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  • 1201.
    Zhang, Cevin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Baalsrud Hauge, Jannicke
    KTH, School of Industrial Engineering and Management (ITM), Sustainable production development. Bremer Institut fuer Produktion und Logistik Bremen Germany.
    Pukk Härenstam, Karin
    Meijer, Sebastiaan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    A Serious Logistical Game of Paediatric Emergency Medicine: Proposed Scoring Mechanism and Pilot Test2019In: Games and Learning Alliance / [ed] Antonios Liapis; Georgios N. Yannakakis; Manuel Gentile; Manuel Ninaus, Springer Publishing Company, 2019, p. 468-478Chapter in book (Refereed)
    Abstract [en]

    Outcomes of care for various diseases and urgent conditions in an emergency department are dependent on balancing the patient’s need and available resources through management and coordination under often rapidly changing preconditions. However, although it is central to resilient operations, decision-making in dynamic resource management is rarely visible to managers. Sometimes the identification of successful strategies is apparent only through adverse event reports. A simulation game could be helpful for the acquisition of non-technical skills in addressing operational conundrums that could threaten the defence ability of a paediatric emergency department under care production pressures. This contribution presents a Sandtable serious logistical game of the care production system and, in particular, proposes its scoring mechanism, which was tested in a set of logistical experiments. The results show that through gamification, participants were challenged in terms of their intrinsic self-interest when it came to approaching the work. More importantly, the proposed extrinsic reward system allows all parallel functional roles to be equally rewarded as the game evolves. Anticipatory human resource management is identified as a successful strategy for achieving a sustainable working environment if the organizational resilience is confronted with patient inflow surges during the busiest hours of the busiest day.

  • 1202.
    Zhang, Chuang
    et al.
    Beijing Univ Posts & Telecommun, Pattern Recognit & Intelligent Syst Lab, Beijing 100876, Peoples R China..
    Wu, Ming
    Beijing Univ Posts & Telecommun, Pattern Recognit & Intelligent Syst Lab, Beijing 100876, Peoples R China..
    Chen, Jinyu
    Beijing Univ Posts & Telecommun, Pattern Recognit & Intelligent Syst Lab, Beijing 100876, Peoples R China..
    Chen, Kaiyan
    Beijing Univ Posts & Telecommun, Pattern Recognit & Intelligent Syst Lab, Beijing 100876, Peoples R China..
    Zhang, Chi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes.
    Xie, Chao
    Natl Meteorol Ctr, Beijing 100081, Peoples R China..
    Huang, Bin
    Natl Meteorol Ctr, Beijing 100081, Peoples R China..
    He, Zichen
    McGill Univ, Dept Stat & Comp Sci, Montreal, PQ H3A 0G4, Canada..
    Weather Visibility Prediction Based on Multimodal Fusion2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 74776-74786Article in journal (Refereed)
    Abstract [en]

    Visibility affects all forms of traffic: roads, sailing, and aviation. Visibility prediction is meaningful in guiding production and life. Different from weather prediction, which relies solely on atmosphere factors, the factors that affect meteorological visibility are more complicated, such as the air pollution caused by factory exhaust emission. However, the current prediction of visibility is mostly based on the numerical prediction method similar to the weather prediction. We proposed a method using multimodal fusion to build a weather visibility prediction system in this paper. An advanced numerical prediction model and a method for emission detection were used to build a multimodal fusion visibility prediction system. We used the most advanced regression algorithm, XGBoost, and LightGBM, to train the fusion model for numerical prediction. Through the estimation of factory emission by the traditional detector in the satellite image, we propose to add the result of estimation based on Landsat-8 satellite images to assist the prediction. By testing our numerical model in atmosphere data of various meteorological observation stations in Beijing-Tianjin-Hebei region from 2002 to 2018, our numerical prediction model turns out to be more accurate than other existing methods, and after fusing with emission detection method, the accuracy of our visibility prediction system has been further improved.

