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  • 46501.
    Yu, Kan
    et al.
    Mälardalens Högskola.
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Åkerberg, Johan
    ABB Corporate Research.
    Björkman, Mats
    Mälardalens Högskola.
    Reliable Real-time Routing Protocol for Industrial Wireless Sensor and Actuator Networks2013Konferensbidrag (Refereegranskat)
  • 46502.
    Yu, Kan
    et al.
    Mälardalens Högskola.
    Gidlund, Mikael
    ABB Corporate Research.
    Åkerberg, Johan
    ABB Corporate Research.
    Björkman, Mats
    Reliable RSS-based Routing Protocol for Industrial Wireless Sensor Networks2012Ingår i: 38th Annual Conference of the IEEE Industrial Electronics Society, (IECON'12), Montreal, Canada, Oct. 2012., 2012, 3231-3237 s.Konferensbidrag (Refereegranskat)
  • 46503.
    Yu, Kan
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Pang, ZB
    Corp Res, ABB AB, Sweden.
    Gidlund, M
    Corp Res, ABB AB, Sweden.
    Åkerberg, Johan
    Corp Res, ABB AB, Sweden.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    REALFLOW: Reliable Real-Time Flooding-Based Routing Protocol for Industrial Wireless Sensor Networks2014Ingår i: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, art. nbr: 936379- s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wireless technologies have been increasingly applied in industrial automation systems due to flexible installation, mobility, and cost reduction. Unlike traditional wireless sensor networks (WSNs), industrial wireless sensor networks (IWSNs), when expanding from wireless monitoring to wireless control, have more stringent requirements on reliability, real-time performance, and robustness in a number of industrial applications. Successive transmission failures or deadline misses in these applications may severely degrade the control quality and result in serious economic losses and safety problems. Therefore, when deploying IWSNs in harsh industrial environments, to achieve reliable and deterministic end-to-end transmissions is critically important. In this paper, we explain the primary challenges of designing appropriate routing protocols and present a reliable real-time flooding-based routing protocol for IWSNs (REALFLOW). Instead of traditional routing tables, related node lists are generated in a simple distributed manner, serving for packet forwarding. A controlled flooding mechanism is applied to improve both reliability and real-time performance. A seamless transition in the event of topology change can be achieved by REALFLOW. Performance evaluations via simulations verify that significant improvements of reliability, real-time performance, and network recovery time can be achieved by REALFLOW, compared with traditional routing protocols.

  • 46504.
    Yu, Kan
    et al.
    Mälardalen University.
    Pang, Zhibo
    ABB Corporate Research, Sweden.
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Åkerberg, Johan
    ABB Corporate Research, Sweden.
    Björkman, Mats
    Mälardalen University.
    REALFLOW: Reliable Real-Time Flooding-Based Routing Protocol for Industrial Wireless Sensor Networks2014Ingår i: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, Vol. 2014, nr Article ID 936379, 1-17 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wireless technologies have been increasingly applied in industrial automation systems due to flexible installation, mobility, and cost reduction. Unlike traditional wireless sensor networks (WSNs), industrial wireless sensor networks (IWSNs), when expanding from wireless monitoring to wireless control, have more stringent requirements on reliability, real-time performance, and robustness in a number of industrial applications. Successive transmission failures or deadline misses in these applications may severely degrade the control quality and result in serious economic losses and safety problems. Therefore, when deploying IWSNs in harsh industrial environments, to achieve reliable and deterministic end-to-end transmissions is critically important. In this paper, we explain the primary challenges of designing appropriate routing protocols and present a reliable real-time flooding-based routing protocol for IWSNs (REALFLOW). Instead of traditional routing tables, related node lists are generated in a simple distributed manner, serving for packet forwarding. A controlled flooding mechanism is applied to improve both reliability and real-time performance. A seamless transition in the event of topology change can be achieved by REALFLOW. Performance evaluations via simulations verify that significant improvements of reliability, real-time performance, and network recovery time can be achieved by REALFLOW, compared with traditional routing protocols.

  • 46505.
    Yu, Li
    et al.
    Högskolan Kristianstad, Sektionen för Hälsa och Samhälle.
    Zhao, Sibin
    Högskolan Kristianstad, Sektionen för Hälsa och Samhälle.
    Design and implementation of an e-healthcare subsystem for chronic renal failure patients2009Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This degree project deals with the analysis, design and implementation of an e-healthcare subsystem. The subsystem is a prototype for the patients in the chronic renal failure unit. The main purpose of this project is to make research on information and communication technology (ICT) applied on health care system and data presentation. The expected result is that a worked e-healthcare subsystem is implemented to demonstrate the application of modern ICT, and a good foundation for applying for new e-healthcare projects.

  • 46506.
    Yu, WeiBin
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för datavetenskap (DV).
    Optimization of Component Placement within a Control Cabinet using Simulated Annealing2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    We aim to prove whether if Simulated Annealing algorithm and Pareto Simulated Annealing are suitable for handle cabinet’s component placement optimization problem and which parameters (e.g. start temperature, optimization objective) for SA and PSA are most appropriate for this problem. The objectives are to minimize total wire length and heat level of placement. We present prototype programs, which automatically generates optimal component placement for customized cabinets with extracted component and wire information from a .csv file. Then test these programs with different parameters to determine which is most suitable. The search space could be ridiculously large, that is why the cost function for the single objective is optimized using SA, and optimization of multi-objective cost function uses PSA. We demonstrate the usefulness of our approach with a set of examples. To the best of our knowledge, this is the first attempt to address the multi-objective optimization of component placement within a control cabinet.

  • 46507.
    Yu, Xingang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Chung, Il-Sug
    Mork, Jesper
    Xiang, Yu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Single-mode InGaAs/GaAs 1.3-mu m VCSELs Based on a Shallow Intracavity Patterning2010Ingår i: SEMICONDUCTOR LASERS AND LASER DYNAMICS IV / [ed] Panajotov, K; Sciamanna, M; Valle, AA; Michalzik, R, 2010, Vol. 7720, 772021- s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    A high-power single-mode 1.3-mu m InGaAs/GaAs vertical-cavity surface-emitting laser (VCSEL) structure employing a novel concept of engineering the optical mode profile to match the gain profile is suggested and demonstrated experimentally and theoretically. In contrast to various singlemode VCSEL approaches reported in the literature so far, based on selective loss or anti-resonant effects to suppress higher order modes, it is due to a novel design to increase the active region size while maintaining single mode emission. The shape of the fundamental mode profile is engineered to be similar to the gain profile which resembles a doughnut shape especially in intra-cavity contacted devices. In this way, the fundamental mode with the best fit to the gain profile can reach the lasing condition earliest and consume all the optical gain, leading to a suppression of higher order modes. Notably, despite this engineered shape of the mode profile, the far field shape remains close to Gaussian. The mode shaping can be achieved by introducing a shallow intracavity patterning before depositing the top mirror. Fabricated device structures consist of a A-Si/SiN/SiO(2) top mirror, modulation-doped current spreading layers, re-grown current confinement layers, three InGaAs/GaAs quantum wells, and a GaAs/AlGaAs bottom mirror. Single mode operation is demonstrated even for devices with active region as large as 10 mu m.

