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  • 2901.
    Aid, Graham
    et al.
    Ragn-Sells AB.
    Lazarevic, David
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology. Finnish Environment Institute SYKE.
    Kihl, Anders
    Ragn-Sells AB.
    Waste to Resources: Moving Toward the 2030 Sustainable Development Goals2016Conference paper (Other academic)
  • 2902.
    AIDANPÄÄ, MATHILDA
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    SJÖBERG, MATHILDA
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    De etiska konsekvenserna av produktutveckling: Oönskade konsekvenser av strävan efter zero-labourfactories2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today’s development of automation happens at an increasing rate driven by innovation and product development. Companies have to keep up with this progress to stay competitive. The question has risen whether we are now facing a new industrial revolution or not. The ethical perspective has now become a concern.

    The purpose of this report is to investigate the following questions:

    • How big of a role has the ethical perspective in decision-making processes with regards to automation?

    • Who is responsible for ethical issues within product development?

    • To what extent should ethics be a part of engineering education?

    The chosen method during the study was extensive literature studies and semi structured interviews with employees and managers from the affected area.

    The result of the report is that the ethical perspective has a smaller impact in the decisionmaking processes compared to other factors. The responsibility of the ethical consequences lies in both product development companies and producing companies. Finally, ethical perspectives should be integrated into engineering education.

  • 2903.
    Aidanpää, Sandra
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Nordmark, Elin MK
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Flexible Updates of Embedded Systems Using Containers2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis the operating-system-level virtualization solution Docker is investigated in the context of updating an embedded system on application level. An updating sequence is designed, modelled and implemented, on which experiments are conducted to measure uptime and current. Within the popular notion of the Internet of Things, more and more things are being connected to the Internet and there by the possibility of dynamic updates over the Internet is created. Being able to update remotely can be very benecial, as systems may be costly or unpractical to reach physically for software updates. Operating-system-level virtualization, software containers, are a lightweight virtualization solution that can be used for dynamic updating purposes. Virtualization properties, like resource isolation and letting software share hardware capabilities are used in determining the architecture. The container architecture used is a microservice architecture, where systems are composed from many smaller, loosely coupled services. The application area for the results of this thesis are start-ups in the Internet of Things eld, delimited to low complexity systems such as consumer products. The update regime is created with the properties of microservice architectures in mind, creating a self-propelling, self-testing, scalable and seamless dynamic updating process that can be used for systems of dierent complexity. The update regime is modeled to give proof of concept and to help design the implementation. The implemented update regime was made on an ARM based single board computer with a Linux-kernel based operating system running Docker. Experiments were then conducted in order to give a clear indication of the behavior of a dynamically updated embedded system. The experiments showed that the update regime can be seamless, meaning that the uptime properties are not aected by this kind of updating. The experiments also showed that no signicant changes in current can be noted for container limitations during this kind of update.

  • 2904. Aidas, Kestutis
    et al.
    Angeli, Celestino
    Bak, Keld L.
    Bakken, Vebjorn
    Bast, Radovan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Boman, Linus
    Christiansen, Ove
    Cimiraglia, Renzo
    Coriani, Sonia
    Dahle, Pal
    Dalskov, Erik K.
    Ekstrom, Ulf
    Enevoldsen, Thomas
    Eriksen, Janus J.
    Ettenhuber, Patrick
    Fernandez, Berta
    Ferrighi, Lara
    Fliegl, Heike
    Frediani, Luca
    Hald, Kasper
    Halkier, Asger
    Hattig, Christof
    Heiberg, Hanne
    Helgaker, Trygve
    Hennum, Alf Christian
    Hettema, Hinne
    Hjertenaes, Eirik
    Host, Stinne
    Hoyvik, Ida-Marie
    Iozzi, Maria Francesca
    Jansik, Branislav
    Jensen, Hans Jorgen Aa.
    Jonsson, Dan
    Jorgensen, Poul
    Kauczor, Joanna
    Kirpekar, Sheela
    Kjrgaard, Thomas
    Klopper, Wim
    Knecht, Stefan
    Kobayashi, Rika
    Koch, Henrik
    Kongsted, Jacob
    Krapp, Andreas
    Kristensen, Kasper
    Ligabue, Andrea
    Lutnaes, Ola B.
    Melo, Juan I.
    Mikkelsen, Kurt V.
    Myhre, Rolf H.
    Neiss, Christian
    Nielsen, Christian B.
    Norman, Patrick
    Olsen, Jeppe
    Olsen, Jogvan Magnus H.
    Osted, Anders
    Packer, Martin J.
    Pawlowski, Filip
    Pedersen, Thomas B.
    Provasi, Patricio F.
    Reine, Simen
    Rinkevicius, Zilvinas
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Ruden, Torgeir A.
    Ruud, Kenneth
    Rybkin, Vladimir V.
    Salek, Pawel
    Samson, Claire C. M.
    de Meras, Alfredo Sanchez
    Saue, Trond
    Sauer, Stephan P. A.
    Schimmelpfennig, Bernd
    Sneskov, Kristian
    Steindal, Arnfinn H.
    Sylvester-Hvid, Kristian O.
    Taylor, Peter R.
    Teale, Andrew M.
    Tellgren, Erik I.
    Tew, David P.
    Thorvaldsen, Andreas J.
    Thogersen, Lea
    Vahtras, Olav
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Watson, Mark A.
    Wilson, David J. D.
    Ziolkowski, Marcin
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    The Dalton quantum chemistry program system2014In: Wiley Interdisciplinary Reviews. Computational Molecular Science, ISSN 1759-0876, Vol. 4, no 3, p. 269-284Article in journal (Refereed)
    Abstract [en]

    Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from for a number of UNIX platforms.

  • 2905. Aidas, Kestutis
    et al.
    Olsen, Jogvan Magnus H.
    Kongsted, Jacob
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Photoabsorption of Acridine Yellow and Proflavin Bound to Human Serum Albumin Studied by Means of Quantum Mechanics/Molecular Dynamics2013In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 117, no 7, p. 2069-2080Article in journal (Refereed)
    Abstract [en]

    Attempting to unravel mechanisms in optical probing of proteins, we have performed pilot calculations of two cationic chromophores-acridine yellow and proflavin-located at different binding sites within human serum albumin, including the two primary drug binding sites as well as a heme binding site. The computational scheme adopted involves classical molecular dynamics simulations of the ligands bound to the protein and subsequent linear response polarizable embedding density functional theory calculations of the excitation energies. A polarizable embedding potential consisting of point charges fitted to reproduce the electrostatic potential and isotropic atomic polarizabilities computed individually for every residue of the protein was used in the linear response calculations. Comparing the calculated aqueous solution-to-protein shifts of maximum absorption energies to available experimental data, we concluded that the cationic proflavin chromophore is likely not to bind albumin at its drug binding site I nor at its heme binding site. Although agreement with experimental data could only be obtained in qualitative terms, our results clearly indicate that the difference in optical response of the two probes is due to deprotonation, and not, as earlier suggested, to different binding sites. The ramifications of this finding for design of molecular probes targeting albumin or other proteins is briefly discussed.

  • 2906.
    Aidas, Kestutis
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Kongsted, Jacob
    Laaksonen, Aatto
    Mocci, Francesca
    A quantum mechanics/molecular dynamics study of electric field gradient fluctuations in the liquid phase. The case of Na+ in aqueous solution2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 5, p. 1621-1631Article in journal (Refereed)
    Abstract [en]

    The Na-23 quadrupolar coupling constant of the Na+ ion in aqueous solution has been predicted using molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics methods for the calculation of electric field gradients. The developed computational approach is generally expected to provide reliable estimates of the quadrupolar coupling constants of monoatomic species in condensed phases, and we show here that intermolecular polarization and non-electrostatic interactions are of crucial importance as they result in a 100% increased quadrupolar coupling constant of the ion as compared to a simpler pure electrostatic picture. These findings question the reliability of the commonly applied classical Sternheimer approximation for the calculations of the electric field gradient. As it can be expected from symmetry considerations, the quadrupolar coupling constants of the 5- and 6-coordinated Na+ ions in solution are found to differ significantly.

