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  • 2701.
    Zhou, Helin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Thottappillil, Rajeev
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Diendorfer, Gerhard
    A new approach to calculate electric fields and charge density distribution when lightning strikes a tall object2014Ingår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 113, nr SI, s. 15-24Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We derive electric field expressions, associated with lightning strikes to a tall object, using the monopole (Continuity Equation) technique which is distinctly different from the traditional dipole (Lorentz Condition) technique. Expressions to calculate the charge density along the tall object and lightning channel based on the assumptions of the transmission line model of the lightning strikes to a tall object and a series point current source placed at the object top, are also derived. These expressions are used to calculate the very close-range electric fields in the monopole (Continuity Equation) technique in terms of the retarded current and charge density along the tower and lightning channel and their results are compared with those calculated from the traditional dipole (Lorentz Condition) technique in terms of the retarded current along the tower and lightning channel. Alternative explanations are provided to the inversion of polarity of the vertical electric field at very close range based on distribution of charge density along the tower and lightning channel.

  • 2702.
    Zhou, Qin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Mao, Jia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Zou, Zhuo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Jonsson, Fredrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Zheng, Li-Rong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    A mixed-signal timing circuit in 90nm CMOS for energy detection IR-UWB receivers2010Ingår i: 23rd IEEE International SOC Conference, SOCC 2010, 2010, s. 413-416Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This paper presents a flexible timing circuit with 1.1ns delay resolution for energy detection IR-UWB receivers. Referenced at 900MHz input clock, the circuit generates multi-phased integration windows and reset signals that enable/disable the operation of analog blocks. The design is highly programmable, adapting the receiver to pulse level synchronization, symbol level synchronization, different data rates and various channel environments. Mixed-signal design flow is adopted to avoid the complexity of full custom design and the large power consumption of full synthesized digital design. The timing circuit is implemented in UMC 90nm CMOS process, with 219 #x03BC;W power consumption and 190*295 #x03BC;m2 die area.

  • 2703.
    Zhou, Weidong
    et al.
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Liu, Shih-Chia
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Ge, Xiaochen
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Zhao, Deyin
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Yang, Hongjun
    Univ Texas Arlington, Dept Elect Engn, Arlington, TX 76019 USA..
    Reuterskiöld-Hedlund, Carl
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Hammar, Mattias
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    On-Chip Photonic Crystal Surface-Emitting Membrane Lasers2019Ingår i: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 25, nr 3, artikel-id 4900211Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photonic crystal lasers can be realized either based on photonic bandgap defect mode or defect-free bandedge mode, while the bandgap is not essential for the latter. We review here defect-free bandedge mode based photonic crystal surface-emitting lasers (PCSELs) for on-chip integration. We first discuss ultra-thin membrane reflector vertical-cavity surface-emitting lasers (MR-VCSELs), where single layer photonic crystal slabs can be designed as a broadband membrane reflector. Later, we discuss another type of defect-free PCSELs where the lasing cavity is formed based on evanescent coupling of gain medium with the photonic crystal bandedge mode near bandedge. Cavity designs were carried out for the optimal modal overlap and high confinement factors. Lateral cavity size scaling was also investigated both theoretically and experimentally in PCSELs. Buried tunnel junction based InGaAsP quantum well heterostructures were also designed and incorporated into electrically injected PCSELs. Finally, discussions are given toward energy efficient lasers.

  • 2704.
    Zhou, Yan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Zha, Chaolin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Bonetti, Stefano
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Persson, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Spin-torque oscillator with tilted fixed layer magnetization2008Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, nr 26, s. 262508-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A spin-torque oscillator with a fixed layer magnetization tilted out of the film plane is capable of strong microwave signal generation in zero magnetic field. Through numerical simulations, we study the microwave signal generation as a function of drive current for two realistic tilt angles. The tilted magnetization of the fixed layer can be achieved by using a material with high out-of-plane magnetocrystalline anisotropy, such as L1(0) FePt.

  • 2705. Zhu, H.
    et al.
    Cai, T.
    Xu, J.
    Wu, S.
    Li, X.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. South China Normal University (SCNU), China.
    Neural correlates of stereoscopic depth perception: A fNIRS study2016Ingår i: 2016 Progress In Electromagnetics Research Symposium, PIERS 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 4442-4446, artikel-id 7735646Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of the present study was to explore the brain region correlated with stereoscopic depth perception with different degree of binocular disparities. fNIRS was used to measure the neural activity of the occipital cortex induced by random-dot stereogram (RDS) with disparities from 0.1° to 1.5° and analyzed the strength and activation pattern from participants with left and right eyedness. Results revealed that the visual cortex was spatial correlated with the binocular disparity and there was a left lateralization effect for right-eye-dominant participants. Furthermore, binocular disparity around 0.5° led the strongest activation, whereas binocular disparity exceed 1.1° led lower activation which could be caused by visual fatigue. The present study supported the feasibility of fNIRS to assess the neural correlates of stereoscopic depth perception, to optimize the stereoscopic vision, and to objective evaluation of visual fatigue.

  • 2706. Zhu, K.
    et al.
    Rahimi, S.
    Nordström, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Zhang, B.
    Design phasor data concentrator as adaptive delay buffer for wide-area damping control2015Ingår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 127, s. 22-31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phasor Data Concentrators (PDCs) are employed to aggregate data frames from multiple Phasor Measurement Units (PMUs) with the same time-stamp into data packets. This function is an essential step in the utilization of PMU data in Wide-Area Monitoring and Control (WAMC) system. This is facilitated by assigning a fixed and heuristically decided wait time to the PDC buffer. The processed PMU data packets are sent to WAMC applications or similarly PDCs at higher hierarchies in the WAMC system when either a PDC buffer is full or its wait time has passed. In this paper, two methods to configure adaptive PDC wait time based on recent PMU traffic delay patterns are proposed. The purpose is to reduce the frequency of performing delay compensations in wide-area damping control system. With the adaptive PDC delay buffer in place, the wide-area damping controller only switches its gain once every five seconds, given the studied PMU traffic delay scenarios, instead of the current practice which requires the control gain to be adapted on a per PMU data frame basis, e.g., 50 or 60 times every second. The proposed methods offer a perspective to efficiently utilize the supporting Information and Communication Technology infrastructure with the purpose to simplify the design and implementation of wide-area damping control system.

