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  • 1.
    Abedin, Ahmad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits.
    Zurauskaite, Laura
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits.
    Asadollahi, Ali
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits. KTH.
    GOI fabrication for Monolithic 3D integrationIn: Article in journal (Other academic)
  • 2.
    Aboode, Adam
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Anomaly Detection in Time Series Data Based on Holt-Winters Method2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today's world the amount of collected data increases every day, this is a trend which is likely to continue. At the same time the potential value of the data does also increase due to the constant development and improvement of hardware and software. However, in order to gain insights, make decisions or train accurate machine learning models we want to ensure that the data we collect is of good quality. There are many definitions of data quality, in this thesis we focus on the accuracy aspect.

    One method which can be used to ensure accurate data is to monitor for and alert on anomalies. In this thesis we therefore suggest a method which, based on historic values, is able to detect anomalies in time series as new values arrive. The method consists of two parts, forecasting the next value in the time series using Holt-Winters method and comparing the residual to an estimated Gaussian distribution.

    The suggested method is evaluated in two steps. First, we evaluate the forecast accuracy for Holt-Winters method using different input sizes. In the second step we evaluate the performance of the anomaly detector when using different methods to estimate the variance of the distribution of the residuals. The results indicate that the suggested method works well most of the time for detection of point anomalies in seasonal and trending time series data. The thesis also discusses some potential next steps which are likely to further improve the performance of this method.

  • 3.
    Ahlström, Marcus
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    Broadening the Reading Experience on Mobile Devices using Tilt-based Input: An Explorative Design Study2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis is an explorative study aimed at the possibility of integrating tilt-based input to improve the reading experience on smartphones. Previous works from the early 2000s have been skeptical towards tilt-based navigation, deeming it unruly and imprecise. To investigate if today’s technology has unlocked new possibilities; two experimental reading methods were designed, created and tested iteratively on 20, respectively 18 participants. The first method is a reassessment of tilt-based auto-scrolling and the second is a novel approach comparable to tilt-based paging. Data from the reading sessions were collected quantitatively in tandem with qualitative data from post-session interviews. The results indicate good potential and a reading performance similar to the standard navigation method. The importance of accommodating people with different reading behaviours was also discussed.

  • 4.
    Ahmed, Laeeq
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Georgiev, Valentin
    Capuccini, Marco
    Toor, Salman
    Schaal, Wesley
    Laure, Erwin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Spjuth, Ola
    Efficient iterative virtual screening with Apache Spark and conformal prediction2018In: Journal of Cheminformatics, ISSN 1758-2946, E-ISSN 1758-2946, Vol. 10, article id 8Article in journal (Refereed)
    Abstract [en]

    Background: Docking and scoring large libraries of ligands against target proteins forms the basis of structure-based virtual screening. The problem is trivially parallelizable, and calculations are generally carried out on computer clusters or on large workstations in a brute force manner, by docking and scoring all available ligands. Contribution: In this study we propose a strategy that is based on iteratively docking a set of ligands to form a training set, training a ligand-based model on this set, and predicting the remainder of the ligands to exclude those predicted as 'low-scoring' ligands. Then, another set of ligands are docked, the model is retrained and the process is repeated until a certain model efficiency level is reached. Thereafter, the remaining ligands are docked or excluded based on this model. We use SVM and conformal prediction to deliver valid prediction intervals for ranking the predicted ligands, and Apache Spark to parallelize both the docking and the modeling. Results: We show on 4 different targets that conformal prediction based virtual screening (CPVS) is able to reduce the number of docked molecules by 62.61% while retaining an accuracy for the top 30 hits of 94% on average and a speedup of 3.7. The implementation is available as open source via GitHub (https://github.com/laeeq80/spark-cpvs) and can be run on high-performance computers as well as on cloud resources.

  • 5.
    Ahmed, Noman
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Efficient Modeling of Modular Multilevel Converters for HVDC Transmission Systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The drive towards getting more and more electrical energy from renewable sources, requires more efficient electric transmission systems. A stronger grid, with more controllability and higher capacity, that can handle power fluctuations due to a mismatch between generation and load is also needed. High-voltage dc (HVDC) provides efficient and economical power transmission over very long distances, and will be a key player in shaping-up the future electric grid. Due to its outstanding features, the modular multilevel converter (MMC) has already been widely accepted as a key converter topology in voltage-source converter (VSC)-based HVDC transmission systems.

    In order to study the feasibility of future MMC-based HVDC grids, adequate simulation models are necessary. The main objective of the thesis is to propose MMC reduced-order simulation models capable of accurately replicating the response of an MMC during all relevant operating conditions. Such models are the basic building blocks in developing efficient simulation models for HVDC grids. This thesis presents two MMC equivalent simulation models, the continuous model (CM) and the detailed equivalent model (DEM). Compared to the CM, the DEM is also capable of demonstrating the individual sumodule behavior of an MMC. These models are validated by comparing with the detailed MMC model as well as with experimental results obtained from an MMC prototype in the laboratory. The most significant feature of the models is the representation of the blocking capability of the MMC, presented for the first time in the literature for an MMC equivalent simulation model. This feature is very important in replicating the accurate transient behavior of an MMC during energization and fault conditions. This thesis also investigates the performance of the MMC with redundant submodules in the arms. Two different control strategies are used and compared for integrating redundant submodules.

    The proposed MMC models are used in developing point-to-point and multiterminal HVDC (MTDC) systems. A reduced-order model of a hybrid HVDC breaker is also developed and employed in the MTDC system, making the test system capable of accurately replicating the behavior of the MMCbased MTDC system employing hybrid HVDC breakers. The conclusion of the analysis of dc-side faults in a MTDC system is that fast-acting HVDC breakers are necessary to isolate only the faulted part in the MTDC system to ensure the power flow in rest of the system is not interrupted.

    A generic four-terminal HVDC grid test system using the CM model is also developed. The simulated system can serve as a standard HVDC grid test system. It is well-suited to electromagnetic transient (EMT) studies in a limited version of commercially available EMT-type software. The dynamic performance of the HVDC grid is studied under different fault conditions.

  • 6.
    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.

  • 7.
    Akhmetova, Dana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Cebamanos, L.
    Iakymchuk, Roman
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Rotaru, T.
    Rahn, M.
    Markidis, Stefano
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Laure, Erwin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Bartsch, V.
    Simmendinger, C.
    Interoperability of GASPI and MPI in large scale scientific applications2018In: 12th International Conference on Parallel Processing and Applied Mathematics, PPAM 2017, Springer Verlag , 2018, p. 277-287Conference paper (Refereed)
    Abstract [en]

    One of the main hurdles of a broad distribution of PGAS approaches is the prevalence of MPI, which as a de-facto standard appears in the code basis of many applications. To take advantage of the PGAS APIs like GASPI without a major change in the code basis, interoperability between MPI and PGAS approaches needs to be ensured. In this article, we address this challenge by providing our study and preliminary performance results regarding interoperating GASPI and MPI on the performance crucial parts of the Ludwig and iPIC3D applications. In addition, we draw a strategy for better coupling of both APIs. 

  • 8. Alm, L.
    et al.
    Farrugia, C. J.
    Paulson, K. W.
    Argall, M. R.
    Torbert, R. B.
    Burch, J. L.
    Ergun, R. E.
    Russell, C. T.
    Strangeway, R. J.
    Khotyaintsev, Y. V.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Marklund, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Giles, B. L.
    Differing Properties of Two Ion-Scale Magnetopause Flux Ropes2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 1, p. 114-131Article in journal (Refereed)
    Abstract [en]

    In this paper, we present results from the Magnetospheric Multiscale constellation encountering two ion-scale, magnetopause flux ropes. The two flux ropes exhibit very different properties and internal structure. In the first flux rope, there are large differences in the currents observed by different satellites, indicating variations occurring over sub-d(i) spatial scales, and time scales on the order of the ion gyroperiod. In addition, there is intense wave activity and particle energization. The interface between the two flux ropes exhibits oblique whistler wave activity. In contrast, the second flux rope is mostly quiescent, exhibiting little activity throughout the encounter. Changes in the magnetic topology and field line connectivity suggest that we are observing flux rope coalescence.