  • 2907.
    Aidas, Nina
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Responsive Textile Geometries: Vanadisbadet Revised2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    How can principles found in textile behaviour be translated into architectural expression? With water as a program in context of a new bath in Vanadislunden, Stockholm, this project studies how a rigid material can be percieved as soft and flexible.

  • 2908.
    Aidi, Laili
    KTH, School of Information and Communication Technology (ICT).
    Business Modelsfor Mobile Broadband Media Services: Case Study Indonesia Telecom Market2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increase mobile data traffic from the emerging Internet services, especially multimedia, has posed considerable challenges for the telecom industry. Their initial mobile data services business models are generally not compatible with these emerging Internet services. Thus, there is a substantial need to investigate the suitable options to make media as a profitable telecom business sector. However, there are different challenges and opportunity factors in developing sustainable mobile media business in each market, due to the unique circumstances applied as the result of customer characteristics, mobile market situation and regulatory/law enforcement.</p><p>The first purpose of this thesis is to explore the business model options to deliver media services on top of mobile broadband. Although, we limit our focus to Indonesia, we first analyzed the worldwide patterns toward the media services in order to get a broader view of the current trend. We mapped multitudes of actor involved in digital online / on the top (OTT)media service, which together they form different types of constellation in the value network,as well as service, delivery and revenue model. We also put our focus to get the lessons learned from Spotify's business model, by framing it using Chesbrough and Rosenbloom's model.</p><p>The second purpose is to understand the Indonesian mobile user's characteristic toward the mobile media services. We conducted survey to 119 Indonesians, analyzed the result with one sample T-tests and validated it with the correlation tests (Cronbach Alpha and Pearson correlation), within the Unified theory of acceptance and use of technology (UTAUT)framework. Our findings confirm the low willingness to pay, but an open attitude for the services. The mobile device and network quality are not the barriers for them to adopt the services, and there is a tight connection between the decisions to adopt the services with the perception that the service is popular.</p><p>Through those findings, we assessed the feasibility of the identified options and formulated the recommendations. We used our understanding about Indonesian market structure (telecom and media), regulation, and mobile user, as well as the lesson that we got from media services provisioning in Sweden and worldwide trend. We found that the pricing tiers, adjustable pricing, and differentiated features are some of the key success factors.Meanwhile, being part in the point-to-multipoint partnership with the well-known OTT player is the potential position that the Mobile network operators (MNOs) in Indonesia should take in provisioning OTT media services, rather than deliver the services by their own.

  • 2909.
    Aidi, Laili
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Huang, Jin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Selvakumar, Ekambar
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Blennerud, Greger
    Ericsson.
    How can Mobile Music Streaming Service Take off in India, China and Indonesia?: Analysis of Drivers and Obstacles2012In: , 2012Conference paper (Refereed)
  • 2910.
    Aidi, Laili
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Blennerud, Greger
    Ericsson.
    Competing or Aligning? Assessment for Telecom Operator's strategy to address OTT TV/Video services2012Conference paper (Refereed)
    Abstract [en]

    Up until recently, it was rarely direct competition between telecom operators, cable and satellite Pay-TV providers in digital TV/Video, as their business area were different and value chain was well established. However, technology advance has altered digital TV/Video landscape, made these Communication Service Providers (CSPs) cross other’s area and opened door for new actor (OTT player) to enter the market. This triggers second change in the landscape, as it potentially bypasses CSP’s role in digital media value chain.

    There are generic potential options for telecom operator to address OTT service‘s treat, where the trend shows gradual shifts toward allowing or promoting. This study assesses telecom operator’s reaction strategies to react to this digital TV/Video convergence trend. Our analysis reveals two typical relation patterns in the value network, used by telecom operators based on strategy options above, which are ”point-to-point” and ”point-to-multipoint” relation model. We explore the underlining motivations that based these strategies, as well as analysis of the eco-systems: actors identification, business roles and distributed responsibilities among them, where we use ARA (Actors, Resource, Activities) point of view to model these value networks.

  • 2911. Aiempanakit, Montri
    et al.
    Aijaz, Asim
    Lundin, Daniel
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Helmersson, Ulf
    Kubart, Tomas
    Understanding the discharge current behavior in reactive high power impulse magnetron sputtering of oxides2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 13, p. 133302-Article in journal (Refereed)
    Abstract [en]

    The discharge current behavior in reactive high power impulse magnetron sputtering (HiPIMS) of Ti-O and Al-O is investigated. It is found that for both metals, the discharge peak current significantly increases in the oxide mode in contrast to the behavior in reactive direct current magnetron sputtering where the discharge current increases for Al but decreases for Ti when oxygen is introduced. In order to investigate the increase in the discharge current in HiPIMS-mode, the ionic contribution of the discharge in the oxide and metal mode is measured using time-resolved mass spectrometry. The energy distributions and time evolution are investigated during the pulse-on time as well as in the post-discharge. In the oxide mode, the discharge is dominated by ionized oxygen, which has been preferentially sputtered from the target surface. The ionized oxygen determines the discharge behavior in reactive HiPIMS.

  • 2912. Aier, Stephan
    et al.
    Buckl, Sabine
    Franke, Ulrik
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Gleichauf, Bettina
    Johnson, Pontus
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Närman, Per
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Schweda, Christian M.
    Ullberg, Johan
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    A Survival Analysis of Application Life Spans based on Enterprise Architecture Models2009In: Proc. 3rd International Workshop on Enterprise Modelling and Information Systems Architectures, EMISA 2009, 2009, Vol. P-152, p. 141-154Conference paper (Refereed)
    Abstract [en]

    Modern enterprises face the challenge to survive in an ever changing environment. One commonly accepted means to address this challenge and further enhance survivability is enterprise architecture (EA) management, which provides a holistic model-based approach to business/IT alignment. Thereby, the decisions taken in the context of EA management are based on accurate documentation of IT systems and business processes. The maintenance of such documentation causes high investments for enter-prises, especially in the absence of information on the change rates of different systems and processes. In this paper we propose a method for gathering and analyzing such in-formation. The method is used to analyze the life spans of the application portfolio of three companies from different industry sectors. Based on the results of the three case studies implications and limitations of the method are discussed.

  • 2913. Aier, Stephan
    et al.
    Ekstedt, MathiasKTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.Matthes, FlorianProper, ErikSanz, Jorge
    Trends in Enterprise Architecture Research and Practice-Driven Research on Enterprise Transformation: 7th Workshop, TEAR 2012, and 5th Working Conference, PRET 2012, Held at The Open Group Conference 2012, Barcelona, Spain, October 23-24, 2012. Proceedings2012Conference proceedings (editor) (Refereed)
  • 2914. Aigelsperger, Lisa
    et al.
    Kummer, Susanne
    Milestad, Rebecka
    Department of Urban and Rural Studies, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Vogl, Christian R.
    Chowdhury, A.
    Knowledge systems, innovations and social learning in organic farming: An Overwiev2010In: Proceedings of the 9th European IFSA Symposium, 2010, p. 664-669Conference paper (Refereed)
  • 2915.
    Aigner, Joachim Felix
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Environmental Implications of Media Consumption embedded in Digital Ecosystems: A bottom-up systems approach to the perennial case of paperless reading in Germany2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Digitalization has been reshaping the media landscape in recent years, often conveying an implicit promise of becoming less dependent on physical resources. At the same time, the current understanding of digital reading goes beyond dedicated e-readers or definable digital media products such as magazines or newspapers. In fact, it must be perceived as a function or service obtained from existing and ever-expanding “digital ecosystems”. There is furthermore a clear and unambiguous trend that relatively small and mobile devices are on the rise for consuming all kinds of media.

    Next to potentially enabling environmental gains compared to traditional paper-based media consumption, there are agreeing indications of a shift from overall electricity consumption dominated by end-user devices towards an increasing importance of less tangible data transmission networks and data centers. Therefore, a bottom-up analysis is deemed to compliment more general top-down observations and assessments. To this end, an elaborated reference scenario is proposed as to bridge the mere analytical method of Life Cycle Assessment (LCA) with behavioral aspects based on German market observations and surveys. The prevailing aim of this study is to detect environmental hot-spots and absolute impacts linked to the service of accessing text-based content via connected electronic devices. In doing so, this study takes the position that both types of media consumption – digital and paper-based - are incommensurable due to the very evident differences in provided functions, markets, and industries. Therefore, an attributional and stand-alone LCA is considered appropriate.

