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  • 151.
    Badel, Xavier
    et al.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Galeckas, Augustinas
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Linnros, Jan
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Kleimann, P.
    LENAC, Université Claude Bernard Lyon-I, Villeurbanne.
    Fröjdh, C.
    Mitthögskolan, Department of Electronics.
    Petersson, C. Sture
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Improvement of an X-ray imaging detector based on a scintillating guides screen2002Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 487, nr 1-2, s. 129-135Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An X-ray imaging detector has been developed for dental applications. The principle of this detector is based on application of a silicon charge coupled device covered by a scintillating wave-guide screen. Previous studies of such a detector showed promising results concerning the spatial resolution but low performance in terms of signal to noise ratio (SNR) and sensitivity. Recent results confirm the wave-guiding properties of the matrix and show improvement of the detector in terms of response uniformity, sensitivity and SNR. The present study is focussed on the fabrication of the scintillating screen where the principal idea is to fill a matrix of Si pores with a CsI scintillator. The photoluminescence technique was used to prove the wave-guiding property of the matrix and to inspect the filling uniformity of the pores. The final detector was characterized by X-ray evaluation in terms of spatial resolution, light output and SNR. A sensor with a spatial resolution of 9 LP/mm and a SNR over 50 has been achieved using a standard dental X-ray source and doses in the order of those used at the moment by dentists (around 25 mR).

  • 152.
    Badel, Xavier
    et al.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Kumar, R. T. R.
    Atomic Physics Division, Stockholm University.
    Kleinmann, P.
    LENAC, Univ. Claude Bernard Lyon-I, Villeurbanne.
    Linnros, Jan
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Formation of ordered pore arrays at the nanoscale by electrochemical etching of n-type silicon2004Ingår i: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 36, nr 1/3, s. 245-254Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrochemical etching has been studied to structure n-type silicon substrates at the nanoscale. In this work, well-ordered pore arrays with diameters in the range of 150-500 nm and depths up to 50 mum have been fabricated. The pores were successfully formed by anodic etching in (100)oriented n-type silicon wafers of low-resistivity, typically 1 Omegacm, using aqueous hydrofluoric acid solutions. The lithographic step was performed in a thermally grown oxide using a stepper and dry oxide etching technique. Two types of oxide openings and pitch sizes were tested. The smallest oxide opening realised at this stage was 0.5 mum for a pitch of 1 mum. Stable pore formation was obtained and the smallest pore size obtained was about 200 nm with an aspect ratio close to 100.

  • 153.
    Badel, Xavier
    et al.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Linnros, Jan
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Electrochemical etching of n-type silicon based on carrier injection from a back side p-n junction2003Ingår i: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 6, nr 6, s. C79-C81Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A technique for electrochemical etching of n-type silicon in aqueous hydrofluoric acid is presented. This technique differs from photoelectrochemical etching because the holes (positive carriers) needed for the dissolution reaction to occur, are not photogenerated. The principle developed here is to inject these positive carriers using a p-n junction under forward bias formed at the back side of the sample. Drift-diffusion of holes through the wafer thickness allows a chemical dissolution reaction at the interface with the electrolyte. To enable holes diffusing through the wafer the minority carrier lifetime must be sufficiently high making the technique well adapted for high resistivity silicon. However, extension to low resistivity wafers has been achieved. Results show the possibility of forming pore arrays and diverse 3D structures.

  • 154.
    Badel, Xavier
    et al.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Linnros, Jan
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Janson, M. S.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Österman, J.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Formation of pn junctions in deep silicon pores for X-ray imaging detector applications2003Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 509, nr 1-3, s. 96-101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The formation of pn junctions in deep silicon pores has been studied for a new concept of X-ray imaging detectors. The sensitive part of the device is an array of CsI(Tl) columns formed by filling a silicon matrix of pores having pn junctions in their walls. Under X-ray illumination, the CsI(TI) scintillator emits photons that are collected by the pn junctions. Relatively high signal collection efficiency is expected. However, the formation of pn junctions inside pore walls represents a challenging step in the detector fabrication. In this work pore matrices were fabricated in n-type silicon by deep reactive ion etching and by photo-electrochemical etching. The pn junctions were formed either by boron diffusion or deposition of boron doped poly-silicon. Various techniques were used to analyze the transverse depth profiles of boron atoms at different pore depths. The study shows successful results for pn-junctions formed both by diffusion and by poly-silicon deposition.

  • 155.
    Badel, Xavier
    et al.
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Linnros, Jan
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Kleimann, P.
    LENAC, Univ.́ Claude Bernard Lyon-I, Villeurbanne.
    Norlin, B.
    Department of Information Technology, Mid-Sweden University, Sundsvall.
    Koskiahde, E.
    Metorex International Oy, Espoo.
    Valpas, K.
    Metorex International Oy, Espoo.
    Nenonen, S.
    Metorex International Oy, Espoo.
    Petersson, Sture
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Fröjdh, C.
    Department of Information Technology, Mid-Sweden University, Sundsvall.
    Metallized and oxidized silicon macropore arrays filled with a scintillator for CCD-based X-ray imaging detectors2004Ingår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 51, nr 3, s. 1001-1005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicon charge-coupled devices (CCDs) covered with a scintillating film are now available on the market for use in digital medical imaging. However, these devices could still be improved in terms of sensitivity and especially spatial resolution by coating the CCD with an array of scintillating waveguides. In this paper, such waveguides were fabricated by first etching pores in silicon, then performing metallization or oxidation of the pore walls and finally filling the pores with CsI(TI). The resulting structures were observed using scanning electron microscopy and tested under X-ray exposure. Theoretical efficiencies of macropore arrays filled with CsI(TI) were also calculated, indicating that the optimal pore depth for metallized macropore arrays is about 80 mum while it is around 350 mum for oxidized ones. This result, together with the roughness of the metal coating, explains why lower SNR values were measured with the metallized macropores. Indeed, the macropore arrays had depths in the range of 210-390 mum, which is favorable to oxidized structures.

  • 156.
    Badel, Xavier
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Norlin, B.
    Department of Information Technology and Media, Mid-Sweden University, Sundsvall.
    Kleimann, P.
    LENAC, Université Claude Bernard Lyon-I, Villeurbanne.
    Williams, L.
    Applied Scintillation Technology, Harlow.
    Moody, S. J.
    Applied Scintillation Technology, Harlow.
    Tyrell, G. C.
    Applied Scintillation Technology, Harlow.
    Fröjdh, C.
    Department of Information Technology and Media, Mid-Sweden University, Sundsvall.
    Linnros, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Performance of scintillating waveguides for CCD-based X-ray detectors2006Ingår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 53, nr 1, s. 3-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scintillating films are usually used to improve the sensitivity of CCD-based X-ray imaging detectors. For an optimal spatial resolution and detection efficiency, a tradeoff has to be made on the film thickness. However, these scintillating layers can also be structured to provide a pixellated screen. In this paper, the study of CsI(TI)-filled pore arrays is reported. The pores are first etched in silicon, then oxidized and finally filled with CsI(TI) to form scintillating waveguides. The dependence of the detector sensitivity on pore depth, varied from 40 to 400 mu m here, follows rather well theoretical predictions. Most of the detectors produced in this work have a detective quantum efficiency of the incoming X-ray photons of about 25%. However, one detector shows that higher efficiency can be achieved approaching almost the theoretical limit set by Poisson statistics of the incoming X-rays. Thus, we conclude that it is possible to fabricate scintillating waveguides with almost ideal performance. Imaging capabilities of the detectors are demonstrated.