  • 9.
    Almeida, Diogo
    et al.
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL. KTH.
    Ambrus, Rares
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Caccamo, Sergio
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Chen, Xi
    KTH.
    Cruciani, Silvia
    Pinto Basto De Carvalho, Joao F
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Haustein, Joshua
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Marzinotto, Alejandro
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Vina, Francisco
    KTH.
    Karayiannidis, Yannis
    KTH.
    Ögren, Petter
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Jensfelt, Patric
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL.
    Kragic, Danica
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL.
    Team KTH’s Picking Solution for the Amazon Picking Challenge 20162017In: Warehouse Picking Automation Workshop 2017: Solutions, Experience, Learnings and Outlook of the Amazon Robotics Challenge, 2017Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    In this work we summarize the solution developed by Team KTH for the Amazon Picking Challenge 2016 in Leipzig, Germany. The competition simulated a warehouse automation scenario and it was divided in two tasks: a picking task where a robot picks items from a shelf and places them in a tote and a stowing task which is the inverse task where the robot picks items from a tote and places them in a shelf. We describe our approach to the problem starting from a high level overview of our system and later delving into details of our perception pipeline and our strategy for manipulation and grasping. The solution was implemented using a Baxter robot equipped with additional sensors.

  • 10.
    Almeida, Diogo
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Karayiannidis, Yiannis
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL. Dept. of Electrical Eng., Chalmers University of Technology.
    Cooperative Manipulation and Identification of a 2-DOF Articulated Object by a Dual-Arm Robot2018In: / [ed] IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    In this work, we address the dual-arm manipula-tion of a two degrees-of-freedom articulated object that consistsof two rigid links. This can include a linkage constrainedalong two motion directions, or two objects in contact, wherethe contact imposes motion constraints. We formulate theproblem as a cooperative task, which allows the employment ofcoordinated task space frameworks, thus enabling redundancyexploitation by adjusting how the task is shared by the robotarms. In addition, we propose a method that can estimate thejoint location and the direction of the degrees-of-freedom, basedon the contact forces and the motion constraints imposed bythe object. Experimental results demonstrate the performanceof the system in its ability to estimate the two degrees of freedomindependently or simultaneously.

  • 11.
    Almeida, Diogo
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Karayiannidis, Yiannis
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL. Chalmers University of Technology.
    Folding Assembly by Means of Dual-Arm Robotic Manipulation2016In: 2016 IEEE International Conference on Robotics and Automation, IEEE conference proceedings, 2016, p. 3987-3993Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider folding assembly as an assembly primitive suitable for dual-arm robotic assembly, that can be integrated in a higher level assembly strategy. The system composed by two pieces in contact is modelled as an articulated object, connected by a prismatic-revolute joint. Different grasping scenarios were considered in order to model the system, and a simple controller based on feedback linearisation is proposed, using force torque measurements to compute the contact point kinematics. The folding assembly controller has been experimentally tested with two sample parts, in order to showcase folding assembly as a viable assembly primitive.

  • 12. Ambrazaitis, G.
    et al.
    House, David
    KTH, School of Electrical Engineering and Computer Science (EECS), Speech, Music and Hearing, TMH. KTH, Superseded Departments (pre-2005), Speech, Music and Hearing. KTH, Superseded Departments (pre-2005), Speech Transmission and Music Acoustics.
    Multimodal prominences: Exploring the patterning and usage of focal pitch accents, head beats and eyebrow beats in Swedish television news readings2017In: Speech Communication, ISSN 0167-6393, E-ISSN 1872-7182, Vol. 95, p. 100-113Article in journal (Refereed)
    Abstract [en]

    Facial beat gestures align with pitch accents in speech, functioning as visual prominence markers. However, it is not yet well understood whether and how gestures and pitch accents might be combined to create different types of multimodal prominence, and how specifically visual prominence cues are used in spoken communication. In this study, we explore the use and possible interaction of eyebrow (EB) and head (HB) beats with so-called focal pitch accents (FA) in a corpus of 31 brief news readings from Swedish television (four news anchors, 986 words in total), focusing on effects of position in text, information structure as well as speaker expressivity. Results reveal an inventory of four primary (combinations of) prominence markers in the corpus: FA+HB+EB, FA+HB, FA only (i.e., no gesture), and HB only, implying that eyebrow beats tend to occur only in combination with the other two markers. In addition, head beats occur significantly more frequently in the second than in the first part of a news reading. A functional analysis of the data suggests that the distribution of head beats might to some degree be governed by information structure, as the text-initial clause often defines a common ground or presents the theme of the news story. In the rheme part of the news story, FA, HB, and FA+HB are all common prominence markers. The choice between them is subject to variation which we suggest might represent a degree of freedom for the speaker to use the markers expressively. A second main observation concerns eyebrow beats, which seem to be used mainly as a kind of intensification marker for highlighting not only contrast, but also value, magnitude, or emotionally loaded words; it is applicable in any position in a text. We thus observe largely different patterns of occurrence and usage of head beats on the one hand and eyebrow beats on the other, suggesting that the two represent two separate modalities of visual prominence cuing.

  • 13. Ansari, R. Jaberzadeh
    et al.
    Karayiannidis, Yiannis
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Reducing the human effort for human-robot cooperative object manipulation via control design2017In: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2017, Vol. 50, no 1, p. 14922-14927Conference paper (Refereed)
    Abstract [en]

    This study is concerned with the shared object manipulation problem in a physical Human-Robot Interaction (pHRI) setting. In such setups, the operator manipulates the object with the help of a robot. In this paper, the operator is assigned with the lead role, and the robot is passively following the forces/torques exerted by the operator. We propose a controller that is free from the well-known translation/rotation problem and enhances the operator's ability to move the object by reducing the human effort. The key point in our study is that the controller is defined based on the instantaneous center of rotation. The passivity of the system including the object and the manipulator has been evaluated. Simulation results validate the theoretical findings on different scenarios of subsequent rotations and translations of the object.

  • 14. Antichi, Gianni
    et al.
    Castro, Ignacio
    Chiesa, Marco
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab). Université catholique de Louvain.
    Fernandes, Eder L.
    Lapeyrade, Remy
    Kopp, Daniel
    Han, Jong Hun
    Bruyere, Marc
    Dietzel, Christoph
    Gusat, Mitchell
    Moore, Andrew W.
    Owezarski, Philippe
    Uhlig, Steve
    Canini, Marco
    ENDEAVOUR: A Scalable SDN Architecture For Real-World IXPs2017In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 11, p. 2553-2562Article in journal (Refereed)
    Abstract [en]

    Innovation in interdomain routing has remained stagnant for over a decade. Recently, Internet eXchange Points (IXPs) have emerged as economically-advantageous interconnection points for reducing path latencies and exchanging ever increasing traffic volumes among, possibly, hundreds of networks. Given their far-reaching implications on interdomain routing, IXPs are the ideal place to foster network innovation and extend the benefits of software defined networking (SDN) to the interdomain level. In this paper, we present, evaluate, and demonstrate ENDEAVOUR, an SDN platform for IXPs. ENDEAVOUR can be deployed on a multi-hop IXP fabric, supports a large number of use cases, and is highly scalable, while avoiding broadcast storms. Our evaluation with real data from one of the largest IXPs, demonstrates the benefits and scalability of our solution: ENDEAVOUR requires around 70% fewer rules than alternative SDN solutions thanks to our rule partitioning mechanism. In addition, by providing an open source solution, we invite everyone from the community to experiment (and improve) our implementation as well as adapt it to new use cases.

