Ändra sökning
Avgränsa sökresultatet
2458245924602461246224632464 123001 - 123050 av 124243
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 123001.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Viotti, Anne-Lise
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Highly-efficient cascaded mirrorless OPO in sub-µm periodically poled RKTP crystals2017Konferensbidrag (Refereegranskat)
  • 123002.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Viotti, Anne-Lise
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Highly-efficient cascaded mirrorless OPO in sub-μm periodically poled RKTP crystals2017Ingår i: Optics InfoBase Conference Papers, Optical Society of America, 2017, Vol. Part F41Konferensbidrag (Refereegranskat)
    Abstract [en]

    We demonstrate low threshold mirrorless optical parametric oscillation in sub-μm periodically poled RKTP crystals reaching an efficiency of 43%. The generated signal serves as a pump in a cascaded MOPO process in the same crystal.

  • 123003.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Bulk Self-assembled Ferroelectric Domain Structures in RKTP2016Konferensbidrag (Refereegranskat)
  • 123004.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Quasi-periodic self-assembled sub-micrometer ferroelectric bulk domain gratings in Rb-doped KTiOPO42013Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, nr 25, s. 252905-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a simple technique for fabricating quasi-periodic bulk sub-μm ferroelectric domain gratings in Rb-doped KTiOPO4 (RKTP) based on self-organized ferroelectric domain formation. One-dimensional ferroelectric domain structures, with an average periodicity of 650 ± 200 nm and extending throughout 1 mm thick crystals, are obtained by etching and subsequent electric field poling using planar electrodes. The sub-μm structures in RKTP were used to demonstrate 5th order non-collinear quasi-phase matched backward second harmonic generation.

  • 123005.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Second-harmonic generation in periodically poled bulk Rb-doped KTiOPO4 below 400 nm at high peak-intensities2013Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, nr 2, s. 1395-1403Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate that bulk Rb-doped KTiOPO4 (RKTP) shows improved susceptibility to gray-tracking compared to flux-grown KTiOPO4. We show high-fidelity periodic poling of 1 mm thick RKTP with a period of 3.18 mu m for second harmonic generation at 398 nm with a normalized conversion efficiency of 1.79%/Wcm. The crystal is used to frequency-double 138 fs-long pulses with an efficiency of 20% and a peak intensity of 560 MW/cm(2) without visible gray-tracking signs. We demonstrate that two-photon absorption is the predominant mechanism limiting the SHG efficiency in this spectral range at high peak powers and high repetition rates.

  • 123006.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Fan-out periodically poled structures in Rb-doped KTiOPO4 for continuously tunable QPM devices2019Ingår i: NONLINEAR FREQUENCY GENERATION AND CONVERSION: MATERIALS AND DEVICES XVIII / [ed] Schunemann, PG Schepler, KL, SPIE-INT SOC OPTICAL ENGINEERING , 2019, artikel-id UNSP 109020NKonferensbidrag (Refereegranskat)
    Abstract [en]

    Since the first demonstration of electric field poling in 1993, the use of quasi-phase matching (QPM) technique has gained wide adoption in a multitude of applications. The QPM field today is dominated mainly by the ferroelectric oxide materials from LiNbO3 (LN) and KTiOPO4 (KTP) families, where QPM structures are implemented by the electric field poling technique. While typical QPM devices have a fixed-period, one-dimensional domain grating design, which is the most straightforward to implement, numerous applications require the ability to continuously tune the wavelength over a wider spectral range. For applications where temperature tuning is not desired, a fan-out QPM grating design may be advantageous. The tuning here is performed by transverse translation of the structure in respect to the pump beam, while keeping the crystal temperature constant. While the implementation of fan-out gratings is reasonably well researched in LN, there is a lack of reliable data for KTP isomorphs. Taking into account the high domain growth anisotropy in KTP, an important factor becomes the angle between the domain walls and the b-axis of the crystal. This angle directly affects the quality and dimensions of the QPM device. However, its upper boundary has not been determined to date. In this work we discuss the prospects and limitations of PPKTP devices with fan-out grating designs. We present a fan-out PPRKTP device, where the transverse fan-out rate is 0.5 mu m/mm. In an OPO configuration pumped by 532 nm such PPRKTP crystal is able to provide continuously tunable radiation between 0.7 -2.2 mu m.

  • 123007.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Grey-Track Resistant Periodically Poled Rb-doped KTiOPO4 For Blue-Light Generation2010Ingår i: Optics InfoBase Conference Papers, 2010, s. 5500148-Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present periodic poling of Rb-doped KTiOPO4. The crystal is used to obtain blue radiation at 398 nm with an efficiency of 30% and a peak intensity of 2 MW/cm2 without grey-tracking.

  • 123008.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Royal Inst Technol, Dept Appl Phys, S-10691 Stockholm, Sweden..
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Grey-Track Resistant Periodically Poled Rb-doped KTiOPO(4) For Blue-Light Generation2010Ingår i: 2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), IEEE , 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present periodic poling of Rb-doped KTiOPO(4). The crystal is used to obtain blue radiation at 398 nm with an efficiency of 30% and a peak intensity of 2 MW/cm(2) without grey-tracking.

  • 123009.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    High-fidelity periodic domain structures in KTiOAsO4 for the visible spectral range2013Ingår i: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 3, nr 9, s. 1444-1449Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate room temperature periodic poling of KTiOAsO4 crystals with a period of 8.49 mu m for second harmonic generation of 1066 nm wavelength. The crystals are tested in a continuous wave SHG setup at 533 nm and show high quality periodic ferroelectric domain structure across the whole 1 mm crystal thickness, exhibiting d(eff) = 10.5 pm/V and normalized conversion efficiency of 1.2%/Wcm.

  • 123010.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Periodically poled KTiOAsO4 for second harmonic generation in the green region2013Ingår i: 2013 Conference on Lasers and Electro-Optics, CLEO 2013, IEEE Computer Society, 2013, s. 6833702-Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present high-quality room temperature periodic poling of KTiOAsO4 with a period of 8.49 μm. The crystals are evaluated for SHG at 533 nm, and show deff = 10.5 pm/V and ηnorm = 1.19%/Wcm. OCIS codes: 190.4400 (Nonlinear optics, materials); 160.2260 (Ferroelectrics).

  • 123011.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Self-assembled ferroelectric nano-domain gratings in bulk RKTP2012Ingår i: 2012 Conference on Lasers and Electro-Optics, CLEO 2012, IEEE , 2012, s. 6325938-Konferensbidrag (Refereegranskat)
    Abstract [en]

     We present the fabrication of self-assembled bulk domain gratings of sub-μm periodicity in Rb-doped KTiOPO4 crystals. The structures are used to demonstrate QPM backwards propagating non-collinear second harmonic generation.