  • 2707.
    Zhu, Kun
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Data Quality in Wide-Area Monitoring and Control Systems: PMU Data Latency, Completness, and Design of Wide-Area Damping Systems2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The strain on modern electrical power system operation has led to an ever increasing utilization of new Information Communication Technology (ICT) systems to enhance the reliability and efficiency of grid operation. Among these proposals, Phasor Measurement Unit (PMU)-based Wide-Area Monitoring and Control (WAMC) systems have been recognized as one of the enablers of “Smart Grid”, particularly at the transmission level, due to their capability to improve the real-time situational awareness of the grid. These systems differ from the conventional Supervisory Control And Data Acquisition (SCADA) systems in that they provide globally synchronized measurements at high resolutions. On the other hand, the WAMC systems also impose several stringent requirements on the underlying ICT systems, including performance, security, and availability, etc. As a result, the functionality of the WAMC applications is heavily, but not exclusively, dependent on the capabilities of the underlying ICT systems. This tight coupling makes it difficult to fully exploit the benefits of the synchrophasor technology without the proper design and configuration of ICT systems to support the WAMC applications. The strain on modern electrical power system operation has led to an ever increasing utilization of new Information Communication Technology (ICT) systems to enhance the reliability and efficiency of grid operation. Among these proposals, Phasor Measurement Unit (PMU)-based Wide-Area Monitoring and Control (WAMC) systems have been recognized as one of the enablers of “Smart Grid”, particularly at the transmission level, due to their capability to improve the real-time situational awareness of the grid. These systems differ from the conventional Supervisory Control And Data Acquisition (SCADA) systems in that they provide globally synchronized measurements at high resolutions. On the other hand, the WAMC systems also impose several stringent requirements on the underlying ICT systems, including performance, security, and availability, etc. As a result, the functionality of the WAMC applications is heavily, but not exclusively, dependent on the capabilities of the underlying ICT systems. This tight coupling makes it difficult to fully exploit the benefits of the synchrophasor technology without the proper design and configuration of ICT systems to support the WAMC applications.

    In response to the above challenges, this thesis addresses the dependence of WAMC applications on the underlying ICT systems. Specifically, two of the WAMC system data quality attributes, latency and completeness, are examined together with their effects on a typical WAMC application, PMU-based wide-area damping systems. The outcomes of this research include quantified results in the form of PMU communication delays and data frame losses, and probability distributions that can model the PMU communication delays. Moreover, design requirements are determined for the wide-area damping systems, and three different delay-robust designs for this WAMC application are validated based on the above results. Finally, a virtual PMU is developed to perform power system and communication network co-simulations.

    The results reported by this thesis offer a prospect for better predictions of the performance of the supporting ICT systems in terms of PMU data latency and completeness. These results can be further used to design and optimize the WAMC applications and their underlying ICT systems in an integrated manner. This thesis also contributes a systematic approach to design the wide-area damping system considering the PMU data latency and completeness. Finally, the developed virtual PMU, as part of a co-simulation platform, provides a means to investigate the dependence of WAMC applications on the capabilities of the underlying ICT systems in a cost-efficient manner.

  • 2708.
    Zhu, Kun
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Al-Hammouri, A. T.
    Nordström, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    To concentrate or not to concentrate: Performance analysis of ICT system with data concentrations for Wide-area Monitoring and Control Systems2012Ingår i: Power and Energy Society General Meeting, 2012 IEEE, IEEE , 2012, s. 6344977-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Timely and synchronized phasor data at high resolutions holds great promise for more responsible and advanced power grid operations. It is expected that combined effort of developing new application paradigms and the supporting Information and Communication Technology (ICT) will enable the miracle of Smart Grid at the transmission level. This paper addresses the design of the supporting ICT system for Wide Area Monitoring and Control applications from the performance perspective. The major contribution that distinguishes this paper from previous research efforts in the same area is that this study quantifies the end-to-end data delay with consideration of different levels of data concentrations. The analysis performed in this paper is not limited to the delay caused by individual ICT components but also provides means to view and analyze the delay of the entire supporting ICT system. Moreover, the quantified delay results drawn in this paper will potentially provide valuable input to the discussion on the coming standards for synchronized phasor measurements.

  • 2709.
    Zhu, Kun
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Honeth, Nicholas
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Xu, Yuan
    Nordström, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Investigation of data exchange requirements for cooperative grid planning and operation2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    IEC 61970 and 61968 together referred as Common Information Model (CIM), are proposed to facilitate integration of EMS applications with proprietary data formats and information exchange between control centers. To use Information and Communication Technology (ICT) systems in an optimized manner, it is necessary to partition the potentially voluminous data into subsets given their sources, expected exchange frequency, and subscribing applications. In response to these requirements, the concept of CIM profiles is brought up by CIMug. In this paper, functions illustrating the dependency between exchange data volume and basic grid parameters for each data profile are presented. A CIM/XML/RDFfile for a commonly available 40 bus test system modeled according to CIM 13 together with examples provided by standards are used as references. The method is validated by estimating the CIM/XML/RDF file sizes of similarly available 100 bus and 60 bus test systems. The contribution of this paper is that it provides ICT system designers with a means to estimate the corresponding requirements for various CIM based data exchange scenarios. The estimations are performed based on commonly known grid parameters such as number of buses, branches, generators, transformers and loads.

