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  • 501.
    Aghaee Ghaleshahi, Nima
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Efficient Test Application for Rapid Multi-Temperature Testing2015Ingår i: Proceedings of the 25th edition on Great Lakes Symposium on VLSI, Association for Computing Machinery (ACM), 2015, s. 3-8Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Different defects may manifest themselves at different temperatures. Therefore, the tests that target such temperature-dependent defects must be applied at different temperatures appropriate for detecting them. Such multi-temperature testing scheme applies tests at different required temperatures. It is known that a test's power dissipation depends on the previously applied test. Therefore, the same set of tests when organized differently dissipates different amounts of power. The technique proposed in this paper organizes the tests efficiently so that the resulted power levels lead to the required temperatures. Consequently a rapid multi-temperature testing is achieved. Experimental studies demonstrate the efficiency of the proposed technique.

  • 502.
    Aghaee Ghaleshahi, Nima
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Process-variation and Temperature Aware SoC Test Scheduling Technique2013Ingår i: Journal of electronic testing, ISSN 0923-8174, E-ISSN 1573-0727, Vol. 29, nr 4, s. 499-520Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High temperature and process variation are undesirable phenomena affecting modern Systems-on-Chip (SoC). High temperature is a well-known issue, in particular during test, and should be taken care of in the test process. Modern SoCs are affected by large process variation and therefore experience large and time-variant temperature deviations. A traditional test schedule which ignores these deviations will be suboptimal in terms of speed or thermal-safety. This paper presents an adaptive test scheduling method which acts in response to the temperature deviations in order to improve the test speed and thermal safety. The method consists of an offline phase and an online phase. In the offline phase a schedule tree is constructed and in the online phase the appropriate path in the schedule tree is traversed based on temperature sensor readings. The proposed technique is designed to keep the online phase very simple by shifting the complexity into the offline phase. In order to efficiently produce high-quality schedules, an optimization heuristic which utilizes a dedicated thermal simulation is developed. Experiments are performed on a number of SoCs including the ITC'02 benchmarks and the experimental results demonstrate that the proposed technique significantly improves the cost of the test in comparison with the best existing test scheduling method.

  • 503.
    Aghaee Ghaleshahi, Nima
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Tekniska högskolan.
    Process-Variation and Temperature Aware SoC Test Scheduling Using Particle Swarm Optimization2011Ingår i: The 6th IEEE International Design and Test Workshop (IDT'11), Beirut, Lebanon, December 11–14, 2011., IEEE , 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    High working temperature and process variation are undesirable effects for modern systems-on-chip. It is well recognized that the high temperature should be taken care of during the test process. Since large process variations induce rapid and large temperature deviations, traditional static test schedules are suboptimal in terms of speed and/or thermalsafety. A solution to this problem is to use an adaptive test schedule which addresses the temperature deviations by reacting to them. We propose an adaptive method that consists of a computationally intense offline-phase and a very simple onlinephase. In the offline-phase, a near optimal schedule tree is constructed and in the online-phase, based on the temperature sensor readings, an appropriate path in the schedule tree is traversed. In this paper, particle swarm optimization is introduced into the offline-phase and the implications are studied. Experimental results demonstrate the advantage of the proposed method.

  • 504.
    Aghaee Ghaleshahi, Nima
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Process-Variation Aware Multi-temperature Test Scheduling2014Ingår i: 27th International Conference on VLSI Design and 13th International Conference on Embedded Systems, IEEE conference proceedings, 2014, s. 32-37Konferensbidrag (Refereegranskat)
    Abstract [en]

    Chips manufactured with deep sub micron technologies are prone to large process variation and temperature-dependent defects. In order to provide high test efficiency, the tests for temperature-dependent defects should be applied at appropriate temperature ranges. Existing static scheduling techniques achieve these specified temperatures by scheduling the tests, specially developed heating sequences, and cooling intervals together. Because of the temperature uncertainty induced by process variation, a static test schedule is not capable of applying the tests at intended temperatures in an efficient manner. As a result the test cost will be very high. In this paper, an adaptive test scheduling method is introduced that utilizes on-chip temperature sensors in order to adapt the test schedule to the actual temperatures. The proposed method generates a low cost schedule tree based on the variation statistics and thermal simulations in the design phase. During the test, a chip selects an appropriate schedule dynamically based on temperature sensor readings. A 23% decrease in the likelihood that tests are not applied at the intended temperatures is observed in the experimental studies in addition to 20% reduction in test application time.

  • 505.
    Aghaee Ghaleshahi, Nima
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Temperature-Gradient Based Burn-In for 3D Stacked ICs2013Ingår i: The 12th Swedish System-on-Chip Conference (SSoCC 2013), Ystad, Sweden, May 6-7, 2013 (not reviewed, not printed)., 2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    3D Stacked IC fabrication, using Through-Silicon-Vias, is a promising technology for future integrated circuits. However, large temperature gradients may exacerbate early-life-failures to the extent that the commercialization of 3D Stacked ICs is challenged. The effective detection of these early-life-failures requires that burn-in is performed when the IC’s temperatures comply with the thermal maps that properly specify the temperature gradients. In this paper, two methods that efficiently generate and maintain the specified thermal maps are proposed. The thermal maps are achieved by applying heating and cooling intervals to the chips under test through test access mechanisms. Therefore, no external heating system is required. The scheduling of the heating and cooling intervals is based on thermal simulations. The schedule generation is guided by functions that are derived from the temperature equations. Experimental results demonstrate the efficiency of the proposed method.

  • 506.
    Aghaee Ghaleshahi, Nima
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Temperature-Gradient Based Test Scheduling for 3D Stacked ICs2013Ingår i: 2013 IEEE International Conference on Electronics, Circuits, and Systems, IEEE conference proceedings, 2013, s. 405-408Konferensbidrag (Refereegranskat)
    Abstract [en]

    Defects that are dependent on temperature-gradients (e.g., delay-faults) introduce a challenge for achieving an effective test process, in particular for 3D ICs. Testing for such defects must be performed when the proper temperature gradients are enforced on the IC, otherwise these defects may escape the test. In this paper, a technique that efficiently heats up the IC during test so that it complies with the specified temperature gradients is proposed. The specified temperature gradients are achieved by applying heating sequences to the cores of the IC under test trough test access mechanism; thus no external heating mechanism is required. The scheduling of the test and heating sequences is based on thermal simulations. The schedule generation is guided by functions derived from the IC's temperature equation. Experimental results demonstrate that the proposed technique offers considerable test time savings.

  • 507.
    Aghaee, Naghmeh
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Finding Potential Problems in the Thesis Process in Higher Education: Analysis of e-mails to develop a support system2015Ingår i: Education and Information Technologies: Official Journal of the IFIP technical committee on Education, ISSN 1360-2357, E-ISSN 1573-7608, Vol. 20, nr 1, s. 21-36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Autonomous learning hype has created much speculation in educational systems regarding how to develop the learning process. Final project (thesis) in Bachelor’s and Master’s levels is a significant part of study for students in higher education. However, there are some problems, which lead students not managing to do or finish their thesis. As a part of a solution to these problems, the Department of Computer and Systems Sciences (DSV) at Stockholm University, Sweden, has established an information and communication platform, called SciPro. The system was initiated in 2011 to support students and supervisors during the thesis process courses. This study contributes by exploring problems that learners have faced during the final project courses and analyzing discussed issues in the emails, sent to the SciPro support group, ThesisSupport. A random sample of one hundred emails has been analyzed with the help of a content analysis tool, in order to develop the categories, which cover the discussed issues. The result of the study shows six exhaustive and mutually exclusive categories of problems: 1) Thesis initiation (26 %), 2) Info-mail (4.7 %), 3) Technical issues (17.1 %), 4) Exemption (18.7 %), 5) Supervision (17.1 %), 6) Final seminar (16.4 %). Consequently, based on the significance of the categories, two groups of strategic suggestions are developed: 1) developing communications and 2) developing instructions. These strategies intend to enhance support for the autonomous learning process for the thesis courses in higher education.