  • 15.
    Anwar, Monib
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Effect of X-ray Irradiation on the Blinking of CdSe/ZnS Nanocrystals2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Different semiconductor nanocrystals exhibit size dependent properties due to confinement effect. Light emission from these nanocrystals may turn ON and OFF seemingly at random, an effect known as blinking. In this work blinking studies have been done to monitor the effect of X-ray exposure and to investigate the radiation hardness of CdSe/ZnS QD’s. Correct parameters to dilute and spin-coat the obtained sample were found to get access to individual single dots. Blinking of these dots was analyzed using Image J and MATLAB plug-in, where ON and OFF-times distribution power exponents Mon and Moff have been extracted to see the change in emission intermittency after a total cumulative dose of ~1026 Gy (absorbed by SiO2) in steps. It was observed that blinking was quenched and consequently the QD’s went permanently to off state as a result of X-ray exposure.

  • 16.
    Apanasevic, Tatjana
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Opportunities and challenges of mobile payment services: The perspective of service providers2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

     Mobile payments are transforming the payments industry. These services open up the opportunity for non-banking actors to enter the market. In order to embrace this challenge, banks, traditional payments market players, are forced to launch mobile payments. However, in Europe and most developed economies, a big number of launched services get terminated soon after their introduction in the market. Hence, the ability of different actors to act locally calls for additional research.

    The main objective of this thesis is to broaden knowledge and understanding about the ways mobile payment service providers address the opportunities and challenges of mobile payment services. In order to investigate this problem, this research (i) explores factors stimulating and hindering the introduction of mobile payments using perspectives of different types of service providers (i.e., banks, independent providers, direct operator billing providers, retailers, and public transport companies) and (ii) seeks to explain the importance of these factors for each type of provider.

    The primary data collected using interview method. More than 40 industry representatives in six countries were contacted. The Service, Technology, Organisation, and Finance (STOF) model was used as a theoretical research framework. This is a business modelling framework that specifies a set of critical design issues that have to  be considered within each model’s domain.

    Research findings highlight that the organisation domain is the key domain, which  affects all other domains and has an impact on the general viability of the business model. A comparison of the approaches used by different service providers to address each of the critical design issues helped to identify the factors that are most important within each domain. These factors stimulate or hinder development of a viable business model within each category of service providers.

    This research contributes to a better understanding of challenges and success factors associated with the design of business models for new mobile services and uses the lens of the STOF model. The contributions to the academic research on mobile payments are: (i) collection and analysis of a rich empirical data set on mobile payment services implemented in six Northern European countries, (ii) discussion of a bigger picture by connecting research findings to the context of the existing payment system, (iii) extension  of knowledge on business models for mobile ticketing, and (iv) extension of knowledge on the value of mobile ticketing services in the business-to-business (B2B) context.

  • 17.
    Apanasevic, Tatjana
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Primary data collection: Approaches of service providers towards mobile payments2018Report (Other academic)
    Abstract [en]

    Mobile payments are new services enabled by evolution of information and communication technologies. These services can be provided by different types of actors both banks and non-banks. The understanding of capabilities and limitations of different service providers to act in local markets requires further understanding. Implemented research seeks to extend knowledge in this area. I have implemented research focused on approaches used by different types of service providers including banks, independent providers, operator billing providers, retailers, and public transport companies in six Northern European countries.

    Exploratory part of the research aims to address the following research question: What factors stimulate and hinder the introduction of mobile payments? The main objective of this report is to present primary data collected during the research through interviews with contacted companies.

    The collected primary data is classified and organised using the STOF (Service, Technology, Organisation, and Finance) model. Evidence is presented in tables. This primary data is further used for explanatory study. At the same time, this data can be used by other researchers studying the same area. The collected data is reach in facts and presents the overview of different strategies. 

  • 18.
    Apanasevic, Tatjana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Arvidsson, Niklas
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability and Industrial Dynamics.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Mobile payments: a proposal for a context-oriented approach based on socio-technical system theoryIn: Journal of Innovation Management, ISSN 2183-0606Article in journal (Refereed)
    Abstract [en]

    A recent review on mobile payment research by Dahlberg et al. (2015) concludes that there is a need to synthesise this research area by studying contexts in which innovation is done as well as to integrate different aspects of research. This article aims to provide a proposal for how to achieve such integration and context-orientation by building on previous studies as well as an additional review. Our systematic literature review of mobile payments research is focused on papers published during 2006–2016. The main objective is to examine how mobile payments research has been conducted from the methodological and theoretical perspectives. Our findings show that research on mobile payments is a multidisciplinary research. Three main themes, which are in line with previous studies, in research are: customer adoption, technological aspects, and business aspects. Moreover, research is mainly analytical based on deductive approach. To meet the challenge formulated in the previous research, we propose and apply a socio-technical system framework to achieve synthesis and context-specific consideration in future research on mobile payments.

  • 19.
    Apanasevic, Tatjana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Mobile ticketing services in the Northern Europe: Critical business model issues2018In: Internet of Things Business Models, Users, and Networks, 2017 / [ed] Morten Falch, Copenhagen, Denmark: IEEE, 2018, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Started as SMS ticketing, today, mobile ticketing services become a platform for combined mobility solutions that integrate mobile ticketing, bike renting, car sharing, and parking payment services. Mobile ticketing services provide a number of benefits for public transport companies and passengers, however, in some Northern European countries, the share of mobile ticket sales does not exceed 10 percent. In this paper, we analyse business models of three types of mobile ticketing services (SMS, in-app, and “Be-In Be-Out” (BIBO)) in order to identify factors that negatively affect wider penetration of mobile ticketing. In order to do so, we use STOF (Service, Technology, Organisation, and Finance) model. The research reveals that there are a number of challenges related to service, technology, and finance domains of mobile ticketing. Due to this, with the help of price policy, many public transport companies push choices of their customers towards use of plastic travel card.

  • 20.
    Apanasevic, Tatjana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Mobile ticketing services in the Northern Europe Critical business model issues2017In: 2017 JOINT 13TH CTTE AND 10TH CMI CONFERENCE ON INTERNET OF THINGS - BUSINESS MODELS, USERS, AND NETWORKS / [ed] Falch, M, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Started as SMS ticketing, today, mobile ticketing services become a platform for combined mobility solutions that integrate mobile ticketing, bike renting, car sharing, and parking payment services. Mobile ticketing services provide a number of benefits for public transport companies and passengers, however, in some Northern European countries, the share of mobile ticket sales does not exceed 10 percent. In this paper, we analyse business models of three types of mobile ticketing services (SMS, in-app, and "Be-InBe-Out" (BIBO)) in order to identify factors that negatively affect wider penetration of mobile ticketing. In order to do so, we use STOF (Service, Technology, Organisation, and Finance) model. The research reveals that there are a number of challenges related to service, technology, and finance domains of mobile ticketing. Due to this, with the help of price policy, many public transport companies push choices of their customers towards use of plastic travel card.

  • 21.
    Apanasevic, Tatjana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    The value of mobile ticketing from a public transport perspective2018In: Journal of Payments Strategy & Systems, Vol. 11, no 4, p. 292-305Article in journal (Refereed)
    Abstract [en]

    Within the field of mobile payments, the market segment for mobile ticketing services is expected to grow, driven by the public transport sector. Although a large number of studies have explored the value of mobile payments to customers (ie service end users), there is a lack of research exploring the value of mobile payment and mobile ticketing for business customers (ie transport companies and retailers). This paper aims to address this gap and to explore the kinds of value that mobile ticketing services create for public transport companies. The research considers mobile ticketing services in six Northern European countries. The research findings suggest that within the business-to-business context, mobile ticketing services create multiple dimensions of value, namely enhanced technical functionality; financial value; better working environment; operational value; and reputational and customer relationship value. For passengers, meanwhile, value takes the form of convenience and service enhancement. These benefits are factors driving adoption of mobile ticketing and mobile payment services by public transport companies.