  • 123012.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Safinas, Maratas
    Ekspla Ltd..
    Michailovas, Andrejus
    Ekspla Ltd..
    High-Performance Periodically Poled Rb-doped KTP For Frequency Conversion In Blue/Green Region2010Ingår i: Conference digest, 2010Konferensbidrag (Refereegranskat)
  • 123013.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Strömqvist, Gustav
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Fokine, Michael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Fabrication of submicrometer quasi-phase-matched devices in KTP and RKTP [Invited]2011Ingår i: Optical Materials Express, ISSN 2159-3930, Vol. 1, nr 7, s. 1319-1325Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We review the techniques used for fabrication of bulk submicrometer ferroelectric domain gratings in KTiOPO4 (KTP) and demonstrate that bulk Rb-doped KTiOPO4 (RKTP) is an excellent candidate for implementation of dense domain gratings. Compared to KTP, RKTP presents predominant domain propagation along the polar c-direction, substantially reduced lateral domain broadening, and higher poling yield. As a result we obtain homogeneous sub-μm periodic poling of RKTP with a period of 690 nm in 1 mm thick samples.

  • 123014.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    5 mm thick periodically poled Rb-doped KTP for high energy optical parametric frequency conversion2011Ingår i: Optical Materials Express, ISSN 2159-3930, Vol. 1, nr 2, s. 201-206Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A 5 mm thick periodically poled bulk Rb-doped KTiOPO4 (KTP) crystal with a period of 38.86 μm was fabricated by electric field poling. Chemical etching and optical evaluation show a high quality of the periodic ferroelectric domain structure through the whole crystal aperture. The fabricated quasi-phase matching (QPM) device was used in an optical parametric oscillator pumped at 1064 nm with 12 ns pulses at 100 Hz repetition rate to generate 60 mJ parametric radiation with a conversion efficiency of 50%.

  • 123015.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    5 mm Thick Periodically Poled Rb:KTiOPO4 for High Power Optical Frequency Conversion2011Ingår i: Advanced Solid State Photonics 2011, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    A periodically poled bulk Rb-doped KTiOPO 4crystal with 5 mm aperture was fabricated at room temperature. The ferroelectric domain structure is shown to be homogeneous across the whole aperture with a deffof 11 pm/V.

  • 123016.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    High Fidelity Large Aperture Periodically Poled Rb:KTiOPO(4) for High Energy Frequency Conversion2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    We demonstrate periodic poling of 5 mm thick Rb-doped KTiOPO(4) crystals at room temperature. The ferroelectric domain grating is shown to be uniform and homogeneous across the whole crystal aperture.

  • 123017.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Periodically poled KTiOAsO4 for highly efficient midinfrared optical parametric devices2009Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, nr 19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate high pattern-fidelity periodic poling of KTiOAsO4 at room temperature. The periodically poled crystal shows a d(eff) of 10.1 pm/V and is used in an optical parametric oscillator pumped at 1064 nm to generate parametric radiation at 1538 and 3452 nm with a conversion efficiency of 45%.

  • 123018.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Periodically Poled KTiOAsO4 For Mid-Infrared Light Generation2010Ingår i: Advanced Solid-State Photonics 2010, 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    A periodically poled KTiOAsO4crystal was fabricated at room temperature. The poled crystal shows a deffof 10.1 pm/V and gives a parametric conversion efficiency of 45%.

  • 123019.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Viotti, Anne-Lise
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Cascaded counter-propagating nonlinear interactions inhighly-efficient sub-μm periodically poled crystals2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikel-id 8037Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mirrorless optical parametric oscillators (MOPOs) are very attractive parametric devices that rely on the nonlinear interaction of counter-propagating photons to inherently establish distributed feedback, without the use of external mirrors or surface coatings. These devices offer unique spectral and coherence properties that will benefit a large variety of applications ranging from spectroscopy to quantum communications. The major obstacle in exploiting their full potential is ascribed to the difficulty in engineering a nonlinear material in which the generation of counter-propagating waves can be phase matched. Here we present a reliable and consistent technique for fabrication of highly-efficient sub-micrometer periodically poled Rb-doped KTiOPO4. We experimentally demonstrate the first cascaded counter-propagating interactions in which the generated forward signal serves as a pump for a secondary MOPO process, reaching pump depletion larger than 60%. The cascaded process exemplifies the high efficiency of our nonlinear photonic structures. Our domain-engineering technique paves the way to realize counter-propagating schemes and devices that have been deemed unfeasible until now.

  • 123020.
    Zuleger, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Modeling Sheet Forming of CompositeAerospace Component2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The aerospace industry becomes more and more accustomed with automated processing.Current manufacturing techniques are under development for higher automation. Within thiswork the behavior of prepreg material during forming is investigated, conducting simulationson previously performed experiments at SAAB AB. The aim is to implement materialbehavior in the AniForm Virtual Forming Tool simulation. The results of various experimentshave been combined to generate the basic material properties to assemble the materialbehavior and the experiment. With the use of investigated simplifications, the possibilities ofthe AniForm Virtual Forming Tool are used to compare two experiments conducted. Byrelating the simulations of wrinkled and non-wrinkled trials, the analysis of stresses andstrains within the simulation output is conducted. With the outcomes of these simulations,previously taken assumptions on fiber direction behavior are investigated. With the resultsshowing no geometrical wrinkling of the prepreg material itself, indicators for wrinkling areexamined on the output of the results. It can be seen that looking at various parametersexclusively does not necessarily explain the wrinkling of the prepreg material. Multiplefactors need to be taken into account at the same time. The results indicate that alignment ofstress- and strain behavior next to the fiber angle deviations play important parts in futureinvestigations regarding wrinkle development.Die Luftfahrtindustrie wird mehr und mehr mit automatisierten Prozessen vertraut.Fertigungstechnologien werden in Bezug auf einen höheren Automatisierungsgrad entwickelt.Innerhalb dieser Arbeit wird das Verhalten von Prepreg Material während des Formprozessesuntersucht, indem bereits durch die SAAB AB durchgeführte Experimente simuliert werden.Das Ziel ist, das Materialverhalten in die Simulationen mit dem AniForm Virtual FormingTool einzubinden. Die Resultate verschiedener Experimente werden zusammen geführt, umdie Materialeigenschaften für das Prepreg sowie die Simulation zusammen zu stellen. Durchdie Nutzung untersuchter Vereinfachungen werden die Möglichkeiten des AniForm VirtualForming Tools genutzt, um zwei durchgeführte Experimente zu prüfen. Durch dasvergleichen der Simulationsergebnisse von Experimenten mit und ohne Faltenbildung könnendie Resultate im Hinblick auf Spannungen und Dehnungen analysiert werden. Außerdem wirdIImit den Ergebnissen der Simulation das vorausgesagte Verhalten von Faserrichtungenuntersucht. Da die Ergebnisse keine geometrische Faltenbildung des Prepreg Materials selbstzeigen, werden andere Indikatoren für die Faltenbildung untersucht. Es lässt sich erkennen,dass das Betrachten von einzelnen Parametern ohne Verknüpfung mit anderen Resultaten eineeventuelle Faltenbildung im Prepreg Material nicht notwendiger weise erklären kann.Verschiedene Faktoren müssen gleichzeitig betrachtet werden. Die Resultate deuten daraufhin, dass die Ausrichtung von Stress- und Dehnungs-Verhalten sowie die Abweichungen derFaserwinkel eine wichtige Rolle bei zukünftigen Betrachtungen von Faltenbildung spielen.

