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  • 124201. Zwiller, V.
    et al.
    Chitica, N.
    Persson, J.
    Pistol, M. -E
    Seifert, W.
    Samuelson, L.
    Hammar, M.
    Streubel, K.
    Goobar, E.
    Björk, G.
    Studies of self-assembled InP quantum dots in planar microcavities2000In: Materials Science and Engineering B: Solid-State Materials for Advanced Technology, Vol. 69, no Lausanne, Switzerland, p. 314-317Article in journal (Refereed)
    Abstract [en]

    Self-assembled InP quantum dots have been grown in planar microcavities. The dots were embedded in a Ga0.52In0.48P spacer grown on top of a high reflectance epitaxial Al0.29Ga0.71As/AlAs distributed Bragg reflector (DBR) to obtain a 33λ/4 cavity. The Fabry-Perot microcavity is formed between the AlGaAs/AlAs DBR and a dielectric SiNx/SiO2 DBR deposited on top of the GaInP spacer. The quantum dot emission is centered at 1.62 eV at 7 K. The microcavity resonance is centered at 1.65 eV, with a linewidth of 2 meV. Micro-photoluminescence (PL) studies using different objectives with different numerical apertures enable the collection of transversal modes.

  • 124202. Zwiller, V.
    et al.
    Falth, S.
    Persson, J.
    Seifert, W.
    Samuelson, L.
    Björk, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Fabrication and time-resolved studies of visible microdisk lasers2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 4, p. 2307-2309Article in journal (Refereed)
    Abstract [en]

    We report on the fabrication and characterization of microdisk lasers emitting at around 650 nm. The structures were grown by metalorganic vapor phase epitaxy and processed using electron beam lithography and wet etching. Time-resolved photoluminescence measurements done at low temperature show a lasing threshold of 60 muW average power. A redshift in the whispering modes energy is observed.

  • 124203.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, School of Electrical Engineering (EES).
    Quantum optics with nanowires (Conference Presentation)2017In: QUANTUM DOTS AND NANOSTRUCTURES: GROWTH, CHARACTERIZATION, AND MODELING XIV / [ed] Huffaker, DL Eisele, H, SPIE-INT SOC OPTICAL ENGINEERING , 2017, article id UNSP 101140IConference paper (Refereed)
  • 124204.
    Zwiller, Val
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Nano Photonics.
    Zadeh, I. E.
    Los, J. W. N.
    Gourgues, R. B. M.
    Steinmetz, V.
    Dobrovolskiy, S. M.
    Dorenbos, S. N.
    Single-photon detection with near unity efficiency, ultrahigh detection-rates, and ultra-high time resolution2017In: CLEO: Science and Innovations part of CLEO: 2017 : 4-19 May 2017, San Jose, California, United States, Optical Society of America, 2017Conference paper (Refereed)
    Abstract [en]

    Single-photon detectors with high efficiency, high time resolution, low dark counts and high photon detection-rates are vital for most demanding quantum optics experiments. Combining all performances in a single device has been challenging. Here, we demonstrate a broadband detector with efficiency higher than 92%, over 150 MHz photon detection-rate and dark counts below 130 Hz operated in a conventional Gifford-McMahon cryostat. Furthermore, using our custom made cryogenic amplifiers and optimized detector, we reach a record low jitter of 14.80 ps while maintaining high efficiency.

  • 124205. Zwiller, Valéry
    et al.
    Blom, Hans
    KTH, Superseded Departments, Electronics.
    Jonsson, Per
    KTH, Superseded Departments, Electronics.
    Panev, Nikolay
    Jeppesen, Sören
    Tsegaye, Tedros
    Goobar, Edgard
    Pistol, Mats-Erik
    Samuelson, Lars
    Björk, Gunnar
    KTH, Superseded Departments, Electronics.
    Single quantum dots emit single photons at a time: Antibunching experiments2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 17, p. 2476-Article in journal (Refereed)
    Abstract [en]

    We have studied the photoluminescence correlation from a single InAs/GaAs self-assembled Stranski–Krastanow quantum dot under continuous, as well as under pulsed excitation. Under weak continuous excitation, where the single dot luminescence is due primarily to single exciton recombinations, antibunching is observed in the single dot emission correlation. Under weak pulsed excitation, the number of photons emitted by the quantum dot per pulse is close to one. We present data obtained under both conditions and are able to show that devices based on single quantum dots can be used to generate single photons.

  • 124206. Zwiller, Valéry
    et al.
    Jonsson, Per
    Blom, Hans
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Jeppesen, Sören
    Pistol, Mats-Erik
    Samuelson, Lars
    Katznelson, A. A.
    Kotelnikov, E. Yu.
    Evtikhiev, Vadim
    Björk, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Correlation spectroscopy of excitons and biexcitons on a single quantum dot2002In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 66, no 2, p. 053814-053814-7Article in journal (Refereed)
    Abstract [en]

    We report the observation of antibunched emission from single self-assembled InAs quantum dots under various conditions. We have measured the correlation function of the photon emission pertaining to single emission lines from single quantum dots under continuous and pulsed laser excitation, as well as under continuous white light excitation. The measurements were performed under different excitation intensities at liquid helium temperatures on two samples with distinct structures. At higher temperatures ~30 K!, an antibunching dip was still observed. We have also observed antibunching on a second emission line in the quantum dot spectrum, attributed to the biexciton, demonstrating the possibility of generating photon pairs with a single quantum dot. Polarization correlations on the biexciton and exciton line were also measured in an attempt to generate entangled photon pairs.

  • 124207.
    Zwinderman, Matthijs
    et al.
    Technical University of Eindhoven, The Netherlands.
    Rybski, Paul E.
    The Robotics Institute, Carnegie Mellon University, Pittsburgh, PA.
    Kootstra, Gert
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    A Human-Assisted Approach for a Mobile Robot to Learn 3D Object Models using Active Vision2010In: Proceedings of the IEEE International Symposium on Robot and Human Interactive Communication (ROMAN 2010), IEEE , 2010, p. 397-403Conference paper (Refereed)
    Abstract [en]

    In this paper we present an algorithm that allows a human to naturally and easily teach a mobile robot how to recognize objects in its environment. The human selects the object by pointing at it using a laser pointer. The robot recognizes the laser reflections with its cameras and uses this data to generate an initial 2D segmentation of the object. The 3D position of SURF feature points are extracted from the designated area using stereo vision. As the robot moves around the object, new views of the object are obtained from which feature points are extracted. These features are filtered using active vision. The complete object representation consists of feature points registered with 3D pose data. We describe the method and show that it works well by performing experiments on real world data collected with our robot. We use an extensive dataset of 21 objects, differing in size, shape and texture.

  • 124208. Zybailov, Boris
    et al.
    Rutschow, Heidi
    Friso, Giulia
    Rudella, Andrea
    Emanuelsson, Olof
    Stockholms universitet.
    Sun, Qi
    van Wijk, Klaas J.
    Sorting signals, N-terminal modifications and abundance of the chloroplast proteome2008In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 3, no 4Article in journal (Refereed)
    Abstract [en]

    Characterization of the chloroplast proteome is needed to understand the essential contribution of the chloroplast to plant growth and development. Here we present a large scale analysis by nanoLC-Q-TOF and nanoLC-LTQ-Orbitrap mass spectrometry (MS) of ten independent chloroplast preparations from Arabidopsis thaliana which unambiguously identified 1325 proteins. Novel proteins include various kinases and putative nucleotide binding proteins. Based on repeated and independent MS based protein identifications requiring multiple matched peptide sequences, as well as literature, 916 nuclear-encoded proteins were assigned with high confidence to the plastid, of which 86% had a predicted chloroplast transit peptide (cTP). The protein abundance of soluble stromal proteins was calculated from normalized spectral counts from LTQ-Obitrap analysis and was found to cover four orders of magnitude. Comparison to gel-based quantification demonstrates that 'spectral counting' can provide large scale protein quantification for Arabidopsis. This quantitative information was used to determine possible biases for protein targeting prediction by TargetP and also to understand the significance of protein contaminants. The abundance data for 550 stromal proteins was used to understand abundance of metabolic pathways and chloroplast processes. We highlight the abundance of 48 stromal proteins involved in post-translational proteome homeostasis (including aminopeptidases, proteases, deformylases, chaperones, protein sorting components) and discuss the biological implications. N-terminal modifications were identified for a subset of nuclear- and chloroplast-encoded proteins and a novel N-terminal acetylation motif was discovered. Analysis of cTPs and their cleavage sites of Arabidopsis chloroplast proteins, as well as their predicted rice homologues, identified new species-dependent features, which will facilitate improved subcellular localization prediction. No evidence was found for suggested targeting via the secretory system. This study provides the most comprehensive chloroplast proteome analysis to date and an expanded Plant Proteome Database (PPDB) in which all MS data are projected on identified gene models.

