tal, musik och hörsel, TMH.
    Birbaumer, Niels
    Institute for Medical Psychology and Behavioral Neurobiology, University of Tübingen, Germany;Wyss Center for Bio and Neuroengeneering, Chenin de Mines 9, 1202, Geneva, Switzerland.
    Kleber, Boris
    Institute for Medical Psychology and Behavioral Neurobiology, University of Tübingen, Germany;Center for Music in the Brain, Department of Clinical Medicine, Aarhus University;The Royal Academy of Music Aarhus/Aalborg, Denmark.
    Enhanced insular connectivity with speech sensorimotor regions in trained singers – a resting-state fMRI studyManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The insula contributes to the detection and integration of salient events during goaldirected behavior and facilitates the interaction between motor, multisensory, and cognitive networks. Task-fMRI studies have suggested that experience with singing can enhance access to these resources. However, the long-term effects of vocal motor training on insula-based networks are currently unknown. In thisstudy, we used restingstate fMRI to explore experience-dependent differences in insula co-activation patterns between conservatory-trained singers and non-singers. We found enhanced insula connectivity in singers compared to non-singers with constituents of the speech sensorimotor network, including the cerebellum (lobule VI, crus 2), primary somatosensory cortex, the parietal lobes, and the thalamus. Moreover, accumulated singing training correlated positively with increased co-activation in bilateral primary sensorimotor cortices in the somatotopic representations of the larynx (left dorsal anterior insula, dAI) and the diaphragm (bilateral dAI)—crucial regions for motorcortical control of complex vocalizations—together with the thalamus (bilateral posterior insula/left dAI) and the left putamen (left dAI). The results of this study support the view that the insula plays a central role in the experience-dependent modulation of sensory integration within the vocal motor system, possibly by optimizing conscious and non-conscious aspects of salience processing associated with singing-related bodily signals.

  • 3929.
    Zander, Jens
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Beckman, Claes
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Nilsson, Mats
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Remissvar: "Betänkande av Utredningen om radiospektrumanvändningi framtiden – Frekvenser i samhällets tjänst" (SOU 2018:92): Diarie nummer N2019/00192/D2019Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Betänkandet slår fast att frekvensspektrum är en viktig naturresurs som ur samhällets synpunkt måste användas så effektivt som möjligt. När olika användningsmöjligheter står mot varandra blir det svårt att avgöra vilken användning som ger störst samhällsnytta. Detta eftersom teknologi och innehåll för många tjänster är oklar eller tom okänd i det tidsperspektiv som anges. En fortsättning av pågående evolution är dock säkert, gäller också för metodiken runt spektrumallokering. Det är viktigt att spektrumallokering hantereras av en myndighet som i varje tidsskede har kompetens och inflytande för att utföra uppgiften på samma sätt som PTS gör idag.

     

    KTH instämmer med konstaterandet att utvecklingen inom radio och kommunikation för tidsperioden 2027-2047 är omöjlig att förutse. Med detta följer också att metodiken för tilldelning av spektrum också kommer att behöva förändras över tid. Vi kommer att se nya tekniker för adaptivt val av frekvenser och effektiv delning av spektrum. Nya satellitbaserade system är under införande vilket förändrar distribution av ägande och tjänster i en global riktning.

     

    Betänkandet är drivet av antagande om att efterfrågan på spektrum kommer att öka och därmed kommer bristen att öka dramatiskt. Huvudlösningen som förs fram är nya avgifter för att spegla nyttan. Vi inser att nya avgifter kan lösa en del av problemet men ser också att spektrumtilldelning är ett hantverk där många hänsyn måste tas. Helt olika motiv för användning måste vägas mot varandra. I det läget räcker inte en enda optimeringsmetod till, dvs nya avgifter. Vi ser ett stort behov av en myndighet som har nödvändig kompetens för att ta in alla dessa behov och göra de avvägningar som krävs.