  • 123021.
    Zuleta, Marcelo
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Electrochemical and ion transport characterisation of a nanoporous carbon derived from SiC2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this doctoral project, a relatively new form of carbon material, with unique narrow pore size distribution around 7 Å and with uniform structure, has been electrochemically characterised using the single particle microelectrode technique. The carbon has been used as electrode material for supercapacitors. This type of capacitors is used as high power energy buffers in hybrid vehicles and for stationary power backup. The principle for the microelectrode technique consists of connecting a carbon particle with a carbon fibre by means of a micromanipulator. The single particle and carbon fibre together form a microelectrode. Combination of this technique with electroanalytical methods such as cyclic voltammetry and potential step measurements allows for the survey of electrochemical phenomena and for the determination of ion transport parameters inside the nanopores.

    A mathematical model based on Fick’s second law, for diffusion of ions inside the nanopores at non steady state, was used for the determination of effective diffusion coefficients (Deff). The coefficients were calculated from an asymptotic solution of Fick’s equation, applied for a thin layer adjacent to the external surface of the carbon particles and valid for the current response in a short time region. Another asymptotic solution was obtained, using spherical geometry and valid for the current response in a long time region.

    In this doctoral work, the carbon particles have been exposed to potential cycling, which mimics that of large electrodes during operation of a double layer capacitor. The potential-current response, E-I, for the nanoporous carbon, shows a pure capacitive behaviour between –0.5 V and 0.1 V vs. the Hg|HgO reference electrode. The detection of the faradaic processes beyond these potentials was possible by lowering of the voltammometric sweep rate. The electrochemical processes occurring at positive and at negative potential were investigated separately.

    Cyclic voltammometric measurements showed that the chemisorption of hydroxyl groups, occurring between 0.1 and 0.3 V, leads to a mild oxidation of the carbon structure, resulting in surface groups containing an oxygen atom at a specific carbon site (e.g., phenolic or quinine type). These oxygen-containing surface groups caused an increase of the specific capacitance, which remained constant throughout a number of voltammometric cycles. The Deff decreased on the other hand with the number of cycles. The Deff decreases also with the positive potential. The evaluation of Deff indicates adsorption of hydroxyl groups and an increase of the effective tortuosity of the pore system.

    The oxidation of the carbon particles, between 0 and 0.5 V, leads to more extensive oxidation and to surface groups containing two oxygen atoms at a single carbon site, followed by formation of carbonate ions. The oxygen-containing surface groups and carbonate ions formed at these potentials do not contribute to the specific capacitance and drastically retard or obstruct the ion transport inside the nanopores.

    At negative potentials the carbon particles show a dominantly capacitive behaviour. The faradaic processes taking place below –0.5 V vs. Hg|HgO reference electrode are generation and adsorption of hydrogen. These processes do not perturb significantly the electrochemical and ion transport properties of the nanoporous carbon particles. It was found that hydrogen generation occurs at –0.5 V vs. Hg|HgO and that two hydrogen oxidation processes take place at positive potentials. The results indicate that the weakly adsorbed hydrogen undergoes oxidation between 0 and 0.1 V and that the strongly adsorbed hydrogen is oxidised at more positive potentials.

    The single particle technique was adapted for the determination of diffusion coefficients of an organic electrolyte. The different size of the anions and cations caused different transport characteristics at negative and positive potentials. Slow cycling was found important for ion penetration inside the nanopores and for the evaluation of the effective diffusion coefficients.

    The effective diffusion coefficients for the nanoporous carbon using aqueous 6M KOH and 0.1M TEABF4 in acetonitrile were estimated to 1.4 (±0.8).10-9 cm2 s-1 and 1.3 (±0.4) 10-8 cm2 s-1, respectively.

  • 123022.
    Zuleta, Marcelo
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Björnbom, Pehr
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Characterization of the electrochemical and ion-transport properties of a nanoporous carbon at negative polarization by the single-particle method2006Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, nr 1, s. A48-A57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, the electrochemical processes occurring in a nanoporous carbon, obtained from silicon carbide and used as negative electrode material for supercapacitors, have been investigated by means of the single-particle microelectrode method. The processes studied deal with hydrogen adsorption, evolution, and oxidation using 6 M KOH as electrolyte. It was found that adsorption of hydrogen started at -0.5 V, hydrogen evolution at -1.4 V vs Hg vertical bar HgO, and that hydrogen oxidation occurs in two steps. The first oxidation process takes place between 0 and 0.1 V, shown by a well-defined current peak on the voltammograms. The second oxidation stage occurs between 0.1 and 0.5 V, indicated by a successive increase in current with the number of cycles. It was also found that after the first oxidation process, subsequent cycling between -0.5 and -1 V leads to a larger accumulation of hydrogen inside the nanopores and to a decrease of the effective diffusion coefficient (D-eff) of potassium ions. Subsequent oxidation, in a second process, leads to a total consumption of hydrogen and to an increase of D-eff.