  • 46508.
    Yu, Xixun
    et al.
    The State Key Laboratory on Integrated Services Networks, School of Cyber Engineering, Xidian University, Xi’an.
    Yan, Zheng
    The State Key Laboratory on Integrated Services Networks, School of Cyber Engineering, Xidian University, Xi’an.
    Vasilakos, Athanasios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Survey of Verifiable Computation2017Ingår i: Mobile Networks and Applications, ISSN 1383-469X, Vol. 22, nr 3, 438-453 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Internet of Things (IoT) has taken place to motivate various intelligent applications with the data collected by the things”. Meanwhile, Cloud computing offers an efficient and convenient way to store, process and analyze huge amount of data. Because a Cloud Service Provider (CSP) that is employed to store and process user private data is actually not in the trust domains of cloud users, data security becomes a serious issue in cloud computing. One crucial problem in cloud is the cloud data processing result may be incorrect, thus cannot be fully trusted. This calls for research to verify the correctness of data processing at the cloud in order to enhance its trustworthiness, especially for encrypted data processing. At present, various cryptosystems have been proposed to achieve verifiability with different characteristics and quality. However, the literature still lacks a thorough survey to review the current state of art in order to get a comprehensive view of this research field, named verifiable computation. In this paper, we review existing work of verifiable computation by comparing and discussing pros and cons according to performance requirements, highlight open research issues through serious review and analysis and propose a number of research directions in order to guide future research

  • 46509.
    Yu, Yiting
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Energy- and Cost-Efficient 5G Networks in Rural Areas2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Energi- och kostnadseffektivitet blir ett kriterium av ständigt ökande betydelse i utformningen av 5G trådlösa lösningar, särskilt för förorts- och landsbygdsområden där den realistiska hinder att ge mobilt bredband ligger i den ekonomiska nackdelen med låg intäktspotential. Således nätverksoperatörer är mycket känsliga för energi och ekonomiska överkomliga till potentiella lösningar i futuristiska 5G trådlöst nätverk.

    I denna avhandling undersöker vi energiprestanda av 5G trådlösa nätverk med två viktiga tekniska komponenter (massiv strålformning och ultra-lean design) i en lantlig miljö för två verkliga fall som nätverksoperatörerna vanligen står inför: (1) uppgraderingar av maskinvara till 5G i befintliga LTE platser (2) 5G greenfield distributioner. Resultaten jämförs med en idag sköts LTE-nät i lantlig miljö.

    Dessutom genomför vi ekonomiska utvärderingar i en studie av energikostnader avvägning på landsbygden scenario att härleda villkoret när de föreslagna energieffektiva 5G lösningar är också kostnadseffektivt. Analysen genomförs separat i två fall på olika metoder.

    Simuleringsresultaten visar att 5G system ger mycket bättre energiprestanda jämfört med LTE system. 5G uppnår en minskning 56 % och 64 % i genomsnittlig daglig område strömförbrukning i hårdvara uppgradering fall och gröna driftsättning fallet respektive. Den betydande besparing kommer främst från den innefattade effekten av strålformning teknik och möjlighet till längre sömn löptider.

    För kostnadseffektivitet, är en hårdvara uppgradering till 5G ekonomiskt mycket motiverade i högre regionerna energi prissättning eller i system med längre sömn löptider. Greenfield distributioner visar analysresultatet att det alltid är kostnadseffektivt att distribuera andra än LTE lösningar på landsbygden 5G lösningar trots variationen i regionala energipriser, nätverk livstid förväntan och DTX faktor i 5G lösningar.

  • 46510.
    Yu, Yong
    et al.
    Big Data Research Center, School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu.
    Xue, Liang
    Department of Computing, The Hong Kong Polytechnic University.
    Au, Man Ho
    Department of Computing, The Hong Kong Polytechnic University.
    Susilo, Willy
    Center for Computer and Information Security Research, School of Computing and Information Technology, University of Wollongong.
    Ni, Jianbin
    Big Data Research Center, School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu.
    Zhang, Yafang
    Big Data Research Center, School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu.
    Vasilakos, Athanasios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Shen, Jian
    School of Computer and Software at Nanjing University of Information Science and Technology, Nanjing.
    Cloud data integrity checking with an identity-based auditing mechanism from RSA2016Ingår i: Future generations computer systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 62, 85-91 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cloud data auditing is extremely essential for securing cloud storage since it enables cloud users to verify the integrity of their outsourced data efficiently. The computation overheads on both the cloud server and the verifier can be significantly reduced by making use of data auditing because there is no necessity to retrieve the entire file but rather just use a spot checking technique. A number of cloud data auditing schemes have been proposed recently, but a majority of the proposals are based on Public Key Infrastructure (PKI). There are some drawbacks in these protocols: (1) It is mandatory to verify the validity of public key certificates before using any public key, which makes the verifier incur expensive computation cost. (2) Complex certificate management makes the whole protocol inefficient. To address the key management issues in cloud data auditing, in this paper, we propose ID-CDIC, an identity-based cloud data integrity checking protocol which can eliminate the complex certificate management in traditional cloud data integrity checking protocols. The proposed concrete construction from RSA signature can support variable-sized file blocks and public auditing. In addition, we provide a formal security model for ID-CDIC and prove the security of our construction under the RSA assumption with large public exponents in the random oracle model. We demonstrate the performance of our proposal by developing a prototype of the protocol. Implementation results show that the proposed ID-CDIC protocol is very practical and adoptable in real life.

  • 46511.
    Yu, Yun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Quantitative Comparison of SensibleThings and ThingsWorx2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Internet of things is a technology innovation which connects thousands of mil- lions of sensors and actuators. Platform is which provides both hardware and software service. There are so many platforms existed in the market. The objective of this study has been to answer the question which IoT platform fits bests for different scenarios by performing a quantitative comparison between SensibleThings and ThingWorx. The study has been conducted with the aid of my su- pervisor Stefan Forsström and professor TingTing Zhang. The study has shown that SensibleThings and ThingWorx both has its innovation features thus it fits to the different cases according to cases’ need. If the sensor need to update data quicker than 25 times/sec, it is better to choose ThingWorx. If the sensor doesn’t have good hardware it is better to use SensibleThings cause it is light- weight enough. For the case that more than one sensors’ data rush into one point simultaneously, ThingWorx has better performance. In this paper I use a health care system as an example. I think ThingWorx is more suitable for this case regard of its mature service on security and graphical visualization. Finally I presented my future work for platform evaluation.