     

    Ömmande behov av säkerhet och trygghet i samhället, försvar, vetenskap, är näst intill omöjliga att hantera via en prissättning. De operatörer som idag har stor omsättning inom mobilt Internet har i regel betalt stora summor via auktion och betalar löpande operatörsavgifter i relation till omsättning (PTSFS 2018:06). Att mer eller mindre överföra denna princip på statliga organisationer och på så sätt rotera pengar runt mellan dem känns inte meningsfullt, däremot skall givetvis väl underbyggda hänsyn tas vid varje allokering.

  • 3930.
    Zandi Shafagh, Reza
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Thiol-ene Nanostructuring2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Improving the health and well-being of humankind does not only constitute

    part of our moral codes, but is also enlisted as the number three goal of

    the 2030 agenda for sustainable development set by the UN. Fulfilling such

    objective in the regions of resource-poor settings or for age groups with more

    vulnerability to infectious agents demands immediate actions. This has necessitated

    novel ways of rapid and ultra-sensitive diagnostics to provide compact

    and affordable systems, e.g. for an early detection of bacteria and viruses.

    The fields of bio-micro/nanoelectromechanical systems (BioMEMS/NEMS)

    and lab-on-a-chip (LoC) have been founded based on such demands, but

    critically challenged by problems partly associated with manufacturing and

    material domains and biosensing methods. The fabrication methods for the

    miniaturization of features and components are often complicated and expensive,

    the commonly used materials are typically not adaptable to industrial

    settings, and the sensing mechanisms are sometimes not sensitive enough for

    the detection of lowly-concentrated samples.

    In this thesis, new methods of ultra-miniaturization, as well as conventional

    cleanroom-based techniques, for nanopatterning of well-defined topographies

    in off-stoichiometry thiol-ene-(epoxy) polymers are presented. In addition,

    their use for several sensing applications has been demonstrated. The

    first part of the thesis gives an introduction to the field of BioMEMS/NEMS.

    The second part of the thesis presents a technical background about the

    prevalent methods of polymer micro- and nanofabrication, implementation

    of the resulting polymer structures for different sensing applications, along

    with the existing challenges and shortcomings associated with state of the

    art. The third part of the thesis presents e-beam nanostructuring of thiol-ene

    resist, for the first time, achieving the smallest and densest features reported

    in these polymer networks. The thiol-ene-based polymer also represents a

    novel class of e-beam resist resulting in structures with reactive surface nature.

    The fourth part of the thesis demonstrates the use of thiol-ene-epoxy

    systems for nanoimprint lithography and further shows the structuring of

    high-aspect-ratio and hierarchical topologies via single-step UV-NIL. The fifth

    part of the thesis introduces Micro- and NanoRIM platforms for scalable and

    off-cleanroom manufacturing of microfluidic devices and nanostructuring of

    materials in thiol-ene (-epoxy) systems. The sixth part of the thesis exhibits

    the implementation of the noted nanofabrication methods for different

    BioMEMS/NEMS applications including protein nanopatterning, simultaneous

    molding and surface energy patterning, ultra-sensitive digital biosensing,

    and facile quartz crystal microbalance (QCM) sensor packaging.

  • 3931.
    Zandi Shafagh, Reza
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Decrop, Deborah
    Ven, Karen
    Vanderbeke, Arno
    Hanusa, Robert
    Breukers, Jolien
    Pardon, Gaspard
    Haraldsson, Klas Tommy
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Lammertyn, Jeroen
    van der Wijngaart, Wouter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Reaction Injection Molding of Hydrophilic-in-Hydrophobic Femtolitre-Well Arrays2019Ingår i: Microsystems & Nanoengineering, E-ISSN 2055-7434, nr 5, artikel-id 25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Patterning of micro- and nanoscale topologies and surface properties of polymer devices is of particular importance for a broad range of life science applications, including cell-adhesion assays and highly sensitive bioassays. The manufacturing of such devices necessitates cumbersome multiple-step fabrication procedures and results in surface properties which degrade over time. This critically hinders their wide-spread dissemination. Here, we simultaneously mold and surface energy pattern microstructures in off-stoichiometric thiol-ene by area-selective monomer self-assembly in a rapid micro-reaction injection molding cycle. We replicated arrays of 1,843,650 hydrophilic-in-hydrophobic femtolitre-wells with long-term stable surface properties and magnetically trapped beads with 75% and 87.2% efficiency in single- and multiple-seeding events, respectively. These results form the basis for ultrasensitive digital biosensors, specifically, and for the fabrication of medical devices and life science research tools, generally.