  • 157.
    Bagger, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Olsson, Håkan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    RF Power Amplifier IC with Low Memory Effect, Reduced Low Frequency Gain Peak and Isolated Temperature Tracking Circuitry2008Ingår i: 2008 IEEE CSIC Symposium: GaAs ICs Celebrate 30 Years in Monterey, Technical Digest 2008, IEEE , 2008, s. 60-63Konferensbidrag (Refereegranskat)
    Abstract [en]

    A highly linear wideband power amplifier IC with low memory effect for W-CDMA applications is presented utilizing Si LDMOS process technology. The IC was optimized to reduce typical low frequency gain peak often observed in LDMOS power devices. Topology of the interstage matching contributes to reduction of the electrical memory effect to specification level of maximum 2 dB imbalance over power between upper and lower Adjacent Channel Power Ratio when using II-tone wideband modulated signal. The on-chip temperature compensation circuitry tracks the active device temperature characteristic without degradation of the linearity or worsens the memory effect. The measured gain of the IC was 28.5 dB and 3-dB bandwidth of 600 MHz around 2100 MHz was achieved. The IC attained -50 dBc ACPR at 5 W output power. At power level of 45 W and IMD3 = -30dBc (two-tone) the IC exhibited power densities in excess of 469 mW/mm, in which matching losses were included. The IC demonstrated state-of-the-art RF power performance in terms of good linearity, low memory effects, well-suppressed low frequency gain peak and temperature tracking without linearity and IMD balance degradation.

  • 158.
    Baghchehsaraei, Zargham
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Waveguide-Integrated MEMS Concepts for Tunable Millimeter-Wave Systems2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis presents two families of novel waveguide-integrated components based on millimeter-wave microelectromechanical systems (MEMS) for reconfigurable systems. The first group comprises V-band (50–75 GHz) and W-band (75–110 GHz) waveguide switches and switchable irises, and their application as switchable cavity resonators, and tunable bandpass filters implemented by integration of novel MEMS-reconfigurable surfaces into a rectangular waveguide. The second category comprises MEMS-based reconfigurable finlines integrated as phase shifters into a rectangular waveguide array to demonstrate beams steering with a phased array antenna.

    The first group of the presented reconfigurable waveguide components is based on a novel MEMS-reconfigurable surface structured in the device layer of a silicon-on-insulator (SOI) wafer using metallized mono-crystalline silicon as structural and functional material. The chip containing the reconfigurable surface is integrated in the cross-section of a WR-12 rectangular waveguide perpendicular to the wave propagation. The reconfigurable surface is modified for different states by on-chip push-pull electrostatic comb-drive MEMS actuators. The switch is ON when the reconfigurable surface is in its transmissive state and OFF when the reconfigurable surface is in its blocking state for the propagating wave. This millimeter-wave waveguide switch shows an insertion loss and isolation very similar to high-performance but bulky mechanical rotary waveguide switches, despite being extremely compact (30 μm thick), and thus combines the high electrical performance of mechanical switches with the size of (high power consuming and inferior performance) PIN-diode waveguide switches. This thesis also investigates the optimization to decrease the number of contact points for the OFF state and presents a device yield analysis. The same concept is developed further to MEMS-switchable inductive and capacitive irises, with the performance similar to ideal irises. With such MEMS-reconfigurable irises a switchable cavity resonator was implemented and the potential of tunable bandpass filters are demonstrated. Since these devices feature all-metal design as no dielectric layers are utilized, no dielectric charging effect is observed. Furthermore, this thesis investigates the low-loss integration of millimeter-wave MEMS-reconfigurable devices into rectangular waveguide with conductive polymer interposers.

    The second group of components comprises finlines which are fabricated out of two bonded silicon wafers with bilateral gold structures integrated into a WR-12 rectangular waveguide. A 2-bit waveguide phase shifter is designed for 77-GHz automotive radar. Such phase shifters are used as individual building blocks of a two-dimensional antenna array for beam steering frontends.

  • 159.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    MEMS-reconfigurable irises for millimeter-wave waveguide componentsManuskript (preprint) (Övrigt vetenskapligt)
  • 160.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    MEMS-reconfigurable wavguide iris for switchable V-band cavity resonators2014Ingår i: 2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS), IEEE , 2014, s. 206-209Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents for the first time a novel MEMS-reconfigurable inductive iris based on a 30-μm thick reconfigurable transmissive surface and reports on its application to create a switchable cavity resonator in a WR-12 rectangular waveguide (60-90 GHz). The reconfigurable surface incorporates 252 simultaneously switched contact points for activating (ON state) and deactivating (OFF state) the inductive iris by a 24 μm lateral displacement of two sets of distributed vertical cantilevers. In the ON state, these contact points are short-circuiting the electric field lines of the TE10 waveguide mode on the cross-sectional areas of a symmetric inductive waveguide iris, and are not interfering with the wave propagation in the OFF state. Thus, this novel concept allows for completely switching the inductive iris ON or OFF. The inductive iris has an insertion loss of better than 1.0 dB in the OFF state, of which 0.8 dB is attributed to the measurement setup alone. In the ON state the measured performance of the switchable iris is in good agreement with the simulation results. Furthermore, a novel, switchable cavity resonator was implemented based on such a MEMS-reconfigurable iris, and was characterized to a Q-factor of 186.13 at the resonance frequency of 68.87 GHz with the iris switched ON, and an OFF-state insertion loss of less than 2 dB (including the measurement setup) without any resonance, which is for the first time reported in this paper.

  • 161.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Parameter Analysis of Millimeter-Wave Waveguide Switch Based on a MEMS-Reconfigurable Surface2013Ingår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 61, nr 12, s. 4396-4406Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a novel concept of a millimeter-wave waveguide switch based on amicroelectromechanical (MEMS)-reconfigurable surface with insertion loss and isolation very similar to high performance but bulky rotary waveguide switches, despite its thickness of only 30 mu m. A set of up to 1470 micromachined cantilevers arranged in vertical columns are actuated laterally by on-chip integrated MEMS comb-drive actuators, to switch between the transmissive state and the blocking state. In the blocking state, the surface is reconfigured so that the wave propagation is blocked by the cantilever columns short-circuiting the electrical field lines of the TE10 mode. A design study has been carried out identifying the performance impact of different design parameters. The RF measurements (60-70 GHz) of fabricated, fully functional prototype chips show that the devices have an isolation between 30 and 40 dB in the OFF state and an insertion loss between 0.4 and 1.1 dB in the ON state, of which the waveguide-assembly setup alone contributes 0.3 dB. A device-level yield analysis was carried out, both by simulations and by creating artificial defects in the fabricated devices, revealing that a cantilever yield of 95% is sufficient for close-to-best performance. The actuation voltage of the active-opening/active-closing actuators is 40-44 V, depending on design, with high reproducibility of better than (sigma = 0.0605 V). Lifetime measurements of the all-metal, monocrystalline-silicon core devices were carried out for 14 h, after which 4.3 million cycles were achieved without any indication of degradation. Furthermore, a MEMS-switchable waveguide iris based on the reconfigurable surface is presented.