  • 2710.
    Zhu, Kun
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Yuan, Xu
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Honeth, Nicholas
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Nordström, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Data Volume Estimation for CIM based Information Exchange2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    IEC 61970 and 61968, which are commonly referred as Common Information Model (CIM), are proposed to facilitate integration of EMS applications and information exchange between EMS systems with propitiatory data structures. To use communication network in an optimized manner, it is necessary to partition the potentially voluminous data into subsets given their sources, expected exchange frequency, and subscribing applications. In response to these requirements, the concept of CIM profiles is brought up by CIMug. In this paper, functions illustrating the dependency between exchange data volume and basic grid parameters for each data profile are presented. A CIM/XML/RDF file for a generally available 40 bus test system (CIM 13) and examples provided by standards are used as references. The method is validated by estimating the data sizes of similarly available 100bus and 60bus test systems that are modeled according to CIM 13 as well. The contribution of this paper is that it provides ICT system designers with a means to estimate the corresponding requirements for various CIM/XML based data exchange patterns. The estimations are performed based on commonly known grid parameters such as number of buses, branches, generators, transformers and loads together with execution frequency of particular grid planning and operation applications.

  • 2711. Zhu, Y.
    et al.
    Wu, F.
    Xiong, Q.
    Lu, Zhonghai
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik.
    Xie, C.
    ALARM: A Location-Aware Redistribution Method to Improve 3D FG NAND Flash Reliability2017Ingår i: 2017 IEEE International Conference on Networking, Architecture, and Storage, NAS 2017 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, artikel-id 8026841Konferensbidrag (Refereegranskat)
    Abstract [en]

    3D NAND flash memory is enjoying an increasing popularity as it dramatically increases the bit density, presenting a grand opportunity to satisfy the growing demand on the storage capacity. However, this vertically stacked structure also introduces more serious read disturb problems compared with planar flash devices. Characterization results show that the read disturb errors on 3D floating gate (FG) MLC NAND flash chips exhibit a large discrepancy on the locations and types of pages, implying that pages should not be treated equally when designing migration schemes. This paper makes a thorough observation on read access characteristics by analyzing contemporary workloads collected from a wide range of applications with various read ratios. Based on the characterization results, we build a read disturb error model and propose a location-aware redistribution method (ALARM) that utilizes the intrinsic characteristics of the 3D floating gate NAND flash and redistributes read-hot pages to locations inducing less read disturb errors to improve its reliability. We implement the read disturb error model and our proposed design on an event-driven simulator, and the experimental results show that ALARM can reduce the maximum and average raw bit error rates (RBERs) by up to 99.49% and 91.80% with an operation overhead of 0.70%.

  • 2712. Zima-Bockarjova, Marija
    et al.
    Matevosyan, Julija
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Zima, Marek
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Sharing of Profit From Coordinated Operation Planning and Bidding of Hydro and Wind Power2010Ingår i: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 25, nr 3, s. 1663-1673Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Depending on market rules, namely congestion management and balancing management, coordination between wind and hydro producers may be mutually beneficial. In this paper we propose a new collaboration scheme and a fair and transparent method, based on the Shapley value, for splitting the extra value caused by a coordinated bidding and operation strategy. We account for uncertainties in wind forecast and energy price evolution. We demonstrate the proposed approaches on a realistic system including congested lines, wind farm and a hydro plant consisting of several reservoir stages.

  • 2713. Zimmer, Fabian
    et al.
    Bring, Martin
    List, Matthias
    Lapisa, Martin
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Fabrication of mono-crystalline Silicon Micro-mirror Arrays using adhesive Wafer Transfer Bonding2009Ingår i: MikroSystemTechnik KONGRESS 2009, 2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Spatial light modulators (SLMs) based on indivvidually addressable micro-mirrors do show an increased use in projection displays, DUV lithography and adaptive optics. Mirror planarity and deflection characteristics are important issues for these applications. Mono-crystalline silicon as mirror material offers a great possibility to combine the perfect surface with the good mechanical properties of the crystalline material. Nevertheless, the challenge is the integration of mono-crystalline silicon in a CMOS process with low temperature budget (below 450deg C) and restricted material options. Thus, standard processes like epitaxial growth or re-crystallization of poly-silicon cannot be used. We will present a CMOS-compatible approach, using adhesive wafer transfer bonding with Benzocyclobutene (BCB) of a 300nm thin silicon membrane, located on a SOI donor wafer. After the bond process, the SOI donor wafer is grinded and spin etched to remove the handle silicon and the buried oxide layer, which results in a transfer of the mono-crystalline silicon membrane to the CMOS wafer. This technology is fully compatible for integration in a CMOS process, in order to fabricate SLMs, consisting of one million indivvidually addressable mono-crystalline silicon micro-mirrors. In this paper, we present fabrication process as well as first results of SLM devices with a pixel pitch of 16 micrometer.

  • 2714. Zimmer, Fabian
    et al.
    Lapisa, Martin
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Bakke, Thor
    Bring, Martin
    Stemme, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    One-Megapixel Monocrystalline-Silicon Micromirror Array on CMOS Driving Electronics Manufactured With Very Large-Scale Heterogeneous Integration2011Ingår i: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 20, nr 3, s. 564-572Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we demonstrate the first high-resolution spatial-light-modulator chip with 1 million tilting micromirrors made of monocrystalline silicon on analog high-voltage complementary metal-oxide-semiconductor driving electronics. This device, as result of a feasibility study, shows good optical and excellent mechanical properties. The micromirrors exhibit excellent surface properties, with a surface roughness below 1-nm root mean square. Actuated micromirrors show no imprinting behavior and operate drift free. Very large-scale heterogeneous integration was used to fabricate the micromirror arrays. The detailed fabrication process is presented in this paper, together with a characterization of the SLM devices. Large arrays of individually controllable micromirrors are the enabling component in high-perfomance mask-writing systems and promising for high throughput deep-ultraviolet maskless lithography systems. The adoption of new materials with enhanced characteristics is critical in meeting the challenging demands with regard to surface quality and operation stability in the future. Very large-scale heterogeneous integration may enable virtually any solid-state material to be integrated together with CMOS electronics. [2010-0272]

  • 2715.
    Zografos, Dimitrios
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Estimation of Power System Inertia2016Ingår i: Power and Energy Society General Meeting (PESGM), 2016 17-21 July 2016, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Information about power system inertia is of utmost importance for the Transmission System Operators (TSOs), so that it can be guaranteed that the stability of the system is not under risk. A new offline inertia estimation method is proposed in this paper. The method includes the calculation of the total power change after a disturbance in the system, based on selection of appropriate time ranges of the Rate Of Change Of Frequency(ROCOF) curve. Nordic32 test system is used for the simulations, where different disturbances, load dynamics and data processing tools are considered. Finally, a comparison of the proposed method to two methods proposed in the past takes place.