  • 46512.
    Yu, Z
    et al.
    RISE., Swedish ICT, Acreo.
    Djupsjöbacka, A
    RISE., Swedish ICT, Acreo.
    Popov, M
    RISE., Swedish ICT, Acreo.
    Fonjallaz, P-Y
    Direct Detection of Direct Optically Filtered Millimeter-Wave Signals2007Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, nr 4, 233-35 s.Artikel i tidskrift (Refereegranskat)
  • 46513.
    Yu, Z
    et al.
    RISE., Swedish ICT, Acreo.
    Knape, H
    Tarasenko, O
    RISE., Swedish ICT, Acreo.
    Koch, R
    Margulis, W
    RISE., Swedish ICT, Acreo.
    All-fiber single-pulse selection nanosecond gating2009Ingår i: Optics Letters, Vol. 34, nr 7, 1024-26 s.Artikel i tidskrift (Refereegranskat)
  • 46514.
    Yu, Z
    et al.
    RISE., Swedish ICT, Acreo.
    Malmström, M
    Sterner, C
    RISE., Swedish ICT, Acreo.
    Tarasenko, O
    RISE., Swedish ICT, Acreo.
    Margulis, W
    RISE., Swedish ICT, Acreo.
    Fonjallaz, P-Y
    Dynamics of long-period gratings tuned with internal fiber electrodes2011Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 36, nr 5Artikel i tidskrift (Refereegranskat)
  • 46515.
    Yu, Z
    et al.
    RISE., Swedish ICT, Acreo.
    Margulis, W
    RISE., Swedish ICT, Acreo.
    Tarasenko, O
    RISE., Swedish ICT, Acreo.
    Knape, H
    Fonjallaz, P-Y
    Nanosecond switching of fiber Bragg gratings2007Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 15, nr 22, 14948-53 s.Artikel i tidskrift (Refereegranskat)
  • 46516. Yu, Z.
    et al.
    Song, William Wei
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Zheng, X.
    Chen, D.
    Combining trust propagation and topic-level user interest expansion in recommender systems2016Ingår i: International Journal of Web Services Research, ISSN 1545-7362, E-ISSN 1546-5004, Vol. 13, nr 2, 1-19 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the development of E-commerce and Internet, items are becoming more and more, which brings a so called information overload problem that it is hard for users to find the items they would be interested in. Recommender systems emerge to response to this problem through discovering user interest based on their rating information automatically. But the rating information is usually sparse compared to all the possible ratings between users and items. Therefore, it is hard to find out user interest, which is the most important part in recommender systems. In this paper, we propose a recommendation method TT-Rec that employs trust propagation and topic-level user interest expansion to predict user interest. TT-Rec uses a reputation-based method to weight users' influence on other users when propagating trust. TT-Rec also considers discovering user interest by expanding user interest in topic level. In the evaluation, we use three metrics MAE, Coverage and F1 to evaluate TT-Rec through comparative experiments. The experiment results show that TT-Rec recommendation method has a good performance. 

  • 46517.
    Yu, Z
    et al.
    RISE., Swedish ICT, Acreo.
     Tarasenko, O
    RISE., Swedish ICT, Acreo.
    Margulis, W
    RISE., Swedish ICT, Acreo.
    Fonjallaz, P-Y
    Birefringence switching of Bragg gratings in fibers with internal electrodes2008Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 16, nr 11, 8229-35 s.Artikel i tidskrift (Refereegranskat)
  • 46518.
    Yu, Zukun
    et al.
    Zhejiang University.
    Song, William Wei
    Högskolan Dalarna, Akademin Industri och samhälle, Informatik.
    Zheng, Xiaolin
    Zhejiang University.
    Chen, Deren
    Zhejiang University.
    A Recommender System Model Combining Trust with Topic Maps2013Ingår i: World Wide Web: Internet and Web Information Systems: APWeb 2013, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Recommender Systems (RS) aim to suggest users with items that they might like based on users' opinion on items. In practice, information about the users' opinion on items is usually sparse compared to the vast information about users and items. Therefore it is hard to analyze and justify users' favorites, particularly those of cold start users. In this paper, we propose a trust model based on the user trust network, which is composed of the trust relationships among users. We also introduce the widely used conceptual model Topic Map, with which we try to classify items into topics for Recommender analysis. We novelly combine trust relations among users with Topic Maps to resolve the sparsity problem and cold start problem. The evaluation shows our model and method can achieve a good recommendation effect.

  • 46519.
    Yuan, Fang
    et al.
    Applied Informatics, Bielefeld University, 33615 Bielefeld, Germany.
    Swadzba, Agnes
    Applied Informatics, Bielefeld University, 33615 Bielefeld, Germany.
    Philippsen, Roland
    Robotics and Artificial Intelligence Lab., Stanford University, Stanford, 94305, United States.
    Engin, Orhan
    Applied Informatics, Bielefeld University, 33615 Bielefeld, Germany.
    Hanheide, Marc
    Applied Informatics, Bielefeld University, 33615 Bielefeld, Germany.
    Wachsmuth, Sven
    Applied Informatics, Bielefeld University, 33615 Bielefeld, Germany.
    Laser-Based Navigation Enhanced with 3D Time-of-Flight Data2009Ingår i: Robotics and Automation, 2009. ICRA '09. IEEE International Conference on, Washington, DC: IEEE Computer Society, 2009, 2844-2850 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Navigation and obstacle avoidance in robotics using planar laser scans has matured over the last decades. They basically enable robots to penetrate highly dynamic and populated spaces, such as people's home, and move around smoothly. However, in an unconstrained environment the twodimensional perceptual space of a fixed mounted laser is not sufficient to ensure safe navigation. In this paper, we present an approach that pools a fast and reliable motion generation approach with modern 3D capturing techniques using a Timeof-Flight camera. Instead of attempting to implement full 3D motion control, which is computationally more expensive and simply not needed for the targeted scenario of a domestic robot, we introduce a "virtual laser". For the originally solely laserbased motion generation the technique of fusing real laser measurements and 3D point clouds into a continuous data stream is 100% compatible and transparent. The paper covers the general concept, the necessary extrinsic calibration of two very different types of sensors, and exemplarily illustrates the benefit which is to avoid obstacles not being perceivable in the original laser scan.

  • 46520. Yuan, Qilong
    et al.
    Chen, I-Ming
    Lembono, Teguh Santoso
    Landén, Simon Nelson
    KTH, Skolan för industriell teknik och management (ITM).
    Malmgren, Victor
    KTH, Skolan för industriell teknik och management (ITM).
    Strategy for robot motion and path planning in robot taping2016Ingår i: FRONTIERS OF MECHANICAL ENGINEERING, ISSN 2095-0233, Vol. 11, nr 2, 195-203 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Covering objects with masking tapes is a common process for surface protection in processes like spray painting, plasma spraying, shot peening, etc. Manual taping is tedious and takes a lot of effort of the workers. The taping process is a special process which requires correct surface covering strategy and proper attachment of the masking tape for an efficient surface protection. We have introduced an automatic robot taping system consisting of a robot manipulator, a rotating platform, a 3D scanner and specially designed taping end- effectors. This paper mainly talks about the surface covering strategies for different classes of geometries. The methods and corresponding taping tools are introduced for taping of following classes of surfaces: Cylindrical/ extended surfaces, freeform surfaces with no grooves, surfaces with grooves, and rotational symmetrical surfaces. A collision avoidance algorithm is introduced for the robot taping manipulation. With further improvements on segmenting surfaces of taping parts and tape cutting mechanisms, such taping solution with the taping tool and the taping methodology can be combined as a very useful and practical taping package to assist humans in this tedious and time costly work.