  • 508.
    Aghaee, Naghmeh
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    The Usefulness of ICT Support Systems for Thesis Courses: Learners' Perspectives at Bachelor and Master Level2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Doing a bachelor’s or master’s degree is a journey that leads to success or attrition (dropout). Previous research show to the significance of considering learners’ perspectives and their need for information and different types of interaction. This can be done through online ICTSS (information and communication technology support systems). The overall aim of this dissertation was to create knowledge about how the use of ICTSS can facilitate different types of interaction and support learners in order to reduce thesis problems and attrition and to enhance the quality of the thesis outcomes. The aim was operationalized by two research questions scrutinizing the interaction problems in the thesis process and investigating how the use of ICTSS can facilitate different types of interaction to reduce such problems and attrition, and to enhance the learning opportunities and quality of the thesis outcomes. To answer the research questions, five main studies were performed by applying different research methods on a case study. The empirical studies were performed at the Department of Computer and Systems Sciences (DSV) at Stockholm University, Sweden. The respondents were different learners (students) with active thesis projects at the bachelor or master level in different programs at DSV between 2012 and 2015. For the first two studies, conceptual and content analysis of the data collected from the case study was performed. For the three other studies, open-ended online questionnaires (survey) and interviews were conducted. On the basis of the findings, three main types of interaction issues were developed which related to the need for more learner-content, peer-to-peer, and learner-supervisor interaction in the thesis process. The hypothesis was that the interaction issues could be reduced by implementing a set of strategic suggestions through the use of an ICTSS including a set of functionalities and resources. The usefulness of these functionalities and resources was evaluated with regard to the learners’ perception and experiences. The findings were categorized to facilitate learner-content, peer-to-peer, and learner-supervisor interaction, as well as management of the contents, supervision, and communication of the supervisory team. From these categories, a conceptual framework was developed in this dissertation to illustrate how the use of the ICTSS supports the thesis process. In conclusion, providing access to a set of structured e-resources and supporting educational communication through different types of interaction with peers and the supervisory team, enables learners’ self-managed learning and facilitates similar learning opportunities for learners in thesis courses.

  • 509.
    Aghaee, Naghmeh
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Hansson, Henrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Peer Portal: Quality Enhancement in Thesis Writing Using Self-Managed Peer Review on a Mass Scale2013Ingår i: International Review of Research in Open and Distance Learning, ISSN 1492-3831, E-ISSN 1492-3831, Vol. 14, nr 1, s. 186-203Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    This paper describes a specially developed online peer-review system, the Peer Portal, and the first results of its use for quality enhancement of bachelor's and master's thesis manuscripts. The peer-review system is completely student driven and therefore saves time for supervisors and creates a direct interaction between students without interference from supervisors. The purpose is to improve thesis manuscript quality, and thereby use supervisor time more efficiently, since peers review basic aspects of the manuscripts and give constructive suggestions for improvements. The process was initiated in 2012, and, in total, 260 peer reviews were completed between 1st January and 15th May, 2012. All peer reviews for this period have been analyzed with the help of content analysis. The purpose of analysis is to assess the quality of the students work. The results are categorized in four groups: 1) excellent (18.1%), 2) good (22.7%), 3) fragmented (18.5%), and 4) poor (40.7%). The overall result shows that almost 40% of the students produced excellent or good peer reviews and almost as many produced poor peer reviews. The result shows that the quality varies considerably. Explanations of these quality variations need further study. However, alternative hypotheses followed by some strategic suggestions are discussed in this study. Finally, a way forward in terms of improving peer reviews is outlined: 1) development of a peer wizard system and 2) rating of received peer reviews based on the quality categories created in this study. A Peer Portal version 2.0 is suggested, which will eliminate the fragmented and poor quality peer reviews, but still keep this review system student driven and ensure autonomous learning.

  • 510.
    Aghaee, Naghmeh
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Hansson, Henrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Tedre, Matti
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Drougge, Ulrika
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Learners’ Perceptions on the Structure and Usefulness of e-Resources for the Thesis Courses2014Ingår i: European Journal of Open and Distance Learning, ISSN 1027-5207, E-ISSN 1027-5207, Vol. 17, nr 1, s. 154-171Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nowadays, utility of information and communication technology (ICT) in education is a way to facilitate interaction and accessing information for learning in higher education. However, finding a set of structured e-resources to facilitate learning within specific courses is still a big challenge in most of the institutions and universities. This includes the problems and challenges for the thesis courses in both undergraduate (Bachelor) and graduate (Master) level in Sweden. To overcome or reduce the problems and enhance quality of outcomes in the thesis courses, the department of Computer and Systems Sciences (DSV) at Stockholm University has developed a Learning Support System, SciPro (Scientific Process), to support thesis process. This study aims at investigating learners’ perspectives on usefulness of structured e-resources in order to reduce challenges for finding information related to the thesis steps in SciPro. This is done based on an open online survey, carried out in 2012-2013 of students’ perspectives at DSV. The study found the actual problems and hence suggested a model as a way forward to sort the useful e-resources to support reducing the problems in the thesis process.

  • 511.
    Aghaee, Naghmeh
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Jobe, William Byron
    Karunaratne, Thashmee
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Smedberg, Åsa
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Hansson, Henrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Tedre, Matti
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Interaction Gaps in PhD Education and ICT as a Way Forward: Results from a Study in Sweden2016Ingår i: The International Review of Research in Open and Distributed Learning, ISSN 1492-3831, Vol. 17, nr 3, s. 360-383Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many research studies have highlighted the low completion rate and slow progress in PhD education. Universities strive to improve throughput and quality in their PhD education programs. In this study, the perceived problems of PhD education are investigated from PhD students' points of view, and how an Information and Communication Technology Support System (ICTSS) may alleviate these problems. Data were collected through an online open questionnaire sent to the PhD students at the Department of (the institution's name has been removed during the double-blind review) with a 59% response rate. The results revealed a number of problems in the PhD education and highlighted how online technology can support PhD education and facilitate interaction and communication, affect the PhD students' satisfaction, and have positive impacts on PhD students' stress. A system was prototyped, in order to facilitate different types of online interaction through accessing a set of online and structured resources and specific communication channels. Although the number of informants was not large, the result of the study provided some rudimentary ideas that refer to interaction problems and how an online ICTSS may facilitate PhD education by providing distance and collaborative learning, and PhD students' self-managed communication.

  • 512.
    Aghaee, Naghmeh
    et al.
    Stockholm University.
    Karunaratne, Thashmee
    Stockholm University.
    Smedberg, Åsa
    Stockholm University.
    Jobe, William
    Högskolan Väst, Institutionen för ekonomi och it, Avd för informatik.
    Communication and Collaboration Gaps among PhD Students and ICT as a Way Forward: Results from a Study in Sweden2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    The low completion rate and slow progress in PhD education have been highlighted in many studies. However, the interaction problems and communication gaps that PhD students encounter make this attempt even more challenging. The aim of this study is to investigate the peer interaction problems and ICT based solutions from PhD students’ perspectives. The data collection method was an online questionnaire and in-depth interviews were used to follow up. The target group for the survey was the PhD students in Computer Science at Stockholm University. The total number of respondents for the survey was 53 PhD students and eleven randomly selected PhD students for the interviews. The results reflected a lack of peer interaction as an important issue in the perspective of the students. Based on this, the study showed several ICT solutions that have the potential to reduce the interaction problems and thereby improve PhD students’ collaborative learning and research quality.