  • 123023.
    Zuleta, Marcelo
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Björnbom, Pehr
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Effects of pore surface oxidation on electrochemical and mass-transport properties of nanoporous carbon2005Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, nr 2, s. A270-A276Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new nanoporous (NP) carbon material with a high surface area and a narrow pore size distribution, around 8 A, has been used to investigate the effects that electrochemical oxidation at positive potentials exerts on the capacitance values and effective diffusion coefficients of ions inside the nanopores. An electroanalytical method, based on the single-particle microelectrode technique with micromanipulator, was applied to calculate the diffusion coefficients of 6 M KOH ions in NP carbon. The results were analyzed for short times using the Cottrell model and for long times using the spherical diffusion model. Using cyclic voltammetry, was found that different stages of oxidation took place between 0 and 0.5 V vs. Hg\HgO. After repeated cycling in the first region of oxidation (0-0.3 V), an activation leading to higher capacitance was observed, but the diffusion coefficients decreased from approximately 2 x 10(-9) to 0.5 x 10(-10) cm(2) s(-1). In the second region of oxidation (0.3-0.5 V), where CO2 and 02 evolution can occur, both the capacitance and the diffusion coefficients decreased more dramatically. The effective diffusion coefficients of ions of an activated carbon particle were dependent on the operation potential; decreasing by an order of magnitude when going from -0.3 to +0.3 V. The results are discussed in terms of chemisorption of small oxygen functional groups (-OH or C=O) and ionic interaction with the pore wall.

  • 123024.
    Zuleta, Marcelo
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Björnbom, Pehr
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Nurk, G.
    Kasuk, H.
    Lust, E.
    Determination of diffusion coefficients of BF4- inside carbon nanopores using the single particle microelectrode technique2006Ingår i: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 586, nr 2, s. 247-259Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrochemical and mass transport properties of TEABF(4) in a nanoporous (NP) carbon material, obtained from silicon carbide, was studied using single particles and a microelectrode technique. The carbon particles of size 100-200 mu m were studied by cyclic voltammetry and potential step measurements. The effective diffusion coefficients (D-eff) were calculated starting from the asymptotic solutions of Fick's second law for short and long time regions. The results show that cycling at low sweep rates was needed in order for the electrolyte to penetrate the inner porosity of the particles. The carbon material showed different electrochemical and mass transport properties depending on the applied potential. At negative polarisation, the results suggest that TEA(+) was adsorbed on the pore wall, however, being transported very slowly inside the pores. The average D-eff after cycling at both positive and negative potentials was 1.1(+/- 0.4) x 10(-8) cm(2) s(-1), using the Cottrell relation and 1.5(+/- 0.6) x 10(-8) cm(2) s(-1), using the radial diffusion solution. The average value of D-eff after cycling at negative potentials was 1.7(+/- 0.6) x 10(-8) cm(2) s(-1) using both mathematical solutions.

  • 123025.
    Zuleta, Marcelo
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Bursell, Martin
    KTH, Tidigare Institutioner, Kemiteknik.
    Björnbom, Pehr
    KTH, Tidigare Institutioner, Kemiteknik.
    Lundblad, Anders
    KTH, Tidigare Institutioner, Kemiteknik.
    Determination of the effective diffusion coefficient of nanoporous carbon by means of a single particle microelectrode technique2003Ingår i: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 549, s. 101-108Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A single particle microelectrode technique with a micromanipulator was applied and adapted for characterisation of mass transport properties of ionic species in a high surface area nanoporous carbon, with uniform pore size of 8 Angstrom. The effective diffusivity of 6 M KOH in this material was determined by means of potential step experiments on nanoporous carbon particles of different sizes. The results were analysed for short times (Cottrell model) and for long times (spherical diffusion model). The average effective diffusion coefficient for short and long times was 1.5x10(-9) and 1.2x10(-9) cm(2) s(-1), respectively. The relatively small diffusivity values are discussed in terms of interaction between the ion hydration shell and water molecules adsorbed on the pore wall.

  • 123026.
    Zuleta, Marcelo
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Bursell, Martin
    KTH, Tidigare Institutioner, Kemiteknik.
    Lundblad, Anders
    KTH, Tidigare Institutioner, Kemiteknik.
    Characterization of ion transport in a nanoporous carbon for double layer capacitors2000Ingår i: Proceedings of Advances in Science and technology 29: (Mass and Charge Transport in Inorganic Materials: Fundamentals to devices, part A), 2000, s. 439-446Konferensbidrag (Refereegranskat)
  • 123027.
    Zuleta, Marcelo
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Edvinsson, Tomas
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Ahmadi, Sareh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Boschloo, Gerrit
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Hagfeldt, Anders
    Light-induced rearrangements of chemisorbed dyes on anatase(101)2012Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 14, nr 30, s. 10780-10788Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photoinduced molecular rearrangements are important in daily events essential for life such as visual perception and photo-protection of light harvesting complexes in plants. In this study we demonstrate that similar photoarrangements appear in an analogous technological application where the device performance is controlled by chromophores in sensitized anatase TiO2, one of the main components for light-harvesting in dye-sensitized solar cells (DSC). STM reveals that illumination leads to distortions of organic dyes containing conjugated backbones and of cis-bis(isothiocyanate)-bis-(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II)-bis(tetrabutylammonium), known as N719. The dyes were adsorbed in a closed-packed mode on an anatase(101) single crystal surface and imaged in the dark and under white light illumination in an ultra-high vacuum (UHV). STM images of N719 clearly suggest rearrangements caused by rotation of the dye. Conversely, organic dyes rearrange by photoisomerization depending on the number of double bonds, their position in the molecular structure and on the ligand modifications.

  • 123028.
    Zuleta, Marcelo
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Ahmadi, Sareh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Boschloo, Gerrit
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Hagfeldt, Anders
    Monitoring N719 Dye Configurations on (1 x n)-Reconstructed Anatase (100) by Means of STM: Reversible Configurational Changes upon Illumination2010Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, nr 16, s. 13236-13244Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report experimental results concerning the STM imaging of cis-bis (isothiocyanate)-bis-(2,2'-bipyridyl-4,4'dicarboxylate)ruthenium(II)bis( tetrabutylammonium) dye (known as N719) adsorbed on a single crystal of anatase TiO2(100). The cleaning pretreatment, by sputtering and annealing, of TiO2(100) yields a reproducible (1 x n) surface reconstruction. Previous to dye deposition, TiO2 was covered with one monolayer of 4-tert-butylpyridine (4-TBP) in ultrahigh vacuum (UHV) in order to protect the surface against air contamination. N719 was subsequently deposited by dipping the crystal into the dye solution. 4-TBP was removed partially in the solution and totally by heating the sample to around 285-300 degrees C in UHV. The images of the deposited 4-TBP on TiO2(100) revealed a complete surface coverage showing three modes of adsorption on TiO2. The relatively uncomplicated desorption of 4-TBP enables the accommodation and chemisorption of most N719 molecules directly onto the TiO2 surface. The STM imaging of N719 was affected, in a reversible way, by illumination, because the quality of the image changed after a few hours in the dark or under illumination conditions. The results presented herein are discussed in terms of changes in molecular configurations and in open circuit potentials.