  • 124209.
    Zymberi, Granit
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Johansson, William
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Spolpump till HCCI-motorn2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Agilis is a concept car that will compete in Shell Eco Marathon Race for the Internal Combustion Engines of the Royal Institute of technology. It is powered by an HCCI engine which is a combination between a diesel engine (compression ignition) and a gasoline engine (spark ignition). The purpose of the project is to construct and to manufacture a working scavenger pump for the HCCI engine. Since the HCCI engine can operate in two different modes, gasoline engine and HCCI, it needs a pump which can run a variable airflow. The air pumps which have been manufactured today have not been good enough or worked desirable as wanted for the HCCI engine for Agilis. The methods used were concept generation, choice of concept, calculations and updates of the chosen concept. The scavenge pump consists of two rotors which generate compressed air to the engine. It delivers air with a compression factor of 1.27 and the total displacement of the pump (both rotors) is 144cc/rev. Because of the high displacement a gear ratio is needed between the engine and scavenge pump of 1.8 which adjusts the correct airflow and at the same time compensates for leakage at low rotational speed. The construction of the pump is also made in a way that it makes it possible to deliver adjustable airflow to fit the requirement of the engine, which is made by shutting the outgoing air flow of one of the rotors. Because of the fact that Agilis is still under development, especially the HCCI engine, there were a lot of doubt in the parameters that should be used on the scavenge pump which made it harder to make accurate calculations. But this is still a good prototype which has gone all the way to production for future testing and modifications.

  • 124210.
    Zytomierski, Patrik
    et al.
    KTH, School of Engineering Sciences (SCI).
    Pettersson, Marcus
    FLYGTEKNIK – DESIGN AV ETT TRANSPORTFLYGPLAN2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this research is to find and display the methods involved in the conceptual design of a transport aircraft. The goal is to examine this process and utilize the restrictions of a specific mission to find the most important aspects of aircraft design. The primary parameters portrayed are payload and aircraft weight, wing loading, and wing and tail design. These have been studied primarily using a literature study, concluding in overarching use of “Aircraft Design: A Conceptual Approach”, by J. S. Przemieniecki for assumptions and methods. Through this a final conceptual design of a transport aircraft could be made, with the capacity of delivering large payloads over vast distances.

  • 124211.
    Zyuzin, Alexander A.
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Zyuzin, A. Yu.
    Flat band in disorder-driven non-Hermitian Weyl semimetals2018In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 97, no 4, article id 041203Article in journal (Refereed)
    Abstract [en]

    We study the interplay of disorder and band-structure topology in a Weyl semimetal with a tilted conical spectrum around the Weyl points. The spectrum of particles is given by the eigenvalues of a non-Hermitian matrix, which contains contributions from a Weyl Hamiltonian and complex self-energy due to electron elastic scattering on disorder. We find that the tilt-induced matrix structure of the self-energy gives rise to either a flat band or a nodal line segment at the interface of the electron and hole pockets in the bulk band structure of type-II Weyl semimetals depending on the Weyl cone inclination. For the tilt in a single direction in momentum space, each Weyl point expands into a flat band lying on the plane, which is transverse to the direction of the tilt. The spectrum of the flat band is fully imaginary and is separated from the in-plane dispersive part of the spectrum by the "exceptional nodal ring" where the matrix of the Green's function in momentum-frequency space is defective. The tilt in two directions might shrink a flat band into a nodal line segment with "exceptional edge points." We discuss the connection to the non-Hermitian topological theory.

  • 124212.
    Zyuzin, Alexander
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Garaud, Julien
    KTH, School of Engineering Sciences (SCI), Physics.
    Babaev, Egor
    KTH, School of Engineering Sciences (SCI), Physics.
    Nematic Skyrmions in Odd-Parity Superconductors2017In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 119, no 16, article id 167001Article in journal (Refereed)
    Abstract [en]

    We study topological excitations in two-component nematic superconductors, with a particular focus on CuxBi2Se3 as a candidate material. We find that the lowest-energy topological excitations are coreless vortices: a bound state of two spatially separated half-quantum vortices. These objects are nematic Skyrmions, since they are characterized by an additional topological charge. The inter-Skyrmion forces are dipolar in this model, i.e., attractive for certain relative orientations of the Skyrmions, hence forming multi-Skyrmion bound states.

  • 124213.
    Zyuzin, Alexander
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Zyuzin, A. Y.
    Chiral anomaly and second-harmonic generation in Weyl semimetals2017In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 95, no 8, article id 085127Article in journal (Refereed)
    Abstract [en]

    We study second-harmonic generation in centrosymmetric Weyl semimetal with broken time reversal symmetry. We calculate electric current density at the double frequency of the propagating electromagnetic field in the presence of an applied constant magnetic field, using the method of kinetic equation for electron distribution function. It is shown that the chiral anomaly contribution to second-harmonic generation in the lowest order is linearly proportional to the applied magnetic field. The limit when the chiral anomaly dominates over the Lorentz-type contribution to second-harmonic generation is discussed.

  • 124214.
    Zywna, Michal
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Analysis of Lining Properties at Landfills Using Geophysical Methods - Case Study: Tveta (Sweden).2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Recently established EU environmental legislation obliged Sweden to close many landfills until year 2020. Such an operation requires a lot of inexpensive and water resistant coverage materials. Six prototypes of linings were constructed at Tveta landfill. Built coverage consisted mainly of residual products such as compost, sludge, fly and bottom ash. Between 2004 and 2007 water permeability through tested coverage was well below the maximum limit for non-hazardous waste. However, recent lysimeter records indicated increased permeability through the constructed linings. Readings of water infiltration were verified. Direct current (DC) resistivity, induced polarization (IP) and ground penetrating radar (GPR) were the methods applied in the research. The data was processed to present resistivity distribution in 2D pseudo-sections and 3D model. Resistivity measurements confirmed increased conductivity at the area with highest lysimeter readings. Unfortunately, GPR and IP output could not be used as reference information for DC resistivity readings. Constructed prototypes seemed to be suitable for coverage lining. Leakage was probably a result of minor mass transport along the slopes of the waste pile. It was recommended to prepare additional DC resistivity measurements to verify correctness of the processed 2D pseudo-sections and 3D model.

  • 124215.
    Zäll, E.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Ülker-Kaustell, Mahir
    KTH. Tyréns AB, Stockholm, Sweden.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. Swedish Transport Administration, Solna, Sweden.
    Evaluation of load model for crowd-induced vibrations of footbridges2016In: IABSE Congress Stockholm, 2016: Challenges in Design and Construction of an Innovative and Sustainable Built Environment, International Association for Bridge and Structural Engineering (IABSE) , 2016, p. 65-72Conference paper (Refereed)
    Abstract [en]

    Due to a trend in designing light and slender structures, many modern footbridges are prone to excessive vibrations. Severely vibrating footbridges can give rise to discomfort for the pedestrians. Therefore, during the last decades, pedestrian-induced vibrations of footbridges have become a subject of great interest. In this study, the performance of a coupled crowd-structure model, where the bridge is described using its first two modes of vibrations and each pedestrian is described as a moving mass-spring-damper system, in combination with a walking load, is evaluated. The model is used to estimate vertical deck accelerations of a real footbridge which is known to be susceptible to vibrations, and the results are then compared to measurements. The model performs satisfactory in the time domain, but poorly in the frequency domain, which is concluded to be mainly due to discrepancies in the simulated load compared to the measured load.