  • 1203.
    Zhang, Guoqiang
    KTH, School of Electrical Engineering (EES), Sound and Image Processing.
    On the rate region of the vector gaussian one-helper distributed source-coding problem2011In: 2011 DATA COMPRESSION CONFERENCE (DCC), 2011, p. 263-272Conference paper (Refereed)
    Abstract [en]

    In this paper we consider the rate region of the vector Gaussian one-helper distributed source coding problem. In particular, we derive optimality conditions under which a weighted sum rate is minimum by using a contradiction-based argument. When the sources are specified to be scalar, the optimality conditions can always be constructed for any weighted sum rate. In the derivation of the optimality conditions, we introduce a new concept of "source enhancement", which can be viewed as a dual to the well-known "channel enhancement" technique. In particular, source enhancement refers to the operation of increasing the covariance matrix of a Gaussian source in a partial ordering sense. This new technique makes the derivation of the optimality conditions straightforward.

  • 1204.
    Zhang, Huimin
    et al.
    School of Electro-Mechanical Engineering, Xidian University.
    Feng, Lei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Wu, Naiqi
    Institute of Systems Engineering, Macau University of Science and Technology.
    Li, Zhiwu
    School of Electro-Mechanical Engineering, Xidian University.
    Integration of Learning-Based Testing and Supervisory Control for Requirements Conformance of Black-Box Reactive Systems2018In: IEEE Transactions on Automation Science and Engineering, ISSN 1545-5955, E-ISSN 1558-3783, Vol. 15, no 1, p. 2-15Article in journal (Refereed)
    Abstract [en]

    A fundamental requirement of the supervisory control theory (SCT) of discrete-event systems is a finite automaton model of the plant. The requirement does not hold for black-box systems whose source code and logical model are not accessible. To apply SCT to black-box systems, we integrate automaton learning technology with SCT and apply the new method to improve the requirements conformance of software reuse. If the reused software component does not satisfy a requirement, the method adds a supervisor component to prevent the black-box system from reaching ''faulty sections.'' The method employs learning-based testing (LBT) to verify whether the reused software meets all requirements in the new context. LBT generates a large number of test cases and iteratively constructs an automaton model of the system under test. If the system fails the test, the learned model is applied as the plant model for control synthesis using SCT. Then, the supervisor is implemented as an executable program to monitor and control the system to follow the requirement. Finally, the integrated system, including the supervisory program and the reused component, is tested by LBT to assure the satisfiability of the requirement. This paper makes two contributions. First, we innovatively integrate LBT and SCT for the control synthesis of black-box reactive systems. Second, software component reuse is still possible even if it does not satisfy user requirements at the outset.

  • 1205.
    Zhang, Kewei
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS. Networked Systems Security (NSS) Group.
    Secure GNSS-based Positioning and Timing: Distance-Decreasing attacks, fault detection and exclusion, and attack detection with the help of opportunistic signals2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    With trillions of devices connected in large scale systems in a wired or wireless manner, positioning and synchronization become vital. Global Navigation Satellite System (GNSS) is the first choice to provide global coverage for positioning and synchronization services. From small mobile devices to aircraft, from intelligent transportation systems to cellular networks, and from cargo tracking to smart grids, GNSS plays an important role, thus, requiring high reliability and security protection.       

    However, as GNSS signals propagate from satellites to receivers at distance of around 20 000 km, the signal power arriving at the receivers is very low, making the signals easily jammed or overpowered. Another vulnerability stems from that civilian GNSS signals and their specifications are publicly open, so that anyone can craft own signals to spoof GNSS receivers: an adversary forges own GNSS signals and broadcasts them to the victim receiver, to mislead the victim into believing that it is at an adversary desired location or follows a false trajectory, or adjusts its clock to a time dictated by the adversary. Another type of attack is replaying GNSS signals: an adversary transmits a pre-recorded GNSS signal stream to the victim receiver, so that the receiver calculates an erroneous position and time. Recent incidents reported in press show that the GNSS functionalities in a certain area, e.g., Black Sea, have been affected by cyberattacks composed of the above-mentioned attack types.        