  • 22.
    Ardah, Khaled
    et al.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, Fortaleza, Ceara, Brazil..
    Silva, Yuri C. B.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, Fortaleza, Ceara, Brazil..
    Freitas, Walter C., Jr.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, Fortaleza, Ceara, Brazil..
    Cavalcanti, Francisco R. P.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    An ADMM Approach to Distributed Coordinated Beamforming in Dynamic TDD Networks2017In: 2017 IEEE 7TH INTERNATIONAL WORKSHOP ON COMPUTATIONAL ADVANCES IN MULTI-SENSOR ADAPTIVE PROCESSING (CAMSAP), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We consider a dynamic time division duplexing wireless network and propose a distributed coordinated beamforming algorithm based on Alternating Direction Method of Multipliers (ADMM) technique assuming the availability of perfect channel state information. Our design objective is to minimize the sum transmit power at the base stations subject to minimum signal-to-interference-plus-noise ratio (SINR) constraints for downlink mobile stations and a maximum interference power threshold for uplink mobile stations. First, we propose a centralized algorithm based on the relaxed Semidefinite Programming (SDP) technique. To obtain the beamforming solution in a distributed way, we further propose a distributed coordinated beamforming algorithm using the ADMM technique. Detailed simulation results are presented to examine the effectiveness of the proposed algorithms. It is shown that the proposed algorithm achieves better performance in terms of the design objective and converges faster than the reference algorithm based on primal decomposition.

  • 23. Argall, M. R.
    et al.
    Paulson, K.
    Alm, L.
    Rager, A.
    Dorelli, J.
    Shuster, J.
    Wang, S.
    Torbert, R. B.
    Vaith, H.
    Dors, I.
    Chutter, M.
    Farrugia, C.
    Burch, J.
    Pollock, C.
    Giles, B.
    Gershman, D.
    Lavraud, B.
    Russell, C. T.
    Strangeway, R.
    Magnes, W.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Khotyaintsev, Yu. V.
    Ergun, R. E.
    Ahmadi, N.
    Electron Dynamics Within the Electron Diffusion Region of Asymmetric Reconnection2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 1, p. 146-162Article in journal (Refereed)
    Abstract [en]

    We investigate the agyrotropic nature of electron distribution functions and their substructure to illuminate electron dynamics in a previously reported electron diffusion region (EDR) event. In particular, agyrotropy is examined as a function of energy to reveal detailed finite Larmor radius effects for the first time. It is shown that the previously reported approximate to 66eV agyrotropic "crescent" population that has been accelerated as a result of reconnection is evanescent in nature because it mixes with a denser, gyrotopic background. Meanwhile, accelerated agyrotropic populations at 250 and 500eV are more prominent because the background plasma at those energies is more tenuous. Agyrotropy at 250 and 500eV is also more persistent than at 66eV because of finite Larmor radius effects; agyrotropy is observed 2.5 ion inertial lengths from the EDR at 500eV, but only in close proximity to the EDR at 66eV. We also observe linearly polarized electrostatic waves leading up to and within the EDR. They have wave normal angles near 90 degrees, and their occurrence and intensity correlate with agyrotropy. Within the EDR, they modulate the flux of 500eV electrons travelling along the current layer. The net electric field intensifies the reconnection current, resulting in a flow of energy from the fields into the plasma. Plain Language Summary The process of reconnection involves an explosive transfer of magnetic energy into particle energy. When energetic particles contact modern technology such as satellites, cell phones, or other electronic devices, they can cause random errors and failures. Exactly how particles are energized via reconnection, however, is still unknown. Fortunately, the Magnetospheric Multiscale mission is finally able to detect and analyze reconnection processes. One recent finding is that energized particles take on a crescent-shaped configuration in the vicinity of reconnection and that this crescent shape is related to the energy conversion process. In our paper, we explain why the crescent shape has not been observed until now and inspect particle motions to determine what impact it has on energy conversion. When reconnection heats the plasma, the crescent shape forms from the cool, tenuous particles. As plasmas from different regions mix, dense, nonheated plasma obscures the crescent shape in our observations. The highest-energy particle population created by reconnection, though, also contains features of the crescent shape that are more persistent but appear less dramatically in the data.

  • 24.
    Armendariz, Mikel
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Gonzalez, Rodrigo
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Korman, Matus
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Nordström, Lars
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems. KTH, Superseded Departments (pre-2005), Electrical Systems.
    Method for Reliability Analysis of Distribution Grid Communications Using PRMs-Monte Carlo Methods2017In: 2017 IEEE POWER & ENERGY SOCIETY GENERAL MEETING, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    This paper presents a method to perform reliability analysis of communication systems for distribution grids. The method uses probabilistic relational models to indicate the probabilistic dependencies between the components that form the communication system and it is implemented by Monte Carlo methods. This method can be used for performing reliability predictions of simulated communication systems and for evaluating the reliability of real systems. The paper contains a case study in which the proposed method is applied to evaluate the reliability of the communication systems that are required for monitoring the network components at low voltage levels using the smart metering infrastructure. This case study is taken from the EU FP7 DISCERN project. Finally, the results are presented in a quantitative way, showing the individual reliability of each component and the combined reliability of the entire system.

  • 25.
    Artho, Cyrille
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Theoretical Computer Science, TCS.
    Ölveczky, P.C.
    Formal Techniques for Safety-Critical Systems (FTSCS 2015)2018In: Science of Computer Programming, ISSN 0167-6423, E-ISSN 1872-7964, Vol. 154, p. 1-2Article in journal (Refereed)
  • 26.
    Asadollahi, Ali
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems. KTH.
    A Study of Surface Treatments and Voids Formation in Low Temperature Wafer BondingManuscript (preprint) (Other academic)
  • 27.
    Asadollahi, Ali
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits. KTH.
    Compressive-Strained Ge and Tensile-Strained SiGe on Insulator Fabrication via Wafer Bonding for Monolithic 3D IntegrationManuscript (preprint) (Other academic)
  • 28.
    Asadollahi, Ali
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits.
    Fabrication of Group IV Semiconductors on Insulator for Monolithic 3D Integration2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The conventional 2D geometrical scaling of transistors is now facing many challenges in order to continue the performance enhancement while decreasing power consumption. The decrease in the device power consumption is related to the scaling of the power supply voltage (Vdd) and interconnects wiring length. In addition, monolithic three dimensional (M3D) integration in the form of vertically stacked devices, is a possible solution to increase the device density and reduce interconnect wiring length. Integrating strained germanium on insulator (sGeOI) pMOSFETs monolithically with strained silicon/silicon-germanium on insulator (sSOI/sSiGeOI) nMOSFETs can increase the device performance and packing density. Low temperature processing (<550 ºC) is essential as interconnects and strained layers limit the thermal budget in M3D. This thesis presents an experimental investigation of the low temperature (<450 ºC) fabrication of group IV semiconductor-on-insulator substrates with the focus on sGeOI and sSiGeOI fabrication processes compatible with M3D.

      To this aim, direct bonding was used to transfer the relaxed and strained semiconductor layers. The void formation dependencies of the oxide thickness, the surface treatment of the oxide and the post annealing time were fully examined. Low temperature SiGe epitaxy was investigated with the emphasis on the fabrication of Si0.5Ge0.5 strain-relaxed buffers (SRBs), etch-stop layer, and the device layer in the SiGeOI and GeOI process schemes. Ge epitaxial growth on Si as thick SRBs and thin device layers was investigated. Thick (500 nm-3 µm) and thin (<30 nm) relaxed GeOI substrates were fabricated. The latter was fabricated by continuous epitaxial growth of a 3-µm Ge (SRB)/Si0.5Ge0.5 (etch stop)/Ge (device layer) stack on Si. The fabricated long channel Ge pFETs from these GeOI substrates exhibit well-behaved IV characteristics with an effective mobility of 160 cm2/Vs.

      The planarization of SiO2 and SiGe SRBs for the fabrication of the strained GeOI and SiGeOI were accomplished by chemical mechanical polishing (CMP). Low temperature processes (<450 ºC) were developed for compressively strained GeOI layers (ɛ ~ -1.75 %, < 20 nm), which are used for high mobility and low power devices. For the first time, tensile strained Si0.5Ge0.5 (ɛ ~ 2.5 %, < 20 nm) films were successfully fabricated and transferred onto patterned substrates for 3D integration.