  • 124216.
    Zäll, Emma
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Footbridge Dynamics: Human-Structure Interaction2018Licentiate thesis, monograph (Other academic)
    Abstract [en]

    For aesthetic reasons and due to an increased demand for cost-effective and environmentally friendly civil engineering structures, there is a trend in designing light and slender structures. Consequently, many modern footbridges are susceptible to excessive vibrations caused by human-induced loads. To counteract this, today's design guidelines for footbridges generally require verification of the comfort criteria for footbridges with natural frequencies in the range of pedestrian step frequencies. To ensure that a certain acceleration limit is not exceeded, the guidelines provide simplified methodologies for vibration serviceability assessment.

    However, shortcomings of these methodologies have been identified. First, for certain footbridges, human-structure interaction (HSI) effects might have a significant impact on the dynamic response. One such effect is that the modal properties of the bridge change in the presence of a crowd; most importantly, the damping of the bridge is increased. If this effect is neglected, predicted acceleration levels might be overestimated. Second, as a running person induces a force of greater amplitude than a walking person, a single runner might cause a footbridge to vibrate excessively. Hence, the running load case is highly relevant. These two aspects have in common that they are disregarded in existing design guidelines.

    For the stated reasons, the demand for improvements of the guidelines is currently high and, prospectively, it might be necessary to require the consideration of both the HSI effect and running loads. Therefore, this licentiate thesis aims at deepening the understanding of these subjects, with the main focus being placed on the HSI effect and, more precisely, on how it can be accounted for in an efficient way.

    A numerical investigation of the HSI effect and its impact on the vertical acceleration response of a footbridge was performed. The results show that the HSI effect reduces the peak acceleration and that the greatest reduction is obtained for a crowd to bridge frequency ratio close to unity and a high crowd to bridge mass ratio. Furthermore, the performance of two simplified modelling approaches for consideration of the HSI effect was evaluated. Both simplified models can be easily implemented and proved the ability to predict the change in modal properties as well as the structural response of the bridge. Besides that, the computational cost was reduced, compared to more advanced models.

    Moreover, a case study comprising field tests and simulations was performed to investigate the effect of runners on footbridges. The acceleration limit given in the design guideline was exceeded for one single person running across the bridge while a group of seven people walking across the bridge did not cause exceedance of the limit. Hence, it was concluded that running loads require consideration in the design of a footbridge.

  • 124217.
    Zäll, Emma
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. Swedish Transport Administration, Sweden.
    Ülker-Kaustell, Mahir
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. Tyrens AB, Sweden.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    An efficient approach for considering the effect of human-structure interaction on footbridges2017In: X International Conference on Structural Dynamics, EURODYN 2017, Elsevier, 2017, Vol. 199, p. 2913-2918Conference paper (Refereed)
    Abstract [en]

    Mainly because of the infamous incident with excessive vibrations of the London Millennium Bridge, the behavior of lively footbridges has been thoroughly studied lately. The liveliness of such bridges is strongly connected to various interaction effects between the pedestrians and the bridges. One such effect is the variation in the modal properties of the bridge, due to the presence of a crowd. In theoretical models of such systems, this is often accounted for by describing each pedestrian as a spring-mass-damper system, having its own dynamic properties, producing a time-variant system. A major drawback with models of this kind is that the computational time increases rapidly with the size of the system, i.e. for a larger crowd. Therefore, with the objective to reduce the computational time needed, this study focuses on describing vertical human-structure interaction by means of a simplified model. The paper describes a new methodology for taking this effect into consideration when predicting the dynamic response of a footbridge, subjected to human-induced, vertical loads. The method is used to predict the vertical bridge deck accelerations of a simply supported footbridge. The predictions produced by the proposed methodology are compared with existing models and it is shown that for certain bridges, it produces an accurate approximation at a significantly reduced computational cost.

  • 124218.
    Zöld, Thomas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aerodynamics.
    Performance assessment of a hybrid electric-powered long-range commercial airliner 2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Despite the recent increase in the amount of smaller electric general aviation aircrafts, a fully electric airliner is not likely to fly in the near future. Partially inspired by the automotive industry’s success with the hybrid car, this thesis investigated the feasibility of an electric-hybrid propulsion system for an Airbus A340-600 on a long-haul flight and its effect on the aircraft’s performance. First, an analysis was done of the reference aircraft, A340-600, using conventional propulsion. Second, a 5700 nautical miles flight was modelled to determine performance data such as the power and thrust requirements during the different flight phases. Third, the flight phases where electric propulsion would be implemented were identified and an optimum ratio between conventional and electric propulsion was calculated. Finally, a detailed performance analysis of the new hybrid electric aircraft comparing it to a conventional aircraft was conducted.

    The maximum available conventional thrust was reduced to a certain percentage of the maximum thrust. Primarily conventional thrust is used, however when it is no longer sufficient, additional thrust is gained through electric propulsion. Conventional thrust ratio of 69.5%, 63.5% and 59.5% of total thrust was investigated yielding 8680 kg, 10500kg and 8585kg of payload decrease respectively. Net energy of 6.70MWh, 11.71MWh and 31.06MWh is required and the electric engines need to provide 21.3 MW, 25.5 MW and 28.3 MW of net power respectively.

    Partial electric propulsion will result in increased weight; however, it will also give room for further performance optimisation and technical innovations. On the one hand, the conventional engines will run at a constant speed throughout the flight allowing for better optimisation at a specific design point. On the other hand, electric engines are more reliable and require less maintenance than conventional engines. Furthermore, lower fuel consumption means less carbon-dioxide emissions. An exemption from CO2-taxes, similar to measures implemented for hybrid cars in certain countries, could financially justify use of the aircraft by airlines and compensate for the decrease in payload. Since a fully electric propelled airliner is not likely to fly for several decades, a hybrid-airliner would be a suitable alternative for the transition period from fossil fuels to electric energy.

  • 124219.
    Ágústsson, Arnar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Fish oil in Icelandic road constructions.: A case study of bituminous binder mixtures modified with bio-oil.2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis an extensive background study on the use of bio-oil modified

    binder, used in surface dressings in Iceland, was carried out. Surface dressings,

    or chip seals, are paved by first spraying out binder and then distributing

    aggregates over the surface before compaction. The bio-oil, most notably fish

    oil ethyl ester or rape seed oil, is included in a binder mixture to lower its

    viscosity, enabling the binder to be sprayed out at a lower temperature than

    unmodified bitumen.

    In January 2013, severe bleeding of binder was noticed on road sections

    paved with bio-oil modified surface dressings in the northern part of Iceland.

    Following the bleeding, the Icelandic Road and Coastal Administration

    (IRCA) sent samples of the sections in question, as well as binder samples, for

    testing at the laboratory of Highway and Railway Engineering at KTH Royal

    Institute of Technology (KTH) in Stockholm, Sweden. The conclusions of that

    study were that the fish oil ethyl ester was highly polar and had solubility issues

    with the bitumen. This was found to have led to the fish oil separating

    from the binder mixture and covering the stones, preventing bonding between

    aggregates and binder [1].

    The laboratory tests in this thesis extend on the aforementioned research.

    Through the background investigation it was found thatWetfix N, an adhesion

    promoter, was used in the binder mixture to facilitate bonding to the aggregates.

    Based on these findings, previous work and field experience in Iceland,

    two sample sets were created. The first sample set included 7.5% of either fish

    oil ethyl ester or rape seed oil by weight, while the second set included 4% of

    the same bio-oils by weight. To determine the effect of the adhesion promoter,

    all samples were tested with and without Wetfix N. Furthermore, all samples

    were put through a short-term aging treatment to simulate the process during

    mixing and paving, and tested again.