  • 3932.
    Zandi Shafagh, Reza
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Guo, Weijin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    van der Wijngaart, Wouter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Haraldsson, Klas Tommy
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Bio-Inspired High-Aspect-Ratio and Hierarchical Nanoimprint LithographyManuskript (preprint) (Övrigt vetenskapligt)
  • 3933.
    Zanni-Merk, Cecilia
    et al.
    Natl Inst Appl Sci Rouen Normandie, LITIS Lab, Normandy, France.;Natl Inst Appl Sci Rouen Normandie, MIND Team, Normandy, France..
    Frydman, Claudia
    Aix Marseille Univ, Marseille, France..
    Håkansson, Anne
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Programvaruteknik och datorsystem, SCS.
    Special Issue: Advances in Knowledge-Based and Intelligent Engineering and Information Systems Preface2018Ingår i: DATA TECHNOLOGIES AND APPLICATIONS, ISSN 2514-9288, Vol. 52, nr 4, s. 462-462Artikel i tidskrift (Övrigt vetenskapligt)
  • 3934.
    Zanuso, Giovanni
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Fodor, Viktória
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Peretti, Luca
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Wallmark, Oskar
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Networked electric drives in the Industry 4.02018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Industrial automation has been recently challenged by new initiatives such as Industry 4.0, which promises higher connectivity between the devices in an industrial plant. The goal of this work is to discuss how electric drives, widely employed in industry, could benefit from this increased connectivity. Specific applications, such as condition monitoring and multi drive systems, are considered to show the advantages of the industrial network presence, combined with the introduction of new data driven methods. Moreover, the status of industrial communication technologies is depicted, and their suitability for condition monitoring and multi-drive systems applications is described.

  • 3935.
    Zanuso, Giovanni
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Peretti, Luca
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Sandulescu, Paul
    ABB Oy, Finland.
    Model-based flux weakening strategy for synchronous machines without additional regulators2018Ingår i: IET Electric Power Applications, ISSN 1751-8660, E-ISSN 1751-8679, Vol. 12, nr 9, s. 1283-1290Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study proposes a model-based control strategy for flux weakening operation of a synchronous reluctance machine, with a methodology that is extendible to any synchronous machine. The strategy leverages in the presence of digital non-linear models that describe the relation between currents and flux linkages in the machine. Such models are usually needed for conventional maximum-torque-per-ampere control and sensorless control, but here they are exploited to achieve flux-weakening operation without the need of flux weakening regulators, ensuring a seamless transition between the operating regions of the machine. The external voltage regulation loop for flux weakening is thus eliminated and substituted by a combination of look-up tables and binary searches, which are executed within one digital control period and which generate the required current and voltage references that fulfil the drive limitations. The method can also be coupled with mechanisms to compensate for magnetic parameter inaccuracies, to achieve an accurate tracking of the reference torque. The proposed solution is simulated and validated in a laboratory test bench on an 11 kW synchronous reluctance machine.

  • 3936.
    Zarei, Tahereh
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Morozovska, Kateryna
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Laneryd, Tor
    ABB AB Corporate Research.
    Hilber, Patrik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Wihlen, Malin
    Ellevio AB.
    Olle, Hansson
    Independent Consultant at Ellevio AB.
    Reliability considerations and economic benefits of dynamic transformer rating for wind energy integration2019Ingår i: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 106, s. 598-606Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An increasing share of renewable energy on the electricity market creates the need for economic and efficient production, operation and integration technologies, associated with the specific behavior of renewable energy sources (RES). Dynamic rating (DR) provides a possibility to apply improvements to the system both during planning and operation stages. The DR benefits are well described in various literature sources. However, DR is often focused on more efficient exploitation of power lines, not power transformers. Power transformers are costly equipment and their efficient usage and planning can have drastic effect on total costs.