  • 162.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    V-Band Single-Pole-Single-Throw Mems Rectangular waveguide Switch2013Ingår i: MME 2013 24th Micromechanics and Microsystems Europe Conference, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a concept of a waveguide single-pole single-throw (SPST) switch based on a MEMS-reconfigurable surface. A set of vertical columns, split into two groups of movable and fixed sections which can be actuated laterally by integrated MEMS comb-drive actuators, allows for the transition between the transmissive and the blocking state. In the totally-blocking state, the vertical columns inhibit the wave propagation by short-circuiting the electrical field lines of the predominantTE10 mode. The paper reports on the integration method for fabricated chips into a WR-12 waveguide by using tailor-made flanges. The RF measurement of fabricated chips show that devices have better than 30 dB isolation in the OFF state and better than 0.65 dB insertion loss in the ON state for60-70 GHz, which is mainly attributed to the integration into the waveguide and the measurement assembly setup. The actuation voltage is 44 V, and lifetime measurements were carried out for 14 hours after which 4.3 million cycles were achieved without any indication on degradation.

  • 163.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Shah, Umer
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Dudorov, Sergey
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Stemme, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Åberg, Jan
    MEMS 30μm-thick W-band Waveguide Switch2012Ingår i: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012, European Microwave Association , 2012, s. 675-678Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents for the first time a novel concept of a MEMS waveguide switch based on a reconfigurable surface, whose working principle is to short-circuit or to allow for free propagation of the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. This transmissive surface is only 30μm thick and consists of up to 1260 reconfiguring cantilevers in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. For the first fabrication run, the yield of these reconfigurable elements on the chips was 80-86%, which still was good enough for resulting in a measured insertion loss in the open state of better than 1dB and an isolation of better than 20dB for the best designs, very wideband from 62 to 75GHz. For 100% fabrication yield, HFSS simulations predict that an insertion loss in the open state of better than 0.1dB and an isolation of better than 30dB in the closed state are possible for designs with 800 and more contact points for this novel waveguide switch concept.

  • 164.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Shah, Umer
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Åberg, J.
    Stemme, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Millimeter-Wave SPST Waveguide Switch Based on Reconfigurable MEMS Surface2013Ingår i: 2013 IEEE MTT-S International Microwave Symposium Digest (IMS), IEEE , 2013, s. 6697774-Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a concept of a waveguide single-pole single-throw (SPST) switch based on a MEMSreconfigurable surface. A set of vertical columns, split into two groups of movable and fixed sections which can be actuated laterally by integrated MEMS comb-drive actuators, allows for the transition between the transmissive and the blocking state. In the totally-blocking state, the vertical columns inhibit the wave propagation by short-circuiting the electrical field lines of the predominant TE10 mode. The paper reports on the integration method for fabricated chips into a WR-12 waveguide by using tailor-made flanges. The RF measurement of fabricated chips show that devices have better than 30 dB isolation in the OFF state and better than 0.65 dB insertion loss in the ON state for 60-70 GHz, which is mainly attributed to the integration into the waveguide and the measurement assembly setup. The actuation voltage is 44 V, and life-time measurements were carried out for 14 hours after which 4.3 million cycles were achieved without any indication on degradation.

  • 165.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Shah, Umer
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Åberg, Jan
    Stemme, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    MEMS reconfigurable millimeter-wave surface for V-band rectangular-waveguide switch2013Ingår i: International Journal of Microwave and Wireless Technologies, ISSN 1759-0787, Vol. 5, nr 3, s. 341-349Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents for the first time a novel concept of a microelectromechanical systems (MEMS) waveguide switch based on a reconfigurable surface, whose working principle is to block the wave propagation by short-circuiting the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. The reconfigurable surface is only 30 mu m thick and consists of up to 1260 micro-machined cantilevers and 660 contact points in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. Measurements of fabricated prototypes show that the devices are blocking wave propagation in the OFF-state with over 30 dB isolation for all designs, and allow for transmission of less than 0.65 dB insertion loss for the best design in the ON-state for 60-70 GHz. Furthermore, the paper investigates the integration of such microchips into WR-12 waveguides, which is facilitated by tailor-made waveguide flanges and compliant, conductive-polymer interposer sheets. It is demonstrated by reference measurements where the measured insertion loss of the switches is mainly attributed to the chip-to-waveguide assembly. For the first prototypes of this novel MEMS microwave device concept, the comb-drive actuators did not function properly due to poor fabrication yield. Therefore, for measuring the OFF-state, the devices were fixated mechanically.

  • 166.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Sterner, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Åberg, Jan
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Integration of microwave MEMS devices into rectangular waveguide with conductive polymer interposers2013Ingår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 12, s. 125020-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper investigates a novel method of integrating microwave microelectromechanical systems (MEMS) chips into millimeter-wave rectangular waveguides. The fundamental difficulties of merging micromachined with macromachined microwave components, in particular, surface topography, roughness, mechanical stress points and air gaps interrupting the surface currents, are overcome by a double-side adhesive conductive polymer interposer. This interposer provides a uniform electrical contact, stable mechanical connection and a compliant stress distribution interlayer between the MEMS chip and a waveguide frame. The integration method is successfully implemented both for prototype devices of MEMS-tuneable reflective metamaterial surfaces and for MEMS reconfigurable transmissive surfaces. The measured insertion loss of the novel conductive polymer interface is less than 0.4 dB in the E-band (60-90 GHz), as compared to a conventional assembly with an air gap of 2.5 dB loss. Moreover, both dc biasing lines and mechanical feedthroughs to actuators outside the waveguide are demonstrated in this paper, which is achieved by structuring the polymer sheet xurographically. Finite element method simulations were carried out for analyzing the influence of different parameters on the radio frequency performance.

  • 167. Baghchehsaraei, Zargham
    et al.
    Vorobyov, Alexander
    IETR (Institut d’Electronique et de Télécommunications de Rennes), Université de Rennes.
    Sauleau, Ronan
    IETR (Institut d’Electronique et de Télécommunications de Rennes), Université de Rennes.
    Fourn, Erwan
    IETR (Institut d’Electronique et de Télécommunications de Rennes), INSA de Rennes.
    Oberhammer, Joachim
    PHASED-ARRAY ANTENNA BASED ON MEMS FIN-LINE PHASESHIFTERS FOR W-BAND BEAM-STEERING APPLICATIONS2012Ingår i: GigaHertz Symposium 2012, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents phased array antenna, which consists of 21×10 integrated phase shifter elements, as a beam steeringdevice for automotive radar applications.