    This thesis, thus, studies GNSS vulnerabilities and proposes detection and mitigation methods for GNSS attacks, notably spoofing and replay attacks. We analyze the effectiveness of one important and powerful replay attack, the so-called Distance-decreasing (DD) attacks that were previously investigated for wireless communication systems, on GNSS signals. DD attacks are physical layer attacks, targeting time-of-flight ranging protocols, to shorten the perceived as measured distance between the transmitter and receiver. The attacker first transmits an adversary-chosen data bit to the victim receiver before the signal arrives at the attacker; upon receipt of the GNSS signal, the attacker estimates the data bit based on the early fraction of the bit period, and then switches to transmitting the estimate to the victim receiver. Consequently, the DD signal arrives at the victim receiver earlier than the genuine GNSS signals would have, which in effect shortens the pseudorange measurement between the sender (satellite) and the victim receiver, consequently, affecting the calculated position and time of the receiver. We study how the DD attacks affect the bit error rate (BER) of the received signals at the victim, and analyze its effectiveness, that is, the ability to shorten pseudorange measurements, on different GNSS signals. Several approaches are considered for the attacker to mount a DD attack with high probability of success (without being detected) against a victim receiver, for cryptographically unprotected and protected signals. We analyze the tracking output of the DD signals at the victim receiver and propose a Goodness of Fit (GoF) test and a Generalized Likelihood Ratio Test (GLRT) to detect the attacks. The evaluation of the two tests shows that they are effective, with the result being perhaps more interesting when considering DD attacks against Galileo signals that can be cryptographically protected.       

    Moreover, this thesis investigates the feasibility of validating the authenticity of the GNSS signals with the help of opportunistic signals, which is information readily available in modern communication environments, e.g., 3G, 4G and WiFi. We analyze the time synchronization accuracy of different technologies, e.g., Network Time Protocol (NTP), WiFi and local oscillator, as the basis for detecting a discrepancy with the GNSS-obtained time. Two detection approaches are proposed and one testbench is designed for the evaluation. A synthesized spoofing attack is used to verify the effectiveness of the approaches.       

    Beyond attack detection, we develop algorithms to detect and exclude faulty signals, namely the Clustering-based Solution Separation Algorithm (CSSA) and the Fast Multiple Fault Detection and Exclusion (FM-FDE). They both utilize the redundant available satellites, more than the minimum a GNSS receiver needs for position and time offset calculation. CSSA adopts data clustering to group subsets of positions calculated with different subsets of available satellites. Basically, these positions, calculated with subsets not containing any faulty satellites, should be close to each other, i.e., in a dense area; otherwise they should be scattered. FM-FDE is a more efficient algorithm that uses distances between positions, calculated with fixed-size subsets, as test statistics to detect and exclude faulty satellite signals. As the results show, FM-FDE runs faster than CSSA and other solution-separation fault detection and exclusion algorithms while remaining equally effective.

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  • 1206.
    Zhang, Kewei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Larsson, Erik G.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Protecting GNSS Open Service-Navigation Message Authentication against Distance-Decreasing AttacksManuscript (preprint) (Other academic)
    Abstract [en]

    As the security of global navigation satellite systems (GNSS) for civilian usage is increasingly important, navigation message authentication (NMA) significantly improves resilience to spoofing attacks. However, not all attacks can be effectively countered: a strong variant of replay/relay attacks, distance-decreasing (DD) attacks, can shorten pseudorange measurements, without manipulating the cryptographically protected navigation message, thus manipulating the position, velocity, and time solution undetected. First, we discuss how DD attacks can tamper with GNSS signals, demonstrating the attack effectiveness on a recorded Galileo signal. DD attacks might introduce bit errors to the forged signals, but the adversary can keep this error rate very low with proper attack parameter settings. Then, based on our mathematical model of the prompt correlator output of the tracking phase at the victim receiver, we find that the correlator output distribution changes in the presence of DD attacks. This leads us to apply hypothesis testing to detect DD attacks, notably a Goodness of Fit (GoF) test and a generalized likelihood ratio test (GLRT), depending on the victim’s knowledge on the DD attacks. Monte Carlo simulations are used to evaluate the detection probability and the receiver operating characteristic (ROC) curves for two tests, for different adversary configuration and noise settings. Then, we evaluate the effectiveness of the GoF and GLRT tests with a synthesized DD signal. Both tests can detect DD attacks with similar performance in high signal-to-noise ratio (SNR) environments. The GLRT detection probability is approximately 20% higher than that of the GoF test in low SNR environments.