    Our analysis focuses on the dynamic transformer rating (DTR) for wind energy applications. The main objective is to study reliability effects of DTR from the component perspective. We utilize existing knowledge about transformer heat balance models from IEC and IEEE standards to obtain information on the loss of life (LOL) of the transformer under investigation and propose possible improvements for the system in question. The method can be employed for identifying the appropriate transformer size by taking into account ambient temperature and load variations and then overloading the transformer beyond nameplate ratings. The reliability of the proposed application is ensured by calculating the risk of overloading the transformer for each day of the year. A risk of overloading is quantified as LOL of the transformer. The risk is presented as a function of ambient temperature and duration of an overload. The final step consists of an economic analysis, which demonstrates economic benefits of DTR application.

  • 3937.
    Zarei, Tahereh
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Morozovska, Kateryna
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Laneryd, Tor
    Corporate Research, ABB AB.
    Hilber, Patrik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Wihlén, Malin
    Ellevio AB.
    Hansson, Olle
    Independent consultant at Ellevio AB.
    Reliability Considerations and Economic Benefits of Dynamic Transformer Rating for Wind Energy IntegrationManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    An increasing share of renewable energy on the electricity market creates the need for economic and efficient production, operation and integration technologies, associated with the specific behavior of renewable energy sources (RES). Dynamic rating (DR) provides a possibility to apply improvements to the system both during planning and operation stages. The DR benefits are well described in various literature sources. However, DR is often focused on more efficient exploitation of power lines, not power transformers. Power transformers are costly equipment and their efficient usage and planning can have drastic effect on total costs.

    Our analysis focuses on the dynamic transformer rating (DTR) for wind energy applications. The main objective is to study reliability effects of DTR from the component perspective. We utilize existing knowledge about transformer heat balance models from IEC and IEEE standards to obtain information on the loss of life (LOL) of the transformer under investigation and propose possible improvements for the system in question. The method can be employed for identifying the appropriate transformer size by taking into account ambient temperature and load variations and then overloading the transformer beyond nameplate ratings. The reliability of the proposed application is ensured by calculating the risk of overloading the transformer for each day of the year. A risk of overloading is quantified as LOL of the transformer. The risk is presented as a function of ambient temperature and duration of an overload. The final step consists of an economic analysis, which demonstrates economic benefits of DTR application.

  • 3938.
    Zeglio, Erica
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Rutz, Alexandra L.
    Winkler, Thomas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Malliaras, George G
    Herland, Anna
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Conjugated Polymers for Assessing and Controlling Biological Functions2019Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 31, nr 22, artikel-id 1806712Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The field of organic bioelectronics is advancing rapidly in the development of materials and devices to precisely monitor and control biological signals. Electronics and biology can interact on multiple levels: organs, complex tissues, cells, cell membranes, proteins, and even small molecules. Compared to traditional electronic materials such as metals and inorganic semiconductors, conjugated polymers (CPs) have several key advantages for biological interactions: tunable physiochemical properties, adjustable form factors, and mixed conductivity (ionic and electronic). Herein, the use of CPs in five biologically oriented research topics, electrophysiology, tissue engineering, drug release, biosensing, and molecular bioelectronics, is discussed. In electrophysiology, implantable devices with CP coating or CP-only electrodes are showing improvements in signal performance and tissue interfaces. CP-based scaffolds supply highly favorable static or even dynamic interfaces for tissue engineering. CPs also enable delivery of drugs through a variety of mechanisms and form factors. For biosensing, CPs offer new possibilities to incorporate biological sensing elements in a conducting matrix. Molecular bioelectronics is today used to incorporate (opto)electronic functions in living tissue. Under each topic, the limits of the utility of CPs are discussed and, overall, the major challenges toward implementation of CPs and their devices to real-world applications are highlighted.