  • 168.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Vorobyov, Alexander
    Åberg, Jan
    Fourn, Erwan
    Sauleau, Ronan
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Waveguide-integrated MEMS-based phase shifter for phased array antenna2014Ingår i: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 8, nr 4, s. 235-243Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigates a new concept of waveguide-based W-band phase shifters for applications in phased array antennas. The phase shifters are based on a tuneable bilateral finline bandpass filter with 22 microelectromechanical system (MEMS) switching elements, integrated into a custom-made WR-12 waveguide with a replaceable section, whose performance is also investigated in this study. The individual phase states are selected by changing the configuration of the switches bridging the finline slot in specific positions; this leads to four discrete phase states with an insertion loss predicted by simulations better than 1 dB, and a phase shift span of about 270°. MEMS chips have been fabricated in fixed positions, on a pair of bonded 300 µm high-resistivity silicon substrates, to prove the principle, that is, they are not fully functional, but contain all actuation and biasing-line elements. The measured phase states are 0, 56, 189 and 256°, resulting in an effective bit resolution of 1.78 bits of this nominal 2 bit phase shifter at 77 GHz. The measured insertion loss was significantly higher than the simulated value, which is assumed to be attributed to narrow-band design of the devices as the influences of fabrication and assembly tolerances are shown to be negligible from the measurement results.

  • 169.
    Baghchehsaraei, Zargham
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Åberg, Jan
    Oberhammer, Joachim
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Mems-reconfigurable millimeter-wave surfaces for waveguide switches, irises and resonators2014Ingår i: The GigaHertz 2014 Symposium, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a concept and prototypes of transmissive millimeter-wave surfaces, which are reconfigurable by integrated micro-electromechanical (MEMS) actuators. The surfaces consist of small vertical elements which can be configured so that they are vertically connected and thus they short-circuit the electrical field lines in the waveguide, which results in total blocking of the wave propagation, or that they are not connected which results in full wave propagation through the surface.

  • 170.
    Bai, Xueyao
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Distributed Visual Processing Based On interest Point Clustering2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this master thesis project, we study the problem in Visual Sensor Networks

    in which only limited bandwidth is provided. The task is to search for ways to

    decrease the transmitting data on the camera side, and distribute the data to dif-

    ferent nodes.

    To do so, we extract the interest points on the camera side by using BRISK in-

    terest point detector, and we distribute the detected interest points into di erent

    number of processing node by implementing proposed clustering methods, namely,

    Number Based Clustering, K-Means Clustering and DBSCAN Clustering.

    Our results show it is useful to extract interest points on the camera side, which

    can reduce almost three quarters of data in the network. A step further, by imple-

    menting the clustering algorithms, we obtained the gain in overhead ratio, interest

    point imbalance and pixel processing load imbalance, respectively. Specically,

    the results show that none of the proposed clustering methods is better than oth-

    ers. Number Based Clustering can balance the processing load between di erent

    processing nodes perfectly, but performs bad in saving the bandwidth resources.

    K-Means Clustering performs middle in the evaluation while DBSCAN is great in

    saving the bandwidth resources but leads to a bad processing balance performance

    among the processing nodes.

  • 171.
    Bakas, Panagiotis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. ABB Corporate Research, Sweden.
    Harnefors, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. ABB Corporate Research, Sweden.
    Norrga, Staffan
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Nami, A.
    Ilves, K.
    Dijkhuizen, F.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Hybrid Topologies for Series and Shunt Compensation of the Line-Commutated Converter2016Ingår i: 8th International Power Electronics and Motion Control Conference - ECCE Asia, IPEMC 2016-ECCE Asia, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 3030-3035, artikel-id 7512779Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents two concepts for enabling the operation of a line-commutated converter (LCC) at leading power angles. The concepts are based on voltage or current injection at the ac side of an LCC, which can be achieved in different ways. However, this paper focuses on the voltage and current injection by series-connected full-bridge cells that can generate voltages that approximate ideal sinusoids. Thus, hybrid configurations of an LCC connected at the ac side in series or in parallel with fullbridge cells are presented. Finally, these hybrid configurations are compared in terms of voltage and current rating.

  • 172.
    Bakas, Panagiotis
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. ABB Corporate Research, Sweden.
    Harnefors, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. ABB Corporate Research, Sweden.
    Norrga, Staffan
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Nami, Alireza
    ABB Corporate Research, Sweden.
    Ilves, Kalle
    ABB Corporate Research, Sweden.
    Dijkhuizen, Frans
    ABB Corporate Research, Sweden.
    Nee, Hans-Peter
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    A Review of Hybrid Topologies Combining Line-Commutated and Cascaded Full-Bridge Converters2017Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 32, nr 10, s. 7435-7448, artikel-id 7750589Artikel, forskningsöversikt (Refereegranskat)
    Abstract [sv]

    This paper presents a review of concepts for enabling the operation of a line-commutated converter (LCC) at leading power angles. These concepts rely on voltage or current injection at the ac or dc sides of the LCC, which can be achieved in different ways. We focus on the voltage and current injection by full-bridge (FB) arms, which can be connected either at the ac or dc sides of the LCC and can generate voltages that approximate ideal sinusoids. Hybrid configurations of an LCC connected at the ac side in series or in parallel with FB arms are presented. Moreover, a hybrid configuration of an LCC connected in parallel at the ac side and in series at the dc side with an FB modular multilevel converter (MMC) is outlined. The main contribution of this paper is an analysis and comparison of the mentioned hybrid configurations in terms of the capability to independently control the active (P) and reactive power (Q).

  • 173.
    Bakas, Panagiotis
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik. ABB Corp Res, Västerås, Sweden..
    Ilves, K.
    Harnefors, Lennart
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik. ABB Corp Res, Västerås, Sweden..
    Norrga, S.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Nee, H.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Hybrid Converter With Alternate Common Arm and Director Thyristors for High-Power Capability2018Ingår i: 2018 20th European Conference on Power Electronics and Applications (EPE’18 ECCE Europe), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the basic operating principles of a new hybrid converter that combines thyristors and full-bridge (FB) arms for achieving high active-power capability. This converter consists of a modular multilevel converter (MMC) equipped with additional common arms, which alternate between the upper and lower dc poles. This alternation is achieved by the thyristors that are utilized as director switches and allow the parallel connection of the common arms and the arms of the MMC. The main contributions of this paper are the analysis of the operating principles, the simulation verification of the functionality of the proposed converter, and the comparison of the latter with the full-bridge modular multilevel converter (FB-MMC).

  • 174.
    Bakhiet, Mohammed
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Automated Tests of Computer-based Interlocking Systems: Developing a test case generator2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Automated tests have become the most sought after method of testing

    in today’s market. Automating systems is generally found to be

    cheaper, faster and more reliable than manually operating them. For

    this reason many companies decide to make the switch over to this inexpensive

    yet efficient way of testing, only to realize that their costs

    have in fact gone up. The reasons for this could be poor planning, automating

    too much too soon or even automating unnecessary parts of

    the system. This study takes a closer look at the effects of automating

    tests used on interlocking systems. A tool has been developed as a part

    of the automated tests at Bombardier. The main function of the tool is

    to speed up the testing process by automatically generating test cases

    rather than having a worker write them down. The aim of this paper is

    to present this recently developed tool and show how its use significantly

    reduces testing time, costs and workload compared to the manual tests

    used today.