  • 1207.
    Zhang, Kuize
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Zhang, L.
    School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an, China.
    Xie, L.
    School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
    Detectability of labeled petri nets2020In: Communications and Control Engineering, Springer International Publishing , 2020, p. 195-209Chapter in book (Refereed)
    Abstract [en]

    In Chap. 9, we studied the verification and complexity problem of the notions of strong detectability and weak detectability for finite-state automata. In this chapter, we characterize these notions for labeled Petri nets (see Sect. 2.4).

  • 1208.
    Zhang, Mengmeng
    et al.
    Airinnova AB, Stockholm, Sweden.
    Gong, Jing
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for High Performance Computing, PDC.
    Axner, Lilit
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for High Performance Computing, PDC.
    Barth, Michaela
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for High Performance Computing, PDC.
    Automation of High-Fidelity CFD Analysis for Aircraft Design and Optimization Aided by HPC2020In: Proceeding of 28th Euromicro International Conference on Parallel, Distributed and Network-Based Processing (PDP), Institute of Electrical and Electronics Engineers (IEEE) , 2020, p. 395-399Conference paper (Refereed)
    Abstract [en]

    In this paper, an automation process to perform Reynolds-Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) analysis is developed to carry out aerodynamic design and optimization. The aircraft model/geometry is defined by a Common Parametric Aircraft Configuration Schema (CPACS) file, and the analyses are facilitated using high performance computers (HPC). As the computational capability of the available HPC systems is a limiting factor in the complexity of analyses that can be performed, a detailed performance analysis of the open source CFD code SU2 is undertaken and the profiling and performance analyses for large simulations are carried out.

  • 1209.
    Zhang, Silun
    et al.
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory. Harbin Institute of Technology, China.
    He, F.
    Yao, Y.
    Hu, Xiaoming
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Spherical formation of regular tetrahedra2017In: 2017 36th Chinese Control Conference, CCC, IEEE Computer Society, 2017, p. 1317-1322, article id 8027533Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the problem of tracking and encircling a moving target by agents in the 3-dimensional space. Specifically, a group of agents are driven to a regular tetrahedron formation on a spherical surface and simultaneously keep the center of this spherical formation coinciding with the target to be tracked. In the proposed method, to avoid the singularity caused by spherical parameterisations in control, we directly consider the spherical formation in space S2. Besides, the protocol proposed does not contain any information of the desired formation beforehand. Rather the constructed formation pattern is attributed to the properties of space S2 and the inter-agent topology.

  • 1210. Zhang, Weiqing
    et al.
    Møller-Pedersen, Birger
    Biehl, Matthias
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    A light-weight tool integration approach: From a tool integration model to OSLC integration services2012In: ICSOFT 2012 - Proceedings of the 7th International Conference on Software Paradigm Trends, 2012, p. 137-146Conference paper (Refereed)
    Abstract [en]

    Existing tool integration approaches integrate various tools directly through tool proprietary APIs. This kind of integration lacks standardization and are different case by case. Integration based upon common tool metamodels also turns to be too complicated and hard to maintain. In this paper we provide an approach which integrates tools based on a combination of tool metamodels and an integration model. Tool element representatives (Artifacts) are defined to make integrations more standardized and flexible compared to direct tool APIs. The approach links the tool integration model to the various tool metamodels, and provides mechanism by which the common integration properties and the various tool metamodels are related. An industrial case study has been performed to validate the approach with both scenarios of traceability and exchange of data based upon common data definitions.

  • 1211.
    Zhang, Xinhai
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Tao, Jianbo
    Power Train Engineering, AVL List GmbH, 118506 Graz, Styria, Austria.
    Tan, Kaige
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Törngren, Martin
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Gaspar Sánchez, José Manuel
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Ramli, Muhammad Rusyadi
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Xin, Tao
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Gyllenhammar, Magnus
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Wotawa, Franz
    Institute for Software Technology, TU Graz, Graz, Styria, Austria, 8010.
    Mohan, Naveen
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Nica, Mihai
    Power Train Engineering, AVL Graz GmbH, Graz, Styria, Austria.
    Felbinger, Hermann
    Power Train Engineering, AVL List GmbH, 118506 Graz, Styria, Austria.
    Finding Critical Scenarios for Automated Driving Systems: A Systematic Mapping Study2022In: IEEE Transactions on Software Engineering, ISSN 0098-5589, E-ISSN 1939-3520, p. 1-1Article in journal (Refereed)
    Abstract [en]