    Publikationen är tillgänglig i fulltext från 2020-03-13 11:58
  • 3939.
    Zelazowska, Claudia
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Strategies for reducing the perception of complexity in a GIS interface2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Komplex mjukvara kan uppstå på grund av att företag lägger till fler och fler funktioner för att försöka göra sin produkt mer attraktiv på marknaden (detta fenomen kallas featuritis eller bloated software) men också för att de inte använt ett användarcentrerat tillvägagångssätt i sin mjukvaruutveckling. Detta kan skapa ett antal problem för användaren: känslor av frustration och förvirring samt att det kostar användaren mer resurser i form av tid att lära sig bemästra mjukvaran och att genomföra sina arbetsuppgifter. Målet med detta forskningsprojektet var att undersöka strategier som kan mildra användarnas frustration och förvirring, när de handskas med komplex mjukvara med instrumentala mål, genom att använda koncept från interaction aesthetics och genom kvalitativa och kvantitativa utvärderingsmetoder. Detta gjordes genom att fokusera på att omdesigna dpPower, som är ett GIS utvecklat av företaget Digpro. Tre strategier identifierades, som kunde hjälpa till att mildra den upplevda komplexiteten och de introducerade koncept från interaction aesthetics in till programvaran: tydlig informationsarkitektur, vilket ökar fluency; anpassningsbart gränssnitt, vilket introducerar pliability; och följdriktighet i interaktionen med det grafiska gränssnittet genom visuell design riktlinjer, som i sin tur introducerar rhythm till interaktionen.

  • 3940.
    Zeng, Jingna
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Programvaruteknik och datorsystem, SCS. INESC-ID/Instituto Superior Tecnico, Universidade de Lisboa, Portugal.
    Romano, P.
    Barreto, J.
    Rodrigues, L.
    Haridi, S.
    Online tuning of parallelism degree in parallel nesting transactional memory2018Ingår i: Proceedings - 2018 IEEE 32nd International Parallel and Distributed Processing Symposium, IPDPS 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 474-483, artikel-id 8425201Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper addresses the problem of self-Tuning the parallelism degree in Transactional Memory (TM) systems that support parallel nesting (PN-TM). This problem has been long investigated for TMs not supporting nesting, but, to the best of our knowledge, has never been studied in the context of PN-TMs. Indeed, the problem complexity is inherently exacerbated in PN-TMs, since these require to identify the optimal parallelism degree not only for top-level transactions but also for nested sub-Transactions. The increase of the problem dimensionality raises new challenges (e.g., increase of the search space, and proneness to suffer from local maxima), which are unsatisfactorily addressed by self-Tuning solutions conceived for flat nesting TMs. We tackle these challenges by proposing AUTOPN, an on-line self-Tuning system that combines model-driven learning techniques with localized search heuristics in order to pursue a twofold goal: i) enhance convergence speed by identifying the most promising region of the search space via model-driven techniques, while ii) increasing robustness against modeling errors, via a final local search phase aimed at refining the model's prediction. We further address the problem of tuning the duration of the monitoring windows used to collect feedback on the system's performance, by introducing novel, domain-specific, mechanisms aimed to strike an optimal trade-off between latency and accuracy of the self-Tuning process. We integrated AUTOPN with a state of the art PN-TM (JVSTM) and evaluated it via an extensive experimental study. The results of this study highlight that AUTOPN can achieve gains of up to 45× in terms of increased accuracy and 4× faster convergence speed, when compared with several on-line optimization techniques (gradient descent, simulated annealing and genetic algorithm), some of which were already successfully used in the context of flat nesting TMs.