  • 123029. Zulkafli, Zed
    et al.
    Perez, Katya
    Vitolo, Claudia
    Buytaert, Wouter
    Karpouzoglou, Timothy
    Public Administration and Policy Group, Wageningen University, Netherlands.
    Dewulf, Art
    De Bièvre, Bert
    Clark, Julian
    Hannah, David M.
    Shaheed, Simrita
    User-driven design of decision support systems for polycentric environmental resources management2017Ingår i: Environmental Modelling & Software, ISSN 1364-8152, E-ISSN 1873-6726, Vol. 88, s. 58-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Open and decentralized technologies such as the Internet provide increasing opportunities to create knowledge and deliver computer-based decision support for multiple types of users across scales. However, environmental decision support systems/tools (henceforth EDSS) are often strongly science-driven and assuming single types of decision makers, and hence poorly suited for more decentralized and polycentric decision making contexts. In such contexts, EDSS need to be tailored to meet diverse user requirements to ensure that it provides useful (relevant), usable (intuitive), and exchangeable (institutionally unobstructed) information for decision support for different types of actors. To address these issues, we present a participatory framework for designing EDSS that emphasizes a more complete understanding of the decision making structures and iterative design of the user interface. We illustrate the application of the framework through a case study within the context of water-stressed upstream/downstream communities in Lima, Peru.

  • 123030.
    Zulu, Andrew Wisdom
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Thick Composite Properties and Testing Methods2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In most application to date reinforced carbon fiber composites have been used in relatively smaller thickness, less than 10mm thick and essentially for carrying in-plane loads. As a result, design and testing procedures were developed which reflected the need to understand the in-plane response of the material. recently, engineers and designers have begun to use reinforced carbon fiber composites in thicker sections, where an understanding of the through-thickness response is of para-mount importance in designing reliable structures, particularly where the through-thickness strength has a controlling influence on the overall structural strength of the component. In this thesis tests will be done on carbon fiber non-crimp fabric (NCF) which will be loaded in compression and shear and elastic moduli and strength will be evaluated. In characterizing the through-thickness mechanical properties of a composite, the objective is to produce a state of stress in the test specimen which is uniform and will repeatedly measure the true properties with accuracy. In this study, specimens were machined from two blocks of thick (~20 mm) laminates of glass/epoxy and NCF carbon fiber infused with vinylester and tested in compression, and shear.

  • 123031.
    Zumalacarregui, Miguel
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Bellini, Emilio
    Sawicki, Ignacy
    Lesgourgues, Julien
    Ferreira, Pedro G.
    hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System2017Ingår i: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, nr 8, artikel-id 019Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the public version of hi cl a ss (www . hiclass-code . net), an extension of the Boltzmann code CLASS to a broad ensemble of modifications to general relativity. In particular, hi cl a ss can calculate predictions for models based on Horndeski's theory, which is the most general scalar-tensor theory described by second-order equations of motion and encompasses any perfect-fluid dark energy, quintessence, Brans-Dicke, f( R) and covariant Galileon models. hi-class has been thoroughly tested and can be readily used to understand the impact of alternative theories of gravity on linear structure formation as well as for cosmological parameter extraction.

  • 123032.
    Zumalacarregui, Miguel
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Berkeley Center for Cosmological Physics, LBNL, University of California at Berkeley, Berkeley, CA 94720, United States; Institut de Physique Théorique, Université Paris Saclay CEA, CNRS, Gif-sur-Yvette, 91191, France.
    Seljak, U.
    Limits on Stellar-Mass Compact Objects as Dark Matter from Gravitational Lensing of Type Ia Supernovae2018Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, nr 14, artikel-id 141101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nature of dark matter (DM) remains unknown despite very precise knowledge of its abundance in the Universe. An alternative to new elementary particles postulates DM as made of macroscopic compact halo objects (MACHO) such as black holes formed in the very early Universe. Stellar-mass primordial black holes (PBHs) are subject to less robust constraints than other mass ranges and might be connected to gravitational-wave signals detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO). New methods are therefore necessary to constrain the viability of compact objects as a DM candidate. Here we report bounds on the abundance of compact objects from gravitational lensing of type Ia supernovae (SNe). Current SNe data sets constrain compact objects to represent less than 35.2% (Joint Lightcurve Analysis) and 37.2% (Union 2.1) of the total matter content in the Universe, at 95% confidence level. The results are valid for masses larger than ∼0.01 M (solar masses), limited by the size SNe relative to the lens Einstein radius. We demonstrate the mass range of the constraints by computing magnification probabilities for realistic SNe sizes and different values of the PBH mass. Our bounds are sensitive to the total abundance of compact objects with M0.01 M and complementary to other observational tests. These results are robust against cosmological parameters, outlier rejection, correlated noise, and selection bias. PBHs and other MACHOs are therefore ruled out as the dominant form of DM for objects associated to LIGO gravitational wave detections. These bounds constrain early-Universe models that predict stellar-mass PBH production and strengthen the case for lighter forms of DM, including new elementary particles.