  • 175. Bakhouya, Mohamed
    et al.
    Daneshtalab, Masoud
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik och Inbyggda System.
    Palesi, Maurizio
    Ghasemzadeh, Hassan
    Many-core System-on-Chip: architectures and applications2016Ingår i: Microprocessors and microsystems, ISSN 0141-9331, E-ISSN 1872-9436, Vol. 43, s. 1-3Artikel i tidskrift (Refereegranskat)
  • 176. Balestra, F.
    et al.
    Parker, E.
    Leadley, D.
    Mantl, S.
    Dubois, E.
    Engstrom, O.
    Clerc, R.
    Cristoloveanu, S.
    Kurz, H.
    Raskin, J. P.
    Lemme, Max C.
    AMO GmbH, AMICA, Aachen, Germany.
    Ionescu, A.
    Moselund, K. E.
    Boucart, K.
    Kasper, E.
    Karmous, A.
    Baus, M.
    Spangenberg, B.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Sangiorgi, E.
    Ghibaudo, G.
    Flandre, D.
    NANOSIL network of excellence-silicon-based nanostructures and nanodevices for long-term nanoelectronics applications2008Ingår i: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 11, nr 5-6, s. 148-159Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    NANOSIL Network of Excellence [NANOSIL NoE web site < www.nanosil-noe.eu >], funded by the European Commission in the 7th Framework Programme (ICT-FP7, no 216171), aims at European scale integration of the excellent European research laboratories and their capabilities in order to strengthen scientific and technological excellence in the field of nanoelectronic materials and devices for terascale integrated circuits (ICs), and to disseminating the results in a wide scientific and industrial community. NANOSIL is exploring and assessing the science and technological aspects of nanodevices and operational regimes relevant to the n+4 technology node and beyond. It encompasses projects on nanoscale CMOS and beyond-CMOS. Innovative concepts, technologies and device architectures are proposed-with fabrication down to the finest features, and utilising a wide spectrum of advanced deposition and processing capabilities, extensive characterization and very rigorous device modeling. This work is carried out through a network of joint processing, characterization and modeling platforms. This critical interaction strengthens European integration in nanoelectronics and will speed up technological innovation for the nanoelectronics of the next two to three decades.

  • 177. Balinsky, Michael
    et al.
    Haidar, Mohammad
    Ranjbar, Mojtaba
    Durrenfeld, Philipp
    Houshang, Afshin
    Slavin, Andrei
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. University of Gothenburg, Sweden.
    Modulation of the Spectral Characteristics of a Nano-Contact Spin-Torque Oscillator via Spin Waves in an Adjacent Yttrium-Iron Garnet Film2016Ingår i: IEEE Magnetics Letters, ISSN 1949-307X, E-ISSN 1949-3088, Vol. 7, artikel-id 3101704Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    NiFe-Cu-Co trilayer nano-contact spin-torque oscillators (NC-STOs) fabricated on an yttrium-iron garnet (YIG) film were studied in two different modes. In passive mode, i.e. without any NC-STO auto-oscillations, a microwave current through the nano-contact can excite spin waves (SW) in the YIG film, and, vice versa, antenna generated SWs in the YIG film can be detected by the nano-contact. In active mode, i.e., in the presence of auto-oscillations, significant changes appear in the NC-STO spectrum when its frequency approaches that of the SWs excited in the YIG. These results demonstrate strong coupling between NC-STOs and SWs in YIG and open new possibilities of 1) pure spin-current generation in YIG by NC-STOs; 2) mutual locking of a number of NC-STOs through SWs in YIG; and 3) improvement of NC-STO spectra through SW feedback in YIG.

  • 178.
    Balliu, Musard
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teoretisk datalogi, TCS.
    Merro, Massimo
    University of Verona.
    Pasqua, Michele
    University of Verona.
    Securing Cross-App Interactions in IoT Platforms2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    IoT platforms enable users to connect various smart devices and online services via reactive apps running on the cloud. These apps, often developed by third-parties, perform simple computations on data triggered by external information sources and actuate the results of computation on external information sinks. Recent research shows that unintended or malicious interactions between the different (even benign) apps of a user can cause severe security and safety risks. These works leverage program analysis techniques to build tools for unveiling unexpected interference across apps for specific use cases. Despite these initial efforts, we are still lacking a semantic framework for understanding interactions between IoT apps. The question of what security policy cross-app interference embodies remains largely unexplored. This paper proposes a semantic framework capturing the essence of cross-app interactions in IoT platforms. The framework generalizes and connects syntactic enforcement mechanisms to bisimulation-based notions of security, thus providing a baseline for formulating soundness criteria of these enforcement mechanisms. Specifically, we present a calculus that models the behavioral semantics of a system of apps executing concurrently, and use it to define desirable semantic policies in the security and safety context of IoT apps. To demonstrate the usefulness of our framework, we define static mechanisms for enforcing crossapp security and safety, and prove them sound with respect to our semantic conditions. Finally, we leverage real-world apps to validate the practical benefits of our policy framework.

  • 179. Bantavis, P. I.
    et al.
    Kolitsidas, Christos
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Jonsson, B. Lars G.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Empliouk, T.
    Kyriacou, G. A.
    A Wideband Switched Beam Antenna System for 5G Femtocell Applications2017Ingår i: 2017 IEEE Antennas and Propagation Society International Symposium, Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 929-930Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work introduces a wideband switched beam system for femtocell 5G base stations. The system consists of a 4 x 1 Vivaldi linear array and a 4 x 4 Butler matrix able to operate from 1.9-5.1 GHz. A soft surface is introduced along the outer edges of the vivaldi elements of the array for side lobes and back radiation suppression.

  • 180.
    Banuazizi, Seyed Amir Hossein
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Determining and Optimizing the Current and Magnetic Field Dependence of Spin-Torque and Spin Hall Nano-Oscillators: Toward Next-Generation Nanoelectronic Devices and Systems2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Spinntroniska oscillatorer är ca 100 nm stora nano-komponenter som kan generera avstämningsbara mikrovågssignaler över ett mycket stort frekvensområde. Frekvensområdet sträcker sig i dagsläget från 0,1 GHz till över 65 GHz och flera forskningsgrupper försöker att nå upp till 200-300 GHz. De spinntroniska oscillatorerna baseras på en effekt som kallas spinnvridmoment och de första oscillatorerna kallades därför spinnvridmomentsnano-oscillatorer (eng. spin torque nano-oscillators) som vanligtvis förkortas STNO:er. De senaste åren har man även använt den s.k. spinn-Hall-effekten och oscillatorer baserade på detta förkortas därför SHNO:er. Båda sorternas oscillatorer är under kraftig utveckling för att kunna användas inom olika högfrekvenstillämpningar som t.ex. mobiltelefon, trådlösa nätverk, basstationer, fordonsradar och även medicinska tillämpningar.

    Denna avhandling täcker ett brett spektrum av olika mätningar på STNO:er och SHNO:er för att bestämma deras ström- och magnetfältsberoenden samt föreslå förbättringar av deras design för att använda dem inom spinntronik och magnonik. Arbetet bygger i första hand på experimentella metoder för att utveckla nya mätsystem, men det innehåller också numeriska och mikromagnetiska simuleringar.

    Experimentella tekniker: För att kunna göra detaljerade och noggranna mätningar, som funktion av ström genom komponenten samt magnetfält runt komponenten, har två nya mätuppställningar utvecklats, båda med målet att enkelt kunna variera styrka och riktning på det magnetiska fältet i tre dimensioner. Dessutom presenteras en ny metod för att studera komponenterna med s.k. magnetkraftsmikroskopi(MFM).

    STNO:er: Avhandlingen presenterar väsentliga förbättringar av prestanda hos STNO:er genom att öka tjockleken på det understa metall-lager som hela STNO:n är uppbyggd på. I sådana förbättrade STNO:er kan mikrovågssignaler med högre frekvens, högre uteffekt, och lägre tröskelström realiseras. Dessutom får komponenterna bättre värmeledningsförmåga så att de kan klara högre drivströmmar. Vidare beskrivs en detaljerad studie av magnetdroppsolitoner och spinnvågsdynamik i STNO:er. Slutligen beskrivs en ultrahög frekvensavstämbarhet i STNO:er baserade på magnetiska tunnlingselement med s.k. vinkelrät anisotropi.

    SHNO:er: Avhandlingen beskriver också mätningar på SHNO:er baserade på olika strukturer och material, studerade med både konventionella och nya metoder. En detaljerad studie av temperatur och magnetfältsprofiler i s.k. nano-gap SHNO:er presenteras. Dessutom presenterar avhandlingen detaljerade studier av magnetfältsberoendet hos s.k. nano-förträngnings-SHNO:er. Vidare har det visat sig att flera sådana SHNO:er kan synkroniseras seriellt och därigenom få en kraftigt ökad uteffekt. Detta möjliggör i förlängningen också s.k. neuromorfiska beräkningar. Avhandlingen visar att en kedja av sådana SHNO:er också kan synkroniseras även vid låga magnetfält. Slutligen beskrivs de första mätningarna på SHNO:er med hjälp av MFM.

  • 181.
    Banuazizi, Seyed
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Sani, S. R.
    Eklund, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Naiini, Maziar Manouchehry
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Mohseni, S.
    Chung, S.
    Dürrenfeld, P.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Order of magnitude improvement of nano-contact spin torque nano-oscillator performance2017Ingår i: 2017 IEEE International Magnetics Conference, INTERMAG 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, artikel-id 8007567Konferensbidrag (Refereegranskat)
    Abstract [en]

    Spin torque nano-oscillators [1,2] (STNO) represent a unique class of nano-scale microwave signal generators where spin transfer torque [3-5] (STT) from a direct spin-polarized current drives and controls the auto-oscillation of the local free layer magnetization, which through its oscillating magnetoresistance transforms the direct current into a tunable microwave voltage.

  • 182.
    Bao, Lei
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Iterative Encoder-Controller Design for Feedback Control Over Noisy Channels2011Ingår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 56, nr 2, s. 265-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study a closed-loop control system with state feedback transmitted over a noisy discrete memoryless channel. With the objective to minimize the expected linear quadratic cost over a finite horizon, we propose a joint design of the sensor measurement quantization, channel error protection, and controller actuation. It is argued that despite that this encoder-controller optimization problem is known to be hard in general, an iterative design procedure can be derived in which the controller is optimized for a fixed encoder, then the encoder is optimized for a fixed controller, etc. Several properties of such a scheme are discussed. For a fixed encoder, we study how to optimize the controller given that full or partial side-information is available at the encoder about the symbols received at the controller. It is shown that the certainty equivalence controller is optimal when the encoder is optimal and has full side-information. For a fixed controller, expressions for the optimal encoder are given and implications are discussed for the special cases when process, sensor, or channel noise is not present. Numerical experiments are carried out to demonstrate the performance obtained by employing the proposed iterative design procedure and to compare it with other relevant schemes.

  • 183.
    Baradar, Mohamadreza
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Afsharnia, Saeed
    University of Tehran.
    Sanaye-Pasand, Majid
    University of Tehran.
    A Fast Method for Fault Section Identification in Series Compensated Transmission Lines2010Ingår i: 2010 9th International Conference on Environment and Electrical Engineering (EEEIC), IEEE, 2010, s. 483-486Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a novel and fast method for fault section identification in compensated series transmission lines based on the high frequency traveling wave has been proposed. The method uses the relation of magnitude and polarity between wavefronts of high frequency travelling waves induced by fault. For accurately and fast extracting polarity and magnitude of travelling wave, wavelet transform and modulus maxima are used. Validation of this method is carried out by PSCAD/EMTP and MATLAB simulations for typical 400 kV power system faults. Simulation results reveal high performance of the method.

  • 184.
    Baradar, Mohamadreza
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Van Hertem, Dirk
    Electrical engineering.
    The Modeling Multi-Terminal VSC-HVDC in Power Flow Calculation Using Unified Methodology2011Ingår i: Innovative Smart Grid Technologies (ISGT) Conference, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a new unified method for power flowcalculation in AC grids with embedded multi-terminal HVDCsystems based on voltage source converter is proposed. In thismethod all DC and AC equations are solved simultaneously inthe same iteration while there is no need to rely on resultsobtained from other iterative loops unlike the other methods.The method can be applied for any number of converters,any DC network configuration and any converter loss model.The algorithm is implemented in MATLAB and to validate theresults, they are compared to results obtained from the simulationsoftware SIMPOW.

  • 185.
    Baradar, Mohamadreza
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Van Hertem, Dirk
    Electrical engineering, Katholieke Universiteit Leuven, Heverlee, Belgium.
    Kargarian, Amin
    Electrical and Computer Engineering, Mississippi State University.
    Power flow calculation of hybrid AC/DC power systems2012Ingår i: Power and Energy Society General Meeting, 2012 IEEE, IEEE , 2012, s. 6343958-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Multi-terminal HVDC systems have recently become an attractive option for interconnection of isolated AC systems such as offshore wind farms and oil platforms to asynchronous large AC systems. This paper deals with power flow calculation (PFC) of hybrid AC/DC power systems where several asynchronous AC systems are interconnected via a common multiterminal VSC-HVDC system. This paper proposes a unified AC-DC approach for PFC of a hybrid AC/DC power system. The proposed approach is then employed for two different analyses, namely a) the separated analysis where the entire hybrid AC/DC system is divided into two groups. The first group (named external AC system) comprises all asynchronous AC systems which are not directly connected to the slack convertor of the DC network, and the second group comprises an AC/DC system where the selected AC system is directly connected to the slack convertor. In this method, a PFC is firstly performed for the the first group, and its relevant obtained results will be used for PFC of the second group. b) the integrated analysis where the entire hybrid system is considered as a unit. Both a) and b) can be used in the practical analysis of the real-size power systems. However, due to practical issues and computational costs the separated analysis may be a more acceptable method. The simulations have been performed using MATLAB, and the obtained results have been compared with those obtained in SIMPOW.