  • 29.
    Asadollahi, Ali
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits. KTH.
    Low Temperature SiGe Epitaxy Using SiH4-GeH4and Si2H6-Ge2H6 Gas PrecursorsIn: Journal of Solid State Science and TechnologyArticle in journal (Other academic)
  • 30. Aslay, Cigdem
    et al.
    Nasir, M. Anis U.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Morales, Gianmarco De Francisci
    Gionis, Aristides
    Mining Frequent Patterns in Evolving GraphsManuscript (preprint) (Other academic)
    Abstract [en]

    Given a labeled graph, the frequent-subgraph mining (FSM) problem asks to find all the k-vertex subgraphs that appear with frequency greater than a given threshold. FSM has numerous appli- cations ranging from biology to network science, as it provides a compact summary of the characteristics of the graph. However, the task is challenging, even more so for evolving graphs due to the streaming nature of the input and the exponential time complexity of the problem. In this paper, we initiate the study of approximate FSM problem in both incremental and fully-dynamic streaming settings, where arbitrary edges can be added or removed from the graph. For each streaming setting, we propose algorithms that can extract a high-quality approximation of the frequent k-vertex subgraphs for a given threshold, at any given time instance, with high probability. In contrast to the existing state-of-the-art solutions that require iterating over the entire set of subgraphs for any update, our algorithms operate by maintaining a uniform sample of k-vertex subgraphs with optimized neighborhood-exploration procedures local to the updates. We provide theoretical analysis of the proposed algorithms and emprically demonstrate that the proposed algorithms generate high-quality results compared to baselines.

  • 31.
    Austrin, Per
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Theoretical Computer Science, TCS.
    Kaski, Petteri
    Koivisto, Mikko
    Nederlof, Jesper
    Sharper Upper Bounds for Unbalanced Uniquely Decodable Code Pairs2018In: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 64, no 2, p. 1368-1373Article in journal (Refereed)
    Abstract [en]

    Two sets of 0-1 vectors of fixed length form a uniquely decodeable code pair if their Cartesian product is of the same size as their sumset, where the addition is pointwise over integers. For the size of the sumset of such a pair, van Tilborg has given an upper bound in the general case. Urbanke and Li, and later Ordentlich and Shayevitz, have given better bounds in the unbalanced case, that is, when either of the two sets is sufficiently large. Improvements to the latter bounds are presented.

  • 32.
    Babazadeh, Davood
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Hohn, Fabian
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Wu, Yimin
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Nordström, Lars
    KTH, Superseded Departments (pre-2005), Electrical Systems. KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Distributed Two-stage Network Topology Processor for HVDC Grid Operation2017In: 2017 IEEE POWER & ENERGY SOCIETY GENERAL MEETING, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    This paper presents the results of an analysis of distributed two-stage coordination of network topology processor for HVDC grids. In the first stage of the two-stage processor, the substation topology is analyzed locally using an automated graph based algorithm. Thereafter, a distributed algorithm is proposed to used the neighboring information to realize the grid connectivity. For distributed islanding detection, the connectivity problem is formulated as a set of linear equations and solved iteratively using successive-over-relaxation method. The performance of the proposed methods versus conventional one-stage method has been tested in an islandinv, scenario for a 5-terminal HVDC grid.

  • 33.
    Barman, Snigdha Roy
    et al.
    VIT Vellore, Sch Biosci & Technol, Vellore 632014, Tamil Nadu, India..
    Nain, Amit
    VIT Vellore, Sch Biosci & Technol, Vellore 632014, Tamil Nadu, India.;Natl Tsing Hua Univ, Dept Engn & Syst Sci, 101 Sect,2 Kuang Fu Rd, Hsinchu 30030, Taiwan..
    Jain, Saumey
    KTH, School of Electrical Engineering and Computer Science (EECS). VIT Vellore, Sch Biosci & Technol, Vellore 632014, Tamil Nadu, India..
    Punjabi, Nirmal
    Indian Inst Technol, Dept Biosci & Bioengn, Bombay 400076, Maharashtra, India..
    Mukherji, Soumyo
    Indian Inst Technol, Dept Biosci & Bioengn, Bombay 400076, Maharashtra, India..
    Satija, Jitendra
    VIT Vellore, Ctr Nanobiotechnol, Vellore 632014, Tamil Nadu, India..
    Dendrimer as a multifunctional capping agent for metal nanoparticles for use in bioimaging, drug delivery and sensor applications2018In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 6, no 16, p. 2368-2384Article, review/survey (Refereed)
    Abstract [en]

    Advances in nanoparticle research, particularly in the domain of surface-engineered, function-oriented nanoparticles, have had a profound effect in many areas of scientific research and aided in bringing unprecedented developments forward, particularly in the biomedical field. Surface modifiers/capping agents have a direct bearing on the major properties of metal nanoparticles (MNPs), ranging from their physico-chemical properties to their stability and functional applications. Among the different classes of capping agents, dendrimers have gained traction as effective multifunctional capping agents for MNPs due to their unique structural qualities, dendritic effect and polydentate nature. Dendrimer-coated metal nanoparticles (DC-MNPs) are typically produced by both (i) a one-pot strategy, where metal ions are reduced in the presence of dendrimer molecules and (ii) a multi-pot strategy, where a sequence of reactions involving the reduction of metal ions, activation, conjugation and purification steps are involved. These DC-MNPs have shown remarkable ability to stabilize MNPs by means of electrostatic interactions, coordination chemistry or covalent attachment, due to them entailing a large number of sites at which further molecular moieties can be conjugated. This review article is an attempt to consolidate the on-going work, particularly over the last five years, in the field of the synthesis of dendrimer-coated MNPs and their potential applications in bioimaging, drug delivery and biochemical sensors.

  • 34.
    Becerra Garcia, Marley
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Long, Mengni
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Schulz, W.
    Thottappillil, Rajeev
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    On the estimation of the lightning incidence to offshore wind farms2018In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 157, p. 211-226Article in journal (Refereed)
    Abstract [en]

    Field observations have shown that the frequency of dangerous lightning events to wind turbines, calculated according to the IEC standard 61400-24:2010, is grossly underestimated. This paper intends to critically revisit the evaluation of the incidence of downward lightning as well as self-initiated and other-triggered upward flashes to offshore wind power plants. Three different farms are used as case studies. The conditions for interception of stepped leaders in downward lightning and the initiation of upward lightning is evaluated with the Self-consistent Leader Inception and Propagation Model (SLIM). The analysis shows that only a small fraction of damages observed in the analysed farms can be attributed to downward lightning. It is also estimated that only a small fraction (less than 19%) of all active thunderstorms in the area of the analysed farms can generate sufficiently high thundercloud fields to self-initiate upward lightning. Furthermore, it is shown that upward flashes can be triggered even under low thundercloud fields once a sufficiently high electric field change is generated by a nearby lightning event. Despite of the uncertainties in the incidence evaluation, it is shown that upward flashes triggered by nearby positive cloud-to-ground flashes produce most of the dangerous lightning events to the case studies.

  • 35.
    Becerra Garcia, Marley
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Pettersson, Jonas
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Optical radiative properties of ablating polymers exposed to high-power arc plasmas2018In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 51, no 12, article id 125202Article in journal (Refereed)
    Abstract [en]

    The radiative properties of polymers exposed to high-intensity radiation are of importance for the numerical simulation of arc-induced ablation. The paper investigates the optical properties of polymethylmethacrylate PMMA and polyamide PA6 films exposed to high-power arc plasmas, which can cause ablation of the material. A four-flux radiative approximation is first used to estimate absorption and scattering coefficients of the tested materials in the ultraviolet (UV) and in the visible (VIS) ranges from spectrophotometric measurements. The temperature-induced variation of the collimated transmissivity of the polymers is also measured from room temperature to the glass temperature of PMMA and the melting temperature of PA6. Furthermore, band-averaged absorption and scattering coefficients of non-ablating and ablating polymers are estimated from the UV to the short-wavelength infrared (SWIR), covering the range of interest for the simulation of arc-induced ablation. These estimates are obtained from collimated transmissivities measured with an additional in situ photometric system that uses a high-power, transient arc plasma to both illuminate the samples and to induce ablation. It is shown that the increase in the bulk temperature of PA6 leads to a strong reversible increase in collimated transmissivity, significantly reducing the absorption and scattering coefficients of the material. A weaker but opposite effect of temperature on the optical properties is found in PMMA. As a consequence, it is suggested that the absorption coefficient of polymers used for arc-induced ablation estimates should not be taken directly from direct collimated transmissivity measurements at room temperature. The band-averaged radiation measurements also show that the layer of products released by ablation of PMMA produces scattering radiation losses mainly in the VIS-SWIR ranges, which are only a small fraction of the total incident arc radiation. In a similar manner, the ablation layer of PA6 leads to weak absorption radiation losses, although mainly in the UV range.