  • 2716.
    Zografos, Dimitrios
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Rabuzin, Tin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Ghandhari, Mehrdad
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Eriksson, Robert
    Prediction of Frequency Nadir by Employing a Neural Network Approach2018Ingår i: 2018 IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe), Institute of Electrical and Electronics Engineers (IEEE), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The increased integration rate of inverter-interfaced devices is affecting the frequency response of the modern power systems. This leads to an increase of the variability of the power generation and to a reduction of the total system's inertia. This evolution of the system necessitates the prediction of frequency metrics, so that the frequency stability of the system can be guaranteed and that necessary mitigation measures can be taken. This paper proposes a method to predict the frequency nadir by using a Neural Network (NN) approach. As the approach uses measurements during a first short time period after the event, it more accurately predicts the frequency nadir compared to using static values. Several inputs for the NN are examined and when the appropriate ones are selected, a highly accurate prediction is accomplished.

  • 2717. Zou, Y.
    et al.
    Hu, X.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, China.
    Lin, Z.
    Compact coplanar waveguide low-pass filter using a novel electromagnetic bandgap structure2006Ingår i: 7th International Symposium on Antennas, Propagation and EM Theory, Proceedings, 2006, s. 1039-1042Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the present paper, a new electromagnetic bandgap (EBG) structure is proposed to design and fabricate low-pass filters on coplanar waveguide (CPW). Using the novel EBG structure, the filter prototypes exhibit sharp cutoff and low insertion loss in the passband. An equivalent lumped L-C circuit mode is introduced to describe the proposed EBG structure, which manifests an elliptic-function low-pass frequency response. Using only three units of this novel EBG cell, a compact low-pass filter device has been fabricated, which achieved sharp cutoff and deep attenuation levels on the stop band. The measured results showed consistency with the simulation using the method of momentum (MoM).

  • 2718. Álvarez, Jesús
    et al.
    Sola, Laura
    Cretich, Marina
    Swann, Marcus J.
    Gylfason, Kristinn B.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Volden, Tormod
    Chiari, Marcella
    Hill, Daniel
    Real time optical immunosensing with flow-through porous alumina membranes2014Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 202, s. 834-839Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Through the presentation of analytical data from bioassay experiments, measured by polarimetry, we demonstrate for the first time a real time immunoassay within a free standing macroporous alumina membrane. The 200 nm nominal pore diameter of the membrane enables flow-through, thereby providing an ideal fluidic platform for the targeted delivery of analytes to bioreceptors immobilized on the pore walls, enabling fast sensing response times and the use of small sample volumes (<100 μL). For the immunoassay, the pore walls were first coated with the functional copolymer, copoly(DMA-NAS) using a novel coupling process, before immobilization of the allergen protein, β-lactoglobulin, by spotting. The immuno-assay then proceeded with the binding of the primary and secondary antibody cognates, rabbit anti-β-lactoglobulin and anti-rabbit IgG respectively. Through the use of streptavidin coated quantum dots as refractive index signal enhancers, a noise floor for individual measurements of 3.7 ng/mL (25 pM) was obtained, with an overall statistical, or formal assay LOD of 33.7 ng/mL (225 pM), for total assay time below 1 h.

  • 2719.
    Ängquist, Lennart
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Antonopoulos, Antonios
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Norrga, Staffan
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Arm-current-based control of modular multilevel converters2013Ingår i: 2013 15th European Conference on Power Electronics and Applications, EPE 2013, IEEE , 2013, s. 6631999-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Inner control of a Modular Multilevel Converter (M2C) based on direct tolerance-band modulation of the arm currents has been studied. This approach is attractive because it allows low switching frequency, directly provides the desired arm-current waveform and enables fast protective actions at the same time as the complexity of the over-all control system is reduced. Issues related to common-mode voltage are discussed and supporting PSCAD simulations are presented together with some results from experiments with a reduced-power prototype converter.

  • 2720.
    Ängquist, Lennart
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
    Bongiorno, Massimo
    Dept. of Energy and Environment, Chalmers University of Technology, Sweden.
    Auto-normalizing Phase-Locked Loop for Grid-connected Converters2009Ingår i: 2009 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION, VOLS 1-6, NEW YORK: IEEE , 2009, s. 2430-2437Konferensbidrag (Refereegranskat)
    Abstract [en]

    A proper synchronization algorithm is a key issue for modern grid-connected power electronic devices, especially in case of weak networks. This paper deals with a novel Phase-Locked Loop (PLL) algorithm for power electronic devices. The proposed algorithm, here named Auto-normalizing PLL (AN-PLL), is able to deal with both amplitude and phase-angle changes in the measured grid voltage. Thus, the proposed concept provides a PLL control performance that is independent on the control signal amplitude. Advantages of the AN-PLL over the conventional PLL approach are highlighted. Experimental results are used to validate the dynamic performance of the proposed synchronization system.

  • 2721.
    Ängskog, Per
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. Högskolan i Gävle.
    Bäckström, Mats
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. SAAB Aeronautics, SAAB AB.
    Vallhagen, Bengt
    SAAB Aeronautics, SAAB AB.
    High Power Microwave Effects on Coated Window Panes2015Ingår i: Asia Electromagnetics Conference (ASIAEM) 2015, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today window panes are usually coated with at least one metal or metal oxide layer to prevent heat energy of the light spectrum from propagating to the other side. This has given problems regarding radio propagation through windows, which might be utilized as a part of a buildings IEMI protection. This paper reports the results from measurements of the shielding effectiveness of a selection of modern window panes before and after irradiation with high power electromagnetic waves. The shielding effectiveness measurements are made in a nested reverberation chamber covering the range 1 – 18 GHz; both before and after high power irradiation at 1.3 GHz. The results show that the shielding effectiveness of window panes may be severely impaired due to thermal stress effects on the coatings during the irradiation, depending of the type of coating.