  • 123033.
    Zuna, Lea
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Understanding and Improving the Utilization of Web and Mobile GIS Solutions for Outdoor Environment Management2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Träd, växter,vattenområden, lekplatser, grönområden och bänkar är bara ett fåtal av mångaandra komponenter som formar en utomhusmiljö. Inte är bara skötsel ochunderhåll nödvändigt för att hålla utomhusmiljön ren och trevlig för allasvälbefinnande, utan även dokumentation och protokoll över den geografiska datasom representerar utomhusmiljön. Skötsel och underhåll kräver planering ochkostnadsberäkningar där geografiska data står till grund. Data måste därförvara pålitlig, kontinuerligt kontrollerad och uppdaterad, speciellt i avseendetill att komponenterna i utomhusmiljöer är i en konstant förändring ochrörelse. Ett effektivt sätt att lagra geografiska data på är att använda sigGeografiska Informationssystems (GIS). I denna studie appliceras en användarcentrerad designmetod för att erhålla enprototyp som uppmuntrar användning av webb- och mobil-GIS ute i fält i sambandmed kontroller och skötsel och därmed resulterar i mer effektivadatauppdateringsprocedurer och skötseloperationer. En fallstudie är utförd ochinvolverar bostadsförvaltningarna Svenska Bostäder och Stockholmshem därskötsel och underhåll av geografiska data som representerarbostadsförvaltningarnas utomhusmiljö ingår i deras arbete och sköts idag medhjälp utav primitiva metoder. Den användarcentrerad designmetoden Focus RapidContextual Design används för att erhålla användarbehov gällande funktionalitetoch användargränssnitt för att vidare kunna utveckla och integrera en prototypi bostadsförvaltningarnas redan existerande GIS-lösningar. Det övergripandemålet är att undersöka, dokumentera och utvärdera hur en användarcentreraddesignmetod kan appliceras för att introducera web-GIS lösningar för attförbättra arbetsflödet mellan kontor och fält, detta genom att reducera antalsteg som utförs under en fältkontroll genom att ersätta primitiva verktyg såsom pappers- och PDF-kartor som används idag med förslagna GIS lösningar. Denpotentiellt långsikta effekt av denna studie är att uppmuntra oerfarnaanvändare som arbetar ute i fält att använda dessa nya lösningar istället förde primitiva lösningar som används idag, detta genom att anpassafunktionaliteter och användargränssnitt efter användarnas behov och nivå genomatt tillämpa den användarcentrereade designmetoden. Focus Rapid Contextual Design metoden visar sig vara effektiv i samband medinsamling och hantering av användardata och utförs på ett strukturerat vis. Pågrund av ett tight tidsschema och en resursbegränsning under denna studie ärden iterativa prototypprocess som föreslås i metoden inte applicerad.Prototypen utvärderades enbart en gång av användarna och utfördes inte ute ifält. Detta ledde till bristfällig användarfeedback vilket innebär att denslutliga prototypen möjligen skulle kunnat anpassats ytterligare efteranvändarnas behov om man hade utfört den iterativa prototypprocessen. Dettaskulle troligtvis också bidra till en snabbare anpassning av webb-GISlösningarna i deras dagliga arbete. Att uppmuntra oerfarna användare att bytafrån ett manuellt till ett digitalt system ansågs som en av de störreutmaningarna under denna studie. Även om den användarcentrerade designmetodenbidrar till att uppmuntra användare att använda de nya lösningarna, behövstroligtvis organisationsförändringar och policys för att uppnåprocessförändringar och få fältarbetare att ändra sina arbetsvanor. En så passliten studie som utförs här skulle möjligen kunna utföras utan processernaWorking Models och Storyboarding i Focus Rapid Contextual Design metoden utanatt påverka det slutliga resultatet avsevärt. Detta skulle bidra till mer tidför att tillämpa den iterativa prototypprocessen och involvera fler användarevilket troligtvis skulle förbättra arbetet i denna studie för att bättre kunnauppnå de satta målen.

  • 123034.
    Zuniga-Arias, Guillermo
    et al.
    Wageningen University.
    Meijer, Sebastiaan
    Wageningen University.
    Hofstede, Gert Jan
    Wageningen University.
    Ruben, Ruerd
    Wageningen University.
    Bargaining power and revenue distribution in the Costa Rican mango supply chain: a gaming simulation approach with local producers2007Ingår i: Journal on Chain and Network Science, ISSN 1569-1829, E-ISSN 1875-0931, Vol. 7, nr 2, s. 143-160Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By the time a European consumer eats a Costa Rican mango, the product has been traded in several transactions between producers, traders, retailers and consumers. This paper investigates the position of Costa Rican smallholders in the mango supply chain in terms of bargaining power and revenue distribution. It examines data derived using a specially developed research tool: the Mango Chain Game (MCG), a gaming simulation that mimics the negotiation conditions in the Costa Rican mango supply chain. The MCG defines roles for all agents in the chain and records transaction attributes. Five sessions with the MCG were played with different groups of mango producers, resulting in a data set of 82 transactions and 43 bargaining power positions. Bargaining power was assessed at a 10-point Likert scale. Revenue distribution was measured in terms of value added. The results show that self-perceived bargaining power was dependent on negotiation skills, wealth and good partnership of the negotiators, but independent of market imperfections. Revenue distribution was related to the bargaining power of the trading partner, risk perception and the duration of the contract. Conclusions include that using a gaming simulation as data source can help identify less tangible issues in supply chain research, which is a new field of application for gaming simulations. Agency cooperation, skills and being able to bear risks play a role for improving the efficiency of the mango supply chain in Costa Rica as seen from a producers' perspective. The gaming results indicate that initiatives for improving the bargaining power of producers are more promising if they focus on improving skills and relations in trade rather than on solving market imperfections.

  • 123035.
    Zuniga-Arias, Guillermo
    et al.
    Wageningen University.
    Meijer, Sebastiaan
    Wageningen University.
    Ruben, Ruerd
    Wageningen University.
    Hofstede, Gert Jan
    Wageningen University.
    Bargaining power in mango supply chains: An experimental gaming approach2006Ingår i: International Agri-Food Chains and Networks: Management and Organization / [ed] J. Bijman, S.W.F. Omta,,, J.H.M. Wijnands & E.M.F. Wubben, Wageningen: Wageningen Academic Publishers, 2006, s. 231-255Konferensbidrag (Refereegranskat)
    Abstract [en]

    Transactions between producers, traders, retailers and consumers in the mango supply chain are characterised by contractual arrangements concerning outlet choice, price, volume, quality and frequency. We used a gaming simulation approach to identify the intrinsic agency characteristics that typically result in specific contracts and assess the underlying differences in perceived bargaining power and that are conducive for reaching these arrangements. A stylised mango chain game is developed that permits the appraisal of different sets of delivery transactions. Agency roles are defined for all participants in the mango supply chain. Attributes of all transactions are recorded, also permitting contract breach, hold-up and repeated contracts. Bargaining power is assessed at a 10-point Likert scale and revenue distribution is measured in terms of money. The game has been played five times with different groups of mango producers, resulting in a data set of 82 transactions and 43 bargaining power positions. The game design closely mimics the negotiation conditions in the Costa Rican mango supply chain. The game results confirm the important role of trust and information exchange for reaching mutually acceptable contracts. Bargaining power is strongly related to the negotiation skills, wealth and partnerships of the negotiator. Revenue distribution is related to the bargaining power of the trade partner, risk and the length of the contract. Transparency and agency cooperation thus play important roles for improving the efficiency of mango supply chains in Costa Rica.