    The findings of this study suggest that the fish oil ethyl ester is more suitable

    for road constructions, compared to the rape seed oil, and that adhesion

    promoter should always be included when paving surface dressings in Iceland.

    Furthermore, the samples tested cannot be recommended for field use due to

    high polarity in the sample with a fish oil concentration of 7.5% and too high

    viscosity in the sample which includes 4% of fish oil. Therefore, it can be said

    that the upper and lower limits have been narrowed to the range between the

    two concentrations tested. To better understand the properties and behavior

    of the sample mixtures, a complete adhesion test with aggregates is advisable.

    Viscosity testing of samples which include between 4.5% and 7% of fish oil

    by weight are recommended and the mixture with the lowest concentration

    that passes IRCA’s guidelines for spraying viscosity at a desired temperature

    should be used in practice.

  • 124220.
    Ágústsson, Eiður
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Hardware-in-The-Loop Simulation of a High Speed Servo System2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In production industries there is a constant demand for shorter time to market and lower development costs. Using models and simulations has been shown to decrease development time and increase product quality. One reason for this is that these methods allow development and testing of control systems before actual prototypes are available. The purpose of this thesis is to implement a Hardware-in-the-loop simulation of the MY500 solder jet printer, which is produced by Micronic Mydata AB. The MY500 has high accuracy and speed requirements, resulting in a short control loop, which puts hard constraints on the model calculation time. The simulation is implemented on a dSPACEMicroAutoBox, using the MATLAB toolboxes Simulink and SimMechanics. It communicates with the control system via SPI and implements an existing SimMechanics model and a newly developed Simulink model. The Simulink model developed in this thesis was found to be a sufficiently realistic simplification of the SimMechanics model. Furthermore, the findings show that the Sim-Mechanics model cannot be run in closed loop on the chosen hardware due to its extensive complexity. The thesis also shows that when using the internal clock, even the shortest model step time allowed by the hardware is not sufficient to perform a stable HIL simulation. Lastly, the SPI implementation tested in this thesis introduced computational delays into the control loop of the MY500, which led to the system only being able to calculate one axis. This thesis concludes that even though the current implementation has some limitations, there is reason to continue the work and making a good simulator of the MY500. Two main avenues of investigation are; firstly, implementing an external interrupt for the HIL simulation, which should allow a larger time step and eliminate jitter in the model output. Secondly, moving the SPI communication code out of the control loop and instead implementing it directly on the FPGA, which should minimize the computational delay added by SPI and thereby allows control of more than one axis.

  • 124221.
    Álvarez Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Bettini, Eleonora
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rutland, Mark
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden, Sweden .
    Friction Coefficient Mapping (FCM) and Contact Adhesion Mapping (CAM): Surface Microstructure and Function2013In: 5th World Tribology Congress, WTC 2013, 2013, Vol. 4, p. 3120-3121Conference paper (Refereed)
  • 124222.
    Álvarez Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Cranston, Emily
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wakeham, Deborah
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Niga, Petru
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Werzer, O.
    Sweeney, J.
    Hausen, F.
    Hayes, R.
    Webber, G. B.
    Endres, F.
    Bennewitz, R.
    Hjalmarsson, Nicklas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Atkin, R.
    Rutland, Mark
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nanotribology: Tribotronics, ionic liquids and control of surface interactions2013In: 5th World Tribology Congress, WTC 2013, 2013, Vol. 4, p. 3106-3108Conference paper (Refereed)
    Abstract [en]

    The interfacial ordering of Ionic liquids leads to interesting nanotribological properties as revealed by colloid probe studies. The first of these is the clear correlation between the number of ion pairs trapped in the tribological contact and the friction coefficient displayed. The second is the fact that the surface electrical potential can be used to control the composition of the boundary layer and thus tune the friction. Thirdly, the interfacial ordering appears to significantly affect the fluid dynamics over large distances.

  • 124223.
    Álvarez Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Sababi, Majid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ejnermark, Sebastian
    Ekman, Lars
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Tech Res Inst Sweden, Sweden.
    Role of microstructure on corrosion initiation of an experimental tool alloy: A Quantitative Nanomechanical Property Mapping study2014In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 89, p. 236-241Article in journal (Refereed)
    Abstract [en]

    The adhesion properties of a FeCrVN experimental tool alloy immersed in pure water and sodium chloride solution have been studied by Quantitative Nanomechanical Property Mapping to understand the influence of microstructure on corrosion initiation of this alloy. The approach used here allows early observation and identification of pre-pitting events that may lead to passivity breakdown of the alloy. Adhesion provides a good distinction between the different regions and we ascribe this to their vanadium and nitrogen contents. Finally, the prepitting is characterized by generation of small particles in specific regions of the surface with low chromium content.

  • 124224.
    Álvarez Carranza, Ricardo
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Digging into Dirty Laundry: e-Standardization of Legal Services Procurement2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is to propose a standardization model for the purchase process of legal professional services leveraging e-Procurement and to validate the benefits brought by the implementation of both, an e-Procurement tool and a new procurement process. The hypotheses of this thesis are applicable to the procurement of legal professional services of large companies with a central legal department in charge of managing the relations with different legal firms (legal services suppliers). The information presented was gathered in a large global manufacturing company with strong presence in Europe. The procurement of legal professional services throughout the entire organization was analyzed and validated by central legal department based in the headquarters. An innovative model for the procurement of the legal services has been proposed based on different findings in the current literature. Also, a model developed by Ronchi et al. was leveraged to quantitatively measure the benefits brought by the implementation of e-Procurement. The model was implemented in the organization with the help of central purchasing and legal departments. The results showed it is possible to standardize the operative procurement of legal professional services for end-users to perceive the same process as the one used for direct purchases of office supplies. In order to accomplish this, some roles and an important transformation within the organization must be carried out. A general model to implement a comprehensive procurement process leveraging e-Procurement is presented in this study. The conclusions are that the specialized procurement literature focuses very little on service procurement standardization and even less in legal professional services or process standardization through e-Procurement, and thus this study and the model introduced might work as a starting point for professional practitioners or academic researchers alike. Further research topics are suggested at the end of this study to continue research on this topic.

  • 124225. Álvarez, Jesús
    et al.
    Sola, Laura
    Cretich, Marina
    Swann, Marcus J.
    Gylfason, Kristinn B.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Volden, Tormod
    Chiari, Marcella
    Hill, Daniel
    Real time optical immunosensing with flow-through porous alumina membranes2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 202, p. 834-839Article in journal (Refereed)
    Abstract [en]

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

  • 124226.
    Álvarez Ruiz, Jesús
    KTH, Superseded Departments, Physics.
    Photon induced fluorescence studies of molecules using synchrotron radiation2003Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This Licentiate thesis presents research accomplished at theSection of Atomic and Molecular Physics at the Royal Instituteof Technology in Stockholm using photon induced fluorescencespectroscopy (PIFS) during the last two years.

    The main results presented are summarized:

    - Neutral photodissociation in CO was observed aftersynchrotron photon excitation in the range 19-26 eV bycollecting dispersed fluorescence from excited neutral C atoms.Follow-up ab initio calculations point out CO Rydberg seriesconverging to the CO+ C and D states as precursors.

    - The branching ratio between N2 + (B-X)(v’=1,v’’=2) and (v’=0,v’’=1)transitions in the 20-46 eV energy range reveals strongnon-Franck-Condon effects. Ab initio calculations indicate thatthe autoionization of certain superexcited states areresponsible for some of the structures present in the branchingratio curve, confirming the important role of non-Rydbergdoubly excited resonant states (NRDERS) in de-excitationprocesses above the ionization potential.

    - Photon induced neutral dissociation processes in NO arereported. Neither Rydberg series nor other molecular states inNO known so far can account for the collected data. From abinitio calculations more information regarding the NO precursorstates and the mechanism behind the observed neutraldissociation were obtained.