  • 46521.
    Yuan, Zhengwu
    et al.
    Chongqing University of Posts and Telecommunications / College of Computer Science and Technology.
    Jiang, Yanli
    Chongqing University of Posts and Telecommunications / College of Computer Science and Technology.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och geoinformatik.
    Geographical and Temporal Similarity Measurement on Location-based Social Networks2013Ingår i: Proceedings of the Second ACM SIGSPATIAL International Workshop on Mobile Geographic Information Systems / [ed] Chi-Yin Chow and Shashi Shekhar, New York, NY, USA: Association for Computing Machinery (ACM), 2013, 30-34 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Using "check-in" data gathered from location-based social networks, this paper proposes to measure the similarity of users by considering the geographical and the temporal aspect of their geographical and temporal aspects of their "check-ins". Temporal neighborhood is added to support the time dimension on the basis of the traditional DBSCAN clustering algorithm, which determines the similarity among users at different scales using the classical Vector Space Model (VSM) with vectors composed of the amount of visits in different cluster area. The spatio-temporal similarity of the user behaviors are obtained through overlapping the different weighted user similarity values. The experimental results show that the proposed approach is effective in measuring user similarity in location-based social networks.

  • 46522. Yuanyuan, Qiao
    et al.
    Zhang, Yanting
    Lindgren, Anders
    RISE., Swedish ICT, SICS, Decisions, Networks and Analytics lab.
    Jie, Yang
    Understanding Online Shopping and Offline Mobility Behavior in Urban Area from the View of Multilayer Network2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    The interactive nature of the Internet offers many opportunities to increase the efficiency of online shopping by improving availability of product information, enabling direct multi-attribute comparisons, and reducing buyer search costs. A great body of research focuses on how consumers shop online or why and how online shopping impacts urban development, but the understanding of mutual influence between online and offline behavior of consumers remains somewhat underserved. This paper bridges that gap by quantifying the relationship between consumers' online shopping and offline mobility behavior. The results of the study give insights to further understand human behavior from both a cyber and real world point of view, which may help to place location based targeted advertisements, and plan commercial & retail centers in urban areas.

  • 46523.
    Yun, Ruida
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Qin, Yajie
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Signell, Svante
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    LMS-based calibration of pipelined ADCs including linear and nonlinear errors2007Ingår i: 2007 European Conference On Circuit Theory And Design: Vols 1-3, 2007, 348-351 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    A least mean square (LMS) based calibration algorithm is proposed to calibrate most known error sources in 1.5 bit/stage pipelined ADCs, known to be immune to moderate comparator offsets. The error sources include linear gain errors, reference voltage errors, systematic offset errors and amplifier non-linear errors of each pipeline stage. LMS is used to estimate the error parameters in the digital domain. After estimation the proposed algorithm calibrate the pipelined ADC using the estimated parameter errors. Simulation results show that the proposed algorithm can improve the ENOB from 6.6 bits to 13.9 bits for a 14 bit 1.5 bits/stage pipelined ADC.

  • 46524.
    Yun, Se-Young
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Proutiere, Alexandre
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Distributed Load Balancing in Heterogenous Systems2014Ingår i: 2014 48TH ANNUAL CONFERENCE ON INFORMATION SCIENCES AND SYSTEMS (CISS), 2014, 6814133- s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    We consider the problem of distributed load balancing in heterogenous parallel server systems, where the service rate achieved by a user at a server depends on both the user and the server. Such heterogeneity typically arises in wireless networks (e.g., servers may represent frequency bands, and the service rate of a user varies across bands). Users select servers in a distributed manner. They initially attach to an arbitrary server. However, at random instants of time, they may probe the load at a new server and migrate there to improve their service rate. We analyze the system dynamics under the natural Random Local Search (RLS) migration scheme, introduced in [5]. Under this scheme, when a user has the opportunity to switch servers, she does it only if this improves her service rate. The dynamics under RLS may be interpreted as those generated by strategic players updating their strategy in a load balancing game. We show that this game has pure Nash Equilibriums (NEs), and we analyze their efficiency. We further prove that when the user population grows large, pure NEs get closer to a Proportionally Fair (PF) allocation of users to servers, and we characterize the gap between equilibriums and this ideal allocation depending on user population. Under the RLS algorithm, the system converges to pure NEs: we study the time it takes for the system to reach the PF allocation within a certain margin.

  • 46525.
    Yun, Seyoung
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Shin, J.
    Yi, Y.
    CSMA over time-varying channels: Optimality, uniqueness and limited backoff rate2013Ingår i: MobiHoc '13 Proceedings of the fourteenth ACM international symposium on Mobile ad hoc networking and computing, ACM Press, 2013, 137-146 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Recent studies on MAC scheduling have shown that carrier sense multiple access (CSMA) algorithms can be throughput optimal for arbitrary wireless network topology. However, these results are highly sensitive to the underlying assumption on 'static' or 'fixed' system conditions. For example, if channel conditions are time-varying, it is unclear how each node can adjust its CSMA parameters, so-called backoff and channel holding times, using its local channel information for the desired high performance. In this paper, we study 'channel-aware' CSMA (A-CSMA) algorithms in time-varying channels, where they adjust their parameters as some function of the current channel capacity. First, we show that the achievable rate region of A-CSMA equals to the maximum rate region if and only if the function is exponential. Furthermore, given an exponential function in ACSMA, we design updating rules for their parameters, which achieve throughput optimality for an arbitrary wireless network topology. They are the first CSMA algorithms in the literature which are proved to be throughput optimal under time-varying channels. Moreover, we also consider the case when back-off rates of A-CSMA are highly restricted compared to the speed of channel variations, and characterize the throughput performance of A-CSMA in terms of the underlying wireless network topology. Our results not only guide a high-performance design on MAC scheduling under highly time-varying scenarios, but also provide new insights on the performance of CSMA algorithms in relation to their backoff rates and underlying network topologies.

  • 46526.
    Yun, Seyoung
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Shin, J.
    Yi, Y.
    CSMA using the Bethe approximation for utility maximization2013Ingår i: IEEE International Symposium on Information Theory: Proceedings, IEEE conference proceedings, 2013, 206-210 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    CSMA (Carrier Sense Multiple Access), which resolves contentions over wireless networks in a fully distributed fashion, has recently gained a lot of attentions since it has been proved that appropriate control of CSMA parameters guarantees optimality in terms of system-wide utility. Most algorithms rely on the popular MCMC (Markov Chain Monte Carlo) technique, which enables one to find optimal CSMA parameters through iterative loops of simulation-and-update. However, such a simulation-based approach often becomes a major cause of exponentially slow convergence, being poorly adaptive to flow/topology changes. In this paper, we develop a distributed iterative algorithm which produces approximate solutions with convergence in polynomial time. Our approach is motivated by a scheme in statistical physics, referred to as the Bethe approximation, allowing us to express approximate solutions via a certain non-linear system with polynomial size. We provide numerical results to show that the algorithm produces highly accurate solutions and converges much faster than prior ones.