    Scenario-based approaches have been receiving a huge amount of attention in research and engineering of automated driving systems. Due to the complexity and uncertainty of the driving environment, and the complexity of the driving task itself, the number of possible driving scenarios that an Automated Driving System or Advanced Driving-Assistance System may encounter is virtually infinite. Therefore it is essential to be able to reason about the identification of scenarios and in particular critical ones that may impose unacceptable risk if not considered. Critical scenarios are particularly important to support design, verification and validation efforts, and as a basis for a safety case. In this paper, we present the results of a systematic mapping study in the context of autonomous driving. The main contributions are: (i) introducing a comprehensive taxonomy for critical scenario identification methods; (ii) giving an overview of the state-of-the-art research based on the taxonomy encompassing 86 papers between 2017 and 2020; and (iii) identifying open issues and directions for further research. The provided taxonomy comprises three main perspectives encompassing the problem definition (the why), the solution (the methods to derive scenarios), and the assessment of the established scenarios. In addition, we discuss open research issues considering the perspectives of coverage, practicability, and scenario space explosion.

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  • 1212.
    Zhao, Xin
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Language-based Approaches to Safe and Efficient Distributed Programming2021Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Distributed systems address the increasing demand for fast access to resources and fault tolerance for data. Strong consistency ensures that all clients observe consistent data updates atomically on all servers in a distributed system, and it is widely used in systems such as relational databases. However, such systems need to sacrifice availability when synchronization occurs. Due to scalability requirements, software developers need to trade consistency for performance, which introduces new challenges. First, there is a lack of comprehensive understanding of how to choose a suitable consistency model. Second, consistency guarantees for specific data may be weakened if the application correctness is unaffected, but it is hard to reason the safety of mixed usage of weakly and strongly consistent data. Third, for an operation sequence such as a transaction, the co-existence of mixed consistency data complicates the reasoning about the implementation correctness.

    This thesis explores how to aid distributed program developers of mixed consistency systems through language-based approaches. First, we propose a new consistency protocol, the observable atomic consistency protocol (OACP), to make write-dominant applications as fast as possible and as consistent as needed. OACP combines the advantages of (1) mergeable data types, specifically, convergent replicated data types, to reduce synchronization and (2) reliable total order broadcast, to provide on-demand strong consistency. We also provide a high-level programming interface to improve the efficiency and correctness of distributed programming.

    Second, we propose lattice-based consistency types for replicated data (CTRD), a higher-order static consistency-typed language with replicated data types. The type system of CTRD supports shared data among multiple clients and statically enforces noninterference between data types with weaker consistency and data types with stronger consistency. The language can be applied to many distributed applications and guarantees that weakly-consistent data updates can never affect strongly-consistent data. 

    Finally, we propose a type-based approach for statically verifying transaction correctness. A standard property for correctness is serializability, which means that the actual execution of transactions is equivalent to a corresponding serial execution with equivalent behavior in which the instructions of each transaction are not interleaved with instructions from other transactions.  We formalize an information-flow type system, SerialT, to keep track of data consistency levels and use the noninterference between consistent and available data to postpone available operations within a transaction. Moreover, we use location information generated from type checking to enforce serializability properties for transactions, and we also introduce two additional commutative operations to reduce unnecessary locks.

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  • 1213.
    Zojaji, Sahba
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Matviienko, Andrii
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Leite, Iolanda
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Robotics, Perception and Learning, RPL.
    Peters, Christopher
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Join Me Here if You Will: Investigating Embodiment and Politeness Behaviors When Joining Small Groups of Humans, Robots, and Virtual Characters2024Conference paper (Refereed)
    Abstract [en]

    Politeness and embodiment are pivotal elements in Human-Agent Interactions. While many previous works advocate the positive role of embodiment in enhancing Human-Agent Interactions, it remains unclear how embodiment and politeness affect individuals joining groups. In this paper, we explore how polite behaviors (verbal and nonverbal) exhibited by three distinct embodiments (humans, robots, and virtual characters) influence individuals' decisions to join a group of two agents in a controlled experiment (N=54). We assessed agent effectiveness regarding persuasiveness, perceived politeness, and participants' trajectories when joining the group. We found that embodiment does not significantly impact agent persuasiveness and perceived politeness, but polite behaviors do. Direct and explicit politeness strategies have a higher success rate in persuading participants to join at the furthest side. Lastly, participants adhered to social norms when joining at the furthest side, maintained a greater physical distance from humans, chose longer paths, and walked faster when interacting with humans.