  • 3941.
    Zeng, Ming
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Fodor, Viktória
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Energy-efficient Resource Allocation for NOMA-assisted Mobile Edge Computing2018Ingår i: 2018 IEEE 29TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE , 2018, s. 1794-1799Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we evaluate the effect of increased wireless spectral efficiency on the performance of mobile edge computing. Specifically, we study the energy minimization of computation offloading for a multi carrier non-orthogonal multiple access (NOMA) assisted mobile edge computing (MEC) system. A joint radio-and-computational resource allocation problem is formulated, in which three different resources should be appropriately allocated, including subcarriers, transmission power and computational resources. The formulated resource allocation problem belongs to mixed integer nonlinear programming (MILNP) and is NP-hard. We propose therefore a heuristic solution consisting of two steps, NOMA clustering and subcarrier allocation, and joint computational resource and power allocation. Our numerical results show that NOMA based MEC significantly outperforms its OMA counterpart, especially in scenarios with strict delay limits, where both the transmission and the computational resources become scarce.

  • 3942.
    Zeng, Ming
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Fodor, Viktória
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    On the Performance of Parallel Processing in Dynamic Resource Sharing Systems2019Ingår i: Proceedings - 20th International Conference on High Performance Computing and Communications, 16th International Conference on Smart City and 4th International Conference on Data Science and Systems, HPCC/SmartCity/DSS 2018, Institute of Electrical and Electronics Engineers Inc. , 2019, s. 30-36Konferensbidrag (Refereegranskat)
    Abstract [en]

    Parallel processing has the potential of significantly decreasing the service time for a single computational task. Meanwhile, as each task occupies more resources, the number of simultaneously supported tasks declines. This tradeoff is interesting when resources are accessed by many users in a dynamic way, like in the case of cloud or fog computing. In this paper, we evaluate how the level of parallelization and the eventual overheads affect the response time in these dynamic resource sharing systems. We show the counterintuitive finding that even when parallelization has no overhead, the allocation of all resources to a task is suboptimal if the service times have large coefficient of variation. Moreover, we evaluate the scalability properties, and provide guidelines for the optimal level of parallelization under different types of overhead.

  • 3943.
    Zeng, Ming
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Fodor, Viktória
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Sum-Rate Maximization under QoS Constraint in MIMO-NOMA Systems2018Ingår i: 2018 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper addresses the power allocation challenge for the downlink transmission in non-orthogonal multiple access (NOMA) systems applying multiple input multiple output transceivers. We consider the case when users are paired to form NOMA clusters, and share a common power budget. We provide low complexity power allocation methods within the clusters and across the clusters, that, together, maximize the sum-rate of the network, while guaranteeing a minimum quality of service for the users with weak channel condition. We show that compared to equal power allocation for the clusters, the proposed power allocation scheme improves the system fairness significantly, without decreasing the aggregate performance.

  • 3944.
    Zettergren, Carl
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Tavakoli, Mina
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Skillnad i skärmstorlek och skärmtyp: påverkan på inlärning2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I ett allt mer digitaliserat samhälle har även utbildningen blivit genomsyrad av denna digitalisering. Det har lett till en ökning i produktion av videoföreläsningar som studenter, på högskolenivå främst, allt oftare använder sig av i inlärningssyfte. E-lärande har många fördelar eftersom det bland annat leder till ökad studieflexibilitet. Det finns ett rikt utbud av tidigare forskning som kretsar kring områdena inlärningsbeteenden, skärmstorlekar och videoföreläsningar. Tidigare studier visar både på att det kan skilja sig i inlärning beroende på skärmstorlek men det finns också studier som tyder på motsatsen. Detta kandidatarbete undersöker om skärmstorlek har någon påverkan på hur mycket man lär sig av att se på en videoföreläsning. Det gjordes genom att gruppera 34 försöksdeltagare i tre grupper där alla fick se en vald föreläsningsvideo på tre olika grupper av skärmstorlekar: liten (4-7 tum), medel (13-17 tum) eller stor (27 tum). Några dagar innan och direkt efter undersökningen besvarade deltagarna även en enkät med sakfrågor om innehållet i den valda videon. Utifrån de resultat som framkom så visar det sig att olikheter mellan dessa skärmstorlekar inte ger en signifikant påverkan på hur mycket man lär sig av en föreläsningsvideo av intervju-typ. Det innebär alltså att man för sådana föreläsningvideor inte behöver ta hänsyn till skärmstorleken, varken som student eller som videoproducent.