  • 46527.
    Yunus, Ender
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    THE ROLE OF SOCIAL MEDIA IN CREATING POLITICAL AWARENESS AND MOBILIZING POLITICAL PROTESTS: A Focus on Turkey2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the recent years, the internet penetration, social media production and consumption have increased dramatically all over the world. This increase has affected the politics in most parts of the world in many ways. Social media became a tool for politicians to carry out their political campaigns and for activists to create awareness on political issues and mobilize protests. Today almost in all social movements in the countries with high rate of internet access, the role of social media is being discussed. Social media has become a costless and extremely effective tool in reaching mass audiences with political purposes.

    This thesis research focuses on the strength of social media in creating political awareness and mobilizing political protests in Turkey. In this study the recent social movements in Turkey are examined as case studies, to understand the role of social media in political movements, to be able to make predictions for the future. The prob-lem was approached with combining qualitative and quantitative research methods. Literature review regarding the subjects related to the social media and politics and information flow in social networks was conducted. After that, two interviews, a sur-vey and a social network analysis to comprehend the role of social media in the two recent major social movements in Turkey, Gezi Parki Protests and Internet Censor-ship Protests, were carried out.

    Depending on the results from research methods conducted, it was found that social media has already become a fundamental part of social movements in Turkey. The young generation in Turkey is extremely interested in joining online social networks. These social networks establish connections between people that are related with weak ties. These connections enable political information to flow on these networks virally, costless and rapidly. Information can be on political news or thoughts to cre-ate political awareness and also to mobilize political protests. These advantages of social media combined with biased and ignorant attitude of mainstream media on po-litical events; social media created an alternative source of information in the eyes of the society. Considering the increasing internet penetration, smart phone and social media use for political purposes, the strength of social media in creating political awareness and mobilizing political protests is expected to rise in the future as well.

  • 46528.
    Yusuf, Adewale
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kreativa teknologier.
    Challenges associated with effective task execution in a Virtual Learning Environment: A case study of Graduate Students of a University2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Context: In recent years, more and more people have started showing an increasing interest in distance or web-based education. Some of the reasons for this are the improvement in information and communication technology, as well as advancement in computer networking infrastructures. However, although computer technology has played an important role for the development of distance learning management systems, the underlying goal of such systems is the delivery of competitive and qualitative education via the distance learning environment. There have been a number of research studies and investigations in the field of Computer supported collaborative learning. This particular study is focused on the challenges associated with task execution in a distance learning environment as perceived by graduate students at a university.

    Objectives: The main focus or rationale behind this study is to investigate the importance of computer mediated communication tools in a virtual learning environment, as well as the problems facing the teachers or facilitators in their attempt to help learners (students) in the process of task execution, and towards achieving the learning goals in a web-based learning system.

    Methods: The author has adopted a qualitative case study approach. Questionnaires were sent out to some of the graduate students of BTH that participated in the online course under investigation, “Work integrated e-learning”, and some of these students were interviewed as well. Interviews were also conducted with two professors of Informatics and active researchers in distributed or e-learning in a University in Sweden that has had many years of experience in providing distance learning education. The empirical material was then analyzed, using cultural historical activity theory (CHAT) as a theoretical framework

    Results: The results indicate that more communication and collaborative interaction is needed in the context of the studied e-learning management system. The students expected the provision of more video communication through the learning platform. Furthermore, the results show that the learning in the studied web-based environment is centered on the students. 

    Conclusions: The author concludes that in order to diminish the gap that exists between face-to-face learning/teaching and an e-learning environment, there is a need for the designers and facilitators of the e-learning management system to make this platform more interactive. Additionally, the author concludes that the concept of Open start free pace (OSFP) or strict deadlines may need to be introduced into distance learning education in order to solve the challenges facing the teachers and facilitators.  

     

  • 46529.
    Yusuf, Adewale
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Lartey, Jerry
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Wareus, Vilhelm
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Network Admission Control (NAC)Securing end point devices2010Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    There have been remarkable growths in wireless communication networks in

    recent years; this is because of its merits over the wired networks such as

    Mobility and convenience. Wireless networks transmit the signal over the

    open air via radio waves of different frequencies, this makes it to be

    vulnerable to several attacks and anybody on the street can easily intercept the

    wireless data or inject new data into the entire network. There has been

    existence of wired equivalent privacy (WEP) protocol (IEEE 802.11i), which

    was designed for wireless network security. There were concerns of security

    vulnerabilities in WEP; this made it necessary for the implementation of

    another solution to overcome the weaknesses of the previous wireless

    network security. The IEEE 802.1X (port-based network admission control)

    which is defined on Extensible Authentication protocol (EAP) provides

    effective and efficient admission control to wireless and other networks

    devices [8].

    Our thesis investigates the efficiency of NAC (IEEE 802.1X) as a security

    solution, access different vendor solutions, protocols supported and look into

    the inter-operability of these various vendors. In as much as we support the

    premise of NAC being an excellent solution, we will also make brilliant

    recommendations in this thesis to be considered for future refinements of this

    security solution as well as deployment scenarios for the university network.

  • 46530.
    Yusuf Isse, Jamila
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Teoretisk datalogi, TCS.
    El Ghouch, Chaimae
    KTH, Skolan för datavetenskap och kommunikation (CSC), Teoretisk datalogi, TCS.
    Information Theoretic Similarity Measures for Robust Image Matching: Multimodal Imaging - Infrared and Visible light2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna studie syftade till att undersöka tillämpligheten av tre olika informationsteoretiska likhetsmått vid matchning av bilder, mutual information (MI), cross cumulative residual entropy (CCRE) och sum of conditional variances (SCV). Ett experiment genomfördes för att bedöma hur de olika likhetsmåtten påverkades i kontexten av multimodalitet, i detta fall i samband med infrarött och synligt ljus. Detta uppnåddes genom att köra simuleringar av fyra olika scenarier med hjälp av bilder tagna i infrarött och synligt ljus, och dessutom med variationer i mängden detaljer för att skapa olika experimentella uppsättningar. Nämligen experimentuppsättning A: unimodala datamängder med mer / mindre detaljer och experimentuppsättning B: multimodala datamängder med mer / mindre detaljer.

     

    Resultatet visade att multimodalitet har en statistiskt signifikant påverkan på alla likhetsmått. Observationer gjordes att likhetsmåttens beteenden, när man försöker matcha bilder med olika mängd detaljer, skilde sig från varandra. Detta gav en grund för bedömning av vilken av dessa likhetsmått som då kunde användas för att ge de mest tydliga och stabila resultaten som möjligt beroende på variationen av mängden detaljer i datat. Med denna studie drogs slutsatsen att likhetsmåttet CCRE gav mest de tydliga och stabila resultaten i samband med multimodalitet gällande infrarött och synligt ljus för båda fallen av mer eller mindre detaljer. Även om de andra likhetsmåtten också gav goda resultat i vissa fall, skulle CCRE vara att rekommendera, som observerat i denna studie.