  • 513.
    Aghaee, Naghmeh
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Karunaratne, Thashmee
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Smedberg, Åsa
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Jobe, William Byron
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    ICT for Communication and Collaborative Learning among PhD peers: Results of the Needs and Desires from a PhD Survey2014Ingår i: DSV writers hut 2014: proceedings, August 21-22, Åkersberga, Sweden / [ed] Gustaf Juell-Skielse, Stockholm: Department of Computer and Systems Sciences, Stockholm University , 2014, s. 33-40Konferensbidrag (Refereegranskat)
  • 514.
    Aghaee, Naghmeh
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Keller, Christina
    ICT-supported peer interaction among learners in Bachelor's and Master's thesis courses2016Ingår i: Computers and education, ISSN 0360-1315, E-ISSN 1873-782X, Vol. 94, s. 276-297Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Peer interaction and collaborative learning through the use of ICT (Information and Communication Technology) is used to an increasing extent in higher education. Universities attempt to motivate learners (students) to support their peers to enhance the quality of learning outcomes. This study monitors how an ICTSS (ICT-based Support System) facilitates peer interaction in the Bachelor’s and Master’s thesis process. The aim of the study was to investigate learners’ perception of usefulness of an ICTSS for peer interaction and the influencing factors on the quality of the peer interaction. The ICTSS was developed at an institution in Sweden (the institution’s name has been removed during the double-blind review). The system facilitates peer interaction in three ways: peer reviews, active participation, and final opposition. The study employed a mixed-method approach, which included an online survey followed by in-depth interviews. The target groups were learners at the Bachelor’s and Master’s level in computer science and information systems. The findings showed that learners perceived the peer interaction useful to enhance the quality of the thesis outcomes. However, there are influencing factors affecting the quality of peer interaction, in different phases of the thesis process. Examples of these factors are the quality of thesis manuscripts, supervisors’ control and grading of the process, clear instructions and guidelines, learners’ understanding of the peer interaction and why it takes place, previous training and learners’ motivation to perform peer reviews. Following these factors, the study developed a set of strategic suggestions from both pedagogical and technical aspects to enhance the peer interaction in the thesis process. Considering these suggestions makes the use of the ICTSS more effective to enhance the quality of thesis learning outcomes. 

  • 515.
    Aghaee, Naghmeh
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Larsson, Ken
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Students’ Perspectives on Utility of Mobile Applications in Higher Education2013Ingår i: Trends in Mobile Web Information Systems: Revised Selected Papers / [ed] Maristella Matera, Gustavo Rossi, Springer Publishing Company, 2013, s. 44-56Konferensbidrag (Refereegranskat)
    Abstract [en]

    Use of Information and Communication Technologies (ICT) in pedagogy and learning in higher education supports the concept of Technology Enhanced Learning (TEL). Mobile devices and applications with educational purposes are part of using online ICT and facilitate autonomous learning in education. Using mobile applications for education has significantly improved in the last few years. However, there is still a gap, in which this concept is still not widely known and frequently experienced by learners. As a part of supporting TEL in higher education and filling this gap, the department of Computer and System Sciences at Stockholm University in Sweden is planning to develop a mobile application for the SciPro system. SciPro is the computer-mediated communication platform to support enhancement of thesis quality and facilitate autonomous learning in higher education, at both Bachelor and Master levels. This study aims to investigate and evaluate learners’ perspectives about utility of mobile applications in higher education and specifically to support SciPro functionalities. Almost 95% of the respondents use mobile applications for higher education and believe in the utility of mobile applications for supporting learning in higher education. This is while there are a few respondents (less than 5%), who do not fully share this opinion. More than 70% of the respondents think that a SciPro mobile application will add value to their thesis process. Even though it may not directly affect the speed and quality of the thesis, it will increase mobility, availability, and flexibility of accessing information and resources in SciPro.

  • 516.
    Aghaee, Naghmeh
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Larsson, Ulf
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Hansson, Henrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Improving the Thesis Process: Analysis of Scipro Support e-mails2012Manuskript (preprint) (Övrig (populärvetenskap, debatt, mm))
  • 517.
    Aghaee, Nam
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Karunaratne, Thashmee
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Smedberg, Åsa B.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Jobe, William
    Communication and Collaboration Gaps among PhD Students and ICT as a Way Forward: Results from a Study in Sweden2015Ingår i: E-Learn: 20 th annual World Conference on E-Learning in Corporate, Government, Healthcare, and Higher Education 2015, 2015Konferensbidrag (Refereegranskat)
  • 518.
    Aghaee, Nima
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Tekniska fakulteten.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Tekniska fakulteten.
    A Test-Ordering Based Temperature-Cycling Acceleration Technique for 3D Stacked ICs2015Ingår i: Journal of electronic testing, ISSN 0923-8174, E-ISSN 1573-0727, ISSN 0923-8174, Vol. 31, nr 5, s. 503-523Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    n a modern three-dimensional integrated circuit (3D IC), vertically stacked dies are interconnected using through silicon vias. 3D ICs are subject to undesirable temperature-cycling phenomena such as through silicon via protrusion as well as void formation and growth. These cycling effects that occur during early life result in opens, resistive opens, and stress induced carrier mobility reduction. Consequently these early-life failures lead to products that fail shortly after the start of their use. Artificially-accelerated temperature cycling, before the manufacturing test, helps to detect such early-life failures that are otherwise undetectable. A test-ordering based temperature-cycling acceleration technique is introduced in this paper that integrates a temperature-cycling acceleration procedure with pre-, mid-, and post-bond tests for 3D ICs. Moreover, it reduces the need for costly temperature chamber based temperature-cycling acceleration methods. All these result in a reduction in the overall test costs. The proposed method is a test-ordering and schedule based solution that enforces the required temperature cycling effect and simultaneously performs the tests whenever appropriate. Experimental results demonstrate the efficiency of the proposed technique.

  • 519.
    Aghaee, Nima
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Temperature-Gradient-Based Burn-In and Test Scheduling for 3-D Stacked ICs2015Ingår i: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, E-ISSN 1557-9999, Vol. 23, nr 12, s. 2992-3005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Large temperature gradients exacerbate various types of defects including early-life failures and delay faults. Efficient detection of these defects requires that burn-in and test for delay faults, respectively, are performed when temperature gradients with proper magnitudes are enforced on an Integrated Circuit (IC). This issue is much more important for 3-D stacked ICs (3-D SICs) compared with 2-D ICs because of the larger temperature gradients in 3-D SICs. In this paper, two methods to efficiently enforce the specified temperature gradients on the IC, for burn-in and delay-fault test, are proposed. The specified temperature gradients are enforced by applying high-power stimuli to the cores of the IC under test through the test access mechanism. Therefore, no external heating mechanism is required. The tests, high power stimuli, and cooling intervals are scheduled together based on temperature simulations so that the desired temperature gradients are rapidly enforced. The schedule generation is guided by functions derived from a set of thermal equations. The experimental results demonstrate the efficiency of the proposed methods.

  • 520.
    Aghaee, Saeed
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Matematiska och systemtekniska institutionen.
    Random Stream Cipher2007Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [en]

    Stream ciphers are counted as an important part of symmetric encryption method. Their basic idea comes from One-Time-Pad cipher using XOR operator on the plain text and the key to generate the cipher. The present work brings a new idea in symmetric encryption method, which inherits stream key generation idea from synchronous stream cipher and uses division instead of xoring. The Usage of division to combine the plain text with stream key gives numerous abilities to this method that the most important one is using random factors to produce the ciphers.

  • 521.
    Aghanavesi, Somayeh
    et al.
    School of Technology and Business Studies, Computer Engineering, Dalarna University, Falun, Sweden.
    Memedi, Mevludin
    Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Dougherty, Mark
    School of Technology and Business Studies, Computer Engineering, Dalarna University, Falun, Sweden.
    Nyholm, Dag
    Department of Neuroscience, Neurology, Uppsala University, Uppsala, Sweden.
    Westin, Jerker
    School of Technology and Business Studies, Computer Engineering, Dalarna University, Falun, Sweden.
    Verification of a Method for Measuring Parkinson’s Disease Related Temporal Irregularity in Spiral Drawings2017Ingår i: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 17, nr 10, artikel-id 2341Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Parkinson’s disease (PD) is a progressive movement disorder caused by the death of dopamine-producing cells in the midbrain. There is a need for frequent symptom assessment, since the treatment needs to be individualized as the disease progresses. The aim of this paper was to verify and further investigate the clinimetric properties of an entropy-based method for measuring PD-related upper limb temporal irregularities during spiral drawing tasks. More specifically, properties of a temporal irregularity score (TIS) for patients at different stages of PD, and medication time points were investigated. Nineteen PD patients and 22 healthy controls performed repeated spiral drawing tasks on a smartphone. Patients performed the tests before a single levodopa dose and at specific time intervals after the dose was given. Three movement disorder specialists rated videos of the patients based on the unified PD rating scale (UPDRS) and the Dyskinesia scale. Differences in mean TIS between the groups of patients and healthy subjects were assessed. Test-retest reliability of the TIS was measured. The ability of TIS to detect changes from baseline (before medication) to later time points was investigated. Correlations between TIS and clinical rating scores were assessed. The mean TIS was significantly different between healthy subjects and patients in advanced groups (p-value = 0.02). Test-retest reliability of TIS was good with Intra-class Correlation Coefficient of 0.81. When assessing changes in relation to treatment, TIS contained some information to capture changes from Off to On and wearing off effects. However, the correlations between TIS and clinical scores (UPDRS and Dyskinesia) were weak. TIS was able to differentiate spiral drawings drawn by patients in an advanced stage from those drawn by healthy subjects, and TIS had good test-retest reliability. TIS was somewhat responsive to single-dose levodopa treatment. Since TIS is an upper limb high-frequency-based measure, it cannot be detected during clinical assessment.