  • 3945.
    Zeuner, Katharina D.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Paul, Matthias
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Lettner, Thomas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Reuterskiold Hedlund, Carl
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik.
    Schweickert, Lucas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Steinhauer, Stephan
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Yang, Lily
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Zichi, Julien
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Hammar, Mattias
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik.
    Jöns, Klaus D.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Zwiller, Val
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    A stable wavelength-tunable triggered source of single photons and cascaded photon pairs at the telecom C-band2018Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, nr 17, artikel-id 173102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The implementation of fiber-based long-range quantum communication requires tunable sources of single photons at the telecom C-band. Stable and easy-to-implement wavelength-tunability of individual sources is crucial to (i) bring remote sources into resonance, (ii) define a wavelength standard, and (iii) ensure scalability to operate a quantum repeater. So far, the most promising sources for true, telecom single photons are semiconductor quantum dots, due to their ability to deterministically and reliably emit single and entangled photons. However, the required wavelength-tunability is hard to attain. Here, we show a stable wavelength-tunable quantum light source by integrating strain-released InAs quantum dots on piezoelectric substrates. We present triggered single-photon emission at 1.55 mu m with a multi-photon emission probability as low as 0.097, as well as photon pair emission from the radiative biexciton-exciton cascade. We achieve a tuning range of 0.25 nm which will allow us to spectrally overlap remote quantum dots or tuning distant quantum dots into resonance with quantum memories. This opens up realistic avenues for the implementation of photonic quantum information processing applications at telecom wavelengths. 

  • 3946.
    Zhai, Kai
    et al.
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Ma, Zheng
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Lei, Xianfu
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Closed-formed distribution for the SINR of MMSE-detected MIMO systems and performance analysis2018Ingår i: AEU - International Journal of Electronics and Communications, ISSN 1434-8411, E-ISSN 1618-0399, Vol. 97, s. 16-24Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we investigate the error performance of multiple-input multiple-output (MIMO) wireless communications systems using minimum mean-square error (MMSE) detection. Particularly, a new closed-form statistical distribution for the output signal-to-interference-plus-noise ratio (SINR) of MMSE receiver is derived, for independent Rayleigh fading channels. The expression for the distribution of SINR is shown to be a linear combination of gamma distributions and polynomial of where xis the SINR. Base on the derived distribution for the SINR, closed-form and approximated expressions for the symbol error probability (SEP) of quadrature amplitude modulation (QAM) and phase shift keying (PSK) signaling are obtained, respectively. The derived SINR density and SEP are valid for arbitrary number of transmit and receive antennas. Furthermore, a reduced complexity approximation is introduced to obtain the SINR distribution and SEP performance of MMSE-Detected MIMO Systems with a large number of antennas. The provided simulation results confirm the validity of our theoretical analysis for both the SINR and SEP. All rights reserved.

  • 3947.
    Zhan, Junkai
    et al.
    Univ Elect Sci & Technol China, Inst Integrated Circuits & Syst, Chengdu, Sichuan, Peoples R China..
    Huang, Letian
    Univ Elect Sci & Technol China, Inst Integrated Circuits & Syst, Chengdu, Sichuan, Peoples R China..
    Wang, Junshi
    Univ Elect Sci & Technol China, Inst Integrated Circuits & Syst, Chengdu, Sichuan, Peoples R China..
    Ebrahimi, Masoumeh
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik.
    Li, Qiang
    Univ Elect Sci & Technol China, Inst Integrated Circuits & Syst, Chengdu, Sichuan, Peoples R China..
    Online Path-based Test Method for Network-on-Chip2019Ingår i: 2019 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS (ISCAS), IEEE , 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    A considerable amount of routers and links remains idle after each mapping application onto the Network-on-Chip based many-core systems. Online path-based test method is a kind of self-test for these idle components. In this paper, a path-based fabric for NoC is firstly proposed. A path serves as the basic component, covering one link and its associated control logic in the routers. One possibility is to apply fault detection on the idle paths, while the other paths continue to operate normally. Moreover, this paper details the hardware implementation, targeting the stuck-at and bridging faults. It suggests a good trade-off between fault coverage, hardware overhead and test time. Experimental results show that the approach achieves 93% of the stuck-at faults in control unit and cover 100% of the stuck-at and bridging faults on the global link within 256 clock cycles.