  • 36. Beck, O.
    et al.
    Kenan Modén, N.
    Seferaj, S.
    Lenk, Gabriel
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Helander, A.
    Study of measurement of the alcohol biomarker phosphatidylethanol (PEth) in dried blood spot (DBS) samples and application of a volumetric DBS device2018In: Clinica Chimica Acta, ISSN 0009-8981, E-ISSN 1873-3492, Vol. 479, p. 38-42Article in journal (Refereed)
    Abstract [en]

    Phosphatidylethanol (PEth) is a group of phospholipids formed in cell membranes following alcohol consumption. PEth measurement in whole blood samples is established as a specific alcohol biomarker with clinical and medico-legal applications. This study further evaluated the usefulness of dried blood spot (DBS) samples collected on filter paper for PEth measurement. Specimens used were surplus volumes of venous whole blood sent for routine LC–MS/MS quantification of PEth 16:0/18:1, the major PEth homolog. DBS samples were prepared by pipetting blood on Whatman 903 Protein Saver Cards and onto a volumetric DBS device (Capitainer). The imprecision (CV) of the DBS sample amount based on area and weight measurements of spot punches were 23–28%. Investigation of the relationship between blood hematocrit and PEth concentration yielded a linear, positive correlation, and at around 1.0–1.5 μmol/L PEth 16:0/18:1, the PEth concentration increased by ~ 0.1 μmol/L for every 5% increase in hematocrit. There was a close agreement between the PEth concentrations obtained with whole blood samples and the corresponding results using Whatman 903 (PEthDBS = 1.026 PEthWB + 0.013) and volumetric device (PEthDBS = 1.045 PEthWB + 0.016) DBS samples. The CV of PEth quantification in DBS samples at concentrations ≥ 0.05 μmol/L were ≤ 15%. The present results further confirmed the usefulness of DBS samples for PEth measurement.

  • 37.
    Belic, Jovana
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST).
    Untangling Cortico-Striatal Circuitry and its Role in Health and Disease - A computational investigation2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The basal ganglia (BG) play a critical role in a variety of regular motor and cognitive functions. Many brain diseases, such as Parkinson’s diseases, Huntington’s disease and dyskinesia, are directly related to malfunctions of the BG nuclei. One of those nuclei, the input nucleus called the striatum, is heavily connected to the cortex and receives afferents from nearly all cortical areas. The striatum is a recurrent inhibitory network that contains several distinct cell types. About 95% of neurons in the striatum are medium spiny neurons (MSNs) that form the only output from the striatum. Two of the most examined sources of GABAergic inhibition into MSNs are the feedback inhibition (FB) from the axon collaterals of the MSNs themselves, and the feedforward inhibition (FF) via the small population (1-2% of striatal neurons) of fast spiking interneurons (FSIs). The cortex sends direct projections to the striatum, while the striatum can affect the cortex only indirectly through other BG nuclei and the thalamus. Understanding how different components of the striatal network interact with each other and influence the striatal response to cortical inputs has crucial importance for clarifying the overall functions and dysfunctions of the BG.

        In this thesis I have employed advanced experimental data analysis techniques as well as computational modelling, to study the complex nature of cortico-striatal interactions. I found that for pathological states, such as Parkinson’s disease and L-DOPA-induced dyskinesia, effective connectivity is bidirectional with an accent on the striatal influence on the cortex. Interestingly, in the case of L-DOPA-induced dyskinesia, there was a high increase in effective connectivity at ~80 Hz and the results also showed a large relative decrease in the modulation of the local field potential amplitude (recorded in the primary motor cortex and sensorimotor striatum in awake, freely behaving, 6-OHDA lesioned hemi-parkinsonian rats) at ~80 Hz by the phase of low frequency oscillations. These results suggest a lack of coupling between the low frequency activity of a presumably larger neuronal population and the synchronized activity of a presumably smaller group of neurons active at 80 Hz.

        Next, I used a spiking neuron network model of the striatum to isolate the mechanisms underlying the transmission of cortical oscillations to the MSN population. I showed that FSIs play a crucial role in efficient propagation of cortical oscillations to the MSNs that did not receive direct cortical oscillations. Further, I have identified multiple factors such as the number of activated neurons, ongoing activity, connectivity, and synchronicity of inputs that influenced the transfer of oscillations by modifying the levels of FB and FF inhibitions. Overall, these findings reveal a new role of FSIs in modulating the transfer of information from the cortex to striatum. By modulating the activity and properties of the FSIs, striatal oscillations can be controlled very efficiently. Finally, I explored the interactions in the striatal network with different oscillation frequencies and showed that the features of those oscillations, such as amplitude and frequency fluctuations, can be influenced by a change in the input intensities into MSNs and FSIs and that these fluctuations are also highly dependent on the selected frequencies in addition to the phase offset between different cortical inputs.

        Lastly, I investigated how the striatum responds to cortical neuronal avalanches. Recordings in the striatum revealed that striatal activity was also characterized by spatiotemporal clusters that followed a power law distribution albeit, with significantly steeper slope. In this study, an abstract computational model was developed to elucidate the influence of intrastriatal inhibition and cortico-striatal interplay as important factors to understand the experimental findings. I showed that one particularly high activation threshold of striatal nodes can reproduce a power law-like distribution with a coefficient similar to the one found experimentally. By changing the ratio of excitation and inhibition in the cortical model, I saw that increased activity in the cortex strongly influenced striatal dynamics, which was reflected in a less negative slope of cluster size distributions in the striatum.  Finally, when inhibition was added to the model, cluster size distributions had a prominently earlier deviation from the power law distribution compared to the case when inhibition was not present. 

  • 38.
    Belic, Jovana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST). KTH, Centres, Science for Life Laboratory, SciLifeLab. Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany.
    Kumar, Arvind
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST). Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany.
    Hellgren Kotaleski, Jeanette
    KTH, School of Electrical Engineering and Computer Science (EECS), Computational Science and Technology (CST). KTH, Centres, Science for Life Laboratory, SciLifeLab. Department of Neuroscience, Karolinska Institute, Solna, 17177, Sweden.
    The role of striatal feedforward inhibition in propagation of cortical oscillations2017In: BMC neuroscience (Online), ISSN 1471-2202, E-ISSN 1471-2202, Vol. 18, p. 91-91Article in journal (Refereed)
    Abstract [en]

    Fast spiking interneurons (FSIs) and feedforward (FF) inhibition are a common property of neuronal networks throughout the brain and play crucial role in neural computations. For instance, in the cortex FF inhibition sets the window of temporal integration and spiking and thereby contributes to the control of firing rate and correlations [1]. In the striatum (the main input structure of the basal ganglia) despite their high firing rates and strong synapses, FSIs (comprise 1–2% of striatal neurons) do not seem to play a major role in controlling the firing of medium spiny neurons (MSNs; comprise 95% of striatal neurons) [2] and so far, it has not been possible to attribute a functional role to FSIs in the striatum. Here we use a spiking neuron network model in order to investigate how externally induced oscillations propagate through striatal circuitry. Recordings in the striatum have shown robust oscillatory activity that might be in fact cortical oscillations transmitted by the corticostriatal projections [3–5]. We propose that FSIs can perform an important role in transferring cortical oscillations to the striatum especially to those MSNs that are not directly driven by the cortical oscillations. Strong and divergent connectivity of FSIs implies that even weak oscillations in FSI population activity can be spread to the whole MSN population [6]. Further, we have identified multiple factors that influence the transfer of oscillations to MSNs. The variables such as the number of activated neurons, ongoing activity, connectivity, and synchronicity of inputs influence the transfer of oscillations by modifying the levels of feedforward and feedback inhibitions suggesting that the striatum can exploit different parameters to impact the transfer of oscillatory signals.