  • 2722.
    Ängskog, Per
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. Högskolan i Gävle.
    Bäckström, Mats
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. SAAB Aeronautics, SAAB AB.
    Vallhagen, Bengt
    SAAB Aeronautics, SAAB AB.
    Measurement of Radio Signal Propagation through Window Panes and Energy Saving Windows2015Ingår i: Proceedings of Electromagnetic Compatibility (EMC), 2015 IEEE International Symposium on, IEEE conference proceedings, 2015, s. 74-79Konferensbidrag (Refereegranskat)
    Abstract [en]

    Glass windows have undergone an energy saving evolution over the past three, four decades, from single panes till today’s ultralow-emission windows. While the earliest energy saving windows were constructed as a sandwich of clear glass panes using the vacuum-flask principle, modern low-emission windows includes panes with coatings of metal and/or metal oxides. This coating has caused radio propagation problems for communication systems; something that may be utilized to protect a building from intentional electromagnetic interference (IEMI) attacks and to help protecting against information leakage. In this paper measurements of the shielding performance of different generations of windows and qualities of window panes are presented. The intention is to include the results in a guide-line for IEMI protection of critical infrastructures. Measurements are made using two complementary methods; in a nested reverberation chamber and in a semi-anechoic chamber, both over the range 1 – 18 GHz. The results show a clear generation dependency where the energy saving windows largely do not attenuate RF signals at all and low-emission windows offer shielding effectiveness values between 10 and 45 dB with potentially as much as around 60 dB in the upper half of the spectrum.

  • 2723. Åberg, J.
    et al.
    Persson, S
    Hellberg, P.-E.
    Zhang, S.-L.
    Smith, U
    Ericsson, F
    Engström, M
    Kaplan, W
    Electrical properties of the TiSi2-Si transition region in contacts: The influence of an interposed layer of Nb2001Ingår i: Journal of Applied Physics, Vol. 90, s. 2380-2388Artikel i tidskrift (Refereegranskat)
  • 2724.
    Åkerman, Johan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    DeHerrera, M.
    Slaughter, J. M.
    Dave, R.
    Sun, J.
    Tehrani, S.
    Intrinsic reliability of AlOx-based magnetic tunnel junctions2006Konferensbidrag (Refereegranskat)
  • 2725.
    Ållebrand, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930).
    On SiC JFET converters: components, gate-drives and main-circuit conditions2005Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with Silicon Carbide Junction Field Effect Transistors (SiC JFETs) - how to use them to their full potential in power electronic circuits, how to model them in a power electronic simulation program, and how a gate drive can be built.

    To fully utilize the low on-state losses of SiC JFETs it is suggested that SiC JFETs should not be equipped with anti-parallel diodes. This is possible due to that JFETs can conduct current in the reverse direction. The circuit making use of this property is called the Diode-less SiC JFET Inverter Bridge (DJIB). The DJIB was studied regarding blanking times, negative voltages, and other special cases.

    A gate drive circuit for use with SiC JFETs in industrial applications is presented. The design is with voltage controlled devices(MOSFETs) for use in industrial applications.

    Since the JFET model in PSpice had never been validated for SiC power devices, a validation of the PSpice JFET model is presented for SiC JFETs manufactured by SiCED. The PSpice JFET model shows good agreement with measured results up to saturation. For high currents the SiCED SiC JFET saturates much earlier than the PSpice model and this has to be taken into account when making simulations with PSpice.

    Due to the high gate-drain capacitance of the SiCED SiC JFETs, there are commutation transients during switching. A short-circuit of the bridge-leg appears due to the high gate-drain capacitance. This is studied and some solutions to this problem are presented.

    Simulations on a 1~MW converter utilizing possible future high-voltage SiC JFETs showed that an efficiency of 99,7% could be achieved compared to an efficiency of 98,8% for a converter with Si IGBTs. However, even though the high gate-drain capacitance was reduced in the simulation, undesired commutation transients was observed. This problem has to be considered when designing converters in the future.

  • 2726.
    Åstrand, Max
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. ABB Corporate Research, Sweden.
    Saarinen, K.
    Sander-Tavallaey, S.
    Surrogate models for design and study of underground mine ventilation2018Ingår i: 22nd IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2017, Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ventilation is vital for the production in an underground mine. Therefore, it is important to have efficient and accurate design tools in order to ensure and optimize the airflows in the mine. There are several commercial software for airflow simulation based on first principles. However, the computational cost of simulation together with integrational obstacles when connecting simulation to control strategies limits the benefit of these tools. In this paper an approach utilizing surrogate models as a complementary design tool is presented. It is shown that using surrogate models one can with rather low computational expense evaluate and benchmark different control strategies. It is also shown that the models can be used for identifying possible bottlenecks in the system in advance. Moreover, the use of surrogate models transfer the simulation into a development-friendly environment (such as Matlab). A test case is used based on a real underground mine ventilation design. Two types of surrogate models are fitted to process data; multiple least squares regression and a Gaussian process model. Sensitivity analysis on the surrogate shows the potential of using surrogate models for identifying bottlenecks. Furthermore, the surrogate is used to benchmark two different control strategies for mine ventilation.