  • 123036.
    Zunino, Guido
    KTH, Tidigare Institutioner                               , Numerisk analys och datalogi, NADA.
    Simultaneous localization and mapping for navigation in realistic environments2002Licentiatavhandling, monografi (Övrigt vetenskapligt)
  • 123037.
    Zuo, Haisu
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.).
    How could the innovation policy be implemented effectively?: A comparative analysis of institution between Sweden and China2011Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 123038.
    Zuo, Minyu
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Enhanced phosphorus removal from wastewater using virgin and modified slags: performance, speciation and mechanisms2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Argon oxygen decarburization slag (AOD) was tested in batch and column experiments to investigate its phosphorus (P) removal performance. The effects of factors such as AOD dose, initial P concentration of the feeding solution, and aging on the P removal ability of the slags were analyzed. In a column experiment, electric arc furnace slag (EAF), blast furnace slag (BFS) and AOD were combined in five different ways to determine optimal conditions for P removal. In another column experiment, the three types of slag were modified with polyethylene glycol (PEG) and NaOH to adjust their dissolution properties and the effect on P removal performance was examined. In the batch experiments, AOD exhibited very promising P removal ability. It removed 94.8% of P from 6.5 mg P L-1 synthetic solution in 4 hours with a dose of 5 g L-1. Maximum P removal capacity of 27.5 mg P g-1 was achieved. In the dual-filter column experiment, the column packed with only EAF had the best P removal performance (consistently above 93%). Amorphous calcium phosphate (ACP) was identified as the main P species in the five slag samples collected from the outlet chambers. The contributions from crystalline calcium phosphate (Ca-P) and P adsorbed on iron/aluminum (hydr)oxides were greater in samples from the inlet chambers. The P speciation results revealed that P was predominantly removed by the slags through formation of ACP. The second column experiment showed that modification with PEG and NaOH solution only enhanced short-term P removal by the slags. However, exhaustion of the modified slags occurred much earlier, indicating that the modification process had shortened the lifespan of the slags. Untreated AOD showed better P removal than untreated EAF until pore volume 244, probably due to faster dissolution rate of gamma dicalcium silicate (dominating in AOD according to the XRD results) than of beta dicalcium silicate (dominating in EAF).

  • 123039.
    Zuo, Minyu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Gustafsson, Jon Petter
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Effect of aging on phosphorus removal of metallurgical slag and heat reactivation of aged slag2016Konferensbidrag (Övrigt vetenskapligt)
  • 123040.
    Zuo, Minyu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Gustafsson, Jon Petter
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. Swedish University of Agricultural Sciences, Sweden.
    Klysubun, Wantana
    Dual slag filters for enhanced phosphorus removal from domestic waste water: performance and mechanisms2018Ingår i: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 25, nr 8, s. 7391-7400Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The phosphorus (P) removal of five combinations of dual filters consisting of blast furnace slag (BFS), argon oxygen decarburisation slag (AOD) and electric arc furnace slag (EAF) was evaluated in column experiments with domestic waste water. The columns were fed with waste water for 24 days. The column with only EAF had the best P removal performance (above 93% throughout the experiment). The speciation of the bound P was evaluated by P K-edge X-ray absorption near-edge structure (XANES) spectroscopy. In all five columns, the main P species of the slag packed in the outlet chamber was amorphous calcium phosphate (ACP). In samples from the inlet chambers, the contributions from crystalline Ca phosphates, P adsorbed on gibbsite and P adsorbed on ferrihydrite were usually much greater, suggesting a shift of P removal mechanism as the waste water travelled from the inlet to the outlet. The results provide strong evidence that P was predominantly removed by the slags through the formation of ACP. However, as the pH decreased with time due to the progressively lower dissolution of alkaline silicate minerals from the slag, the ACP was rendered unstable and hence redissolved, changing the P speciation. It is suggested that this process strongly affected the lifespan of the slag filters. Of the slags examined, EAF slag had the best P removal characteristics and BFS the worst, which probably reflected different dissolution rates of alkaline silicates in the slags.

  • 123041.
    Zuo, Minyu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Gustafsson, Jon Petter
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. Swedish University of Agricultural Sciences, Uppsala.
    Klysubun, Wantana
    Dual slag filters for enhanced phosphorus removal from domestic wastewater: performance and mechanismsIngår i: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499Artikel i tidskrift (Refereegranskat)
  • 123042.
    Zuo, Minyu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Gustafsson, Jon Petter
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. Swedish University of Agricultural Sciences, Uppsala.
    Klysubun, Wantana
    Synchrontron Light Research Institute.
    Phosphorus removal performance and lifespan prediction through mineralogical composition: A comparative study of AOD and EAF slagsManuskript (preprint) (Övrigt vetenskapligt)
  • 123043.
    Zuo, Minyu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Gustafsson, Jon Petter
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Klysubun, Wantana
    Phosphorus removal performance and lifespan prediction through minerology analysis: A comparative study of AOD and EAF slagsManuskript (preprint) (Övrigt vetenskapligt)
  • 123044.
    Zuo, Minyu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Gustafsson, Jon Petter
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. Swedish University of Agricultural Sciences, Sweden.
    Renman, Agnieszka
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Phosphorus removal performance and speciation in virgin and modified argon oxygen decarburisation slag designed for wastewater treatment2015Ingår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 87, s. 271-281Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Argon oxygen decarburisation (ADD) slag may be used for phosphorus (P) removal, as its high pH and weatherable calcium (Ca) minerals provide sufficient Ca2+ and OH- for calcium phosphate (Ca-PO4) precipitation. This study examined the P removal performance of AOD slag for use as wastewater treatment material. Batch experiments were carried out using both synthetic P solution and real wastewater, followed by chemical modelling and X-ray absorption near edge structure (XANES) spectroscopy. The influences of initial P concentration, slag dose and modification by polyethylene glycol (PEG), an effective agent for generation of porous materials, were investigated to determine the optimal conditions for P removal by AOD slag. It was found that virgin AOD slag removed 94.8% of P from a synthetic P solution in 4 h and 97.8% in 10 h. This high P removal was accompanied by a rapid increase in pH from 7.0 to 10.74. The maximum P removal capacity (PRC) from synthetic P solution ranged from 1.3 to 27.5 mg P g(-1). The optimal AOD dose for P removal from wastewater, determined in 8-h batch experiments, was 25 g L-1. PEG modification increased the reaction rate and resulted in higher final pH, increasing PRC by 47.9%. Combined Visual MINTEQ and XANES analysis for detailed examination of P removal mechanisms revealed that the main P removal mechanism was precipitation of calcium phosphate. According to the XANES analysis, the main Ca-PO4 precipitate formed on virgin AOD slag under low initial P concentration and high pH was apatite, while brushite was the dominant product at high initial P concentration and low pH.