    References

    1. Isaacson, J. S., & Scanziani, M. (2011). How inhibition shapes cortical activity. Neuron, 72(2), 231–243. 

    2. Berke, J. D. (2011). Functional properties of striatal fast-spiking interneurons. Frontiers in systems neuroscience, 5.

    3. Belić, J. J., Halje, P., Richter, U., Petersson, P., & Kotaleski, J. H. (2016). Untangling cortico-striatal connectivity and cross-frequency coupling in L-DOPA-induced dyskinesia. Frontiers in systems neuroscience, 10.

    4. Berke, J. D. (2009). Fast oscillations in cortical‐striatal networks switch frequency following rewarding events and stimulant drugs. European Journal of Neuroscience, 30(5), 848–859.

    5. Boraud, T., Brown, P., Goldberg, J. A., Graybiel, A. M., & Magill, P. J. (2005). Oscillations in the basal ganglia: the good, the bad, and the unexpected. In The basal ganglia VIII (pp. 1–24). Springer US.

    6. Belić, J. J., Kumar, A., & Kotaleski, J. H. (2017). Interplay between periodic stimulation and GABAergic inhibition in striatal network oscillations. PloS one, 12(4), e0175135.

  • 39. Belov, Ilja
    et al.
    Rydén, Jan
    Lindeblom, Joakim
    Zhang, Yafan
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems. RISE Acreo.
    Hansson, Torgny
    Bergner, Fredrik
    Leisner, Peter
    Application of CFD modelling for energy efficient humidity management of an electronics enclosure in storage under severe climatic conditions2008Conference paper (Refereed)
  • 40.
    Bergsmark, Moa
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    From Patchwork to Appliqué: Exploring Material Properties Through an Interaction Design Remake2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Materials and materiality in interaction design has become more and more important perspectives within the field. Material explorations of a specific material could contribute to this ongoing discussion. As means to investigate how material properties affect interactive qualities for a tangible interaction design, a remake of an existing design was created. The starting point for remake is a tangible programming space for children called Patcher where custom built RFID readers is interacted with. For this investigation, Android mobile phones with NFC readers is the material of choice when recreating the same concept. Design values in Patcher are identified as collaborative play and open-ended programming play. The creation process of Alfombra Applique, the remake, is presented, the design choices and how they relate to the shift of material. This leads to learnings regarding how material properties differ when using the prebuild product with a lot of design possibilities in relationship to custom built hardware. These learning can be summarized into three topics. (1) When using a prebuilt product as material there will be more limitations to how a designer can change the material, it can only be bent using software. (2) A consumer market product opens up to getting the artefact available to more users, but it could depend on how the product normally is used. (3) The designer and users will have a lot more preknowledge of the material whish gives implications on expectations. Also, the paper investigates how exploring materials and having a bricolage mindset made it possible to create a meaningful remake with other material of an existing design. It is concluded that the choice of materials and how designers work with their properties changes what is relevant and possible to design. 

  • 41.
    Bessman, Alexander
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Soares, Rudi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Software documentation for current-rippleequipment2018Report (Other (popular science, discussion, etc.))
  • 42. Bhattacharya, S.
    et al.
    Chakrabarty, D.
    Henzinger, M.
    Na Nongkai, Danupon
    KTH, School of Electrical Engineering and Computer Science (EECS), Theoretical Computer Science, TCS.
    Dynamic algorithms for graph coloring2018In: Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms, Association for Computing Machinery , 2018, p. 1-20Conference paper (Refereed)
    Abstract [en]

    We design fast dynamic algorithms for proper vertex and edge colorings in a graph undergoing edge insertions and deletions. In the static setting, there are simple linear time algorithms for ( δ + 1)vertex coloring and (2 δ 1)edge coloring in a graph with maximum degree δ. It is natural to ask if we can efficiently maintain such colorings in the dynamic setting as well. We get the following three results. (1) We present a randomized algorithm which maintains a ( δ+1)-vertex coloring with O(log δ) expected amortized update time. (2) We present a deterministic algorithm which maintains a (1 + o(1)) δ-vertex coloring with O(polylog δ) amortized update time. (3) We present a simple, deterministic algorithm which maintains a (2 δ)edge coloring with O(log δ) worst-case update time. This improves the recent O( δ)-edge coloring algorithm with Õ ( p δ) worst-case update time [4]. 

  • 43. Boem, F.
    et al.
    Zhou, Y.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Parisini, T.
    Distributed Pareto-optimal state estimation using sensor networks2018In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 93, p. 211-223Article in journal (Refereed)
    Abstract [en]

    A novel model-based dynamic distributed state estimator is proposed using sensor networks. The estimator consists of a filtering step – which uses a weighted combination of information provided by the sensors – and a model-based predictor of the system's state. The filtering weights and the model-based prediction parameters jointly minimize – at each time-step – the bias and the variance of the prediction error in a Pareto optimization framework. The simultaneous distributed design of the filtering weights and of the model-based prediction parameters is considered, differently from what is normally done in the literature. It is assumed that the weights of the filtering step are in general unequal for the different state components, unlike existing consensus-based approaches. The state, the measurements, and the noise components are allowed to be individually correlated, but no probability distribution knowledge is assumed for the noise variables. Each sensor can measure only a subset of the state variables. The convergence properties of the mean and of the variance of the prediction error are demonstrated, and they hold both for the global and the local estimation errors at any network node. Simulation results illustrate the performance of the proposed method, obtaining better results than state of the art distributed estimation approaches.

  • 44. Bombois, X.
    et al.
    Korniienko, A.
    Hjalmarsson, Håkan
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Scorletti, G.
    Optimal identification experiment design for the interconnection of locally controlled systems2018In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 89, p. 169-179Article in journal (Refereed)
    Abstract [en]

    This paper considers the identification of the modules of a network of locally controlled systems (multi-agent systems). Its main contribution is to determine the least perturbing identification experiment that will nevertheless lead to sufficiently accurate models of each module for the global performance of the network to be improved by a redesign of the decentralized controllers. Another contribution is to determine the experimental conditions under which sufficiently informative data (i.e. data leading to a consistent estimate) can be collected for the identification of any module in such a network. 

  • 45. Bousse, Erwan
    et al.
    Leroy, Dorian
    Combemale, Benoit
    Wimmer, Manuel
    Baudry, Benoit
    KTH, School of Electrical Engineering and Computer Science (EECS), Software and Computer systems, SCS.
    Omniscient debugging for executable DSLs2018In: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 137, p. 261-288Article in journal (Refereed)
    Abstract [en]

    Omniscient debugging is a promising technique that relies on execution traces to enable free traversal of the states reached by a model (or program) during an execution. While a few General-Purpose Languages (GPLs) already have support for omniscient debugging, developing such a complex tool for any executable Domain Specific Language (DSL) remains a challenging and error prone task. A generic solution must: support a wide range of executable DSLs independently of the metaprogramming approaches used for implementing their semantics; be efficient for good responsiveness. Our contribution relies on a generic omniscient debugger supported by efficient generic trace management facilities. To support a wide range of executable DSLs, the debugger provides a common set of debugging facilities, and is based on a pattern to define runtime services independently of metaprogramming approaches. Results show that our debugger can be used with various executable DSLs implemented with different metaprogramming approaches. As compared to a solution that copies the model at each step, it is on average sixtimes more efficient in memory, and at least 2.2 faster when exploring past execution states, while only slowing down the execution 1.6 times on average.