    The perceived current situation (reference scenario) evolves around substantiated estimates and assumptions concerning production of devices, use of devices as well as operation of essential data transmission network components. Looking at potential hot-spots, electricity consumption linked to data transmission could be a decisive factor for the environmental performance of digital reading. However, the actual importance of data transmission infrastructures depends on both methodological choices and a range of parameters or trends. For instance, the relative importance is shifted when more recent estimates of electricity intensities are incorporated. Depending on actual and localized electricity intensity of data transmission, the amount of data required to provide an expected function may inhibit environmental potentials of digital media consumption.

    Postulating average annual consumption of digital contents and assuming actual substitution of equivalent printed media products, about 50 kg CO2-equivalents. could potentially be avoided. This theoretical potential is based on the calculated global warming potential (GWP) associated with digital reading according to the reference scenario which amounts to about 29 kg CO2-equivalents. Therefore, this study supports findings from previous studies that indicated environmental benefits of digital reading.

    Compared to other functions or services (e.g. video/music streaming, podcasts, audio books) embedded in the same “digital ecosystems”, reading requires little amount of data. If allocation of upstream effects is based on time, the relative importance of data transmission networks could be gauged and compared by adopting a “data-to-service time” ratio. Taking the reference scenario as a starting point, a perceivable ratio for digital reading is 0.015 GB/h, including systemic inefficiencies. In contrast, streaming of high-definition video contents can easily consume 3 GB/h, a 200-fold increase.

    The audience of this study comprises providers of digital reading services and/or other media services as well as end-users as integral element in “digital ecosystems”. Besides, the report proposes a conceptual assessment framework which can be applied to other contemporary digital services or functions.

  • 2916. Aijaz, Asim
    et al.
    Sarakinos, Kostas
    Lundin, Daniel
    Brenning, Nils
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Helmersson, Ulf
    A strategy for increased carbon ionization in magnetron sputtering discharges2012In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 23, p. 1-4Article in journal (Refereed)
    Abstract [en]

    A strategy that facilitates a substantial increase of carbon ionization in magnetron sputtering discharges is presented in this work. The strategy is based on increasing the electron temperature in a high power impulse magnetron sputtering discharge by using Ne as the sputtering gas. This allows for the generation of an energetic C+ ion population and a substantial increase in the C+ ion flux as compared to a conventional Ar-HiPIMS process. A direct consequence of the ionization enhancement is demonstrated by an increase in the mass density of the grown films up to 2.8 g/cm(3); the density values achieved are substantially higher than those obtained from conventional magnetron sputtering methods.

  • 2917.
    Aikaterini, Micheli
    KTH, School of Computer Science and Communication (CSC).
    Impact of IoT Enabled Service Solutions in the Downstream Automotive Supply Chain2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The automotive industry has been an integral element of global economy for many decades and has withstood economic downturns by being able to shift their processes along with market needs. With the addition of new innovations in the field of ICT, the automotive industry has addressed the need to restructure to stay afront of customers‘ expectation. Internet of Things and Big Data have advanced to where connected solutions are possible to provide value opportunities in many industries including automotives with the entrance of connected vehicles.

    This thesis aims to investigate the extent that connected services could be applied to the downstream automotive supply chain as a viable long-term business solution. A door-to-door perspective was applied in order to identify the challenges and opportunities towards different stakeholders within this supply chain. Qualitative interviews were conducted with leading OEMs, Logistics Providers, NSC, and car dealers as well as quantitative analysis performed on car buying customers to gauge their opinions of connected vehicles and services.

    There are many opportunities for a viable connected service solution to offer additional value to each stakeholder including efficient supply chain management due to increased visibility, improved lead times, and operational effectiveness. However, with the complexity and variations in the supply chain it cannot be applied rapidly and requires all actors to agree to participation in a network that supports the IT infrastructures and fortifies information flow.

  • 2918. Aikio, A T
    et al.
    Blomberg, Lars
    KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Marklund, Göran
    KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Yamauchi, M
    On the origin of the high-altitude electric field fluctuations in the auroral zone1996In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 101, no A12, p. 27157-27170Article in journal (Refereed)
    Abstract [en]

    Intense fluctuations in the electric field at high altitudes in the auroral zone are frequently measured by the Viking satellite. We have made an analysis of the origin of electric and magnetic fluctuations in the frequency range of 0.1 - 1 Hz by assuming four different sources for the signals: (I) spatial structures, (2) spatial structures with a parallel potential drop below the satellite, (3) traveling; shear Alfven waves, and (4) interfering shear Alfven waves. We will shaw that these different sources of the signals may produce similar amplitude ratios and phase differences between the perpendicular electric and magnetic fields. Since the different sources have different frequency dependencies, this can be used as an additional test if the signals are broadband. In other cases, additional information is needed, for example, satellite particle measurements or ground; magnetic measurements. The ideas presented in the theory were tested for one Viking eveningside pass over Scandinavia, where ground-based magnetometer and EISCAT radar measurements were available. The magnetic conditions were active during this pass and several interfering shear Alfven waves were found. Also, a spatial structure with a parallel potential drop below the satellite was identified. The magnitude of the 10-km-wide potential drop was at least 2 kV and the upward field-aligned current 26 mu A m(-2) (value mapped to the ionospheric level). The held-aligned conductance was estimated as 1.3 - 2.2x10(-8) S m(-2).

  • 2919. Aikio, A. T.
    et al.
    Mursula, K.
    Buchert, S.
    Forme, F.
    Amm, O.
    Marklund, Göran T.
    KTH, Superseded Departments, Alfvén Laboratory.
    Dunlop, M.
    Fontaine, D.
    Vaivads, A.
    Fazakerley, A.
    Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments2004In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 22, no 12, p. 4089-4101Article in journal (Refereed)
    Abstract [en]

    The four Cluster s/c passed over Northern Scandinavia on 6 February 2001 from south-east to north-west at a radial distance of about 4.4 R-E in the post-midnight sector. When mapped along geomagnetic field lines, the separation of the spacecraft in the ionosphere was confined to within 110 km in latitude and 50 km in longitude. This constellation allowed us to study the temporal evolution of plasma with a time scale of a few minutes. Ground-based instrumentation used involved two all-sky cameras, magnetometers and the EISCAT radar. The main findings were as follows. Two auroral arcs were located close to the equatorward and poleward edge of a large-scale density cavity, respectively. These arcs showed a different kind of a temporal evolution. (1) As a response to a pseudo-breakup onset, both the up- and downward field-aligned current (FAC) sheets associated with the equatorward arc widened and the total amount of FAC doubled in a time scale of 1-2 min. (2) In the poleward arc, a density cavity formed in the ionosphere in the return (downward) current region. As a result of ionospheric feedback, a strongly enhanced ionospheric southward electric field developed in the region of decreased Pedersen conductance. Furthermore, the acceleration potential of ionospheric electrons, carrying the return current, increased from 200 to 1000 eV in 70 s, and the return current region widened in order to supply a constant amount of return current to the arc current circuit. Evidence of local acceleration of the electron population by dispersive Alfven waves was obtained in the upward FAC region of the poleward arc. However, the downward accelerated suprathermal electrons must be further energised below Cluster in order to be able to produce the observed visible aurora. Both of the auroral arcs were associated with broad-band ULF/ELF (BBELF) waves, but they were highly localised in space and time. The most intense BBELF waves were confined typically to the return current regions adjacent to the visual arc, but in one case also to a weak upward FAC region. BBELF waves could appear/disappear between s/c crossings of the same arc separated by about 1 min.