  • 186.
    Baradar, Mohamadreza
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Hesamzadeh, Mohammad R.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Transmission Loss Minimisation in Power Systems with Embedded Smart-Grid Technologies2013Ingår i: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679Artikel i tidskrift (Övrigt vetenskapligt)
  • 187.
    Baradar, Mohamadreza
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Hesamzadeh, Mohammad R.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Second-order cone programming for optimal power flow in VSC-type AC-DC grids2013Ingår i: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 28, nr 4, s. 4282-4291Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a second order cone programming (SOCP) formulation of the optimal power flow problem for AC-DC systems with voltage source converter (VSC) technology. Approximation techniques have been used to derive the SOCP formulation of the AC-DC OPF problem. Later, the SOCP formulation can be solved using the interior point method (IPM) by considering the limits on AC-DC grid. The accuracy of SOCP formulation of AC OPF has been proven with numerical examples using IEEE 14-bus, IEEE 30-bus, and IEEE 57-bus example systems. The results of the SOCP formulation are compared with available commercial software. Then a DC system with VSC technology is modeled in the IEEE 30-bus example system. The SOCP formulation of AC-DC OPF is applied to the modified IEEE 30-bus example system and the results are discussed. The limitations of derived SOCP formulation are also discussed.

  • 188.
    BARREIRO MANERO, ALBA
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Study of privacy aware distributed detection in a heating and ventilation system2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    De senaste studierna om sensorn ̈atverk ̈ar f ̈oranledd av en snabb utveckling inomtr ̊adl ̈os kommunikation. Studierna motiveras av de lovande till ̈ampningar somfinns inom ett flertal omr ̊aden. Utvecklingen av sensorn ̈atverk st ̊ar dock inf ̈orett antal utmaningar. Den personliga integriteten ̈ar en utav dessa utmaningar.Studien om sekretessbegr ̈ansade sensorn ̈atverk finns presenterad i tidigare verkd ̈ar integritetsrisken vid avlyssnings tas i beaktning inom det f ̈ordelade fysiskalagrets detektionsdesign. Dock saknas en rigor ̈os under ̈okning p ̊a mottagarensdriftegenskaper (ROC).Denna avhandling kommer att fokusera p ̊a ett parallellt distribuerat detek-tionsn ̈atverk med en fusions nod som fattar det slutgiltiga beslutet. Vi visar hurfusions ROC ̈andras med olika inst ̈allningar n ̈ar man tar h ̈ansyn till begr ̈ansadsekretess. F ̈orst studeras ett Bayesianskt detekteringsscenario. Sedan kommervissa parametrar modifieras i syfte att studera dess inverkan p ̊a ROC. Slutligenanalyseras det andra scenariot d ̈ar avlyssningen modelleras som en Neyman-Pearson detektion medan inst ̈allningarna f ̈or det Bayesiansk distribuerade de-tekteringssystemet fortfarande h ̊aller.

  • 189.
    Barreto, Sergio
    et al.
    EPFL.
    Shereen, Ezzeldin
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Pignati, Marco
    EPFL.
    Dán, György
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Le Boudec, Jean-Yves
    EPFL.
    Paolone, Mario
    EPFL.
    A Continuum of Undetectable Timing-Attacks on PMU-based Linear State-Estimation2017Ingår i: 2017 IEEE International Conference on Smart Grid Communications, SmartGridComm 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 473-479Konferensbidrag (Refereegranskat)
  • 190. Barrios, C. A.
    et al.
    Holgado, M.
    Guarneros, O.
    Gylfason, Kristinn Björgvin
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Sanchez, B.
    Casquel, R.
    Sohlström, Hans
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Reconfiguration of microring resonators by liquid adhesion2008Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, nr 20, artikel-id 203114Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a procedure to reconfigure microring resonators based on liquid surface adhesion. Droplets of organic solvents were deposited over Si3N4/SiO2 strip- and slot-waveguide ring resonators, and the transmission spectra were measured several hours after the evaporation of the droplets at room temperature. Our measurements show that the optical properties of the microrings are significantly modified by liquid adhered to the waveguides, persisting even 96 h after bulk evaporation. Liquid-solid interfacial forces slow down liquid evaporation at the nanoscale, enabling permanent photonic configurations. Rewriteability is achieved by removing the adhered liquid with heat.

  • 191.
    Barrios, Carlos Angulo
    et al.
    Univ. Politécnica de Valencia.
    Gylfason, Kristinn B.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Sanchez, Benito
    Griol, Amadeu
    Univ. Politécnica de Valencia.
    Sohlström, Hans
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Holgado, Miguel
    Univ. Politécnica de Madrid.
    Casquel, Rafael
    Integrated slot-waveguide microresonator for biochemical sensing2008Ingår i: Proceedings Europtrode IX, 2008Konferensbidrag (Refereegranskat)
  • 192. Barrios, Carlos Angulo
    et al.
    Sanchez, Benito
    Gylfason, Kristinn Björgvin
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Griol, Amadeu
    Sohlström, Hans
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Holgado, Miquel
    Casquel, Raphael
    Demonstration of slot-waveguide structures on silicon nitride / silicon oxide platform2007Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 15, nr 11, s. 6846-6856Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the first demonstration of guiding light in vertical slot-waveguides on silicon nitride/silicon oxide material system. Integrated ring resonators and Fabry-Perot cavities have been fabricated and characterized in order to determine optical features of the slot-waveguides. Group index behavior evidences guiding and confinement in the low-index slot region at O-band (1260-1370nm) telecommunication wavelengths. Propagation losses of < 20 dB/cm have been measured for the transverse-electric mode of the slot-waveguides.

  • 193. Barrios, Carlos
    et al.
    Gylfason, Kristinn B.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Sánches, Benito
    Sohlström, Hans
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Griol, Amadeu
    Casquel, Rafael
    Holgado, Miguel
    Integrated Si3N4/SiO2 Slot-Waveguide Microresonators2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    We demonstrate slot-waveguide microring resonators and Fabry-Perot microcavities on Si3N4/SiO2. Characterization indicates guiding and confinement in the waveguide nanometric-size low-index slot region at O-band (1260-1370nm) wavelengths. We measured propagation losses <20 dB/cm.