  • 1214.
    Zojaji, Sahba
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Peters, Christopher
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Towards Virtual Agents for Supporting Appropriate Small Group Behaviors in Educational Contexts2019In: Proceedings of the 11th International Conference on Virtual Worlds and Games for Serious Applications, 2019Conference paper (Refereed)
    Abstract [en]

    Verbal and non-verbal behaviors that we use in order to effectively communicate with other people are vital for our success in our daily lives. Despite the importance of social skills, creating standardized methods for training them and supporting their training is challenging. Information and Communications Technology (ICT) may have a good potential to support social and emotional learning (SEL) through virtual social demonstration games. This paper presents initial work involving the design of a pedagogical scenario to facilitate teaching of socially appropriate and inappropriate behaviors when entering and standing in a small group of people, a common occurrence in collaborative social situations. This is achieved through the use of virtual characters and, initially, virtual reality (VR) environments for supporting situated learning in multiple contexts. We describe work done thus far on the demonstrator scenario and anticipated potentials, pitfalls and challenges involved in the approach.

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  • 1215.
    Zou, Zhuo
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    Impulse Radio UWB for the Internet-of-Things: A Study on UHF/UWB Hybrid Solution2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation investigates Ultra-Wideband (UWB) techniques for the next generation Radio Frequency Identification (RFID) towards the Internet-of-Things (IoT). In particular, an ultra-high frequency (UHF) wireless-powered UWB radio (UHF/UWB hybrid) with asymmetric links is explored from system architecture to circuit implementation.

    Context-aware, location-aware, and energy-aware computing for the IoT demands future micro-devices (e.g., RFID tags) with capabilities of sensing, processing, communication, and positioning, which can be integrated into everyday objects including paper documents, as well as food and pharmaceutical packages. To this end, reliable-operating and maintenance-free wireless networks with low-power and low-cost radio transceivers are essential. In this context, state-of-the-art passive RFID technologies provide limited data rate and positioning accuracy, whereas active radios suffer from high complexity and power-hungry transceivers. Impulse Radio UWB (IR-UWB) exhibits significant advantages that are expected to overcome these limitations. Wideband signals offer robust communications and high-precision positioning; duty-cycled operations allow link scalability; and baseband-like architecture facilitates extremely simple and low-power transmitters. However, the implementation of the IR-UWB receiver is still power-hungry and complex, and thus is unacceptable for self-powered or passive tags.

    To cope with μW level power budget in wireless-powered systems, this dissertation proposes an UHF/UWB hybrid radio architecture with asymmetric links. It combines the passive UHF RFID and the IR-UWB transmitter. In the downlink (reader-tag), the tag is powered and controlled by UHF signals as conventional passive UHF tags, whereas it uses an IR-UWB transmitter to send data for a short time at a high rate in the uplink (tag-reader). Such an innovative architecture takes advantage of UWB transmissions, while the tag avoids the complex UWB receiver by shifting the burden to the reader. A wireless-powered tag providing -18.5 dBm sensitivity UHF downlink and 10 Mb/s UWB uplink is implemented in 180 nm CMOS. At the reader side, a non-coherent energy detection IR-UWB receiver is designed to pair the tag. The receiver is featured by high energy-efficiency and flexibility that supports multi-mode operations. A novel synchronization scheme based on the energy offset is suggested. It allows fast synchronization between the reader and tags, without increasing the hardware complexity. Time-of-Arrival (TOA) estimation schemes are analyzed and developed for the reader, which enables tag localization. The receiver prototype is fabricated in 90 nm CMOS with 16.3 mW power consumption and -79 dBm sensitivity at 10 Mb/s data rate. The system concept is verified by the link measurement between the tag and the reader. Compared with current passive UHF RFID systems, the UHF/UWB hybrid solution provides an order of magnitude improvement in terms of the data rate and positioning accuracy brought by the IR-UWB uplink.