  • 2920. Aikio, A. T.
    et al.
    Pitkanen, T.
    Fontaine, D.
    Dandouras, I.
    Amm, O.
    Kozlovsky, A.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Fazakerley, A.
    EISCAT and Cluster observations in the vicinity of the dynamical polar cap boundary2008In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 26, no 1, p. 87-105Article in journal (Refereed)
    Abstract [en]

    The dynamics of the polar cap boundary and auroral oval in the nightside ionosphere are studied during late expansion and recovery of a substorm from the region between Tromso (66.6 degrees cgmLat) and Longyearbyen (75.2 degrees cgmLat) on 27 February 2004 by using the coordinated EISCAT incoherent scatter radar, MIRACLE magnetometer and Cluster satellite measurements. During the late substorm expansion/early recovery phase, the polar cap boundary (PCB) made zig-zag-type motion with amplitude of 2.5 degrees cgmLat and period of about 30 min near magnetic midnight. We suggest that the poleward motions of the PCB were produced by bursts of enhanced reconnection at the near-Earth neutral line (NENL). The subsequent equatorward motions of the PCB would then represent the recovery of the merging line towards the equilibrium state (Cowley and Lockwood, 1992). The observed bursts of enhanced westward electrojet just equatorward of the polar cap boundary during poleward expansions were produced plausibly by particles accelerated in the vicinity of the neutral line and thus lend evidence to the Cowley-Lockwood paradigm. During the substorm recovery phase, the footpoints of the Cluster satellites at a geocentric distance of 4.4 R-E mapped in the vicinity of EISCAT measurements. Cluster data indicate that outflow of H+ and O+ ions took place within the plasma sheet boundary layer (PSBL) as noted in some earlier studies as well. We show that in this case the PSBL corresponded to a region of enhanced electron temperature in the ionospheric F region. It is suggested that the ion outflow originates from the F region as a result of increased ambipolar diffusion. At higher altitudes, the ions could be further energized by waves, which at Cluster altitudes were observed as BBELF (broad band extra low frequency) fluctuations. The four-satellite configuration of Cluster revealed a sudden poleward expansion of the PSBL by 2 degrees during similar to 5 min. The beginning of the poleward motion of the PCB was associated with an intensification of the downward FAC at the boundary. We suggest that the downward FAC sheet at the PCB is the high-altitude counterpart of the Earthward flowing FAC produced in the vicinity of the magnetotail neutral line by the Hall effect (Sonnerup, 1979) during a short-lived reconnection pulse.

  • 2921.
    Ailenei, Ivona
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Kahn Skola2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The building is searching for the site’s existing landscape with it’s forests and an existing hidden glade that becomes the core of the project.

    The school is a place which is meant to be discovered step by step, in order to increase the creativity. And it acts like a heart, where the circle becomes a symbol for interaction and movement through the parts of the programme and the surroundings. 

    The building has its heart where the existing glade 

    exists.There are the smaller children, the kindergarden and the dining room which are directed outward. 

    A new , bigger glade is built for the children from the upper classes. This acts also as a social act between the society and the school. The big circle activates the place and takes the 

    children through all parts of the program. There will be an

    challenging investigation to move from the classrooms to the dining room and then to the school garden or the 

    workshops. 

    The classrooms take an articulated form that also

    encourages the idea of that  everyone should find her/his own place and provides a place for everyone.

    The workshops which are located on the ground floor open up to room where they can extend to the exterior  and where the children can work and have acces to the outside and where they can be seen and appreciated.

  • 2922.
    Ailert, Sebastian
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Bevarat boende, Skapat boende: Transformation Tyresö2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    What is a transformation, and what could it be? How could a strategy for how to approach a transformation project look?

    I have defined a transformation as the act of taking an existing building and inserting a new program that creates a new reality.

    There can be many reasons to do a transformation instead of building something new. The most important reason that I have chosen to work with is about capturing the qualities or values that exists in a building and bring them into the new reality and build on them instead of creating whole different values. Values in this case are things like surface area, volumes, height, light conditions, material and details. It is things like the cast concrete stairs and the very special windows in some parts of the building. To me this is the core idea and purpose of any transformation.

    Because the values that are kept ties the present to the history, and carries and keeps memories and identities. They create continuity in the story of the building.

    In a transformation a number of mayor conflicts arise because the new program demands values that the existing building lacks. How you chose to solve these conflicts is the most critical and most difficult aspect of any transformation.

    My transformation is done two steps. The first step is about identifying as much values as possible and trying to bring them into the new program while overlooking the whole. The dwelling was there already, all I had to do was isolate the values and bring them in to the new program. I have kept as much of the existing material as possible to keep the values intact and only added walls to define the new apartments. The result is very particular dwellings; a lot of them have their own entrances, they are spreading out both horizontally and vertically and have sunlight from two directions.

    This is a safe and rather easy way of keeping values. When these kept dwellings are defined the more difficult conflicts arises that makes the transformation so interesting. The surface areas that remain after I have laid out these kept dwellings are hard to create good dwellings from.

    I think it’s important that the additions that has to be made in a transformation relates to the building that used to be. Otherwise there´s a great risk that the existing values are destroyed.

    Relation for me is about picking up things like spatial concepts and concepts relating to form, material or structure.

    The courtyards that exist today are rarely in use. Courtyards are actually something amazing. They don’t only retract sunlight but also shadow, rain, snow, sounds, foliage, bugs and birds deep into a building. Therefore I have chosen to develop the courtyards that already exists by adding some more. In and around the school there are also several stairs in cast concrete. To create connections I’ve added new similar stairs.  

    A good transformation creates the conditions needed for a new demand, while keeping the most important values in a building and adds to the identity instead of destroying it.  

    My strategy for transformations in two steps is about first bringing certain special values into a new program without considering the building as a whole. Afterwards an addition is created which relates to the existing while solving the conflicts that always arise when doing a transformation.

    The result in this case is dwellings that are very particular compared to the dwellings which are usually built today. They are not standard flats but dwellings with surface areas, volumes, details and other characteristics that newly built dwellings rarely has.

  • 2923. Aili, K.
    et al.
    Nyman, Teresia
    KTH, School of Technology and Health (STH).
    Hillert, L.
    Svartengren, M.
    Sleep disturbances predict future sickness absence among individuals with lower back or neck-shoulder pain: A 5-year prospective study2015In: Scandinavian Journal of Public Health, ISSN 1403-4948, E-ISSN 1651-1905, Vol. 43, no 3, p. 315-323Article in journal (Refereed)
    Abstract [en]

    Background: Musculoskeletal pain is one of the most common causes of sickness absence. Sleep disturbances are often co-occurring with pain, but the relationship between sleep and pain is complex. Little is known about the importance of self-reported sleep, when predicting sickness absence among persons with musculoskeletal pain. This study aims to study the association between self-reported sleep quality and sickness absence 5 years later, among individuals stratified by presence of lower back pain (LBP) and neck and shoulder pain (NSP). Methods: The cohort (n = 2286) in this 5-year prospective study (using data from the MUSIC-Norrtälje study) was stratified by self-reported pain into three groups: no LBP or NSP, solely LBP or NSP, and oncurrent LBP and NSP. Odds ratios (ORs) for the effect of self-reported sleep disturbances at baseline on sickness absence (> 14 consecutive days), 5 years later, were calculated. Results: Within all three pain strata, individuals reporting the most sleep problems showed a significantly higher OR for all-cause sickness absence, 5 years later. The group with the most pronounced sleep problems within the concurrent LBP and NSP stratum had a significantly higher OR (OR 2.00; CI 1.09-3.67) also for long-term sickness absence (> 90days) 5 years later, compared to the group with the best sleep. Conclusions: Sleep disturbances predict sickness absence among individuals regardless of co-existing features of LBP and/or NSP. The clinical evaluation of patients should take possible sleep disturbances into account in the planning of treatments.

  • 2924.
    Aili, Katarina
    KTH, School of Technology and Health (STH), Ergonomics.
    Med uppstyckat arbete: En studie som mäter stress bland ackords- och linjestyckare2010Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna jämförande studie på magisternivå gjordes bland styckare på ett företag i Sverige. Studien gjordes i syfte att utreda hur styckare påverkas av de två vanligast förekommande arbetsuppläggen - arbete vid enkelbord och arbete vid linje. Åtta styckare deltog i studien. Ena veckan arbetade deltagarna vid enkelbord, med ackordslön, andra veckan arbetade de vid linje med maskinstyrt tempo, med lön som sätts utifrån takten på bandet. Stress mättes subjektivt med stress-energi-formuläret. Hjärtfrekvens mättes och jämfördes mellan de olika arbetsuppläggen. Observationer och intervjuer av samtliga deltagare utfördes.

    Skillnaden i arbetsuppläggen består i att styckarna vid enkelbord styckar en större del av grisen, att de väljer tempo själva samt att de arbetar ackordstyrt. Vid linje arbetar styckarna på löpande band under maskinstyrd arbetstakt, de har kortare arbetscykel och mer styrt arbete. Lönen vid linje sätts utifrån takten på bandet.