  • 194.
    Barth, Christopher
    et al.
    Univ Illinois, Elect & Comp Engn Dept, 1406 W Green St, Urbana, IL 61801 USA..
    Colmenares, Juan
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Foulkes, Thomas
    Univ Illinois, Elect & Comp Engn Dept, 1406 W Green St, Urbana, IL 61801 USA..
    Coulson, Keith
    Univ Illinois, Mech Sci & Engn Dept, Urbana, IL USA..
    Sotelo, Jesus
    Univ Illinois, Mech Sci & Engn Dept, Urbana, IL USA..
    Modeer, Tomas
    Univ Illinois, Elect & Comp Engn Dept, 1406 W Green St, Urbana, IL 61801 USA..
    Miljkovic, Nenad
    Univ Illinois, Mech Sci & Engn Dept, Urbana, IL USA..
    Pilawa-Podgurski, Robert C. N.
    Univ Illinois, Elect & Comp Engn Dept, 1406 W Green St, Urbana, IL 61801 USA..
    Experimental Evaluation of a 1 kW, Single-Phase, 3-Level Gallium Nitride Inverter in hxtreme Cold Environment2017Ingår i: 2017 THIRTY SECOND ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC), IEEE , 2017, s. 717-723Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work investigates the potential for high power density, high efficiency power conversion at extreme cold temperatures, for hybrid electric aircraft applications. A 1 kW GaN-based 3-level power converter was designed and successfully tested from room temperature down to -140 degrees C, using a custom milled cold-plate. Along with the first demonstration of a flying capacitor multi-level converter and associated components at such low temperature, this work characterized the effect on power conversion losses of various components as a function of temperature. A key finding is that careful attention must be paid to the passive component losses which can increase as the temperature is reduced.

  • 195. Bastos, Miguel Cerqueira
    et al.
    Fernqvist, Gunnar
    Hudson, Gregory
    Pett, John
    Cantone, Andrea
    Power, Francis
    Saab, Alfredo
    Halvarsson, Björn
    KTH.
    Pickering, John
    High Accuracy Current Measurement in the Main Power Converters of the Large Hadron Collider: Tutorial 53 Part 53 in a series of tutorials on instrumentation and measurement2014Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 17, nr 1, s. 66-73Artikel i tidskrift (Refereegranskat)
  • 196.
    Baudette, Maxime
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Fast Real-time Detection of Sub-Synchronous Oscillations in PowerSystems using Synchrophasors2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Recent concerns about the environment have resultedinto large investments in renewable energies for electricityproduction, especially wind power. The integration of renewablesources of energy raises however several problemswhich have not yet been completely understood nor studied.Oscillatory events around 13 Hz have been recorded inthe US by Oklahoma Gas & Electric (OG&E). Such a highfrequency is very different from the traditional and wellstudied Inter-area oscillations, it is also beyond the measurementcapabilities of most of the existing measurementequipments and monitoring tools.

    This Thesis focuses on the development and implementationof algorithms for oscillation detection which can supportreal-time monitoring tools. It proposes a real-timemonitoring tool that exploits synchronized phasor measurementsfrom PMUs, which allow real-time analysis of higherfrequency events, filling the lack of such monitoring applicationin the power systems area. This tool was built as aprototype for real-time applications which utilize real-timePMU data for enhanced monitoring and control of powergrids.

  • 197. Baudette, Maxime
    et al.
    Firouzi, Seyed Reza
    Vanfretti, L.
    The STRONgrid library: A modular and extensible software library for IEEE C37.118.2 compliant synchrophasor data mediation2018Ingår i: Software Quality Professional, ISSN 1522-0540, Vol. 7, s. 281-286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electric power grids expose highly dynamic behaviors that can be mitigated by exploiting Wide-Area Monitoring, Protection And Control (WAMPAC) technologies. These technologies rely on utilizing the synchrophasor measurements provided by the Phasor Measurement Units (PMUs). The IEEE C37.118.2 standard defines a method for real-time communication of synchrophasor data between PMUs, Phasor Data Concentrators (PDCs) and other applications. This paper describes the Smart Transmission Grid Operation and Control (STRONgrid) library, which serves as a real-time data mediator (i.e. interface) between the IEEE C37.118.2 protocol and applications consuming PMU measurements. The STRONgrid library packages all the necessary components to allow the researchers to focus on the development of synchrophasor applications in higher level programming environments (e.g. LabVIEW).

  • 198.
    Baudette, Maxime
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Del Rosario, Gerard
    IREC.
    Ruiz Alvarez, Albert
    IREC.
    Dominguez Garcia, Jose Luis
    IREC.
    Al-Khatib, Iyad
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Shoaib Almas, Muhammad
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Gjerde, Jan Ove
    Statnett SF.
    Validating a real-time PMU-based application for monitoring of sub-synchronous wind farm oscillations2014Ingår i: 2014 IEEE PES Innovative Smart Grid Technologies Conference, 2014, s. 1-5Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents validation experiments performed on a Phasor Measurement Unit (PMU) based fast oscillation detection application. The monitoring application focuses on the detection of sub-synchronous oscillations, utilizing real-time measurements from PMUs. The application was first tested through Hardware-In-the-Loop (HIL) simulation. Validation experiments were carried out with a different set-up by utilizing a micro grid laboratory. This second experimental set-up as well as the results of the validation experiments are presented in this paper.

  • 199.
    Baykov, Vitaly
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Korzhavyi, Pavel A.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Johansson, Börje
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Diffusion of Interstitial Mn in the Dilute Magnetic Semiconductor (Ga,Mn)As: The Effect of a Charge State2008Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, nr 17, s. 177204-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Migration barriers for diffusion of interstitial Mn in the dilute magnetic semiconductor (Ga,Mn)As are studied using first-principles calculations. The diffusion pathway goes through two types of interstitial sites: As coordinated and Ga coordinated. The energy profile along the path is found to depend on the ratio of concentrations between substitutional and interstitial Mn in GaAs. Two regions of distinctly different behavior, corresponding to n-type and p-type (Ga,Mn)As, are identified. The difference in mobility is a reflection of the change in the charge state of Mn interstitials (double donors) that occurs in the presence of substitutional Mn impurities (acceptors). In addition, substitutional Mn impurities are shown to act as traps for interstitial Mn. The effective migration barrier for the positively doubly charged Mn interstitials in p-type (Ga,Mn)As is estimated to vary from 0.55 to about 0.95 eV.

  • 200.
    Becerra Garcia, Marley
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Glow corona discharges and their effect on lightning attachment: Revisited2012Ingår i: Lightning Protection (ICLP), 2012 International Conference on, IEEE , 2012, s. 6344402-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Previous studies in the literature have suggested that glow corona discharges could be potentially used to control the frequency of lightning flashes to grounded objects. Such studies use simplified one-dimensional corona drift models or basic empirical equations derived from high voltage experiments to assess the effect of glow corona on the initiation of both streamers and upward connecting leaders under the influence of a descending lightning leader. In order to revisit the theoretical basis of these studies, a two-dimensional glow corona drift model has been implemented together with a self-consistent upward leader inception and propagation model -SLIM-. A 60 m tall lightning rod is used as a study case. It is found that the shielding effect of the glow corona space charge has been strongly overestimated in the literature. Furthermore, it is shown that streamers under the influence of a descending leader are initiated significantly earlier from the cylindrical body rather than from the corona-emitting area of the rod. Considering the effective shielding potential of glow corona, it is also shown that the presence of glow corona reduces the downward lightning attractiveness of 60 m tall lightning rods by less than 15%. This result shows that the efficiency of lightning rods is not strongly influenced by the generation of glow corona as opposed to the suggestions of previous studies.

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