  • 2727.
    Öberg, Johnny
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Clocking Strategies for Networks-on-Chip2003Ingår i: Networks-on-Chip / [ed] Axel Jantsch, Kluwer Academic Publishers, 2003, s. 153-172Kapitel i bok, del av antologi (Refereegranskat)
  • 2728. Öberg, Johnny
    SpaceBall-1G: Pipelined 1 GHz Cache Memories in GaAs1995Rapport (Övrigt vetenskapligt)
  • 2729.
    Öberg, Johnny
    et al.
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Ellervee, Peeter
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Jantsch, Axel
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Hemani, Ahmed
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    BABBAGE - A Rule basedtool for synthesis of hardware systems1994Ingår i: Proc. of IEEE NORCHIP’94, 1994Konferensbidrag (Refereegranskat)
  • 2730.
    Öberg, Johnny
    et al.
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Ellervee, Peeter
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Kumar, Anshul
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Hemani, Ahmed
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Comparing Conventional HLS with Grammar-Based Hardware Synthesis: A Case Study1997Ingår i: Proc. of IEEE NORCHIP, 1997Konferensbidrag (Refereegranskat)
  • 2731.
    Öberg, Johnny
    et al.
    KTH, Tidigare Institutioner, Elektroniksystemkonstruktion.
    Kumar, Anshul
    Hemani, Ahmed
    Synthesis of Exception Handling in Grammar-based Hardware Synthesis1998Ingår i: Proceedings of APCHDL-98, 1998, s. 135-140Konferensbidrag (Refereegranskat)
  • 2732.
    Öberg, Johnny
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Mellander, Roger
    ABB Research.
    Zahrai, Said
    ABB Research.
    The ABB NoC: A Deflective Routing 2x2 Mesh NoC targeted for Xilinx FPGAs2008Ingår i: Proceedings of FPGAWorld 2008, 2008Konferensbidrag (Refereegranskat)
  • 2733.
    Öberg, Johnny
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Robino, Francesco
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    A NoC Generator for the Sea-of-Cores Era2011Ingår i: Proceedings of FPGAWorld 2011, 2011Konferensbidrag (Refereegranskat)
  • 2734.
    Öberg, Johnny
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Robino, Francesco
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    A NoC system generator for the Sea-of-Cores era2011Ingår i: 8th FPGAworld Conference - Academic Proceedings 2011, 2011, s. 35-40Konferensbidrag (Refereegranskat)
    Abstract [en]

    Multi-core systems are getting bigger. The number of cores is doubling every 18 months, in corollary with the reformulated Moore's law. Soon, the number of cores that can be integrated together in a system will be so large, that it is appropriate to talk about a new SoC design paradigm, the Sea-of-Cores era. This development will not end, even when CMOS cannot be made any smaller. Instead, with the development of Through-Silicon Vias (TSVs), chips will be stacked in 3D, promising continuous scaling for a very long time ahead. As systems grow, programming and debugging of them will become harder. Methods for generating the systems from higher-level specifications will be necessary to manage design complexity. Also, there will be so many processors to be programmed, that the SW also will have to be automatically generated and distributed, much in the same way as a synthesis and place & route tool is doing today for HW. In this paper, we present a NoC generator that can generate an arbitrarily large Multi-core platform from an XML configuration file, targeted for single-chip FPGA platforms. The NoC generator also generates a device driver prototype together with a small test program that can be used as a template for creating larger programs.

  • 2735.
    Öhrström, Magnus
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Geidl, M.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Andersson, G.
    Evaluation of travelling wave based protection schemes for implementation in medium voltage distribution systems2005Ingår i: IEE Conference Publication, 2005, Vol. 3, nr 2005-11034, s. 481-483Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates travelling wave based protection schemes developed for high voltage transmission systems and their adaptation to medium voltage distribution networks in order to enable ultra high speed relaying (within a quarter of a cycle of the power frequency) on a medium voltage level. After different travelling wave algorithms are evaluated using simple test systems, they are applied to an industrial power system where fault detection within one millisecond is required. Difficulties that arise from typical characteristics of medium voltage distribution systems are outlined and requirements to measurement and signal processing systems are discussed.

  • 2736.
    Öhrström, Magnus
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Söder, Lennart
    KTH, Tidigare Institutioner.
    A comparison of two methods used for voltage dip characterization2003Ingår i: 2003 IEEE Bologna Power Tech Conference Proceedings, 2003, Vol. 4, s. 6-Konferensbidrag (Refereegranskat)
    Abstract [en]

    The quality of delivered power is a topic that has received quite a lot of attention lately. Among power quality related phenomena, voltage dips (or sags) have been identified as a great concern for especially industrial customers. In order to estimate the severity of a voltage dip, several methods for characterization has been developed. A straightforward method of voltage dip characterization is to calculate the lowest magnitude of the RMS-voltage during the dip. Another method characterizes a voltage dip by the so-called characteristic voltage. These two methods are applied to measured voltage dips at a Swedish steel factory. This study shows that the two methods give similar results. Hence, characterization of voltage dips by using RMS-voltages can be a good measure of the severity of a dip even though more sophisticated methods exist.

  • 2737.
    Öhrström, Magnus
    et al.
    KTH, Tidigare Institutioner, Elektrotekniska system.
    Söder, Lennart
    KTH, Tidigare Institutioner.
    Fast fault detection for power distribution systems2002Ingår i: Proceedings of the IASTED conference Power and Energy systems, 2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper discusses aspects of fault detection for power systems which require fault removal before the first peak current after the initiation of a short circuit fault. Firstly, speed of fault detection is discussed and in particular how “fast” fault detection should be interpreted in this paper. Secondly, apparatus that would benefit from fast fault de tection is described and in what kind of power systems it could be used. Finally, algorithms appropriate for use in fast fault detection are discussed and analysed in a case study with respect to fault current levels, and requirements for fault detection equipment including detection time and sampling rate.

  • 2738.
    Österlind, Magnus
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Johnson, Pontus
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Karnati, Kiran
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Lagerström, Robert
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Välja, Margus
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Enterprise Architecture Evaluation using Utility theory2013Ingår i: Proceedings 17th IEEE International Enterprise Distributed Object Computing Conference Workshops (EDOCW), IEEE Computer Society, 2013, s. 347-351Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the increase in the number of quality attributes (e.g. cost, availability, reusability), that are being considered in the process of enterprise architecture analysis, the decision maker needs a systematic way to balance these attributes against each other to obtain the best possible architecture. Utility theory addresses this need by providing methods for numerical representation of preferences of a stakeholder involved in a decision-making process. In this paper utility theory key concepts are explained with examples. The process of calculating the utility metric, which reflects stake holder's set of preferences to select the most preferred architecture scenario is explained. The paper provides an explanation of how utility theory can be applied in enterprise architecture models which are meta-object facility compliant. This paper concludes by an example comparing two quality attributes on two architecture scenarios using utility theory and calculating the decision maker's overall utility metric across both quality attributes is provided. This shows the applicability of utility theory on architecture scenario analysis with multiple quality attributes.