    - The details of a new experimental set-up for gas phasefluorescence measurements using synchrotron radiation aredescribed. It is able to perform simultaneous measurements ofdispersed and total fluorescence in the visible range. Thefirst results obtained with this set-up are presented,concerning fluorescence after excitation of the N2 molecules inthe N 1s edge.

    These four studies conform the set of papers enclosed in theLicentiate thesis.

    Finally a pre-study to further apply PIFS to speciespreviously excited by microwave discharge is included as futureplans.

  • 124227.
    Álvarez Ruiz, Jesús
    KTH, Superseded Departments, Physics.
    Synchrotron radiation induced fluorescence spectroscopy of gas phase molecules2004Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    A new experimental set-up for gas phase fluorescence studies using synchrotron radiation has been designed and constructed to perform simultaneously total and dispersed fluorescence measurements.

    Neutral photodissociation of CO has been investigated after excitation with 19-26 eV photons. Fluorescence from 3p 3P, 3p 3S and 3p 1D excited states in carbon was recorded and interpreted by ab initio calculations. The population and dissociation of states belonging to the C and D Rydberg series in CO seem to explain the production of the observed triplet states but not the 3p 1D state.

    Neutral photodissociation of NO is reported in the 17-26 eV energy range. No known molecular states can account for the collected data. New information regarding the precursor states of the observed neutral dissociation is provided by ab initio calculations.

    Autoionization of superexcited states in molecular nitrogen is evidenced by strong deviations of the Franck-Condon ratio in the fluorescence of the N2+ B state. Ab initio calculations predict the existence of autoionizing-excited states that may account for some of the observed structures in the 20-46 eV energy range.

    Selective molecular fluorescence from the npó1Óu+ and npð 1Ðu (n=3-7) Rydberg levels to the E,F 1Óg+ state in H2 was recorded and rotationally analyzed. Vibrational levels of the E,F 1Óg+ state (vEF =0,1,3,6-10) are determined. The predissociation of npð 1Ð+ levels is observed in agreement with the literature.

    Fragmentation of SF6 was investigated after excitation with 25–80 eV photons. Dispersed fluorescence measurements reveal the emission of S, S+, F and F+ excited atoms. These fragments are produced after single, double and triple excitations as well as direct ionizations and shake-ups in SF6.

    Photoabsorption and fluorescence yield have been measured in SF5CF3 using 10-30eV photons. The photoabsorption spectrum can be explained in terms of its similarities to those of the SF6 and CF4 molecules. The dispersed and un-dispersed fluorescence resemble those of the CF3X family. Several features suggest the migration of an F atom across the S-C bond that fragments the molecule producing excited CF4.

    Doubly excited states of H2 have been investigated in the range of 26-60 eV by monitoring Balmer á emission. The experimental data show the already known emission correlated with the fragmentation of the Q1 and Q2 states, and new features which could be attributed to dissociative photoionization and higher lying doubly excited states Qn (n>2) of the hydrogen molecule

  • 124228.
    Álvarez Ruiz, Jesús
    et al.
    KTH, Superseded Departments, Physics.
    Erman, Peter
    KTH, Superseded Departments, Physics.
    Rachlew-Källne, Elisabeth
    KTH, Superseded Departments, Physics.
    Rius Riu, Jaume
    KTH, Superseded Departments, Physics.
    Stankiewicz, Marek
    KTH, Superseded Departments, Physics.
    Veseth, V.
    Neutral dissociation of superexcited states in carbon monoxide2002In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 35, no 13, p. 2975-2983Article in journal (Refereed)
    Abstract [en]

    Neutral photodissociation of CO has been investigated using synchrotron light in the range 19-26 eV by observing dispersed fluorescence from excited neutral C atoms. Follow-up ab initio calculations support the observed neutral carbon excitation functions, which to a large extent are associated with the CO Rydberg - series converging to the CO+ C and D states.

  • 124229.
    Álvarez Sánchez, Miguel
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Dynamics of an ultra-fast Thomson actuated HVDC breaker2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    High Voltage Direct Current (HVDC) is a rapidly growing form of power transmission that offers advantages with respect to conventional AC networks. One of the key elements that will allow the generalization of the HVDC grids is the Circuit Breaker (CB), which has to interrupt high DC currents in extremely short times. The use of a Thomson coil (TC) to generate high driving forces is being considered as a suitable working principle for the mechanical actuator inside the CB.

    This thesis presents the design of a concept of a mechanical actuator based on the Thomson coil for SCiBreak AB, a company whose final objective is to create a complete ultra-fast circuit breaker for HVDC lines. The design phase had to face challenges with the high forces required to open a gap between electrical contacts in just a few milliseconds. A detail design for the different components of the actuator was performed and analytical and CAD models of the system were generated.

    This thesis also included the construction and testing of a prototype at the company’s premises. The final output was the analysis and discussion of the experimental results of the prototype, as well as suggestions for the future development of the mechanical actuator.

  • 124230.
    Álvarez Tirado, Marta
    KTH, School of Chemical Science and Engineering (CHE).
    Wheat gluten - silica foams2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This work presents an alternative to polymer insulators by performing hybrid wheat gluten-silica foams. Nowadays, most of commercial insulators are made from petroleum-based polymers and blowing agents that contribute to the greenhouse effect. Wheat gluten (WG) is a potential and interesting choice to achieve materials with promising insulation properties and environmental agreement.

    A second inorganic phase, silica, has been added to the gluten foam structure in order to achieve this insulation material with additional stability and lifetimes under moisture conditions. Foams have been made by freeze-drying, changing the conditions (temperature, concentration and kind of precursor, mainly) of the process for obtaining different samples. Two kind of precursors have been used to get silica by sol-gel technique: tetraethoxysilane (TEOS) and (3-Mercaptopropyl)trimethoxysilane (MTMOS). A re-heating step on the samples is essential to get these not dissolving water foams.

    Densities of the foams are strongly affected by gluten/silica concentration and temperature: 120 kg/m3 to 195 kg/m3 (139 kg/m3 for only WG foams). MTMOS foams with a re-heating step have higher densities, with large open pores with long “sheets” cell walls. However, both precursor foams have similar cell structure for the same conditions. Furthermore, stiffness has upper values with upper concentrations and upper process temperature, although WG-Silica foams have not excellent mechanical properties with low E-modulus values in the re-heated samples.

    WG-Silica foams have outstanding thermal and combustion properties and an excellent behavior when they are burnt, being classified as V-0 materials according to the standards of the UL 94 test. Thermal conductivity values were between 1 and 1.3 J/(g ºC), which are closed to other commercial closed cell insulation materials as polystyrene and polyurethane (ca. 1.4 J/(g ºC)).

  • 124231.
    Álvarez Álvarez, Òscar
    KTH, School of Information and Communication Technology (ICT).
    Business transformation based on ICT: Smart Grid2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During the recent years several technologies and services based in Internet of Things (IoT) and Machine-to-Machine communications (M2M) have appeared in many different sectors; where IoT can be defined as the idea that any device that can be benefited by being connected will be connected and M2M communications is defined as the kind of communication between devices with minimal human interaction. IoT and M2M solutions can be applied in many sectors, like healthcare, transport, logistics, media or utilities. In every sector the motivations to implement this new services is different, as each sector has different final objectives and different actors and business models.

    When new technologies (like Smart Grid) appear two types of challenges can be defined: technical and business challenges, therefore innovation has to be applied in both of them. Too often innovation is focus on the technologic evolution and underestimated on the business field, however it is a key aspect for new technologies and services to reach commercial success.

    From the technological point of view the state of research on Smart Grid applications and services is quite advanced, while authors consider that innovation in the business part is one of the biggest challenges for Smart Grid technologies to reach success. The goal of this project is to understand the Smart Grid environment and context in different countries and propose business models suitable for the Smart Grid environment.