    En signifikant högre hjärtfrekvens uppmättes vid arbete, samt under pauser, då styckarna arbetade vid enkelbord jämfört med vid linje. Resultatet av svaren på stress-energi-formuläret visade något högre skattad stress vid linje och något högre skattad energi vid enkelbord. Skillnaden var inte signifikant. Beträffande intervjuerna uppgav fyra av åtta att de kände sig mer stressade vid linjearbetet, en av åtta att han kände sig mer stressad vid enkelbord. Fyra av åtta upplevde att de hade mer besvär i nacke/skuldra/rygg efter arbete vid linje, en upplevde mer besvär i nacke/skuldra/rygg efter arbete på enkelbord.

    Endast en av deltagarna uppmätte högre hjärtfrekvens vid arbete och paus vid linje än vid enkelbord. Samma deltagare upplevde arbetet vid linje som mer stressande, samt hade mer besvär av smärta efter arbete vid linje.

    Arbetsbelastningen mätt som hjärtfrekvens verkar således vara högre vid enkelbord. Däremot upplevde fler styckare mer stress och mer besvär i nacke/skuldra/rygg efter arbete vid linje. Det finns det anledning att tro att andra faktorer än den rena mekaniska belastningen styckarna utsätts för i sitt arbete kan vara en bidragande faktor vid besvärsförekomst.

  • 2925. Aimable, Anne
    et al.
    Doubi, Herve Goure
    Stuer, Michael
    Zhao, Zhe
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Bowen, Paul
    Synthesis and Sintering of ZnO Nanopowders2017In: TECHNOLOGIES, ISSN 2227-7080, Vol. 5, no 2, article id 28Article in journal (Refereed)
    Abstract [en]

    Nanopowders are continuously under investigation as they open new perspectives in numerous fields. There are two main challenges to stimulating their development: sufficient low-cost, high throughput synthesis methods which lead to a production with well-defined and reproducible properties; and for ceramics specifically, the conservation of the powders' nanostructure after sintering. In this context, this paper presents the synthesis of a pure nanosized powder of ZnO (dv(50)similar to 60 nm, easily redispersable) by using a continuous Segmented Flow Tubular Reactor (SFTR), which has previously shown its versatility and its robustness, ensuring a high powder quality and reproducibility over time. A higher scale of production can be achieved based on a "scale-out" concept by replicating the tubular reactors. The sinterability of ZnO nanopowders synthesized by the SFTR was studied, by natural sintering at 900 degrees C and 1100 degrees C, and Spark Plasma Sintering (SPS) at 900 degrees C. The performance of the synthesized nanopowder was compared to a commercial ZnO nanopowder of high quality. The samples obtained from the synthesized nanopowder could not be densified at low temperature by traditional sintering, whereas SPS led to a fully dense material after only 5 min at 900 degrees C, while also limiting the grain growth, thus leading to a nanostructured material.

  • 2926.
    Ainomae, Ahti
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Bengtsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Trump, Tonu
    Tallinn Univ Technol, Dept Radio & Telecommun Engn, EE-12616 Tallinn, Estonia..
    Distributed Largest Eigenvalue-Based Spectrum Sensing Using Diffusion LMS2018In: IEEE TRANSACTIONS ON SIGNAL AND INFORMATION PROCESSING OVER NETWORKS, ISSN 2373-776X, Vol. 4, no 2, p. 362-377Article in journal (Refereed)
    Abstract [en]

    In this paper, we propose a distributed detection scheme for cognitive radio (CR) networks, based on the largest eigenvalues (LEs) of adaptively estimated correlation matrices (CMs), assuming that the primary user signal is temporally correlated. The proposed algorithm is fully distributed, there by avoiding the potential single point of failure that a fusion center would imply. Different forms of diffusion least mean square algorithms are used for estimating and averaging the CMs over the CR network for the LE detection and the resulting estimation performance is analyzed using a common framework. In order to obtain analytic results on the detection performance, the exact distribution of the CM estimates are approximated by a Wishart distribution, by matching the moments. The theoretical findings are verified through simulations.

  • 2927.
    Ainomäe, Ahti
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Distributed Detection in Cognitive Radio Networks2017Licentiate thesis, monograph (Other academic)
    Abstract [en]

    One of the problems with the modern radio communication is the lack of availableradio frequencies. Recent studies have shown that, while the available licensed radiospectrum becomes more occupied, the assigned spectrum is significantly underutilized.To alleviate the situation, cognitive radio (CR) technology has been proposedto provide an opportunistic access to the licensed spectrum areas. Secondary CRsystems need to cyclically detect the presence of a primary user by continuouslysensing the spectrum area of interest. Radiowave propagation effects like fading andshadowing often complicate sensing of spectrum holes. When spectrum sensing isperformed in a cooperative manner, then the resulting sensing performance can beimproved and stabilized.

    In this thesis, two fully distributed and adaptive cooperative Primary User (PU)detection solutions for CR networks are studied.

    In the first part of this thesis we study a distributed energy detection schemewithout using any fusion center. Due to reduced communication such a topologyis more energy efficient. We propose the usage of distributed, diffusion least meansquare (LMS) type of power estimation algorithms with different network topologies.We analyze the resulting energy detection performance by using a commonframework and verify the theoretical findings through simulations.

    In the second part of this thesis we propose a fully distributed detection scheme,based on the largest eigenvalue of adaptively estimated correlation matrices, assumingthat the primary user signal is temporally correlated. Different forms of diffusionLMS algorithms are used for estimating and averaging the correlation matrices overthe CR network. The resulting detection performance is analyzed using a commonframework. In order to obtain analytic results on the detection performance, theadaptive correlation matrix estimates are approximated by a Wishart distribution.The theoretical findings are verified through simulations.

  • 2928.
    Ainomäe, Ahti
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. Tallinn University of Technology, Estonia.
    Trump, T.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Distributed largest eigenvalue detection2017In: 2017 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 3519-3523, article id 7952811Conference paper (Refereed)
    Abstract [en]

    Cognitive radio (CR) systems need to detect the presence of a primary user (PU) signal by continuously sensing the spectrum area of interest. Radiowave propagation effects like fading and shadowing often complicate sensing of spectrum holes because the PU signal can be weak in a particular area. Cooperative spectrum sensing is seen as a prospective solution to enhance the detection of PU signals. In this paper we study distributed spectrum sensing, based on the largest eigenvalue of adaptively estimated correlation matrices (CMs) of received signals. The PU signal is assumed to be temporally correlated. In this paper an Combine and Adapt (CTA) least Mean Square (LMS) diffusion based mean vector estimation scheme is proposed. No fusion center (FC) for estimation or detection is used. We analyse the resulting detection performance and verify the theoretical findings through simulations.

  • 2929.
    Ainomäe, Ahti
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Tallinn Univ. of Technol., Tallinn, Estonia.
    Trump, Tõnu
    Tallinn Univ. of Technol., Tallinn, Estonia.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Distributed Diffusion LMS based Energy Detection2014In: Proceedings of 6th International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), 2014, 2014, p. 176-183Conference paper (Refereed)
    Abstract [en]

    Cognitive radio (CR) is seen as a promising technology to make radio spectrum usage more effective by providing an opportunistic access for secondary users to the licensed spectrum areas. CR systems need to detect the presence of a primary user (PU) signal by continuously sensing the spectrum area of interest. Radiowave propagation effects like fading and shadowing often complicate sensing of spectrum holes because the PU signal can be weak in a particular area. Cooperative spectrum sensing is seen as a prospective solution to enhance the detection of PU signals. This paper studies distributed spectrum sensing in a cognitive radio context. We investigate distributed energy detection schemes without using any fusion center. We propose the usage of distributed, diffusion least mean square (LMS) type of power estimation algorithms. In this paper an Adapt and Combine (ATC) diffusion based power estimation scheme is proposed and the performance is compared with the Combine and Adapt (CTA) and ring-around schemes in a common framework. The PU signal is assumed to be slowly fading. We analyse the resulting energy detection performance and verify the theoretical findings through simulations.