  • 522.
    Aghanavesi, Somayeh
    et al.
    Computer Engineering, School of Technology and Business Studies, Dalarna University, Borlänge, Sweden.
    Memedi, Mevludin
    Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Westin, Jerker
    Computer Engineering, School of Technology and Business Studies, Dalarna University, Borlänge, Sweden.
    Measuring temporal irregularity in spiral drawings of patients with Parkinson’s disease2017Ingår i: Abstracts of the 21st International Congress of Parkinson's Disease and Movement Disorders, John Wiley & Sons, 2017, Vol. 32, s. s252-s252, artikel-id 654Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Objective: The aim of this work is to evaluate clinimetric properties of a method for measuring Parkinson’s disease (PD) upper limb temporal irregularities during spiral drawing tasks.

    Background: Basal ganglia fluctuations of PD patients are associated with motor symptoms and relating them to objective sensor-based measures may facilitate the assessment of temporal irregularities, which could be difficult to be assessed visually. The present study investigated the upper limb temporal irregularity of patients at different stages of PD and medication time points.

    Methods: Nineteen PD patients and 22 healthy controls performed repeated spiral drawing tasks on a smartphone. Patients performed the tests before a single levodopa dose and at specific time intervals after the dose was given. Three movement disorder specialists rated the videos of patients' performance according to six items of UPDRS-III, dyskinesia (Dys), and Treatment Response Scale (TRS). A temporal irregularity score (TIS) was developed using approximate entropy (ApEn) method. Differences in mean TIS between two groups of patients and healthy subjects, and also across four subject groups: early, intermediate, advanced patients and, healthy subjects were assessed. The relative ability of TIS to detect changes from baseline (no medication) to later time points when patients were on medication was assessed. Correlations between TIS and clinical rating scales were assessed by Pearson correlation coefficients and test-retest reliability of TIS was measured by intra-class correlation coefficients (ICC).

    Results: The mean TIS was significantly different between healthy subjects and patients (P<0.0001). When assessing the changes in relation to treatment, clinical-based scores (TRS and Dys) had better responsiveness than TIS. However, the TIS was able to capture changes from Off to On, and the wearing off effects. Correlations between TIS and clinical scales were low indicating poor validity. Test-retest reliability correlation coefficient of the mean TIS was good (ICC=0.67).

    Conclusions: Our study found that TIS was able to differentiate spiral drawings drawn by patients from those drawn by healthy subjects. In addition, TIS could capture changes throughout the levodopa cycle.TIS was weakly correlated to clinical ratings indicating that TIS measures high frequency upper limb temporal irregularities that could be difficult to be detected during clinical observations.

  • 523.
    Aghanavesi, Somayeh
    et al.
    Computer Engineering, School of Technology and Business Studies, Dalarna University, Falun, Sweden.
    Nyholm, Dag
    Dept. of Neuroscience, Neurology, Uppsala University, Uppsala, Sweden.
    Senek, Marina
    Dept. of Neuroscience, Neurology, Uppsala University, Uppsala, Sweden.
    Bergquist, Filip
    Dept. of Pharmacology, University of Gothenburg, Gothenburg, Sweden.
    Memedi, Mevludin
    Örebro universitet, Handelshögskolan vid Örebro Universitet. Computer Engineering, School of Technology and Business Studies, Dalarna University, Falun, Sweden.
    A smartphone-based system to quantify dexterity in Parkinson's disease patients2017Ingår i: Informatics in Medicine Unlocked, ISSN 2352-9148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objectives

    The aim of this paper is to investigate whether a smartphone-based system can be used to quantify dexterity in Parkinson's disease (PD). More specifically, the aim was to develop data-driven methods to quantify and characterize dexterity in PD.

    Methods

    Nineteen advanced PD patients and 22 healthy controls participated in a clinical trial in Uppsala, Sweden. The subjects were asked to perform tapping and spiral drawing tests using a smartphone. Patients performed the tests before, and at pre-specified time points after they received 150% of their usual levodopa morning dose. Patients were video recorded and their motor symptoms were assessed by three movement disorder specialists using three Unified PD Rating Scale (UPDRS) motor items from part III, the dyskinesia scoring and the treatment response scale (TRS). The raw tapping and spiral data were processed and analyzed with time series analysis techniques to extract 37 spatiotemporal features. For each of the five scales, separate machine learning models were built and tested by using principal components of the features as predictors and mean ratings of the three specialists as target variables.

    Results

    There were weak to moderate correlations between smartphone-based scores and mean ratings of UPDRS item #23 (0.52; finger tapping), UPDRS #25 (0.47; rapid alternating movements of hands), UPDRS #31 (0.57; body bradykinesia and hypokinesia), sum of the three UPDRS items (0.46), dyskinesia (0.64), and TRS (0.59). When assessing the test-retest reliability of the scores it was found that, in general, the clinical scores had better test-retest reliability than the smartphone-based scores. Only the smartphone-based predicted scores on the TRS and dyskinesia scales had good repeatability with intra-class correlation coefficients of 0.51 and 0.84, respectively. Clinician-based scores had higher effect sizes than smartphone-based scores indicating a better responsiveness in detecting changes in relation to treatment interventions. However, the first principal component of the 37 features was able to capture changes throughout the levodopa cycle and had trends similar to the clinical TRS and dyskinesia scales. Smartphone-based scores differed significantly between patients and healthy controls.

    Conclusions

    Quantifying PD motor symptoms via instrumented, dexterity tests employed in a smartphone is feasible and data from such tests can also be used for measuring treatment-related changes in patients.

  • 524.
    Aghaunor, Lavin
    et al.
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Informatik.
    Fotoh, Xavieria
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Informatik.
    Factors Affecting ecommerce adoption in Nigerian Banks2006Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats
  • 525.
    Aghazadeh, Omid
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Data Driven Visual Recognition2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is mostly about supervised visual recognition problems. Based on a general definition of categories, the contents are divided into two parts: one which models categories and one which is not category based. We are interested in data driven solutions for both kinds of problems.

    In the category-free part, we study novelty detection in temporal and spatial domains as a category-free recognition problem. Using data driven models, we demonstrate that based on a few reference exemplars, our methods are able to detect novelties in ego-motions of people, and changes in the static environments surrounding them.

    In the category level part, we study object recognition. We consider both object category classification and localization, and propose scalable data driven approaches for both problems. A mixture of parametric classifiers, initialized with a sophisticated clustering of the training data, is demonstrated to adapt to the data better than various baselines such as the same model initialized with less subtly designed procedures. A nonparametric large margin classifier is introduced and demonstrated to have a multitude of advantages in comparison to its competitors: better training and testing time costs, the ability to make use of indefinite/invariant and deformable similarity measures, and adaptive complexity are the main features of the proposed model.

    We also propose a rather realistic model of recognition problems, which quantifies the interplay between representations, classifiers, and recognition performances. Based on data-describing measures which are aggregates of pairwise similarities of the training data, our model characterizes and describes the distributions of training exemplars. The measures are shown to capture many aspects of the difficulty of categorization problems and correlate significantly to the observed recognition performances. Utilizing these measures, the model predicts the performance of particular classifiers on distributions similar to the training data. These predictions, when compared to the test performance of the classifiers on the test sets, are reasonably accurate.