  • 124232.
    Álvarez-Asencio, Rubén
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nanotribology, Surface Interactions and Characterization: An AFM Study2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    When two surfaces achieve contact, then contact phenomena such as adhesion, friction and wear can occur, which are of great interest in many disciplines, including physics, physical chemistry, material chemistry, and life and health sciences. These phenomena are largely determined by the nature and magnitude of the surface forces such as van der Waals, capillary and hydration forces. Moreover these forces are length-dependent, and therefore when the system scales down, their contribution scales up, dominating the interaction between the surfaces.

    A goal of my PhD work was to investigate fundamental contact phenomena in terms of the surface forces that regulate their properties. The primary tool applied in this PhD thesis work has been the atomic force microscopy (AFM), which (with all of its sub-techniques) offers the possibility to study such forces with high resolution virtually between all types of materials and intervening media. Therefore, in this work it was possible to study the long ranged interactions presented in air between different industrially relevant materials and how these interactions are shielded when the systems are immersed in an ionic liquid.

    Also investigated was the influence of microstructure on the tribological properties of metal alloys, where their good tribological properties were related with the vanadium and nitrogen contents for a FeCrVN tool alloy and with the chromium content for a biomedical CoCrMo alloy. Moreover, the effect of the intervening media can significantly affect the surface properties, and when the biomedical CoCrMo alloy was immersed in phosphate buffer saline solution (PBS), repulsive hydration forces decreased the friction coefficient and contact adhesion. On the other hand, with the immersion of the FeCrVN tool alloy in the NaCl solution, small particles displaying low adhesion were generated in specific regions on the surface with low chromium content. These particles are assumed to be related to a prepitting corrosion event in the tool alloy.

    The mechanical properties of stratum corneum (SC), which is the outermost layer of the skin, were also studied in this work. The SC presents a highly elastic, but stiff surface where the mechanical properties depend on the nanoscale. A novel probe has been designed with a single hair fibre in order to  understand how the skin deforms locally in response to the interaction with such a fibre probe. This study revealed that is mostly the lateral scale of the deformation which determines the mechanical properties of the SC.

    Finally, important achievements in this work are the developments of two new techniques - tribological property mapping and the Hybrid method for torsional spring constant evaluation. Tribological property mapping is an AFM technique that provides friction coefficient and contact adhesion maps with information attributed to the surface microstructure. The Hybrid method is an approach that was originally required to obtain the torsional spring constants for rigid beam shaped cantilevers, which could not be previously determined from their power torsional thermal spectra (conventional method). However, the applicability is shown to be general and this simple method can be used to obtain torsional spring constants for any type of beam shape cantilever.

     

  • 124233.
    Álvarez-Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Institute for Advanced Studies, IMDEA Nanoscience, C/Faraday 9, Spain.
    Wallqvist, V.
    Kjellin, M.
    Rutland, Mark
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, Sweden.
    Camacho, A.
    Nordgren, N.
    Luengo, G. S.
    Nanomechanical properties of human skin and introduction of a novel hair indenter2016In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 54, p. 185-193Article in journal (Refereed)
    Abstract [en]

    The mechanical resistance of the stratum corneum, the outermost layer of skin, to deformation has been evaluated at different length scales using Atomic Force Microscopy. Nanomechanical surface mapping was first conducted using a sharp silicon tip and revealed that Young’s modulus of the stratum corneum varied over the surface with a mean value of about 0.4 GPa. Force indentation measurements showed permanent deformation of the skin surface only at high applied loads (above 4 μN). The latter effect was further demonstrated using nanomechanical imaging in which the obtained depth profiles clearly illustrate the effects of increased normal force on the elastic/plastic surface deformation. Force measurements utilizing the single hair fiber probe supported the nanoindentation results of the stratum corneum being highly elastic at the nanoscale, but revealed that the lateral scale of the deformation determines the effective elastic modulus.This result resolves the fact that the reported values in the literature vary greatly and will help to understand the biophysics of the interaction of razor cut hairs that curl back during growth and interact with the skin.

  • 124234.
    Árnandóttir, Kristrún Helga
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    BIM Maturity in Iceland: A Study of Contractors and Sub-contractors2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the last decade, BIM has provided the construction industry with countless tools that canbe used during all construction phases (Kam et al., 2016). Implementation of BIM in Icelandat the beginning was driven by the heroic’s individuals. In recent years leadership within theAEC has recognized the opportunities BIM can provide.The aim of this thesis is to map BIM maturity of contractors and sub-contractors in Iceland.The results found that there is a lack of awareness about BIM among small to medium sizedcontractors as well as among sub-contractors. Among the larger contractors and designersmaturity is higher then found in the last study performed for GDDA 2013 (Valdimarssonand Kjartansdóttir, 2013). Recent requirement from large public project owners that requiresBIM has speed up implementation.

  • 124235.
    Ähdel, Victor
    KTH, School of Electrical Engineering and Computer Science (EECS).
    On the effect of architecture on deep learning based features for homography estimation2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Keypoint detection and description is the first step of homography and essential matrix estimation, which in turn is used in Visual Odometry and Visual SLAM. This work explores the effect (in terms of speed and accuracy) of using different deep learning architectures for such keypoints. The fully convolutional networks — with heads for both the detector and descriptor — are trained through an existing self-supervised method, where correspondences are obtained through known randomly sampled homographies. A new strategy for choosing negative correspondences for the descriptor loss is presented, which enables more flexibility in the architecture design. The new strategy turns out to be essential as it enables networks that outperform the learnt baseline at no cost in inference time.

    Varying the model size leads to a trade-off in speed and accuracy, and while all models outperform ORB in homography estimation, only the larger models approach SIFT’s performance; performing about 1-7% worse. Training for longer and with additional types of data might give the push needed to outperform SIFT. While the smallest models are 3× faster and use 50× fewer parameters than the learnt baseline, they still require 3× as much time as SIFT while performing about 10-30% worse. However, there is still room for improvement through optimization methods that go beyond architecture modification, e.g. quantization, which might make the method faster than SIFT.

  • 124236. Älfvåg, Hector
    et al.
    Lindbergh, Jakob
    KTH, School of Engineering Sciences (SCI).
    Optimering av kontakt med kontaktledning hos tåg:: Utplacerade massors påverkan på kontaktkraftens kvalitet2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This project aims to answer whether or not masses placed along a catenary can improve dynamic performance in the contact force between the train's pantograph and the catenary, and more specifically reduce the fluctuation of the contact force. This would be a way to improve the performance with only minor modifications to the infrastructure, rather than needing to replace entire catenaries, which is both economically and environmentally costly. The idea of masses as stabilizers comes from other applications, such as skyscrapers and power lines, where said masses have a positive effect on vibrations and movements. Simulations in ANSYS and post-processing in MATLAB are used to determine the contact force, which then can be quantified and compared between different scenarios. Eight different catenary positions, four different masses and two train speeds are tested in hope of seeing trends of what improves the performance and what doesn't. A few conclusions about the effect of the masses can be drawn from the results. Bigger masses gave a bigger effect, and a very big mass gave fluctuations where it was tested. Regarding the impact the speed has on the effect of the masses, the case studied here indicates lower speed decreases the local effect but increases the global effect. All mass placements that improved the performance, by reducing the fluctuations of the contact force, were at the end of a catenary span, and all placements that decreased the performance were at the centre and start of a span. Some practical limitations on the application of masses on real catenaries, such as mass placements on the contact wire and increased wear on the components involved, are discussed.