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  • 1216.
    Åkerberg, Mathias
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Tibbling, Anders
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Säker identitetshantering på internet: Att minimera bedrägerier och öka konsumentens säkerhet och inflytande vid e-handel2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There's a high risk that an unauthorized party can gain access to and use a consumer's iden-tity. This while the ability to control how and when a personal identity is used is small. The question to be answered were regarding how identity theft and online fraud could be mi-nimized and give the consumers a greater influence and more control over the management of their identity online.

    The goal was to centralize and establish a common approach for identity management on-line, with greater benefits for consumers. Through central service individual consumers would be able to set conditions for which online shops and services would be able to access their identities and grant access in each specific transaction. This would remove the need for non-central control of identities and as a result remove the need for independent storage of identity information.

    The solution would result in a system model with the potential to authenticate the consu-mer, managing conditions for how individual identity documents may be used online and to provide the consumer with a online history by sending notifications of events that has occurred with regard to a specific identity.

    A prototype was developed to demonstrate the basic functionality in practice. This included the functionality to authenticate the consumer with Mobile BankID, send notifications about events and check existing conditions regarding a specific identity. This prototype came to consist of a simplified system according to the model developed, an associated API, and two models representing an online store and a payment provider that would utilize the functionality of the system by calling the API.

    The proposed solution was evaluated through two interviews with experts in the fields of IT Security and e-commerce. The conclusion was that identity fraud would probably drop drastically and the individual consumer influence and awareness would be fortified. The main reason for this was considered to be primarily through the consistent and standardized way for authentication of and communication with the consumer. This would remove the individual risk for online services.

    The challenge with this proposed solution is believed to be getting consumers, online re-tailers and payment providers to accept a central solution instead of relying on internally developed and disconnected solution.

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    Säker identietshantering på internet
  • 1217. Åxeland, A.
    et al.
    Hagfeldt, H.
    Carlsson, M.
    Sergel, L. L.
    Butun, Ismail
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering. Chalmers University of Technology, Sweden & Konya Food and Agriculture University, Turkey .
    Implications of cybersecurity breaches in LPWANs2021In: Decision Support Systems and Industrial IoT in Smart Grid, Factories, and Cities, IGI Global , 2021, p. 1-18Chapter in book (Other academic)
    Abstract [en]

    With the contrast of limited performance and big responsibility of IoT devices, potential security breaches can have serious impacts in means of safety and privacy. Potential consequences of attacks on IoT devices could be leakage of individuals daily habits and political decisions being influenced. While the consequences might not be avoidable in their entirety, adequate knowledge is a fundamental part of realizing the importance of IoT security and during the assessment of damages following a breach. This chapter will focus on two low-powered wide area network (LPWAN) technologies, narrow-band iot (NB-IoT) and long-range wide area network (LoRaWAN). Further, three use cases will be considered-healthcare, smart cities, and industry-which all to some degree rely on IoT devices. It is shown that with enough knowledge of possible attacks and their corresponding implications, more secure IoT systems can be developed. 