    We discuss various aspects of visual recognition problems: what is the interplay between representations and classification tasks, how can different models better adapt to the training data, etc. We describe and analyze the aforementioned methods that are designed to tackle different visual recognition problems, but share one common characteristic: being data driven.

  • 526.
    Aghazadeh, Omid
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Object Segmentation using Spatial and Spatio-Temporal Features.2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 527.
    Aghazadeh, Omid
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Azizpour, Hossein
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Sullivan, Josephine
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Carlsson, Stefan
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Mixture component identification and learning for visual recognition2012Ingår i: Computer Vision – ECCV 2012: 12th European Conference on Computer Vision, Florence, Italy, October 7-13, 2012, Proceedings, Part VI, Springer, 2012, s. 115-128Konferensbidrag (Refereegranskat)
    Abstract [en]

    The non-linear decision boundary between object and background classes - due to large intra-class variations - needs to be modelled by any classifier wishing to achieve good results. While a mixture of linear classifiers is capable of modelling this non-linearity, learning this mixture from weakly annotated data is non-trivial and is the paper's focus. Our approach is to identify the modes in the distribution of our positive examples by clustering, and to utilize this clustering in a latent SVM formulation to learn the mixture model. The clustering relies on a robust measure of visual similarity which suppresses uninformative clutter by using a novel representation based on the exemplar SVM. This subtle clustering of the data leads to learning better mixture models, as is demonstrated via extensive evaluations on Pascal VOC 2007. The final classifier, using a HOG representation of the global image patch, achieves performance comparable to the state-of-the-art while being more efficient at detection time.

  • 528.
    Aghazadeh, Omid
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Carlsson, Stefan
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Large Scale, Large Margin Classification using Indefinite Similarity MeasurensManuskript (preprint) (Övrigt vetenskapligt)
  • 529.
    Aghazadeh, Omid
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Carlsson, Stefan
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Properties of Datasets Predict the Performance of Classifiers2013Ingår i: BMVC 2013 - Electronic Proceedings of the British Machine Vision Conference 2013, British Machine Vision Association, BMVA , 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    It has been shown that the performance of classifiers depends not only on the number of training samples, but also on the quality of the training set [10, 12]. The purpose of this paper is to 1) provide quantitative measures that determine the quality of the training set and 2) provide the relation between the test performance and the proposed measures. The measures are derived from pairwise affinities between training exemplars of the positive class and they have a generative nature. We show that the performance of the state of the art methods, on the test set, can be reasonably predicted based on the values of the proposed measures on the training set. These measures open up a wide range of applications to the recognition community enabling us to analyze the behavior of the learning algorithms w.r.t the properties of the training data. This will in turn enable us to devise rules for the automatic selection of training data that maximize the quantified quality of the training set and thereby improve recognition performance.

  • 530.
    Aghazadeh, Omid
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Carlsson, Stefan
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Properties of Datasets Predict the Performance of Classifiers2013Manuskript (preprint) (Övrigt vetenskapligt)
  • 531.
    Aghazadeh, Omid
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Sullivan, Josephine
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Carlsson, Stefan
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Multi view registration for novelty/background separation2012Ingår i: Computer Vision and Pattern Recognition (CVPR), 2012 IEEE Conference on, IEEE Computer Society, 2012, s. 757-764Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a system for the automatic segmentation of novelties from the background in scenarios where multiple images of the same environment are available e.g. obtained by wearable visual cameras. Our method finds the pixels in a query image corresponding to the underlying background environment by comparing it to reference images of the same scene. This is achieved despite the fact that all the images may have different viewpoints, significantly different illumination conditions and contain different objects cars, people, bicycles, etc. occluding the background. We estimate the probability of each pixel, in the query image, belonging to the background by computing its appearance inconsistency to the multiple reference images. We then, produce multiple segmentations of the query image using an iterated graph cuts algorithm, initializing from these estimated probabilities and consecutively combine these segmentations to come up with a final segmentation of the background. Detection of the background in turn highlights the novel pixels. We demonstrate the effectiveness of our approach on a challenging outdoors data set.

  • 532.
    Aghighi, Meysam
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Bäckström, Christer
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Jonsson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Ståhlberg, Simon
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Analysing Approximability and Heuristics in Planning Using the Exponential-Time Hypothesis2016Ingår i: ECAI 2016: 22ND EUROPEAN CONFERENCE ON ARTIFICIAL INTELLIGENCE, IOS Press, 2016, Vol. 285, s. 184-192Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cost-optimal planning has become a very well-studied topic within planning. Needless to say, cost-optimal planning has proven to be computationally hard both theoretically and in practice. Since cost-optimal planning is an optimisation problem, it is natural to analyse it from an approximation point of view. Even though such studies may be valuable in themselves, additional motivation is provided by the fact that there is a very close link between approximability and the performance of heuristics used in heuristic search. The aim of this paper is to analyse approximability (and indirectly the performance of heuristics) with respect to lower time bounds. That is, we are not content by merely classifying problems into complexity classes - we also study their time complexity. This is achieved by replacing standard complexity-theoretic assumptions (such as P not equal NP) with the exponential time hypothesis (ETH). This enables us to analyse, for instance, the performance of the h(+) heuristic and obtain general trade-off results that correlate approximability bounds with bounds on time complexity.

  • 533.
    Aghighi, Meysam
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Bäckström, Christer
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Jonsson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Ståhlberg, Simon
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Refining complexity analyses in planning by exploiting the exponential time hypothesis2016Ingår i: Annals of Mathematics and Artificial Intelligence, ISSN 1012-2443, E-ISSN 1573-7470, Vol. 78, nr 2, s. 157-175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of computational complexity in planning, and in AI in general, has always been a disputed topic. A major problem with ordinary worst-case analyses is that they do not provide any quantitative information: they do not tell us much about the running time of concrete algorithms, nor do they tell us much about the running time of optimal algorithms. We address problems like this by presenting results based on the exponential time hypothesis (ETH), which is a widely accepted hypothesis concerning the time complexity of 3-SAT. By using this approach, we provide, for instance, almost matching upper and lower bounds onthe time complexity of propositional planning.

  • 534.
    Aghighi, Meysam
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Jonsson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Oversubscription planning: Complexity and compilability2014Ingår i: Proceedings of the Twenty-Eighth AAAI Conference on Artificial Intelligence, AI Access Foundation , 2014, Vol. 3, s. 2221-2227Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many real-world planning problems are oversubscription problems where all goals are not simultaneously achievable and the planner needs to find a feasible subset. We present complexity results for the so-called partial satisfaction and net benefit problems under various restrictions; this extends previous work by van den Briel et al. Our results reveal strong connections between these problems and with classical planning. We also present a method for efficiently compiling oversubscription problems into the ordinary plan existence problem; this can be viewed as a continuation of earlier work by Keyder and Geffner.

  • 535.
    Aghili, Mohammed
    Linköpings universitet, Institutionen för datavetenskap.
    Jämförelse av aggregeringswebbdelar i MOSS 20072010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En typisk funktion på startsidan till många webbportaler är den webbdel som presenterar exempelvis desenaste blogginläggen, nyheterna eller händelserna som har lagts till på webbplatsen. Dessa funktioner ärkända som aggreggeringswebbdelar. Eftersom startsidan är den sida som besöks mest jämfört med alla andrawebbsidor i portalen innebär det i sin tur att denna funktion utnyttjas väldigt ofta.Detta arbete syftar till att finna ett antal olika metoder som kan användas för att uppnå denna funktion ochatt ta reda på hur väl dessa webbdelar presterar.Denna rapport presenterar både de olika metoder som fanns och resultaten på en systematisk testning avdessa. Resultaten av testerna presenteras på ett överskådligt sätt.Slutligen dras slutsatser angående resultaten. Resultaten förespråkar inte en specifik metod, den metod somlämpar sig bäst för varje enskild sammanhang avgörs till största del av andra faktorer såsom frekvens avbesökare eller ändringar på innehållet som metoden söker igenom.

  • 536.
    Agiorgitis, Georgios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för informatik (IK).
    ICTs use in the public Greek Primary Schools: the teachers' experiences2017Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Education is a sector that has the potential to become a critical area of action for the full exploitation of ICT. Educational systems of developed and developing countries have an ever-increasing tendency to apply ICT to education, in an attempt to prepare their students for the future's society. This thesis attempted to explore what kind of ICT is used in the Greek Primary Schools and develop an understanding on the relationship between the ICT and the teachers. The philosophical background is post-phenomenology and the methods chosen for collecting data for this research are policy document analysis and interviews. The empirical findings show that various ICT are being used in the classrooms of the Greek Primary Schools,  others widely and others occasionally. The research compares the legal framework revolving around ICT in Primary Schools in Greece, with the teachers' own experiences and shows that the guidelines suggested by the Greek Ministry of Education cannot be followed easily, due to economical and pedagogical reasons. It also investigates the ICT's effects on the teachers and the students through the teachers' own words and perceptions. The effects are mostly positive, there are mentioned however, some negative ones to take into consideration. Finally, the research presents a number of sectors where the participant teachers suggested there is room for improvement. By comparing the legal framework with the situation in the Primary Schools, this research adds a new perspective to the previous literature. The findings show that the current situation can be improved and the teachers' statements may trigger further research.

  • 537.
    Agiorgitis, Georgios
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för informatik (IK).
    Bennani, Mohamed
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för informatik (IK).
    Drakoularakos, Mixalis
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för informatik (IK).
    McConnon, Paul John
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för informatik (IK).
    Digital Wall: The University’s learning and information space2017Studentarbete övrigt, 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A North American university is engaged in a large transformation project involving the wholeorganisation. Students, Lecturers, departments and additional questions from the shared leadership team are engaging in defining the services offered, in particular from the university library and its associated sub-services. It is an exciting time for the University as it seeks to not only define its services but also how these can be created and consumed.There are many aspects to this re-organisation and many items to be addressed. In this report,we look at the current situation at the University, as well as taking into account the aspirations of the stakeholders. We start by drawing out a Rich Picture, part of Soft System Methodology (SSM) (Checkland, 1981) which we use in order to spot opportunities that are available for further exploration. Much of the information that we use comes from material supplied by the University itself as well as interviews with the Head of Library services and Head of Library IT. We look indepth at how SSM assists in this process of evaluation through its focus on participation and how it may assist us to understand the many different perspectives collected in our research. SSM consequently assists in defining problems with solutions to any areas that have drawn our attention. Following the evaluation of collected data, discussions and our own observations, we identify that a digital wall that is being proposed for the redesigned library presents an opportunity to explore possibilities for exploitation of this technology. Further research on other digital walls such as Brisbane’s Cube (Abdi et al, 2014), and Auraria Library’s Discovery Wall(Burch, 2016) shows some of the uses that these walls have been put to and how the Institutions use them. We then use a number of models to evaluate the data that we collected on digital walls and from the North American University and analyse it in order to inform our thinking. These models can be used independently or collectively to evaluate data from different perspectives. As such we were able to look at problems and solutions from the perspective of many of the actors involved in shaping the future library services. These models and results are discussed in the report. Finally, we take our results and make a number of proposals for the North American University digital wall along with the relevant justifications at the end of this report.

  • 538. Agić, Zeljko
    et al.
    Tiedemann, Jörg
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Språkvetenskapliga fakulteten, Institutionen för lingvistik och filologi.
    Merkler, Danijela
    Krek, Simon
    Dobrovoljc, Kaja
    Moze, Sara
    Cross-lingual Dependency Parsing of Related Languages with Rich Morphosyntactic Tagsets2014Ingår i: Proceedings of the EMNLP’2014 Workshop on Language Technology for Closely Related Languages and Language Variants, 2014, s. 13-24Konferensbidrag (Refereegranskat)
  • 539.
    Agnesson, Daniel
    et al.
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Informatik.
    Önder, Necip Yener
    Högskolan i Jönköping, Internationella Handelshögskolan, IHH, Informatik.
    Customer Maturity Analysis Tool: A case study in designing a Customer MaturityAnalysis Tool2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The IT consultancy industry is characterized by knowledge intensive implementationprojects related to varying levels of standardized information system software. When faced with a large implementation project at a previously unknown customer various assessmentsis usually conducted to identify the level of fit between the software and organizationin order to plan and structure the implementation process. However, there are several aspects of the customer organization that potentially can affect the end result as well as the implementation process that is unrelated to the fit between the software and the implementation organization as well as the potency of the implementation method. By conducting measurements of these maturity factors within the customer organization the implementing procedure can be modified based on the customer maturity level in order to become more aligned with the capabilities present in the customer organization.

    Research question: Which aspects need to be covered by a Customer Maturity Analysis Tool (CMAT) in order to evaluate the pre implementation maturity for potential customersof our case company and how should these aspects be organized and measured? The first task of the research process was to create an underlying model of maturity perspectives and aspects to structure the literature review as well as the empirical data collection. It was decided to adhere to a deductive approach where the theoretical model would be validated and if necessary modified in accordance to feedback from potential users of the CMAT within the case company. This procedure was repeated in the creation of measurements and maturity levels for the aspects to be used in the tool. The research process would therefore transition from a general model based on literature review, through a iterative feedback loop to a final model tailored to the specific requirementsof the case company. The final CMAT ended up containing four main perspectives of customer maturity; ITi nfrastructure, Culture, Process and Business Governance. These four perspectives were in turn divided into subgroups in order to be able to aggregate and compare differentaspects of the perspectives with each other.

  • 540.
    Agnihotri, Mohit Kumar
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Energy efficient topology formation for Bluetooth mesh networks using heterogeneous devices2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Internet of things (IoT) is the latest trend in our living spaces allowing machine to machine (M2M) communications at the extensive scale. To enable massive M2M communication and portable devices to run on limited power supplies for the extended duration of time, low-cost energy efficient wireless technologies are needed. Among the many competing technologies including Wi-Fi, Bluetooth has shown the potential to be one of the strong candidates to act as the connectivity solution for the IoT especially after the introduction of Bluetooth Low Energy (BLE). Nowadays BLE is one of the biggest players in the market of short-range wireless technologies. By 2020, nearly 30 billion BLE devices in the form of mobile phones, tablets, sports utilities, sensors, security systems and health monitors are expected to be shipped. This proliferation of low-cost devices may for the first time actualize the vision of IoT.

    This thesis studies various mesh topology formation techniques that can be used to aid the development of large-scale networks in capillary networks focusing on BLE. In particular, the thesis focuses on how mesh networks can be established over BLE communications especially exploiting the heterogeneous characteristics of the devices. A novel algorithm is proposed called Topology Formation considering Role Suitability (TFRS) to maximize the network lifetime. The algorithm uses a newly introduced metric called role suitability metric (RSM) to assign the best role among master, relay and slave to a device. The RSM metric bases its decision on various device characteristics including, but not limited to, energy, mobility, and computational capability. We use the system-level simulation to evaluate the performance of the proposed algorithm against a reference under homogeneous deployment scenario consisting of heterogeneous devices.

    Results show that the network lifetime can be improved significantly when the topology is formed considering the device characteristics for both master role selection and relay selection. TFRS can achieve moderate improvements ranging from 20% to 40% varying on the deployment characteristics over the reference case.

  • 541.
    Agrawal, P.
    et al.
    Uppsala Universitet.
    Ahlén, Anders
    Uppsala Universitet.
    Olofsson, Tomas
    Uppsala Universitet.
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Long Term Channel Characterization for Energy Efficient Transmission in Industrial Environments2014Ingår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 62, nr 8, s. 3004-3014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the challenges for a successful use of wireless sensor networks in process industries is to design networks with energy efficient transmission, to increase the lifetime of the deployed network while maintaining the required latency and bit-error rate. The design of such transmission schemes depend on the radio channel characteristics of the region. This paper presents an investigation of the statistical properties of the radio channel in a typical process industry, particularly when the network is meant to be deployed for a long time duration, e.g., days, weeks, and even months. Using 17–20-h-long extensive measurement campaigns in a rolling mill and a paper mill, we highlight the non-stationarity in the environment and quantify the ability of various distributions, given in the literature, to describe the variations on the links. Finally, we analyze the design of an optimal received signal-to-noise ratio (SNR) for the deployed nodes and show that improper selection of the distribution for modeling of the variations in the channel can lead to an overuse of energy by a factor of four or even higher.

  • 542.
    Agrawal, Piyush
    et al.
    Uppsala University.
    Ahlén, Anders
    Uppsala University.
    Olofsson, Tomas
    Uppsala University.
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Characterization of Long Term Channel Variations in Industrial Wireless Sensor Networks2014Ingår i: IEEE International Conference on Communications (ICC'14), IEEE conference proceedings, 2014Konferensbidrag (Refereegranskat)
  • 543.
    Agrawal, Vikas
    et al.
    IBM Research, , India.
    Archibald, Christopher
    Mississippi State University, Starkville, United States.
    Bhatt, Mehul
    University of Bremen, Bremen, Germany.
    Bui, Hung Hai
    Laboratory for Natural Language Understanding, Sunnyvale CA, United States.
    Cook, Diane J.
    Washington State University, Pullman WA, United States.
    Cortés, Juan
    University of Toulouse, Toulouse, France.
    Geib, Christopher W.
    Drexel University, Philadelphia PA, United States.
    Gogate, Vibhav
    Department of Computer Science, University of Texas, Dallas, United States.
    Guesgen, Hans W.
    Massey University, Palmerston North, New Zealand.
    Jannach, Dietmar
    Technical university Dortmund, Dortmund, Germany.
    Johanson, Michael
    University of Alberta, Edmonton, Canada.
    Kersting, Kristian
    Fraunhofer-Institut für Intelligente Analyse- und Informationssysteme (IAIS), Sankt Augustin, Germany; The University of Bonn, Bonn, Germany.
    Konidaris, George
    Massachusetts Institute of Technology (MIT), Cambridge MA, United States.
    Kotthoff, Lars
    INSIGHT Centre for Data Analytics, University College Cork, Cork, Ireland.
    Michalowski, Martin
    Adventium Labs, Minneapolis MN, United States.
    Natarajan, Sriraam
    Indiana University, Bloomington IN, United States.
    O’Sullivan, Barry
    INSIGHT Centre for Data Analytics, University College Cork, Cork, Ireland.
    Pickett, Marc
    Naval Research Laboratory, Washington DC, United States.
    Podobnik, Vedran
    Telecommunication Department of the Faculty of Electrical Engineering and Computing, University of University of Zagreb, Zagreb, Croatia.
    Poole, David
    Department of Computer Science, University of British Columbia, Vancouver, Canada.
    Shastri, Lokendra
    Infosys, , India.
    Shehu, Amarda
    George Mason University, Washington, United States.
    Sukthankar, Gita
    University of Central Florida, Orlando FL, United States.
    The AAAI-13 Conference Workshops2013Ingår i: The AI Magazine, ISSN 0738-4602, Vol. 34, nr 4, s. 108-115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The AAAI-13 Workshop Program, a part of the 27th AAAI Conference on Artificial Intelligence, was held Sunday and Monday, July 14-15, 2013, at the Hyatt Regency Bellevue Hotel in Bellevue, Washington, USA. The program included 12 workshops covering a wide range of topics in artificial intelligence, including Activity Context-Aware System Architectures (WS-13-05); Artificial Intelligence and Robotics Methods in Computational Biology (WS-13-06); Combining Constraint Solving with Mining and Learning (WS-13-07); Computer Poker and Imperfect Information (WS-13-08); Expanding the Boundaries of Health Informatics Using Artificial Intelligence (WS-13-09); Intelligent Robotic Systems (WS-13-10); Intelligent Techniques for Web Personalization and Recommendation (WS-13-11); Learning Rich Representations from Low-Level Sensors (WS-13-12); Plan, Activity,, and Intent Recognition (WS-13-13); Space, Time, and Ambient Intelligence (WS-13-14); Trading Agent Design and Analysis (WS-13-15); and Statistical Relational Artificial Intelligence (WS-13-16)

  • 544.
    Agreste, Santa
    et al.
    Department of Mathematics and Computer Science, Physical Sciences and Earth Sciences, University of Messina.
    De Meo, Pasquale
    of Ancient and Modern Civilizations, University of Messina.
    Fiumara, Giacomo
    Department of Mathematics and Computer Science, Physical Sciences and Earth Sciences, University of Messina.
    Piccione, Giuseppe
    Department of Mathematics and Computer Science, Physical Sciences and Earth Sciences, University of Messina.
    Piccolo, Sebastiano
    Department of Management Engineering - Engineering Systems Division at the Technical University of Denmark.
    Rosaci, Domenico
    DIIES Department, University of Reggio Calabria Via Graziella.
    Sarné, Giuseppe M. L.
    DICEAM Department, University of Reggio Calabria Via Graziella.
    Vasilakos, Athanasios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    An empirical comparison of algorithms to findcommunities in directed graphs and theirapplication in Web Data Analytics2017Ingår i: IEEE Transactions on Big Data, E-ISSN 2332-7790, Vol. 3, nr 3, s. 289-306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Detecting communities in graphs is a fundamental tool to understand the structure of Web-based systems and predict their evolution. Many community detection algorithms are designed to process undirected graphs (i.e., graphs with bidirectional edges) but many graphs on the Web - e.g. microblogging Web sites, trust networks or the Web graph itself - are often directed. Few community detection algorithms deal with directed graphs but we lack their experimental comparison. In this paper we evaluated some community detection algorithms across accuracy and scalability. A first group of algorithms (Label Propagation and Infomap) are explicitly designed to manage directed graphs while a second group (e.g., WalkTrap) simply ignores edge directionality; finally, a third group of algorithms (e.g., Eigenvector) maps input graphs onto undirected ones and extracts communities from the symmetrized version of the input graph. We ran our tests on both artificial and real graphs and, on artificial graphs, WalkTrap achieved the highest accuracy, closely followed by other algorithms; Label Propagation has outstanding performance in scalability on both artificial and real graphs. The Infomap algorithm showcased the best trade-off between accuracy and computational performance and, therefore, it has to be considered as a promising tool for Web Data Analytics purposes.

  • 545. Agugiaro, G.
    et al.
    Remondino, F.
    Girardi, G.
    von Schwerin, J.
    Richards-Rissetto, Heather
    Umeå universitet, Humanistiska fakulteten, Humlab.
    De Amicis, R.
    A web-based interactive tool for multi-resolution 3d models of a maya archaeological site2011Ingår i: 4TH ISPRS INTERNATIONAL WORKSHOP 3D-ARCH 2011: 3D VIRTUAL RECONSTRUCTION AND VISUALIZATION OF COMPLEX ARCHITECTURES / [ed] Remondino, F; ElHakim, S, 2011, nr W16, s. 23-30Konferensbidrag (Refereegranskat)
    Abstract [en]

    Continuous technological advances in surveying, computing and digital-content delivery are strongly contributing to a change in the way Cultural Heritage is "perceived": new tools and methodologies for documentation, reconstruction and research are being created to assist not only scholars, but also to reach more potential users (e.g. students and tourists) willing to access more detailed information about art history and archaeology. 3D computer-simulated models, sometimes set in virtual landscapes, offer for example the chance to explore possible hypothetical reconstructions, while on-line GIS resources can help interactive analyses of relationships and change over space and time. While for some research purposes a traditional 2D approach may suffice, this is not the case for more complex analyses concerning spatial and temporal features of architecture, like for example the relationship of architecture and landscape, visibility studies etc. The project aims therefore at creating a tool, called "QueryArch3D" tool, which enables the web-based visualisation and queries of an interactive, multi-resolution 3D model in the framework of Cultural Heritage. More specifically, a complete Maya archaeological site, located in Copan (Honduras), has been chosen as case study to test and demonstrate the platform's capabilities. Much of the site has been surveyed and modelled at different levels of detail (LoD) and the geometric model has been semantically segmented and integrated with attribute data gathered from several external data sources. The paper describes the characteristics of the research work, along with its implementation issues and the initial results of the developed prototype. [GRAPHICS] .