  • 124237.
    Älgenäs, Cajsa
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Agaton, Charlotta
    Fagerberg, Linn
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Asplund, Anna
    Björling, Lisa
    KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Björling, Erik
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Kampf, Caroline
    Lundberg, Emma
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Nilsson, Peter
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Persson, Anja
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Wester, Kenneth
    Pontén, Fredrik
    Wernerus, Henrik
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Ottosson Takanen, Jenny
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Hober, Sophia
    KTH, School of Biotechnology (BIO), Protein Technology.
    Antibody performance in western blot applications is context- dependent2014In: Biotechnology Journal, ISSN 1860-6768, E-ISSN 1860-7314, Vol. 9, no 3, p. 435-445Article in journal (Refereed)
    Abstract [en]

    An important concern for the use of antibodies in various applications, such as western blot (WB) or immunohistochemistry (IHC), is specificity. This calls for systematic validations using well-designed conditions. Here, we have analyzed 13000 antibodies using western blot with lysates from human cell lines, tissues, and plasma. Standardized stratification showed that 45% of the antibodies yielded supportive staining, and the rest either no staining (12%) or protein bands of wrong size (43%). A comparative study of WB and IHC showed that the performance of antibodies is application-specific, although a correlation between no WB staining and weak IHC staining could be seen. To investigate the influence of protein abundance on the apparent specificity of the antibody, new WB analyses were performed for 1369 genes that gave unsupportive WBs in the initial screening using cell lysates with overexpressed full-length proteins. Then, more than 82% of the antibodies yielded a specific band corresponding to the full-length protein. Hence, the vast majority of the antibodies (90%) used in this study specifically recognize the target protein when present at sufficiently high levels. This demonstrates the context- and application-dependence of antibody validation and emphasizes that caution is needed when annotating binding reagents as specific or cross-reactive. WB is one of the most commonly used methods for validation of antibodies. Our data implicate that solely using one platform for antibody validation might give misleading information and therefore at least one additional method should be used to verify the achieved data.

  • 124238.
    Älvenstrand, Daniel
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE).
    Horna, Joakim
    KTH, School of Education and Communication in Engineering Science (ECE).
    Lärande inom vården – Ett digitalt frö: En pilotstudie i att designa ett nätbaserat lärverktyg för att effektivisera introduktionsutbildningen för sjuksköterskor inom hematologi.2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today, the introductory training for the nurses of the clinic for hematology at the Karolinska University hospital is insufficient which could jeopardize the patient safety. The clinic is hoping, by using an interactive net based learning tool, to be able to streamline the nurses’ internal education, make their learning material more easily learnt and motivate them to continue learning.

     

    This thesis examined whether the clinic’s desired results could be achieved. This was examined by creating and evaluate a prototype of a learning tool. By combining theories and research about net based education, user centered design, interaction design and learning perspectives a prototype was developed for net based learning.

     

    In order to identify the nurses’ needs and situation, a pre-study was conducted in the form of surveys and interviews with the clinic’s personnel followed by an interview study with responsible staff at the clinic and the hospital. A prototype was developed and its usability was evaluated together with the nurses. The tool was also evaluated by its ability to streamline the learning of the educational material regarding Cytostatic which was given by the county council; this by designing and testing of a course.

     

    The results of the thesis identifies the factors which contributes to making a net based learning tool usable for the clinics staff. These factors, together with identifying the factors that affect their learning process, contributes to streamline the nurses’ introductory training. In conclusion, a learning tool which has been developed with affected personnel through a combination of design and learning perspectives can be made usable and education in order to ensure the nurses’ competence and contribute to an increased patient safety.

  • 124239.
    Ängeby, William
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Använding av geometrisk akustik för beräkning av efterklangstid i idrottshallar2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When measures for acoustic improvements in sports halls, and other rooms, are to be implemented it is a great advantage to be able to predict how the action is going to affect for example the reverberation time even before it is done in reality. Since it costs money to install acoustic absorbers you want it to be right the first time around. Through the use of geometrical acoustic calculations digital models of the sports halls can be used to predict the results of a certain action. An often used method is to create a model with the existent absorbing materials and compare the calculated reverberation time to the measured reverberation time from the actual hall to check if the model is valid. Apart from calculations of the reverberation time the influence of the measured reverberation time to STI, a measure of speech intelligibility, is analyzed. A sports hall is often used as work places for sports teachers and it is therefore important to achieve a good acoustic environment in the hall.

    One of the aims of this project is to increase the knowledge of what gives a good model for acoustic calculations and how to choose absorption- and scattering coefficients. The goal is to make the calculated reverberation times to match the measured reverberation times. The other aim is to examine if there is a certain reverberation time curve which helps to achieve as good STI as possible.

    This project is part of the final examination in technical acoustics at KTH and has been carried out at Akustikbyrån T4p in Stockholm.

    The reverberation time for five sports halls has been measured. Models and geometrical acoustic calculations has been done for three of the halls. The absorption- and scattering coefficients used have been chosen from an absorption database as well as from analysis using the Eyring reverberation time model. The calculated reverberation times has been compared to the measured reverberation times. The measured STI for each of the five halls has been compared to the measured reverberation time for an analysis of if there is a certain reverberation curve which provides good speech intelligibility.

    The project resulted in recommendations for how detailed a model should be and also a procedure for estimating absorption- and scattering coefficients. Small details in the model usually don’t have a big impact on the calculated reverberation time at the same time as they do have a huge effect on the calculation times. The results also show that the scattering coefficients can have a huge impact on the calculated reverberation times and that they should not be neglected. It was found that both absorption- and scattering coefficients must often be overestimated for the 125 and 250 Hz octave bands for the calculated reverberation time to match the measured reverberation time in those bands. It turns out to be hard to give a specific reverberation time curve which provides for as good STI as possible since there are other parameters affecting the results. A requirement for reverberation times in sports halls used by school students is 1.2 seconds in all octave bands. The results shows that a reverberation time of 1.2 seconds in all octave bands is not necessary for good speech intelligibility.

    The procedure for estimation of absorption- and scattering coefficients hopefully leads to better understanding of how the coefficients can be chosen and how they affect the calculation results. The results could also give better understanding of the limitations when using software based on geometrical acoustics

  • 124240.
    Ängquist, Lennart
    KTH, Superseded Departments, Electrical Systems.
    Synchronous Voltage Reversal Control of Thyristor Controlled Series Capacitor2002Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Series compensation of transmission lines is an effectiveand cheap method of improving the power transmission systemperformance. Series capacitors virtually reduces the length ofthe line making it easier to keep all parts of the power systemrunning in synchronism and to maintain a constant voltage levelthroughout the system. In Sweden this technology has been inuse since almost 50 years.

    The possibility to improve the performance of the ACtransmission system utilizing power electronic equipment hasbeen discussed a lot since about ten years. Some newsemiconductor based concepts have been developed beside thesince long established HVDC and SVC technologies. The ThyristorControlled Series Capacitor (TCSC) is one such concept. Byvarying the inserted reactance an immediate and well-definedimpact on the active power flow in the transmission line isobtained. Several potential applications, specifically poweroscillation damping, benefit from this capability. The conceptimplied the requirement to design a semiconductor valve, whichcan be inserted directly in the high-voltage power circuit.This certainly presented a technical challenge but thestraightforward approach appeared to be a cost-effectivealternative with small losses.

    It was also realized that the TCSC exhibits quite differentbehaviour with respect to subsynchronous frequency componentsin the line current as compared to the fixed series capacitorbank. This was a very interesting aspect as the risk ofsubsynchronous resonance (SSR), which just involves such linecurrent components, has hampered the use of series compensationin power systems using thermal generating plants.

    The thesis deals with the modelling and control aspects ofTCSC. A simplifying concept, the equivalent, instantaneousvoltage reversal, is introduced to represent the action of thethyristor controlled inductive branch, which is connected inparallel with the series capacitor bank in the TCSC. The idealvoltage reversal is used in the thesis in order to describe andexplain the TCSC dynamics, to investigate its apparentimpedance at various frequencies, as a platform forsynthesizing the boost control system and as the base elementin deriving a linear, small-signal dynamical model of thethree-phase TCSC. Quantitative Feedback Theory (QFT) then hasbeen applied to the TCSC model in order to tune its boostregulator taking into account the typical variation ofparameters that exists in a power system. The impact of theboost control system with respect to damping of SSR is finallybeing briefly looked at.