  • 1218.
    Öberg, Johnny
    et al.
    KTH, Superseded Departments (pre-2005), Electronic Systems Design.
    Düring, Morgan
    Millberg, Mikael
    Evaluating the Efficacy of utilizing a Protocol Grammar for Modeling of a Processor Architecture: A Case Study2002In: Proceedings of NORCHIP, 2002, p. 309-315Conference paper (Refereed)
  • 1219.
    Öberg, Johnny
    et al.
    KTH, Superseded Departments (pre-2005), Electronic Systems Design.
    Eles, Petru
    Linköpings Tekniska Högskola.
    Hemani, Ahmed
    KTH, Superseded Departments (pre-2005), Electronic Systems Design.
    Kuchcinski, Krzystof
    Linköpings Tekniska Högskola.
    Peng, Zebo
    Linköpings Tekniska Högskola.
    Specifying Local Timing Constraints in VHDL for HLS of Digital Systems1995In: Proceedings of the 6th Swedish Workshop on Copmuter System Architecture, 1995Conference paper (Refereed)
  • 1220.
    Öberg, Johnny
    et al.
    KTH, Superseded Departments (pre-2005), Electronic Systems Design.
    Ellervee, Johnny
    Revolver: A high-performance MIMD architecture for collision free computing1998Conference paper (Refereed)
  • 1221.
    Öberg, Johnny
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    Ellervee, Peeter
    Kumar, Anshul
    Hemani, Ahmed
    Comparing Conventional HLS with Grammar-Based Hardware Synthesis: A Case Study1997Conference paper (Refereed)
  • 1222.
    Öberg, Johnny
    et al.
    KTH, Superseded Departments (pre-2005), Electronic Systems Design.
    Ellervee, Peeter
    Mokhtari, Mehran
    Jantsch, Axel
    SpaceBall-1G: A 32-bit 1 GIPS Peak Performance MIMD CPU Targeted for GaAs1995Report (Other academic)
  • 1223.
    Öberg, Johnny
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    Robino, Francesco
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    A NoC Generator for the Sea-of-Cores Era2011In: Proceedings of FPGAWorld 2011, 2011Conference paper (Refereed)
  • 1224.
    Östman, Alexander
    KTH, School of Computer Science and Communication (CSC).
    Distributed Dominant Resource Fairness using Gradient Overlay2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Resource management is an important component in many distributed clusters. A resource manager handles which server a task should run on and which user’s task that should be allocated. If a system has multiple users with similar demands, all users should have an equal share of the cluster, making the system fair. This is typically done today using a centralized server which has full knowledge of all servers in the cluster and the different users. Having a centralized server brings problems such as single point of failure, and vertical scaling on the resource manager.

    This thesis focuses on fairness for users during task allocation with a decentralized resource manager. A solution called, Parallel Distributed Gradient-based Dominant Resource Fairness, is proposed. It allows servers to handle a subset of users and to allocate tasks in parallel, while maintaining fairness results close to a centralized server. The solution utilizes a gradient network topology overlay to sort the servers based on their users’ current usage and allows a server to know if it has the user with the currently lowest resource usage.

    The solution is compared to pre-existing solutions, based on fairness and allocation time. The results show that the solution is more fair than the pre-existing solutions based on the gini-coefficient. The results also show that the allocation time scales based on the number of users in the cluster because it allows more parallel allocations by the servers. It does not scale as well though as existing distributed solutions. With 40 users and over 100 servers the solution has an equal time to a centralized solution and outperforms a centralized solution with more users.

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    fulltext
  • 1225.
    Özkahraman, Özer
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Robotics, Perception and Learning, RPL.
    Ögren, Petter
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory. KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Robotics, Perception and Learning, RPL.
    Collaborative Navigation-Aware Coverage in Feature-Poor Environments2022In: International Conference on Intelligent Robots and Systems (IROS), 2022, 2022Conference paper (Refereed)
    Abstract [en]

    Multi agent coverage and robot navigation are two very important research fields within robotics. However, their intersection has received limited attention. In multi agent coverage, perfect navigation is often assumed, and in robot navigation,  the focus is often to minimize the localization error with the aid of stationary features from the environment.The need for integration of the two becomes clear in environments with very sparse features or landmarks, for example when a group of Autonomous Underwater Vehicles (AUVs) are to search a uniform seafloor for mines or other dangerous objects.In such environments, localization systems are often deprived of detectable features to use that could increase their accuracy.In this paper we propose an algorithm for doing navigation aware multi agent coverage in areas with no landmarks.Instead of using identical lawn mower patterns, we propose to mirror every other pattern to enable the agents to meet up and makeinter-agent measurements and share information regularly. This improves performance in two ways,global drift in relation to the area to be covered is reduced, and local coverage gaps between adjacent patterns are reduced.Further, we show that this can be accomplished within the constraints of very limited sensing, computing and communication resources that most AUVs have available.The effectiveness of our method is shown through statistically significant simulated experiments.

    Download full text (pdf)
    fulltext
22232425 1201 - 1225 of 1225
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