  • 2739.
    Österlind, Magnus
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Lagerström, Robert
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Rosell, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Assessing modifiability in application services using enterprise architecture models - A case study2012Ingår i: Trends in Enterprise Architecture Research and Practice-Driven Research on Enterprise Transformation, 2012, s. 162-181Konferensbidrag (Refereegranskat)
    Abstract [en]

    Enterprise architecture has become an established discipline for business and IT management. Architecture models constitute the core of the approach and serve the purpose of making the complexities of the real world understandable and manageable to humans. EA ideally aids the stakeholders of the enterprise to effectively plan, design, document, and communicate IT and business related issues, i.e. they provide decision support for the stakeholders. However, few initiatives explicitly state how one can analyze the EA models in order to aid decision-making. One approach that does focus on analysis is the Enterprise Architecture Modifiability Analysis Tool. This paper suggests changes to this tool and presents a case study in which these have been tested. The results indicate that the changes improved the tool. Also, based on the outcome of the case study further improvement possibilities are suggested.

  • 2740.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Nanoscaled SiGe based MOSETs2010Ingår i: Conference Proceedings - The 8th International Conference on Advanced Semiconductor Devices and Microsystems, ASDAM 2010, 2010, s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an overview of the technological challenges facing the future scaling of device dimensions needed to meet the performance scaling in accordance with Moore's law. A number of performance boosters have to be introduced in order to keep up with the expected performance gain in each new technology node. The introduction of strain engineering is an important feature as well as the implementation of high-k dielectrics. From the 32 nm node and forward there is an urgent search for a fundamental breakthrough to achieve low access resistance to the drain and source areas. This paper will focus to a large extent on this latter area and discuss metallic source/drain (MSD) contacts in nanoscaled MOSFET technology. MSD contacts offer extremely low S/D parasitic resistance, abruptly sharp junctions between S/D and channel and preferably low temperature processing. Recently great efforts have been achieved on Pt- and Ni-silicide implementation. A conclusion is that MSD MOSFETs are competitive candidates for future generations of CMOS technology.

  • 2741.
    Östling, Mikael
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zaring, Carina
    Konstantinov, A.
    Ghandi, Reza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Buono, Benedotto
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hallen, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    SiC bipolar power transistors: Design and technology issues for ultimate performance2010Ingår i: 2010 MRS Spring Meeting, 2010, Vol. 1246, s. 175-186Konferensbidrag (Refereegranskat)
    Abstract [en]

    Silicon carbide (SiC) semiconductor devices for high power are becoming more mature and are now commercially available as discrete devices. Schottky diodes have been on the market since a few years but also bipolar junction transistors (BJTs), JFETs and MOSFETs are now reaching the market. The interest is rapidly growing for these devices in high power and high temperature applications. The BJTs have low conduction losses, fast switching capability, operate in normally-off mode, have high radiation hardness, and can handle high power density.

    This paper will review the current state of the art in active switching device performance with special emphasis on BJTs. Device performance has been demonstrated over a wide temperature interval. A very important feature in high power switch applications is the low on-resistance of a device. Better material quality and epi processes suppress the amount of basal plane dislocations to avoid stacking fault formation generated during high current injection. This has long been a concern for bipolar SiC devices but several research reports and long term reliability measurements of pn-junctions show that the bipolar degradation problem can be solved by a fine-tuned epitaxial technique. A discussion on surface passivation control is included. Finally, an example of a power switching module is given also demonstrating the excellent paralleling capability of BJTs.

  • 2742.
    Östling, Mikael
    et al.
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Koo, Sang-Mo
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Lee, Sang-Kwon
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Zetterling, Carl Mikael
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Grishin, Alex
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Thin films in silicon carbide semiconductor devices2004Ingår i: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5774, s. 5-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicon carbide (SiC) semiconductor devices have been established during the last decade as very useful high power, high speed and high temperature devices because of their inherent outstanding semiconductor materials properties. Due to its large band gap, SiC possesses a very high breakdown field and low intrinsic carrier concentration which according makes A high voltage and high temperature operation possible. SiC is also suitable for high frequency device applications, because of the high saturation drift velocity and low permittivity. Thin film technology for various functions in the devices has been heavily researched. Suitable thin film technologies for Ohmic and low-resistive contact formation, passivation and new functionality utilizing ferroelectric materials have been developed. In ferroelectrics, the spontaneous polarization can be switched by an externally applied electric field, and thus are attractive for non-volatile memory and sensor applications. A novel integration of Junction-MOSFETs (JMOSFETs) and Nonvolatile FETs (NVFETs) on a single 4H-SiC substrate is realized. SiC JMOSFET controls the drain current effectively from the buried junction Late thereby allowing for a constant current level at elevated temperatures. SiC NVFET has similar functions with non-volatile memory capability due to ferroelectric gate stack. which operated up to 300degreesC with memory function retained up to 200degreesC.

  • 2743.
    Östling, Mikael
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Koo, S.-M.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Danielsson, Erik
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    SiC Device Technologies2005Ingår i: Encyclopedia of RF and Microwave Engineering: vol 5 / [ed] Kai Cang, Wiley-Blackwell, 2005, 1, s. 4613-Kapitel i bok, del av antologi (Refereegranskat)
  • 2744.
    Östling, Mikael
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Luo, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Gudmundsson, Valur
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hellström, Per Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, Bengt Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Integration of metallic source/drain (MSD) contacts in nanoscaled CMOS technology2010Ingår i: ICSICT-2010 - 2010 10th IEEE International Conference on Solid-State and Integrated Circuit Technology, Proceedings, 2010, s. 41-45Konferensbidrag (Refereegranskat)
    Abstract [en]

    An overview of metallic source/drain (MSD) contacts in nanoscaled MOSFET technology is provided in this paper. MSD contacts offer several benefits for nanoscaled CMOS, i.e., extremely low S/D parasitic resistance, abruptly sharp junctions between S/D and channel and preferably low temperature processing. In order to achieve high performance MSD MOSFETs, many design parameters such as Schottky barrier height (SBH), S/D to gate underlap, top Si layer thickness, oxide thickness and so on should be optimized. Recently, a lot of efforts have been invested in MSD MOSFETs based on Pt- and Ni-silicide implementation and several promising results have been reported in literature. The experimental work as well as the results of Monte Carlo simulations by this research team and by other research teams is discussed in this paper. It will be shown that the present results place MSD MOSFETs as a competitive candidate for future generations of CMOS technology.