  • 2930.
    Ainomäe, Ahti
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Department of Radio and Telecommunication Engineering, Tallinn University of Technology, Tallinn, Estonia .
    Trump, Tõnu
    Tallin University of Technology.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Distributed Recursive Energy Detection2014In: Proceedings of Wireless Communications and Networking Conference (WCNC), 2014, IEEE Communications Society, 2014, p. 1242-1247Conference paper (Refereed)
    Abstract [en]

    Recent studies have shown that, while the available licensed radio spectrum becomes more occupied, the assigned spectrum is significantly underutilized. To alleviate the situation, cognitive radio (CR) technology has been proposed to provide an opportunistic access to the licensed spectrum areas. CR systems are able to serve the secondary users for detecting and utilizing so called spectrum holes by sensing and adapting to the environment without causing harmful effects or interference to the licensed primary users (PU). CR systems need to detect the presence of a primary user by continuously sensing the spectrum area of interest. Radiowave propagation effects like fading and shadowing often complicate sensing of spectrum holes because the PU signal can be weak in a particular area. Cooperative spectrum sensing is seen as a prospective solution to enhance the detection of PU signals. This paper studies distributed spectrum sensing in a cognitive radio context. We investigate a distributed energy detection scheme without using any fusion center. Due to reduced communication such a topology is more energy efficient. The PU signal is assumed to be in slow fading. A recursive distributed power estimation and detection scheme is proposed. The theoretical findings are verified through simulations.

  • 2931. Airila, M. I.
    et al.
    Aho-Mantila, L.
    Brezinsek, S.
    Coad, J. P.
    Kirschner, A.
    Likonen, J.
    Matveev, D.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Strachan, J. D.
    Widdowson, A.
    Wiesen, S.
    ERO modelling of local deposition of injected C-13 tracer at the outer divertor of JET2009In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T138, p. 014021-Article in journal (Refereed)
    Abstract [en]

    The 2004 tracer experiment of JET with the injection of (CH4)-C-13 into H-mode plasma at the outer divertor has been modelled with the Monte Carlo impurity transport code ERO. EDGE2D solutions for inter-ELM and ELM-peak phases were used as plasma backgrounds. Local two-dimensional (2D) deposition patterns at the vertical outer divertor target plate were obtained for comparison with post-mortem surface analyses. ERO also provides emission profiles for comparison with radially resolved spectroscopic measurements. Modelling indicates that enhanced re-erosion of deposited carbon layers is essential in explaining the amount of local deposition. Assuming negligible effective sticking of hydrocarbons, the measured local deposition of 20-34% is reproduced if re-erosion of deposits is enhanced by a factor of 2.5-7 compared to graphite erosion. If deposits are treated like the substrate, the modelled deposition is 55%. Deposition measurements at the shadowed area around injectors can be well explained by assuming negligible re-erosion but similar sticking behaviour there as on plasma-wetted surfaces.

  • 2932. Airila, M. I.
    et al.
    Jarvinen, A.
    Groth, M.
    Belo, P.
    Wiesen, S.
    Brezinsek, S.
    Lawson, K.
    Borodin, D.
    Kirschner, A.
    Coad, J. P.
    Heinola, K.
    Likonen, J.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Widdowson, A.
    Preliminary Monte Carlo simulation of beryllium migration during JET ITER-like wall divertor operation2015In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 463, p. 800-804Article in journal (Refereed)
    Abstract [en]

    Migration of beryllium into the divertor and deposition on tungsten in the final phase of the first ITER-like-wall campaign of JET are modelled with the 3D Monte Carlo impurity transport code ERO. The simulation covers the inner wall and the inner divertor. To generate the plasma background for Monte Carlo tracing of impurity particles, we use the EDGE2D/EIRENE code set. At the relevant regions of the wall, the estimated plasma conditions vary around T-e approximate to 5eV and n(e) 2 x 10(17) m(-3) (far-scrape-off layer; more than 10 cm away from the LCFS). We calculate impurity distributions in the plasma using the main chamber source as a free parameter in modelling and attempt to reproduce inter-ELM spectroscopic BeII line (527 nm) profiles at the divertor. The present model reproduces the level of emission close to the inner wall, but further work is needed to match also the measured emission peak values and ultimately link the modelled poloidal net deposition profiles of beryllium to post mortem data.

  • 2933. Airila, M. I.
    et al.
    Makkonen, T.
    Järvinen, A.
    Groth, M.
    Brezinsek, S.
    Coad, J. P.
    Jachmich, S.
    Kirschner, A.
    Likonen, J.
    Meigs, A.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Widdowson, A.
    Re-deposition dynamics of trace 13C in H-mode divertor conditions2013In: 40th EPS Conference on Plasma Physics, EPS 2013, 2013, p. 629-632Conference paper (Refereed)
  • 2934. Airiskallio, E.
    et al.
    Nurmi, E.
    Heinonen, M. H.
    Vayrynen, I. J.
    Kokko, K.
    Ropo, M.
    Punkkinen, M. P. J.
    Pitkanen, H.
    Alatalo, M.
    Kollar, J.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    High temperature oxidation of Fe-Al and Fe-Cr-Al alloys: The role of Cr as a chemically active element2010In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 52, no 10, p. 3394-3404Article in journal (Refereed)
    Abstract [en]

    Good high-temperature corrosion resistance of Fe-Al alloys in oxidizing environments is due to the alpha-Al2O3 film which is formed on the surface provided temperature is above 900 degrees C and the Al-content of the alloy exceeds the critical value. Ab initio calculations combined with experiments on Fe-13Al, Fe-18Al, Fe-23Al and Fe-10Cr-10Al alloys show that the beneficial effect of Cr on the oxidation resistance is significantly related to bulk effects. The comparison of experimental and calculated results indicates a clear correlation between the Fe-Cr chemical potential difference and the formation of the protective oxide scales. (C) 2010 Elsevier Ltd. All rights reserved.

  • 2935. Airiskallio, E.
    et al.
    Nurmi, E.
    Heinonen, M. H.
    Vayrynen, I. J.
    Kokko, K.
    Ropo, M.
    Punkkinen, M. P. J.
    Pitkanen, H.
    Alatalo, M.
    Kollar, J.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Third element effect in the surface zone of Fe-Cr-Al alloys2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 3Article in journal (Refereed)
    Abstract [en]

    The third element effect to improve the high temperature corrosion resistance of the low-Al Fe-Cr-Al alloys is suggested to involve a mechanism that boosts the recovering of the Al concentration to the required level in the Al-depleted zone beneath the oxide layer. We propose that the key factor in this mechanism is the coexistent Cr depletion that helps to maintain a sufficient Al content in the depleted zone. Several previous experiments related to our study support that conditions for such a mechanism to be functional prevail in real oxidation processes of Fe-Cr-Al alloys.

  • 2936. Airiskallio, E.
    et al.
    Nurmi, E.
    Vayrynen, I. J.
    Kokko, K.
    Ropo, M.
    Punkkinen, M. P. J.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Magnetic origin of the chemical balance in alloyed Fe-Cr stainless steels: First-principles and Ising model study2014In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 92, p. 135-140Article in journal (Refereed)
    Abstract [en]

    Iron-chromium is the base material for most of the stainless steel grades. Recently, new insights into the origins of fundamental physical and chemical characteristics of Fe-Cr based alloys have been achieved. Some of the new results are quite unexpected and call for further investigations. The present study focuses on the magnetic contribution in the atomic driving forces related to the chemical composition in Fe-Cr when alloyed with Al, Ti, V, Mn, Co, Ni, and Mo. Using the ab initio exact muffin-tin orbitals method combined with an Ising-type spin model, we demonstrate that the magnetic moment of the solute atoms with the induced changes in the magnetic moments of the host atoms form the main factor in determining the mixing energy and chemical potentials of low-Cr Fe-Cr based alloys. The results obtained in the present work are related to the designing and tuning of the microstructure and corrosion protection of low-Cr steels.

  • 2937. Airiskallio, E.
    et al.
    Nurmi, E.
    Vayrynen, I. J.
    Kokko, K.
    Ropo, M.
    Punkkinen, Marko P. J.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Tuning the surface chemistry of Fe-Cr by V doping2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 80, no 15Article in journal (Refereed)
    Abstract [en]

    The reversal of the magnitudes of the bulk and surface chemical-potential differences induces the outburst of Cr on the otherwise pure Fe surface of Fe-Cr alloys. This threshold value for the Cr content is about 10 at. %. It is found that vanadium addition to Fe-Cr shifts the Cr threshold to a substantially lower value suggesting V having a positive effect on the corrosion resistance of low Cr steels. The obtained shift in the Cr threshold is shown to be connected to the change in volume of the alloy.