  • 46531. Yusupov, Roman
    et al.
    Artan, Stefan
    Domain Specific Test Language2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

        Testing is an important part of software development. It ensures that the developed product is of high standard and quality. Tieto frequently develops large complex systems which require comprehensive testing. Testing employs manually designed test cases. According to recent development within software testing it has been shown that design of test cases can be simplified with domain specific test languages (DSTL).

        The thesis project is a research and development study in the field of software testing and has been performed at Tieto office in Karlstad. The project concerns the development of a DSTL and a suitable development environment based on the Eclipse Platform. The project evaluates the development of a domain specific test language using the tools Eclipse JDT, developed by Eclipse Foundation, and Xtext, developed by itemis AG. The experiment was evaluated by its functionality and integrability.

        The project has shown promise in using a domain specific test language with a suitable development environment. The result and evaluation have shown that the subject shows promise, but needs further development if it is to be adapted within Tieto´s organization.

  • 46532.
    Yılmazer, Şafak Enes
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Integrated Coverage Measurement and Analysis System for Outdoor Coverage WLAN2011Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Daily usage of Wireless Local Area Networks (WLAN) in business life for specific purposes has became much more critical than before since it is sometimes crucial to have wireless connectivity and seamless roaming around the working environment. In this thesis, steps required in order to design and implement a large scale outdoor IEEE 802.11g WLAN will be shown. This WLAN project has been deployed in north of Sweden and target coverage was an open area consisting of a deep pit mine, connecting roads, workshops, offices, dumps and storage areas. All telecommunications equipment used in this project is from the manufacturer Cisco using centralized solution. The special purpose of this project is to collect and analyze a series of coverage measurement data and correlate this data to predict the coverage area. Linux bash scripting and Gnuplot has been used to analyze coverage data. Finally, WRAP spectrum management and radio planning software has been used in modeling and designing of the whole network.

  • 46533.
    Zaar, Oskar
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    Interaktionsdesign och UX under utvecklingen av ett pressinfosystem2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Jag har arbetat med framtagningen av ett nytt pressinfosystem till SVT. Framförallt har jag undersökt hur man kan gå till väga när man arbetar arbetarcentrerat med interaktionsdesign. Processen har gått igenom flera steg, från att identifiera användargrupper och följa deras väg över webbplatsen till att identifiera nyckelfunktioner och kritiska sidor. Därefter har en design för sidan tagits fram, testats och delvis implementerats. Processen har gjort att jag har fått en tydligare bild av några best practices och testmetoder samt en fördjupad förståelse för hur arbetet med att ta fram interaktiva produkter kan se ut.

  • 46534.
    Zaar, Oskar
    et al.
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    Sörlin, Anton
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    ”Out of sight, out of mind”: En studie av svenska bokbloggares inställningar till e-boken2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    There are experiential products that through a digital transformation wholly or partially have taken new place in our everyday lives. Just a few years ago, we had music on CDs, movies on tape and books in bookshelves. In Sweden, we are now facing a transformation when the e-book begins to take place alongside the printed book.

    This paper focuses on what values play a role in the attitude towards ebooks among a selected group of Swedish book bloggers. A qualitative content analysis was performed on blog posts concerning the ebook from twelve different Swedish book blogs. The posts were then coded into categories and values. We found five broad categories in which value was displayed; Ownership, Availability, Price, Ergonomics and Environment. These could in turn be linked to two basic ways to give value to ebooks and reading, through its Utilitarian and Experiential value. The findings suggest that Availability was the one most important to the bloggers.  We also found that most posts took place within two discourses - Technology Dissatisfaction and Technology Fear. Technology Dissatisfaction was more frequent and strongly linked to the construction of the e-book and the technical systems that are available today.

  • 46535. Zabel, T
    et al.
    Reuterskiöld Hedlund, C
    Gustafsson, O
    Karim, A
    Berggren, J
    Wang, Q
    RISE., Swedish ICT, Acreo.
    Ernerheim-Jokumsen, C
    Soldemo, M
    Weissenrieder, J
    Götelid, M
    Hammar, M
    Auger recombination in In(Ga)Sb/InAs quantum dots2015Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, 13103- s.Artikel i tidskrift (Refereegranskat)
  • 46536.
    Zabramski, Stanislaw
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    A Hindrance or an Aid?: The Impact of User Interface on Ideation in Computer-Mediated Drawing2014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Users’ performance in ideation during computer-mediated creative drawing can be affected by the design of a computer’s User Interface (UI). This paper presents results from a series of empirical comparative studies in which participants were presented with a creative drawing task and their ideation performance was measured in terms of the number and quality of ideas created with the use of three different input methods (mouse, stylus-, and touch-input), or two graphical UIs (GUIs). The results showed no significant differences between the different computer input methods, or between the simple and more complex GUI. However, when present in combination, these test conditions can be expected to create cumulative effects, which might explain the substantial differences observed in previous research on computerized creative drawing tasks. Quality-quantity trade-off and a new form of operational bias were observed and their effects on user satisfaction and ideation performance are discussed.

  • 46537.
    Zabramski, Stanislaw
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Careless touch: a comparative evaluation of mouse, pen, and touch input in shape tracing task2011Ingår i: Proceedings of the 23rd Australian Computer-Human Interaction Conference (OzCHI '11) / [ed] Cécile Paris, Nathalie Colineau, Vivienne Farrell, Graham Farrell and Weidong Huang, New York, NY, USA: ACM Press, 2011, 329-332 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This short paper is a work-in-progress report on an experimental, exploratory comparison and evaluation of three input methods (mouse, pen, and touch-input) in a line-tracing task. A method to compare the original shape and user-generated version is presented. Measurements of user efficiency and accuracy showed that participants replicating a particular shape using touch-input performed the worst in terms of accuracy but were the fastest in comparison to the remaining input methods. No effect of controlled visual feedback was observed. Additionally, subjective operational biases were observed that, together with input method and expected shape related issues, might strongly affect the results.

  • 46538.
    Zabramski, Stanislaw
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Creating Digital Traces of Ideas: Evaluation of Computer Input Methods in Creative and Non-Creative Drawing2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Ideas are formed in a process of idea generation that includes creation, development, and communication of new ideas. Drawing has been used as a support for ideation for centuries. Today, computerized tools are commonly used for drawing. Such tools form a user interface between the human and the resulting drawing presented on the screen. The interface may come between the user and the drawing in a disruptive way also affecting the ideation process.

    Using controlled laboratory studies, this thesis investigates the consequences of drawing with different user interfaces in two types of tasks: creative drawing tasks (based on a standardized test of creativity) and non-creative drawing tasks (i.e. shape-tracing tasks where no new idea is created). The goal was to identify and evaluate the consequences of the several issues originating from the use of different input devices, the functionality of the graphical user interfaces, the formulation of the drawing task, and the user’s previous experience.