  • 2745.
    Östling, Mikael
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Luo, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Gudmundsson, Valur
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Nanoscaling of MOSFETs and the implementation of Schottky barrier S/D contacts2010Ingår i: 2010 27th International Conference on Microelectronics, MIEL 2010 - Proceedings, 2010, s. 9-13Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper provides an overview of metallic source/drain (MSD) Schottky-barrier (SB) MOSFET technology. This technology offers several benefits for scaling CMOS, i.e., extremely low S/D series resistance, sharp junctions from S/D to channel and low temperature processing. A successful implementation of this technology needs to overcome new obstacles such as Schottky barrier height (SBH) engineering and careful control of SALICIDE process. Device design factors such as S/D to gate underlap, Si film thickness and oxide thickness affect device performance owing to their effects on the SB width. Recently, we have invested a lot of efforts on Pt- and Ni-silicide MSD SB-MOSFETs and achieved some promising results. The present work, together with the work of other groups in this field, places silicide MSD SB-MOSFETs as a competitive candidate for future generations of CMOS technology.

  • 2746.
    Östling, Mikael
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Von Haartman, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Hållstedt, Julius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zhang, Shili
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Critical technology issues for deca-nanometer MOSFETs2007Ingår i: ICSICT-2006: 2006 8th International Conference on Solid-State and Integrated Circuit Technology, Proceedings, 2007, s. 27-30Konferensbidrag (Refereegranskat)
    Abstract [en]

    An overview of critical integration issues for future generation MOSFETs towards 10 nm gate length is presented. Novel materials and innovative structures are discussed. The need for high-K gate dielectrics and a metal gate electrode is discussed. Different techniques for strain-enhanced mobility are discussed.

  • 2747.
    Östlund, Stefan
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska maskiner och effektelektronik (stängd 20110930). KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG.
    Gustafsson, Anders
    Buhrkall, Lars
    Skoglund, Martin
    Condition Monitoring of Pantograph Contact Strip2008Ingår i: IET Seminar Digest, 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    A common issue in electric railway operation is the wearofthepantographcontact strip. This is especially pronounced with ice or rime frost on the overhead line that causes arcing between the contact strip and the contact wire. To monitor the contact strip it is possible to utilise the fact that arcing between the contact strip and the overhead line generates a DC component in the AC locomotive current. The paper presents a method forconditionbased maintenanceofthe contact strip. The wearofthe contact strip is predicted bymonitoringthe running distanceofthepantographas well as the DC componentofthe locomotive current. To evaluate the method, measurements have been carried out on a Swedish Re locomotive during winterconditions.

  • 2748.
    Östman, Kristina
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Hesamzadeh, Mohammad
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Pricing electric-power transmission: The Swedish methodology and a new approach2013Ingår i: 2013 4th IEEE/PES Innovative Smart Grid Technologies Europe (ISGT EUROPE), IEEE , 2013, s. 6695429-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Electricity systems are changing rapidly worldwide, and transmission pricing needs to adapt. As renewable energy production increases, it is vital that the costs for transmission are recovered while recognising the special characteristics of different energy sources. In this paper, a new transmission pricing approach is presented and compared to the approach currently used in Sweden. By calculating nodal transmission tariffs based on marginal transmission costs and incorporating uncertainty in demand and generation, the new approach caters for a changing electricity system. To assess their impacts on renewable energy production, the two methodologies are applied to a case study mimicking the Swedish system with an increased wind power penetration. The results show that location and generation type can strongly influence the transmission tariffs, and that charging renewable energy producers less could be a least-cost option.

  • 2749.
    Östman, Kristina
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Hesamzadeh, Mohammad
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    The suitability of current transmission pricing systems for increased renewable energy production2013Ingår i: 2013 IEEE Power and Energy Society General Meeting (PES), IEEE , 2013, s. 6672674-Konferensbidrag (Refereegranskat)
    Abstract [en]

    As renewable electricity generation increases around the world, transmission networks are forced to adapt. The growing need for balancing services and long transmission distances lead to increased costs, which somehow need to be recovered. This paper considers the transmission pricing methodologies in four countries and assesses them against optimal pricing methodologies as defined in academic literature. The countries Australia, Spain, Great Britain and Sweden, with their different renewable energy potential and energy policies, provide a suitable snapshot of transmission pricing today. While they boast different levels of maturity, none of the methodologies fulfill all identified conditions for effective transmission prices with increased amounts of renewable electricity.

  • 2750.
    Östman, Kristina
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Hesamzadeh, Mohammad Reza
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Transmission pricing in interconnected systems - A case study of the Nordic countries2014Ingår i: ENERGYCON 2014 - IEEE International Energy Conference, IEEE Computer Society, 2014, s. 1480-1486Konferensbidrag (Refereegranskat)
    Abstract [en]

    With renewable energy production increasing around the world, there is a growing need for interconnection to balance intermittent supply. This cross-border trade of electricity requires navigating in multiple regulatory regimes and market designs, not least when it comes to transmission pricing. By considering the Nordic countries as a case study, this paper investigates the impact of different transmission pricing regimes on investment decisions for renewable energy production. A generation expansion problem for wind power is simulated with the current transmission prices in Sweden, Finland, Norway, and Denmark applied, along with a baseline case with no transmission pricing differences, to achieve a quantitative comparison. The importance of coherent transmission pricing is demonstrated through the large discrepancy in wind power investments resulting from the two cases studied.

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