  • 46.
    Brauer, Patrik
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    High-Frequency Voltage Distribution Modelling of a Slotless PMSM from a Machine Design Perspective2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The introduction of inverters utilizing wide band-gap semiconductors allow for higher switching frequency and improved machine drive energy efficiency. However, inverter switching results in fast voltage surges which cause overvoltage at the stator terminals and uneven voltage distribution in the stator winding. Therefore, it is important to understand how next generation machine drives, with higher switching frequency, affect the voltage distribution. For this purpose, a lumped-parameter model capable of simulating winding interturn voltages for the wide frequency range of 0-10 MHz is developed for a slotless PMSM. The model includes both capacitive and inductive couplings, extracted from 2D finite element simulations, as well as analytically estimated resistive winding losses. The developed model of a single phase-winding is used to investigate how machine design aspects such as insulation materials and winding conductor distribution affects both voltage distribution and winding impedance spectrum. Validation measurements demonstrate that the model is accurate for the wide frequency range. The sensitivity analysis suggests that the winding conductor distribution affect both impedance spectrum and voltage distribution. For the slotless machine, capacitance between the winding and the stator is several times smaller than capacitance between turns. Therefore, the high-frequency effects are dominated by the capacitance between turns. Insulation materials that affect this coupling does therefore have an impact on the impedance spectrum but does not have any significant impact on the voltage distribution.

  • 47. Brazalez, Astrid Algaba
    et al.
    Manholm, Lars
    Johansson, Martin
    Quevedo-Teruel, Oscar
    Miao, Jingwei
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Investigation of a Ka-band Luneburg Lens Made of a Glide-Symmetric Holey Structure2017In: 2017 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP 2017), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    A Ka-hand 2D flat-profiled Luneburg lens antenna implemented with a glide-symmetric holey structure is presented. The required refractive index for the lens design has been investigated via an analysis of the hole depth and the gap between the two metallic layers constituting the lens. The final unit cell is described and applied to create the complete metasurface Luneburg lens showing that a plane wave is obtained when feeding at an opposite arbitrary point with a discrete source.

  • 48. Breuillard, H.
    et al.
    Le Contel, O.
    Chust, T.
    Berthomier, M.
    Retino, A.
    Turner, D. L.
    Nakamura, R.
    Baumjohann, W.
    Cozzani, G.
    Catapano, F.
    Alexandrova, A.
    Mirioni, L.
    Graham, D. B.
    Argall, M. R.
    Fischer, D.
    Wilder, F. D.
    Gershman, D. J.
    Varsani, A.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Khotyaintsev, Yu. V.
    Marklund, G.
    Ergun, R. E.
    Goodrich, K. A.
    Ahmadi, N.
    Burch, J. L.
    Torbert, R. B.
    Needell, G.
    Chutter, M.
    Rau, D.
    Dors, I.
    Russell, C. T.
    Magnes, W.
    Strangeway, R. J.
    Bromund, K. R.
    Wei, H.
    Plaschke, F.
    Anderson, B. J.
    Le, G.
    Moore, T. E.
    Giles, B. L.
    Paterson, W. R.
    Pollock, C. J.
    Dorelli, J. C.
    Avanov, L. A.
    Saito, Y.
    Lavraud, B.
    Fuselier, S. A.
    Mauk, B. H.
    Cohen, I. J.
    Fennell, J. F.
    The Properties of Lion Roars and Electron Dynamics in Mirror Mode Waves Observed by the Magnetospheric MultiScale Mission2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 1, p. 93-103Article in journal (Refereed)
    Abstract [en]

    Mirror mode waves are ubiquitous in the Earth's magnetosheath, in particular behind the quasi-perpendicular shock. Embedded in these nonlinear structures, intense lion roars are often observed. Lion roars are characterized by whistler wave packets at a frequency similar to 100Hz, which are thought to be generated in the magnetic field minima. In this study, we make use of the high time resolution instruments on board the Magnetospheric MultiScale mission to investigate these waves and the associated electron dynamics in the quasi-perpendicular magnetosheath on 22 January 2016. We show that despite a core electron parallel anisotropy, lion roars can be generated locally in the range 0.05-0.2f(ce) by the perpendicular anisotropy of electrons in a particular energy range. We also show that intense lion roars can be observed up to higher frequencies due to the sharp nonlinear peaks of the signal, which appear as sharp spikes in the dynamic spectra. As a result, a high sampling rate is needed to estimate correctly their amplitude, and the latter might have been underestimated in previous studies using lower time resolution instruments. We also present for the first-time 3-D high time resolution electron velocity distribution functions in mirror modes. We demonstrate that the dynamics of electrons trapped in the mirror mode structures are consistent with the Kivelson and Southwood (1996) model. However, these electrons can also interact with the embedded lion roars: first signatures of electron quasi-linear pitch angle diffusion and possible signatures of nonlinear interaction with high-amplitude wave packets are presented. These processes can lead to electron untrapping from mirror modes.

  • 49.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Cassak, P. A.
    Univ Virginia, Dept Phys & Astron, Morgantown, WV USA..
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX USA..
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Rager, A. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA..
    Hwang, K. -J
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Genestreti, K. J.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Allen, R. C.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Chen, L. -J
    Wang, S.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Gershman, D.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Le Contel, O.
    Univ Paris Sud, Observ Paris, Lab Phys Plasmas, CNRS,Ecole Polytech,UPMC Univ Paris 06, Paris, France..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Planetary Sci, Los Angeles, CA USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Planetary Sci, Los Angeles, CA USA..
    Wilder, F. D.
    Graham, D. B.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Hesse, M.
    Univ Bergen, Dept Phys & Technol, Bergen, Norway..
    Drake, J. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Swisdak, M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Price, L. M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Shay, M. A.
    Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Pollock, C. J.
    Denali Sci, Healy, AK USA..
    Denton, R. E.
    Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA..
    Newman, D. L.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Localized Oscillatory Energy Conversion in Magnetopause Reconnection2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 3, p. 1237-1245Article in journal (Refereed)
    Abstract [en]

    Data from the NASA Magnetospheric Multiscale mission are used to investigate asymmetric magnetic reconnection at the dayside boundary between the Earth's magnetosphere and the solar wind. High-resolution measurements of plasmas and fields are used to identify highly localized (similar to 15 electron Debye lengths) standing wave structures with large electric field amplitudes (up to 100 mV/m). These wave structures are associated with spatially oscillatory energy conversion, which appears as alternatingly positive and negative values of J . E. For small guide magnetic fields the wave structures occur in the electron stagnation region at the magnetosphere edge of the electron diffusion region. For larger guide fields the structures also occur near the reconnection X-line. This difference is explained in terms of channels for the out-of-plane current (agyrotropic electrons at the stagnation point and guide field-aligned electrons at the X-line).

  • 50.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX USA..
    Genestreti, K. J.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Rager, A. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Allen, R. C.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Chen, L. -J
    Wang, S.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Le Contel, O.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Russell, C. T.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA USA..
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Jaynes, A. N.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Graham, D. B.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Wilder, F. D.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Hwang, K. -J
    Goldstein, J.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Wave Phenomena and Beam-Plasma Interactions at the Magnetopause Reconnection Region2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 2, p. 1118-1133Article in journal (Refereed)
    Abstract [en]

    This paper reports on Magnetospheric Multiscale observations of whistler mode chorus and higher-frequency electrostatic waves near and within a reconnection diffusion region on 23 November 2016. The diffusion region is bounded by crescent-shaped electron distributions and associated dissipation just upstream of the X-line and by magnetic field-aligned currents and electric fields leading to dissipation near the electron stagnation point. Measurements were made southward of the X-line as determined by southward directed ion and electron jets. We show that electrostatic wave generation is due to magnetosheath electron beams formed by the electron jets as they interact with a cold background plasma and more energetic population of magnetospheric electrons. On the magnetosphere side of the X-line the electron beams are accompanied by a strong perpendicular electron temperature anisotropy, which is shown to be the source of an observed rising-tone whistler mode chorus event. We show that the apex of the chorus event and the onset of electrostatic waves coincide with the opening of magnetic field lines at the electron stagnation point.

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