  • 2938.
    Aishwar, Ravichandran
    KTH, School of Engineering Sciences (SCI).
    Aerodynamics of Bird Flight2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    It is the objective of this thesis project to understand the physics behind the different modes of bird flight and to do numerical two dimensional simulations of pure plunging, pure pitching and combined pitch-plunging motion of an aerofoil. First, the different physical models used to understand the generation of thrust are explained. Then the numerical model used for the simulation is explained briefly. Then the results and analysis of the numerical simulations are presented.

  • 2939.
    Ait Ali, Abderrahman
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Lindberg, Per Olov
    KTH.
    Nilsson, Jan-Eric
    Eliasson, Jonas
    Aronsson, Martin
    Disaggregation in Bundle Methods: Application to the Train Timetabling Problem2017Conference paper (Refereed)
    Abstract [en]

    Bundle methods are often used to solve dual problems that arise from Lagrangian relaxations of large scale optimization problems. An example of such problems is the train timetabling problem. This paper focuses on solving a dual problem that arises from Lagrangian relaxation of a train timetabling optimization program. The dual problem is solved using bundle methods. We formulate and compare the performances of two different bundle methods: the aggregate method, which is a standard method, and a new, disaggregate, method which is proposed here. The two methods were tested on realistic train timetabling scenarios from the Iron Ore railway line. The numerical results show that the new disaggregate approach generally yields faster convergence than the standard aggregate approach.

  • 2940.
    Ait Ali, Abderrahman
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Warg, Jennifer
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Eliasson, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Measuring the Socio-economic Benefits of Train Timetables: Application to Commuter Train Services in Stockholm2017In: 20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary, Elsevier, 2017, Vol. 27, p. 849-856Conference paper (Refereed)
    Abstract [en]

    On highly used railway lines with heterogeneous traffic, timetabling is challenging. In particular, the limited existing capacity means that to guarantee an acceptable level of quality, the infrastructure manager must cancel some train services on the expense of others. In this article, we study the conflict between commercial long-distance trains and subsidized commuter trains with a socio-economic perspective (i.e. travelers and train operators). The study attempts to answer the following question: What is the socio-economic effect of modifying the timetable of a commuter service?The case study treats the commuter train services in Stockholm. Trip data was collected from the local commuter train operator. An entropy maximization-based model was implemented to estimate the dynamic network Origin-Destination (OD) matrix. This dynamic matrix, of one full working day, was then used to estimate the number of travelers per train, and further converted for use in the microscopic simulation tool RailSys. Travel and waiting time are estimated for each OD pair and with that the generalized costs for the travelers and operators. The effect of crowding in the trains is included in the estimation. The article can be considered as an initiation to a novel method to calculate effects of changes in commuter train timetables. This novel approach enables to price commercial train slots in the capacity allocation process such as in an auction. It provides a new way to estimate the local train operator´s valuation of the different parameters (i.e. waiting, travel time and interchanges). Using RailSys for the estimation of times makes it possible to include capacity aspects that normally are difficult to reveal.

  • 2941.
    Ait-Ali, Abderrahman
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Integration of Production Scheduling and Energy Management: Software Development2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Demand-Side Management concepts have the potential to positively impact the financial as well as the environmental aspects of energy-intensive industries. More specifically, they allow reducing the energy cost for the industrial plants by dealing with energy-availability fluctuations.

    In this context, efficient frameworks for scheduling with energy awareness have been studied and showed potential to reduce the overall energy bill for energy-intensive industries, for instance stainless steel and paper plants. Those frameworks usually combine scheduling and energy optimization into one monolithic system. This work investigates the possibility of integrating the two systems by specific exchange of signals, while keeping the scheduling model separated from the energy-cost optimization model. Such integration means that the pre-existent schedulers and energy optimizers could be easily modified and reused without re-implementing the whole new system.

    Two industrial problems with different scheduling approaches are studied. The first problem is about pulp and paper production which uses the Resource Task Network (RTN) scheduling approach. The second one is about stainless steel production which is based on a bi-level heuristic implementation of an improved energy-aware scheduler. This work presents the decomposition methods that are available in literature and their application to the two industrial problems. Besides an improvement in the RTN approach for handling storages, this thesis describes a prototype implementation of the energy-aware RTN scheduler for paper and pulp production. Furthermore, this work investigates the performance of the application of different decomposition methods on different problem instances.

    The numerical case studies show that even though the decomposition decreases the solution quality compared to the monolithic system, it still gives good solutions within an acceptable duration with the advantage of having two separate pre-existent systems which are simply exchanging signals.

  • 2942. Aitken, Candice L.
    et al.
    Gorniak, Richard J. T.
    New York University.
    Kramer, Elissa L.
    New York University.
    Noz, Marilyn E.
    New York University.
    Farrell, Eward J.
    IBM Research.
    Maguire Jr., Gerald Q.
    KTH, Superseded Departments, Teleinformatics.
    Reddy, David P.
    Comparison of three methods used for fusion of SPECT-CT images of liver matastases1998In: Fusion98, International Conference on Multisource-Mulltisensor Information Fusion / [ed] Hamid R. Arabnia and Dongping (Daniel) Zhu, CSREA Press , 1998, p. 435-442Conference paper (Refereed)
    Abstract [en]

    We compare three methods for fusing SPECT-CT images: ImageMatch - an automatic three-dimensional/two-dimensional method developed by Focus Imaging; IBM Visualization Data Explorer - a three-diemensional interactive method developed by Internation Business Machines, Inc.; and qsh - an interactive three-dimensional/two-dimensional method developed at New York University. While many fusion methods have proved successful for registering brain images, most methods have been less successful for thoracic and abdominal images. We use images of liver metastases obtained with a radiolabeled breast tumor-directed antibody to illustrate the strengths and weakness of the methods reviewed. The images used are typical clinical images from eigth patients. We conclude that an optimal image fusion program should combine the strengths of each of the methods reviewed.

  • 2943. Aitken, Candice L.
    et al.
    Mahmoud, Faaiza
    McGuinness, Georgeann
    Kramer, Elissa L.
    Maguire, Gerald Q. Jr.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Noz, Marilyn E.
    New York University.
    Tumor localization and image registration of F-18FDG coincidence detection scans with computed tomographic scans2002In: Clinical Nuclear Medicine, ISSN 0363-9762, E-ISSN 1536-0229, Vol. 27, no 4, p. 275-282Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim of this study was to determine the feasibility of registering routine clinical F-18 fluorodeoxyglucose (FDG) coincidence detection (CD) scans with computed tomographic (CT) scans for radiation treatment planning and case management. Methods: F-18 FDG CD and chest CT scans, performed in 10 randomly selected patients with confirmed or possible adenocarcinoma of the lung, were evaluated. The quality of the matches was verified by comparisons of the center-to-center distance between a region of interest (ROI) manually drawn on the CT slice and warped onto the CD slice with an ROI drawn manually directly on the CD slice. In addition, the overlap between the two ROIs was calculated. Results: All 10 F-18 FDG CD and CT scans were registered with good superimposition of soft tissue density on increased radionuclide activity. The center-to-center distance between the ROIs ranged from 0.29 mm to 8.08 mm, with an average center-to-center distance of 3.89 mm 2.42 mm (0.69 pixels +/- 0.34 pixels). The ROI overlap ranged from 77% to 99%, with an average of 90% +/- 5.6%. Conclusions: Although the use of F-18 FDG CD shows great promise for the identification of tumors, it shares the same drawbacks as those associated with radiolabeled monoclonal antibody SPECT and ligand-based positron emission tomographic scans in that anatomic markers are limited. This study shows that image registration is feasible and may improve the clinical relevance of CD images.