  • 546.
    Aguilar, Xavier
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), High Performance Computing and Visualization (HPCViz).
    Fuerlinger, Karl
    Laure, Erwin
    KTH, Skolan för datavetenskap och kommunikation (CSC), High Performance Computing and Visualization (HPCViz).
    Automatic On-Line Detection of MPI Application Structure with Event Flow Graphs2015Ingår i: EURO-PAR 2015: PARALLEL PROCESSING, Springer Berlin/Heidelberg, 2015, s. 70-81Konferensbidrag (Refereegranskat)
    Abstract [en]

    The deployment of larger and larger HPC systems challenges the scalability of both applications and analysis tools. Performance analysis toolsets provide users with means to spot bottlenecks in their applications by either collecting aggregated statistics or generating loss-less time-stamped traces. While obtaining detailed trace information is the best method to examine the behavior of an application in detail, it is infeasible at extreme scales due to the huge volume of data generated. In this context, knowing the application structure, and particularly the nesting of loops in iterative applications is of great importance as it allows, among other things, to reduce the amount of data collected by focusing on important sections of the code. In this paper we demonstrate how the loop nesting structure of an MPI application can be extracted on-line from its event flow graph without the need of any explicit source code instrumentation. We show how this knowledge on the application structure can be used to compute postmortem statistics as well as to reduce the amount of redundant data collected. To that end, we present a usage scenario where this structure information is utilized on-line (while the application runs) to intelligently collect fine-grained data for only a few iterations of an application, considerably reducing the amount of data gathered.

  • 547.
    Aguilar, Xavier
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC.
    Schliephake, Michael
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC.
    Vahtras, Olav
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC.
    Gimenez, Judit
    Barcelona Supercomputing Center, Universitat Politecnica de Catalunya, Barcelona, Spain.
    Laure, Erwin
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC.
    Scaling Dalton, a molecular electronic structure program2011Ingår i: Seventh International Conference on e-Science, e-Science 2011, 5-8 December 2011, Stockholm, Sweden, IEEE conference proceedings, 2011, s. 256-262Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dalton is a molecular electronic structure program featuring common methods of computational chemistry that are based on pure quantum mechanics (QM) as well as hybrid quantum mechanics/molecular mechanics (QM/MM). It is specialized and has a leading position in calculation of molecular properties with a large world-wide user community (over 2000 licenses issued). In this paper, we present a characterization and performance optimization of Dalton that increases the scalability and parallel efficiency of the application. We also propose asolution that helps to avoid the master/worker design of Daltonto become a performance bottleneck for larger process numbers and increase the parallel efficiency.

  • 548.
    Aguirre Quiroz, Gerardo Daniel
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Evaluation of the potential benefits of using Licensed Shared Access in the Americas2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Internet har blivit en allmänt förekommande service och mänskliga behov. Mobilnät har kämpat med "Mobile Data Tsunami", en ökning av mobilt konsumtions bredband på grund av snabbare nät, kraftfulla enheter och fler trafik-krävande applikationer, samt en högre penetration volym. Enligt Cisco mobil datatrafik förväntas växa till 15,9 exabyte per månad år 2018, är att nästan elva gånger den mobila datatrafiken 2013.

    Spektrum är en nyckelfaktor för nätutbyggnad, eftersom det avgör kapaciteten i nätet. Ändå är spektrum en begränsad naturresurs, dvs en ändlig, icke-ändliga gemensam resurs. För att uppfylla de höga resultatmål för framtida mobilt bredband (MBB) system, en effektivare användning och effektivare hantering av spektrumresurser måste utvecklas.

    Licensierad Shared Access är en ny kompletterande tillgång spektrum system som gör det möjligt att dela med sig av delvis använda licensierat spektrum från en befintlig (t.ex. en statlig organisation), med ett begränsat antal "LSA licenstagare" (t.ex. Mobile Network Operators). LSA Avtalet följer fördefinierade dynamiska eller statiska delningsvillkor, som bestämmer var, när och hur man använder den dominerande operatörens spektrumet.

    Genomförandet av Licensed delat tillträde behöver stöd från en mycket bra regelverk och följer den harmoniserade vägen spektrumet. Spectral harmonisering, eller en enhetlig fördelning av frekvensband över hela regionen sänker teknikkostnader, vilket gör det lättare för något land att överväga dess genomförande. En gång är anpassad efter hela regioner, är skalfördelar uppnås.

    Några första steg mot en ny ram baserad på LSA har fått i Europa och Nordamerika, men att betrakta LSA som ett verkligt alternativ, krävs en fullständig analys med tanke på fler marknader. Det är viktigt att fundera på hur andra regioner runt om i världen kan påverkas av denna nya metod för att se om LSA är en möjlig lösning eller inte.

    Ansatsen i denna forskning omfattar samspelet mellan tekniska, marknadsmässiga och rättsliga villkoren i Amerika för att presentera det möjliga värdet av LSA. Den första delen av studien behandlar analysen av de tekniska aspekterna av LSA. Följande delar behandlar vilka villkor utvärderingen görs. Först behandlar studien med de marknadsförhållanden som finns i Amerika som helhet, för att sedan ta itu med en mer specifik undersökning av marknaden och regler i utvalda länder iregionen.

    Forskningen visade hur det finns flera sätt LSA kan ge positivt värde till etablerade och nya aktörer i Amerika, speciellt i högtrafikerade områden, och / eller inomhusmiljöer. Men trots fördelarna med LSA, är tidpunkten inte där ännu. Regionen har fortfarande gott om spektrum att fördelas exklusiv spektrum, som föredras av operatörerna. Den låg mobilpenetration bredband i större delen av regionen är också en faktor för det låga värdet av LSA i tiden för denna studie.

  • 549.
    Aguiño, Gonzalo Iglesias
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Performance of VoIP strategies for hybrid Mobile Ad Hoc Networks2007Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Last decade, a lot of research has been done in wireless communication technologies. Mobile

    nodes such personal digital assistants (PDAs), notebooks and cell phones are nowadays used

    in human’s daily life.

    MANETs are networks consisting of two or more mobile nodes equipped with wireless

    communication and networking capabilities, but they don’t have any network centrilized

    infrastructure.

    In last few years, MANETs have been emerged to be an important researched subject in the

    field of wireless networking.

    MANETs are autonomous; however they can communicate with other external networks such

    the internet. They are linked to such external networks by mobile nodes acting as gateways.

    This kind of networks is known as hybrid MANETs.

    Voice over Internet Protocol (VoIP), is a technology that allows you to make voice calls using

    a Internet connection instead of a regular (or analog) phone line.

    The goal of this thesis is evaluate the performance of VoIP strategies for hybrid MANETs.

    Two different aspects are evaluated, the session establishment performance and the voice

    quality.

    Network Simulator 2 is used to run several simulations, two different applications are used to

    run voice simulations (Session Initiation Protocol and Exponential traffic generator). We

    evaluate two different cases for voice traffics, voice calls between two MANET nodes and

    voice calls between MANET nodes and external nodes.

    After running the simulations, there are some performance parameters which will reveal the

    results. The key findings of the simulations are: adding gateways, number of voice traffic

    flows and the number of hops between source and destinations. There are some interesting

    results which reveal for example, that adding gateways is not always beneficial.

  • 550.
    Agushi, Camrie
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för programvarusystem.
    Innovation inom Digital Rights Management2005Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    Uppsatsen behandlar ämnet Digital Rights Management (DRM), mer specifikt innovationstrenderna inom DRM. Fokus är på tre drivkrafter i DRM. För det första, DRM teknologier, för det andra, DRM standarder, och för det tredje, DRM interoperabilitet. Dessa drivkrafter diskuteras och analyseras för att kunna utforska innovationstrenderna inom DRM. Avslutningsvis formas en multifacetterad översikt av dagens DRM-kontext. En slutsats är att aspekten av Intellectual Property Rights anses vara en viktig indikator av den riktning som DRM innovationen går mot.

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