  • 3948. Zhan, M.
    et al.
    Pang, Z.
    Dzung, D.
    Xiao, Ming
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Channel Coding for High Performance Wireless Control in Critical Applications: Survey and Analysis2018Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 6, s. 29648-29664Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Demanded by high-performance wireless (WirelessHP) networks for industrial control applications, channel coding should be used and optimized. However, the adopted coding schemes in modern wireless communication standards are not sufficient for WirelessHP applications, in terms of both low latency and high reliability. Starting from the essential characteristics of WirelessHP regarding channel coding, this paper gives a detailed analysis of currently used short packet coding schemes in industrial wireless sensor networks, including seven coding schemes and their possible variants. The metrics employed for evaluation are bit-error rate, packet error rate, and throughput. To find suitable coding schemes from a large number of options, we propose four principles to filter the most promising coding schemes. Based on overall comparison from the perspective of practical implementation, challenges of the available coding schemes are analyzed, and directions are recommended for future research. Some reflections on how to construct specially designed coding schemes for short packets to meet the high reliability and low-latency constraints of WirelessHP are also provided.

  • 3949. Zhan, M.
    et al.
    Pang, Z.
    Xiao, Ming
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Wen, H.
    A state metrics compressed decoding technique for energy-efficient turbo decoder2018Ingår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2018, nr 1, artikel-id 152Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the energy resource-constrained wireless applications, turbo codes are frequently employed to guarantee reliable data communication. To both reduce the power dissipation of the turbo decoder and the probability of data frame retransmission in the physical layer, memory capacity reduced near optimal turbo decoder is of special importance from the perspective of practical implementation. In this regard, a state metrics compressed decoding technique is proposed. By inserting two modules in the conventional turbo decoding architecture, a smaller quantization scheme can be applied to the compressed state metrics. Furthermore, structure of the inserted modules is described in detail. We demonstrate that one or two rounds of compression/decompression are performed in most cases during the iterative decoding process. At the cost of limited dummy decoding complexity, the state metrics cache (SMC) capacity is reduced by 53.75%. Although the proposed technique is a lossy compression strategy, the introduced errors only have tiny negative influence on the decoding performance as compared with the optimal Log-MAP algorithm. 

  • 3950. Zhan, M.
    et al.
    Tu, Ruibo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Yu, Q.
    Understanding readers: Conducting sentiment analysis of instagram captions2018Ingår i: PROCEEDINGS OF 2018 THE 2ND INTERNATIONAL CONFERENCE ON COMPUTER SCIENCE AND ARTIFICIAL INTELLIGENCE (CSAI 2018) / 2018 THE 10TH INTERNATIONAL CONFERENCE ON INFORMATION AND MULTIMEDIA TECHNOLOGY (ICIMT 2018), Association for Computing Machinery (ACM), 2018, s. 33-40Konferensbidrag (Refereegranskat)
    Abstract [en]

    The advent of media transition highlights the importance of user-generated content on social media. Amongst the methods of analysis of user-generated content, sentiment analysis is widely used. Nevertheless, few studies use sentiment analysis to investigate user-generated content on Instagram in the context of public libraries. Therefore, this study aims to fill this research gap by conducting sentiment analysis of two million captions on Instagram. Supervised machine learning algorithms were employed to create the classifier. Three opinion polarities and six emotions were ultimately identified via these captions. These polarities provide new insights for understanding readers, thus helping libraries to deliver better services.

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