    The results showed that drawing tasks are oriented toward quality of outcomes and that higher input accuracy led to higher quality of outcomes of both creative and non-creative drawing tasks. This came with a trade-off between the quantity and quality. In ideation, less accurate input devices facilitated significantly more ideas but these were of lower quality. In non-creative tracing, higher speeds caused lower quality of outcomes.

    The users subjectively preferred higher accuracy, also when an inaccurate user interface offered an eraser function. However, using the eraser allowed avoiding reinterpretations of ideas and led to ideation strategies characterized by laborious drawing that negatively affected the quality and quantity of the ideas produced. For non-creative drawing, the more difficult the shapes were, the lower the tracing accuracy.

    In the thesis a new framework for interaction analysis is introduced that improves the theoretical and practical understanding of computerized drawing tasks and the phenomena resulting from different aspects of the user interface design of computerized drawing tools.

    This thesis demonstrates that the inaccuracy of computerized tools cannot only make our drawings less aesthetically pleasing but also negatively affect ideas that are created in the process.

  • 46539.
    Zabramski, Stanislaw
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Creative drawing with computers2012Ingår i: CHI EA '12: Proceedings of the 2012 ACM annual conference extended abstracts on Human Factors in Computing Systems - Extended Abstracts, 2012, 963-966 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    The output of creative drawing is negatively influenced by any constrains imposed on the artist. That may be the case especially in computer-based environments. In my research I focus on the identification and assessment of the influence computer input methods (i.e. mouse, stylus-, and touch-input) might have on the results of free-hand drawing tasks in terms of user's creativity and drawing performance.

  • 46540.
    Zabramski, Stanislaw
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Quickly touched: Shape replication with use of mouse, pen- and touch-input2011Ingår i: User Interface - Kansei in practice 2011: Interfejs użytkownika - Kansei w praktyce 2011 / [ed] Leonard Bolc, Warsaw, Poland: Wydawnictwo Polsko‐Japońskiej Wyższej Szkoły Technik Komputerowych , 2011, 134-141 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents results of an experimental study of unconstrained line-tracing task with use of mouse, pen- and touch-input. Our results show that participants using touch input performed as good as with use of mouse in terms of similarity of reproduced shape with pen-input as the best tool for drawing. Touch-input users were also the fastest in comparison to the remaining input methods. Additionally, we have observed subjective operational biases that together with shape-related issues might have an influence on the final scores.

  • 46541.
    Zabramski, Stanislaw
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media.
    Gkouskos, Dimitrios
    Lind, Mats
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media.
    A comparative evaluation of mouse, pen- and touch-input in computerized version of the Torrance tests of creative thinking2011Ingår i: Proceedings of the DESIRE'11 Conference - Creativity and Innovation in Design / [ed] Clare J. Hooper, Jean-Bernard Martens, Panos Markopoulos, New York, USA: The Association for Computing Machinery , 2011, 383-386 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the results of an experiment comparing mouse, pen- and touch-inputs in computerized figural creativity test. The results show no statistically significant differences in creativity scores obtained by participants using mentioned devices as computer input methods. The results indicate that creativity testing can be introduced to a variety of modern computer devices with insignificant influence of the three most popular input devices tested. That also shows that the differences between the computerized and paper-based TTCT noticed in a previous research might be the result of User Interface artifacts used.

  • 46542.
    Zabramski, Stanislaw
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Gkouskos, Dimitrios
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Lind, Mats
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    A comparative evaluation of mouse, stylus and finger input in shape tracing2011Ingår i: Proceedings of the 1st European Workshop on HCI Design and Evaluation: The inuence of domain on Human Computer Interaction design and evaluation / [ed] Georgios Christou, Panayiotis Zaphiris, Ee Lai-Chong Law, Toulouse, France: IRIT Press , 2011, 57-61 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    A comparison of the aggregated performance measurements for three input methods in a line-tracing task is presented. Results indicate that users perform best using touch input, both in tasks with and without visual feedback, therefore we recommend touch input as the preferred input method for simple drawing tasks.

  • 46543.
    Zabramski, Stanislaw
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Ivanova, Vita
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Yang, Guo
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Gadima, Nur
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Leepraphantkul, Rathakan
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    The Effects of GUI on Users’ Creative Performance in Computerized Drawing2013Ingår i: Proceedings of MIDI '13: Proceedings of the International Conference on Multimedia, Interaction, Design and Innovation, New York, NY, USA: Association for Computing Machinery (ACM), 2013, 142-151 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the results of an empirical comparative study investigating how the outcomes of a computerized figural creativity test are affected when the participants use two different versions of the Graphical User Interface (GUI) on a mouse-operated desktop PC. The results show that participants get insignificantly lower creativity scores with the elaborated GUI, contrary to the GUI that has no visual artifacts available and offers more similar user experience to pen and paper, even though they spend significantly more time on drawing with the elaborated one. That phenomenon is expected to contribute to the cumulative effect of GUI and input method noticed by previous research. That implies that creative drawing and testing should be carefully introduced into computer-based environments.

  • 46544.
    Zabramski, Stanislaw
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media.
    Neelakannan, Sarathkumar
    Paper equals screen: A comparison of a pen-based figural creativity test in computerized and paper form2011Ingår i: Proceedings of the DESIRE'11 Conference - Creativity and Innovation in Design / [ed] Clare J. Hooper, Jean-Bernard Martens, Panos Markopoulos, New York, USA: The Association for Computing Machinery , 2011, 47-50 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we present the results of an experiment investigating how the results of a figural creativity test are affected when paper and pen or tablet PC and stylus are used to test participants. The results show no effect of the testing method on creativity scores obtained by participants. The results indicate that the differences between computerized and paper-based figural creativity tests noticed by previous research might be limited to the influence of User Interface artifacts used. That implies that creativity testing can be introduced to a variety of stylus based computer devices with insignificant influence of the transition from regular pen and paper to screen and stylus as a computer input device.

  • 46545.
    Zabramski, Stanislaw
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Shrestha, Suman
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Stuerzlinger, Wolfgang
    York University, Toronto, Canada.
    Easy vs. Tricky: The Shape Effect in Tracing, Selecting, and Steering With Mouse, Stylus, and Touch2013Ingår i: Academic MindTrek '13: Proceedings of International Conference on Making Sense of Converging Media / [ed] Artur Lugmayr, New York, NY, USA: Association for Computing Machinery (ACM), 2013, 99-103 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper is a work-in-progress report on an experimental comparison and evaluation of users' performance in four line-tracing tasks based on two shapes and performed with three input methods (mouse, stylus, and touch-input). The shapes' properties used in the study created the two classes of shapes: easy and hard to replicate. As expected these two classes had different impact on user's performance in each task tested (tracing, lasso selection, steering through narrow and wide tunnel). The results show that participants replicating the shapes using touch-input were the least accurate but were the fastest in comparison to the remaining input methods. The stylus was the least error-prone method and the mouse was the slowest device in drawing tasks (tracing and selection). The differences in error distances between the input methods were less pronounced in steering tasks but timing data showed that mouse was still the slowest one. While the time of replication did not differ between the two shapes tested, the differences between the errors participants made were significant for all tasks and input devices, and patterns of these differences were consistent between the shapes. These results confirm predictions from a previous study and show which shapes' properties can make their replication more difficult. The results can be used to design shapes that are easy to replicate, e.g., in surface-based gestural interaction.