    Keywords:Thyristor Controlled Series Capacitor, TCSC,FACTS, reactive power compensation, boost control, phasorestimation, Quantitative Feedback Theory, subsynchronousresonance, SSR.

  • 124241.
    Ängquist, Lennart
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Antonopoulos, Antonios
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Arm-current-based control of modular multilevel converters2013In: 2013 15th European Conference on Power Electronics and Applications, EPE 2013, IEEE , 2013, p. 6631999-Conference paper (Refereed)
    Abstract [en]

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

  • 124242.
    Ängquist, Lennart
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Antonopoulos, Antonios
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Siemaszko, Daniel
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Ilves, Kalle
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Vasiladiotis, Michail
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Open-Loop Control of Modular Multilevel Converters Using Estimation of Stored Energy2011In: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 47, no 6, p. 2516-2524Article in journal (Refereed)
    Abstract [en]

    The internal control of a modular multilevel converter aims to equalize and stabilize the submodule capacitor voltages independent of the loading conditions. It has been shown that a submodule selection mechanism, included in the modulator, can provide voltage sharing inside the converter arm. Several procedures for controlling the total stored energy in each converter arm exist. A new approach is described in this paper. It is based on estimation of the stored energy in the arms by combining the converter electromotive force reference, the measured alternating output current, and the known direct voltage. No feedback controllers are used. Experimental verification on a three-phase 10 kVA prototype is presented along with the description of the new procedure.

  • 124243.
    Ängquist, Lennart
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Bongiorno, Massimo
    Dept. of Energy and Environment, Chalmers University of Technology, Sweden.
    Auto-normalizing Phase-Locked Loop for Grid-connected Converters2009In: 2009 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION, VOLS 1-6, NEW YORK: IEEE , 2009, p. 2430-2437Conference paper (Refereed)
    Abstract [en]

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

  • 124244.
    Ängquist, Lennart
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Haider, Arif
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Jiang, Hongbo
    Trafikverket, Borlänge, Sweden.
    Open-loop approach to control a Modular Multilevel Frequency Converter2011In: Proceedings of the 2011-14th European Conference on Power Electronics and Applications (EPE 2011) / [ed] EPE Association, 2011Conference paper (Refereed)
    Abstract [en]

    Frequency converters are required to supply power from the public three-phase network to railways using 16.7 Hz single-phase in their rolling stock. The emerging Modular Multilevel Converter (M2C) technology offers the possibility to make such power conversion in one step using Modular Multilevel Frequency Converters (MMFC) with full-bridge sub-modules. A detailed study of the modulation and control of such converters is presented in this paper. The voltage inserted by each arm of the MMFC is a mixture of the three-phase 50 Hz voltage and the single phase 16.7 Hz voltage. It is important that the voltage reference given to the modulator will be carefully reproduced by the converter because any deviation can introduce undesired frequency components from the single-phase side to the three-phase side and vice versa. The fact that the low frequency, single-phase load causes low-frequency ripple in the total capacitor voltage complicates the problem to generate the correct modulation pattern. In this paper it is proposed to solve that difficulty by estimating the instaneous total capacitor voltages in each arm and provide that information to the modulator. It is shown that such estimations can be performed using measured currents on the single- and three-phase sides. Stable single-phase voltage, symmetrical undistorted three-phase currents and stable converter capacitor voltages are achieved under varying loading conditions. Models in Matlab/Simulink (continuous) and EMTDC/PSCAD (discrete sub-modules) have been developed in this study.

  • 124245.
    Ängskog, Per
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap.
    Avsiktliga elektromagnetiska störningar: Det osynliga hotet2014In: Electronics and the Environment, ISSN 1095-2020, Vol. 1, p. 16-17Article in journal (Other academic)
    Abstract [sv]

    I vårt moderna samhälle blir vi alltmer beroende av olika elektroniska kommunikations- och styrsystem, något som redan har upptäckts av kriminella, som utnyttjat svagheter i systemen för att begå brott. Detta är ett nytt scenario vi måste acceptera och lära oss hantera.

  • 124246.
    Ängskog, Per
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap.
    EMP-symposium 8-9 maj 2014 i Oslo2014In: Electronic Environment, Vol. 2, p. 22-23Article in journal (Other (popular science, discussion, etc.))
  • 124247.
    Ängskog, Per
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Bäckström, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Samuelsson, Carl
    Saab Aeronaut, SE-58188 Linkoping, Sweden..
    Vallhagen, Bengt Kangashaka
    Saab Aeronaut, SE-58188 Linkoping, Sweden..
    Shielding Effectiveness and HPM Vulnerability of Energy-Saving Windows and Window Panes2019In: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 61, no 3, p. 870-877Article in journal (Refereed)
    Abstract [en]

    In this paper, we report results from shielding effectiveness measurements on energy-saving windows and individual, coated window panes of different generations, as well as results from high-power microwave irradiation on single panes. Shielding effectiveness was measured with two complementary methods: first, with near isotropic irradiation in nested reverberation chambers, and the other with irradiation at normal incidence in a semianechoic chamber. The measurements show that the construction of the energy conserving windows has a clear impact on how well they attenuate radio frequency signals. The more modern the window or pane, the higher is the shielding effectiveness. The high-power irradiation on coated panes showed that depending on the type of coating, hotspots can build up causing the coating to crack and, hence, deteriorate the shielding effectiveness. These results may serve as guidance when reviewing high-altitude electromagnetic pulse (EMP), high-power microwave, or intentional electromagnetic interference protection of critical infrastructures, and provide assistance in the work with reduction of compromising emanations.

  • 124248.
    Ängskog, Per
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Högskolan i Gävle.
    Bäckström, Mats
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. SAAB Aeronautics, SAAB AB.
    Vallhagen, Bengt
    SAAB Aeronautics, SAAB AB.
    High Power Microwave Effects on Coated Window Panes2015In: Asia Electromagnetics Conference (ASIAEM) 2015, 2015Conference paper (Refereed)
    Abstract [en]

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

  • 124249.
    Ängskog, Per
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Högskolan i Gävle.
    Bäckström, Mats
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. SAAB Aeronautics, SAAB AB.
    Vallhagen, Bengt
    SAAB Aeronautics, SAAB AB.
    Measurement of Radio Signal Propagation through Window Panes and Energy Saving Windows2015In: Proceedings of Electromagnetic Compatibility (EMC), 2015 IEEE International Symposium on, IEEE conference proceedings, 2015, p. 74-79Conference paper (Refereed)
    Abstract [en]

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

  • 124250.
    Ängskog, Per
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Bäckström, Mats
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Vallhagen, Bengt
    Samuelsson, Carl
    Shielding Effectiveness of Energy Saving Windows and HPM Effects on Coated Window Panes Measurements Conducted 2014-2016-Results and Lessons Learned2016In: PROCEEDINGS OF THE 2016 INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY - EMC EUROPE, IEEE conference proceedings, 2016, p. 461-466Conference paper (Refereed)
    Abstract [en]

    The past few decades have shown a veritable explosion of new versions of energy-saving windows and coated window panes. In the wake of this, problems with radio communications into and from within buildings has arisen. However, this unexpected attenuation of radio signals may also be used to shield a facility from incoming intentional electromagnetic interference (IEMI). With the intention to investigate the shielding effectiveness (SE) of modern windows and window panes a two-year measurement campaign was launched mid-2014. Another, little investigated area is what happens to coated glass when irradiated by a high-power microwave (HPM) source. Shielding effectiveness has been measured for different types of energy saving windows and coated window panes both in a semi-anechoic chamber and in a reverberation chamber over the frequency range 1-18 GHz. The effects of HPM irradiation were studied by comparing SE measured before and after the pulsed 28 kV/m L-band irradiation. The main conclusion is that with the right choice of window the shielding effectiveness of a building can reach up 40-50 dB. In this paper we summarize these measurements and lessons learned from the measurement campaign.

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