  • 2944.
    Aitken, Candice L.
    et al.
    New York University.
    McGuinness, Georgeann
    New York University.
    Siddiqui, Faaiza
    New York University.
    Ton, Anthony
    New York University.
    Kramer, Elissa L
    New York University.
    Maguire Jr., Gerald Q.
    KTH, Superseded Departments, Teleinformatics.
    Noz, Marilyn E.
    New York University, Department of Radiology.
    Tumor localization and image registration of 18-FDG SPECT scans with CT scans1999In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 40, no 5, p. 290P-291PArticle in journal (Refereed)
    Abstract [en]

    PURPOSE:

    The aim of this study was to determine the feasibility of registering routine clinical F-18 fluorodeoxyglucose (FDG) coincidence detection (CD) scans with computed tomographic (CT) scans for radiation treatment planning and case management.

    METHODS:

    F-18 FDG CD and chest CT scans, performed in 10 randomly selected patients with confirmed or possible adenocarcinoma of the lung, were evaluated. The quality of the matches was verified by comparisons of the center-to-center distance between a region of interest (ROI) manually drawn on the CT slice and warped onto the CD slice with an ROI drawn manually directly on the CD slice. In addition, the overlap between the two ROIs was calculated.

    RESULTS:

    All 10 F-18 FDG CD and CT scans were registered with good superimposition of soft tissue density on increased radionuclide activity. The center-to-center distance between the ROIs ranged from 0.29 mm to 8.08 mm, with an average center-to-center distance of 3.89 mm +/- 2.42 mm (0.69 pixels +/- 0.34 pixels). The ROI overlap ranged from 77% to 99%, with an average of 90% +/- 5.6%.

    CONCLUSIONS:

    Although the use of F-18 FDG CD shows great promise for the identification of tumors, it shares the same drawbacks as those associated with radiolabeled monoclonal antibody SPECT and ligand-based positron emission tomographic scans in that anatomic markers are limited. This study shows that image registration is feasible and may improve the clinical relevance of CD images.

  • 2945.
    Ait-Lakbir, Hanane
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Study and Industrialization of Computational Methods for Orbital Maneuvers2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of electric propulsion is a watershed in the space field. Indeed, due to its eÿciency in term of mass consumption, the actors of the space industries see in this piece of technology a means to manufacture lighter satellites and to launch them at lower cost. To face with this new market, industries need to develop new tools to handle these satellites and their missions. This report will elaborate on the methods used to compute maneuvers for all-electric spacecraft.

    One of the main phases during satellite operations is maneuvering to ensure on the one hand a correct configuration to achieve the mission and on the other hand the integrity of the satellite. The present work is focused on the computation of the orbital maneuvers during the early phase of the mission: orbit raising. Due to the characteristics of electric propulsion, an overall approach provided by the application of the optimal control theory is required to compute these maneuvers performed by low-thrust engines. This report will develop the use of an indirect method based on the Pontryagin minimum principle. Two types of problems related to the constraints during the space missions are presented. Because electric maneuvers are longer than chemical maneuvers, it is usually necessary to seek to minimize the duration of a maneuver. The second interesting performance is the remaining propellant mass to achieve the mission: therefore, the minimization of the mass consumption during the maneuver is the second performance considered in the report.

    During the internship, a JAVA implementation of the resolution of these two problems has been done. The report will present the preliminary results as well as the encountered difficulties and some possible solutions.

  • 2946.
    Aittokoski, Timo
    et al.
    Department of Mathematical Information Technology, University of Jyväskylä, Finland.
    Miettinen, Kaisa
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Cost Effective Simulation-Based Multiobjective Optimization in Performance of Internal Combustion Engine2008In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 40, no 7, p. 593-612Article in journal (Refereed)
    Abstract [en]

    Solving real-life engineering problems requires often multiobjective, global, and efficient (in terms of objective function evaluations) treatment. In this study, we consider problems of this type by discussing some drawbacks of the current methods and then introduce a new population-based multiobjective optimization algorithm UPS-EMOA which produces a dense (not limited to the population size) approximation of the Pareto-optimal set in a computationally effective manner.

  • 2947.
    Aittokoski, Timo
    et al.
    Department of Mathematical Information Technology, University of Jyväskylä, Finland.
    Miettinen, Kaisa
    Department of Mathematical Information Technology, University of Jyväskylä, Finland.
    Decreasing Computational Cost of Simulation Based Interactive Multiobjective Optimization with Adustable Solution Accuracy2008Report (Other academic)
  • 2948.
    Aittokoski, Timo
    et al.
    Department of Mathematical Information Technology, University of Jyväskylä, Finland.
    Miettinen, Kaisa
    Department of Mathematical Information Technology, University of Jyväskylä, Finland.
    Efficient Evolutionary Method to Approximate the Pareto Optimal Set in Multiobjective Optimization2008In: Proceedings of the International Conference on Engineering Optimization EngOpt 2008, 2008Conference paper (Other academic)
    Abstract [en]

    Solving real-life engineering problems requires often multiobjective, global and efficient (in terms of ob-jective function evaluations) treatment. In this study, we consider problems of this type by discussingsome drawbacks of the current methods and then introduce a new population based multiobjective op-timization algorithm which produces a dense (not limited to the population size) approximation of thePareto optimal set in a computationally effective manner.

  • 2949.
    Aittokoski, Timo
    et al.
    Department of Mathematical Information Technology, University of Jyväskylä, Finland.
    Äyrämö, Sami
    Department of Mathematical Information Technology, University of Jyväskylä, Finland.
    Miettinen, Kaisa
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Clustering aided approach for decision making in computationally expensive multiobjective optimization2009In: Optimization Methods and Software, ISSN 1055-6788, E-ISSN 1029-4937, Vol. 24, no 2, p. 157-174Article in journal (Refereed)
    Abstract [en]

    Typically, industrial optimization problems need to be solved in an efficient, multiobjective and global manner, because they are often computationally expensive (as function values are typically based on simulations), they may contain multiple conflicting objectives, and they may have several local optima. Solving such problems may be challenging and time consuming when the aim is to find the most preferred Pareto optimal solution.

    In this study, we propose a method where we use an advanced clustering technique to reveal essential characteristics of the approximation of the Pareto optimal set, which has been generated beforehand. Thus, the decision maker (DM) is involved only after the most time consuming computation is finished. After the initiation phase, a moderate number of cluster prototypes projected to the Pareto optimal set is presented to the DM to be studied. This allows him/her to rapidly gain an overall understanding of the main characteristics of the problem without placing too much cognitive load on the DM. Furthermore, we also suggest some ways of applying our approach to different types of problems and demonstrate it with an example related to internal combustion engine design.

  • 2950. Ai-Xi, Chen
    et al.
    Hong, Wang
    Duan, Sai
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hai-Ming, Zhang
    Xin, Xu
    Li-Feng, Chi
    Potential-Induced Phase Transition of N-Isobutyryl-L-cysteine Monolayers on Au(111) Surfaces2017In: Wuli huaxue xuebao, ISSN 1000-6818, Vol. 33, no 5, p. 1010-1016Article in journal (Refereed)
    Abstract [en]

    Functional solid substrates modified by self-assembled monolayers (SAMs) have potential applications in biosensors, chromatography, and biocompatible materials. The potential-induced phase transition of N-isobutyryl-L-cysteine (L-NIBC) SAMs on Au(111) surfaces was investigated by in-situ electrochemical scanning tunneling microscopy (EC-STM) in 0.1 mol.L-1 H2SO4 solution. The NIBC SAMs with two distinct structures (alpha phase and beta phase) can be prepared by immersing the Au(111) substrate in pure NIBC aqueous solution and NIBC solution controlled by phosphate buffer at pH 7, respectively. The as-prepared a phase and beta phase of NIBC SAMs show various structural changes under the control of electrochemical potentials of the Au(111) in H2SO4 solution. The a phase NIBC SAMs exhibit structural changes from ordered to disordered structures with potential changes from 0.7 V (vs saturated calomel electrode, SCE) to 0.2 V. However, the beta phase NIBC SAMs undergo structural changes from disordered structures (E < 0.3 V) to y phase (0.4 V < E < 0.5 V) and finally to the beta phase (0.5 V < E < 0.7 V). EC-STM images also indicate that the phase transition from the alpha phase NIBC SAMs to the a phase occurs at positive potential. Combined with density functional theory (DFT) calculations, the phase transition from the beta phase to the a phase is explained by the potential-induced break of bonding interactions between -COO- and the negatively charged gold surfaces.

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