  • 46546.
    Zabramski, Stanislaw
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Stuerzlinger, Wolfgang
    York University, Toronto, Canada.
    Activity or Product?: Drawing and HCI2013Ingår i: Proceedings of MIDI '13: Proceedings of the International Conference on Multimedia, Interaction, Design and Innovation, New York, NY, USA: Association for Computing Machinery (ACM), 2013, 29-38 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Drawing tasks are rarely addressed experimentally by the HCI community, and even then pointing, steering, or gesturing is promoted as an approach towards drawing. We critically analyze the status quo, propose an improved framework for task analysis, and give suggestions on how to perceive drawing task at a meta-level.

  • 46547.
    Zabramski, Stanislaw
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Stuerzlinger, Wolfgang
    York University, Toronto, Canada.
    Did We Miss Something? Correspondence Analysis of Usability Data2013Ingår i: Human-Computer Interaction – INTERACT 2013: 14th IFIP TC 13 International Conference, Cape Town, South Africa, September 2-6, 2013, Proceedings, Part IV / [ed] Paula Kotzé, Gary Marsden, Gitte Lindgaard, Janet Wesson, Marco Winckler, Berlin/Heidelberg: Springer Berlin/Heidelberg, 2013, 272-279 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    We have applied a multivariate exploratory technique called Correspondence Analysis (CA) to create and analyze a model of the dataset of experiment results. The dataset originates from a comparative usability study of tracing with the use of mouse, pen, and touch input and contains both categorical and continuous data – i.e. results of questionnaires and task measurements. CA allowed to visually and numerically assess the main variables in the dataset and how they interact with each other. In our study, pen input had the best measured performance and was preferred by the users. Touch input was the least accurate of all input methods tested but it was preferred by users over mouse especially in the conditions lacking of visual feedback of drawing. CA helped to detect that secondary effect even though it cannot be explained by the performance results alone. The importance of the influence of user’s previous experience is also noted. We conclude that CA helped to identify all major phenomena known from previous studies but also was sensitive to minor and secondary effects, what makes it a well suited method to quickly evaluate usability data.

  • 46548.
    Zabramski, Stanislaw
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media, Människa-datorinteraktion.
    Stuerzlinger, Wolfgang
    York University, Toronto, Canada.
    The Effect of Shape Properties on Ad-hoc Shape Replication with Mouse, Pen, and Touch Input2012Ingår i: MindTrek '12 Proceeding of the 16th International Academic MindTrek Conference / [ed] Artur Lugmayr, New York, NY, USA: ACM Press, 2012, 275-278 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper summarizes observations from four empirical studies focusing on shape replication with three input methods. The aim was to identify and assess how the components of several semirandomly generated shapes influence how accurately untrained users can replicate each of these components. We found that the pen is the least and touch the most error-prone method when used for drawing. Additionally, the distribution of errors was analyzed. The results may be used to predict which shape properties make shape replication more difficult. Additionally, the results may be used to design shapes that are easy to replicate.

  • 46549.
    Zacarias, Orlando P.
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap. Eduardo Mondlane University, Moçambique.
    Andersson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Mapping malaria incidence distribution that accounts for environmental factors in Maputo Province - Mozambique2010Ingår i: Malaria Journal, ISSN 1475-2875, E-ISSN 1475-2875, Vol. 9, 79Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: The objective was to study if an association exists between the incidence of malaria and some weather parameters in tropical Maputo province, Mozambique. Methods: A Bayesian hierarchical model to malaria count data aggregated at district level over a two years period is formulated. This model made it possible to account for spatial area variations. The model was extended to include environmental covariates temperature and rainfall. Study period was then divided into two climate conditions: rainy and dry seasons. The incidences of malaria between the two seasons were compared. Parameter estimation and inference were carried out using MCMC simulation techniques based on Poisson variation. Model comparisons are made using DIC. Results: For winter season, in 2001 the temperature covariate with estimated value of -8.88 shows no association to malaria incidence. In year 2002, the parameter estimation of the same covariate resulted in 5.498 of positive level of association. In both years rainfall covariate determines no dependency to malaria incidence. Malaria transmission is higher in wet season with both covariates positively related to malaria with posterior means 1.99 and 2.83 in year 2001. For 2002 only temperature is associated to malaria incidence with estimated value 2.23. Conclusions: The incidence of malaria in year 2001, presents an independent spatial pattern for temperature in summer and for rainfall in winter seasons respectively. In year 2002 temperature determines the spatial pattern of malaria incidence in the region. Temperature influences the model in cases where both covariates are introduced in winter and summer season. Its influence is extended to the summer model with temperature covariate only. It is reasonable to state that with the occurrence of high temperatures, malaria incidence had certainly escalated in this year.

  • 46550.
    Zacarias, Orlando P.
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap. Eduardo Mondlane University, Mozambique.
    Andersson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Spatial and temporal patterns of malaria incidence in Mozambique2011Ingår i: Malaria Journal, ISSN 1475-2875, E-ISSN 1475-2875, Vol. 10, 189Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: The objective of this study is to analyze the spatial and temporal patterns of malaria incidence as to determine the means by which climatic factors such as temperature, rainfall and humidity affect its distribution in Maputo province, Mozambique. Methods: This study presents a model of malaria that evolves in space and time in Maputo province-Mozambique, over a ten years period (1999-2008). The model incorporates malaria cases and their relation to environmental variables. Due to incompleteness of climatic data, a multiple imputation technique is employed. Additionally, the whole province is interpolated through a Gaussian process. This method overcomes the misalignment problem of environmental variables (available at meteorological stations points) and malaria cases (available as aggregates for every district - area). Markov Chain Monte Carlo (MCMC) methods are used to obtain posterior inference and Deviance Information Criteria (DIC) to perform model comparison. Results: A Bayesian model with interaction terms was found to be the best fitted model. Malaria incidence was associated to humidity and maximum temperature. Malaria risk increased with maximum temperature over 28 degrees C (relative risk (RR) of 0.0060 and 95% Bayesian credible interval (CI) of 0.00033-0.0095) and humidity (relative risk (RR) of 0.00741 and 95% Bayesian CI 0.005141-0.0093). The results would suggest that additional non-climatic factors including socio-economic status, elevation, etc. also influence malaria transmission in Mozambique. Conclusions: These results demonstrate the potential of climate predictors particularly, humidity and maximum temperature in explaining malaria incidence risk for the studied period in Maputo province. Smoothed maps obtained as monthly average of malaria incidence allowed to visualize months of initial and peak transmission. They also illustrate a variation on malaria incidence risk that might not be related to climatic factors. However, these factors are still determinant for malaria transmission and intensity in the region.

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