  • 123045.
    Zurauskaite, Laura
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Fabrication and electrical characterization of Ge/GeOx/Al2O3/HfO2 MOS capacitors2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Kontinuerlig skalning av komplementär MOS teknologi (CMOS), har lett till konstant förbättrad prestanda hos integrerade CMOS-kretsar. Fortsatt nerskalning möter dock större hinder för varje teknologinod och forskare undersöker alternativa material till kisel (Si) [1]. Germanium (Ge) är ett attraktivt material eftersom hålmobiliteten är fyra gånger och elektron mobilitet två gånger högre än hos kisel [2]. En utmaning med att bygga CMOOS pp Ge är att det är svårt att passivera Ge. I denna avhandling undersöks en modifikation på metoden att oxidera genom ett barriärlager som föreslagits av gruppen som leds av Takagi [3]. Ozon oxidering har utförts in-situ i en atmoic layer deposition (ALD) kammare där Al2O3 användes som ett barriär lager och MOS kondensatorer har tillverkats och karakteriserats. Kombinationer av barriär tjocklek och ozongeneratoreffekt har undersökts tillsammans med influensen av oxideringstid. Karakterisering av elektriska egenskaper har visat att gränsytan mellan germanium och oxid förbättras då en hög ozongeneratoreffekt används för att oxidera genom en tunn (~0.47 nm) barriär och genom att använda en förlängd oxideringstid upp till 15 min. Defektdensiteten (Dit) vid gränssnittet till Ge sjönk med oxideringstiden och som lägst uppmättes till ~3·1012 cm-2eV-1.

  • 123046.
    Zurauskaite, Laura
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    The impact of atomic layer depositions on high quality Ge/GeO2 interfaces fabricated by rapid thermal annealing in O-2 ambient2017Ingår i: 2017 IEEE Electron Devices Technology and Manufacturing Conference, EDTM 2017 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 164-166, artikel-id 7947553Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work demonstrates high quality Ge/GeO2 interfaces fabricated by O-2 RTA that are degraded by a good quality SiO2 layer deposited by ALD. However, neither O-3 and H2O precursors commonly used during subsequent high-k ALDs nor Si precursor AP-LTO-330 do not degrade the interface. Thus Dit increase after SiO2 deposition is likely due to intermixing. Therefore, the effect of subsequent ALDs on the interface quality has to be considered while designing Ge-based gate stacks.

  • 123047.
    Zurauskaite, Laura
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik.
    Jones, L.
    Dhanak, V. R.
    Mitrovic, I. Z.
    Hellström, Per-Erik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik.
    Östling, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik.
    Investigation of Tm2Oj as a gate dielectric for Ge MOS devices2018Ingår i: ECS Transactions, Electrochemical Society, 2018, Vol. 86, nr 7, s. 67-73Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work atomic layer deposited TnOj has been investigated as a high-k dielectric for Ge-based gate stacks. It is shown that when Tm203 is deposited on high-quality Ge/Ge02 gates, the interface state density of the gate stack is degraded. A series of post-deposition anneals are studied in order to improve the interface state density of Ge/GeO/TmjOs gates, and it is demonstrated that a rapid thermal anneal in O2 ambient can effectively reduce the interface state density to below 5-10" cmeV1 without increasing the equivalent oxide thickness. Fixed charge density in Ge/GeOx/Tm20j gates has also been investigated, and it is shown that while O2 post-deposition anneal improves the interface state density, the fixed charge density is degraded.

  • 123048. Zurauskiene, N.
    et al.
    Asmontas, S.S.
    Dargys, A.
    Kundrotas, J.
    Janssen, G.
    Goovaerts, E.
    Marcinkevicius, Saulius
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Koenraad, P.M.
    Wolter, J.H.
    Leon, R.
    Semiconductor nanostructures for infrared applications2004Ingår i: Functional Nanomaterials For Optoelectronics And Other Applications / [ed] Lojkowski, W; Blizzard, JR, Trans Tech Publications Inc., 2004, Vol. 99-100, s. 99-108Konferensbidrag (Refereegranskat)
    Abstract [en]

    The results of time-resolved photo luminescence (TRPL) and optically detected microwave resonance (ODMR) spectroscopy investigations of semiconductor quantum dots and quantum wells are presented. The ODMR spectra of InAs/GaAs QDs were detected via modulation of the total intensity of the QDs emission induced by 95 GHz microwave excitation and the exciton fine structure was studied. Very long life times (up to 10 ns) of photoexcited carriers were observed in this system using TRPL at low temperatures and excitation intensities promising higher responsitivity of such QDs for infrared photodetector development. The effects of proton and alpha particles irradiation on carrier dynamics were investigated on different InGaAs/GaAs, InAlAs/AlGaAs and GaAs/AlGaAs QD and QW systems. The results showed that carrier lifetimes in QDs are much less affected by proton irradiation than that in QWs. A strong influence of irradiation on PL intensity was observed in multiple QWs after high-energy alpha particles irradiation.

  • 123049. Zurauskiene, N.
    et al.
    Marcinkevicius, Saulius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Janssen, G.
    Goovaerts, E.
    Notzel, R.
    Koenraad, P. M.
    Wolter, J. H.
    Optically detected microwave resonance and carrier dynamics in InAs/GaAs quantum dots2005Ingår i: Acta Physica Polonica. A, ISSN 0587-4246, E-ISSN 1898-794X, Vol. 107, nr 2, s. 435-439Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The properties of small-sized high density InAs/GaAs quantum dots (emitting at 1.25 eV) are studied by means of optically detected microwave resonance spectroscopy and time resolved photoluminescence techniques. The results are discussed in terms of trapping and thermal escape of the carriers as well as their relaxation and recombination in quantum dots. The data are compared with those recently obtained on shallowly formed InAs quantum dot structures.

  • 123050.
    Zurita Ares, Benigno
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Park, Pan Gun
    KTH, Skolan för elektro- och systemteknik (EES).
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Speranzon, Alberto
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    On power control for wireless sensor networks: System model, middleware component and experimental evaluation2015Ingår i: 2007 European Control Conference, ECC 2007, 2015, s. 4293-4300Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we investigate strategies for radio power control for wireless sensor networks that guarantee a desired packet error probability. Efcient power control algorithms are of major concern for these networks, not only because the power consumption can be signicantly decreased but also because the interference can be reduced, allowing for higher throughput. An analytical model of the Received Signal Strength Indicator (RSSI), which is link quality metric, is proposed. The model relates the RSSI to the Signal to Interference plus Noise Ratio (SINR), and thus provides a connection between the powers and the packet error probability. Two power control mechanisms are studied: a Multiplicative-Increase Additive-Decrease (MIAD) power control described by a Markov chain, and a power control based on the average packet error rate. A component-based software implementation using the Contiki operating system is provided for both the power control mechanisms. Experimental results are reported for a test-bed with Telos motes.

2458245924602461246224632464 123001 - 123050 av 124243
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf