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  • 1.
    Abdelraheem, Mohamed Ahmed
    et al.
    SICS Swedish ICT AB, SWE.
    Gehrmann, Christian
    SICS Swedish ICT AB, SWE.
    Lindström, Malin
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Nordahl, Christian
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Executing Boolean queries on an encrypted Bitmap index2016In: CCSW 2016 - Proceedings of the 2016 ACM Cloud Computing Security Workshop, co-located with CCS 2016, Association for Computing Machinery (ACM), 2016, p. 11-22Conference paper (Refereed)
    Abstract [en]

    We propose a simple and efficient searchable symmetric encryption scheme based on a Bitmap index that evaluates Boolean queries. Our scheme provides a practical solution in settings where communications and computations are very constrained as it offers a suitable trade-off between privacy and performance.

  • 2.
    Adamov, Alexander
    et al.
    Kharkiv Natl Univ Radio Elect, NioGuard Secur Lab, Kharkov, Kharkiv Oblast, Ukraine..
    Carlsson, Anders
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    A Sandboxing Method to Protect Cloud Cyberspace2015In: PROCEEDINGS OF 2015 IEEE EAST-WEST DESIGN & TEST SYMPOSIUM (EWDTS), IEEE Communications Society, 2015Conference paper (Refereed)
    Abstract [en]

    This paper addresses the problem of protecting cloud environments against targeted attacks, which have become a popular mean of gaining access to organization's confidential information and resources of cloud providers. Only in 2015 eleven targeted attacks have been discovered by Kaspersky Lab. One of them - Duqu2 - successfully attacked the Lab itself. In this context, security researchers show rising concern about protecting corporate networks and cloud infrastructure used by large organizations against such type of attacks. This article describes a possibility to apply a sandboxing method within a cloud environment to enforce security perimeter of the cloud.

  • 3.
    Angelova, Milena
    et al.
    Technical University of Sofia-branch Plovdiv, BUL.
    Vishnu Manasa, Devagiri
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Boeva, Veselka
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    Lavesson, Niklas
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    An Expertise Recommender SystemBased on Data from an InstitutionalRepository (DiVA)2018In: Proceedings of the 22nd edition of the International Conference on ELectronic PUBlishing, 2018Conference paper (Refereed)
    Abstract [en]

    Finding experts in academics is an important practical problem, e.g. recruiting reviewersfor reviewing conference, journal or project submissions, partner matching for researchproposals, finding relevant M. Sc. or Ph. D. supervisors etc. In this work, we discuss anexpertise recommender system that is built on data extracted from the Blekinge Instituteof Technology (BTH) instance of the institutional repository system DiVA (DigitalScientific Archive). DiVA is a publication and archiving platform for research publicationsand student essays used by 46 publicly funded universities and authorities in Sweden andthe rest of the Nordic countries (www.diva-portal.org). The DiVA classification system isbased on the Swedish Higher Education Authority (UKÄ) and the Statistic Sweden's (SCB)three levels classification system. Using the classification terms associated with studentM. Sc. and B. Sc. theses published in the DiVA platform, we have developed a prototypesystem which can be used to identify and recommend subject thesis supervisors inacademy.

  • 4.
    Brodka, Piotr
    et al.
    Wroclaw Univ Technol, Inst Informat, PL-50370 Wroclaw, Poland..
    Sobas, Mateusz
    Wroclaw Univ Technol, Inst Informat, PL-50370 Wroclaw, Poland..
    Johnson, Henric
    Blekinge Institute of Technology, School of Computing.
    Profile Cloning Detection in Social Networks2014In: 2014 EUROPEAN NETWORK INTELLIGENCE CONFERENCE (ENIC), IEEE Computer Society, 2014, p. 63-68Conference paper (Refereed)
    Abstract [en]

    Profile cloning is a severe security issue in social networks since it is used to make a profile identical to existing ones. Profile cloning detection creates a possibility to detect frauds that would use people's trust to gather social information. This paper proposes two novel methods of profile cloning detection and also presents state-of-the-art research. The first method is based on the similarity of attributes from both profiles and the second method is based on the similarity of relationship networks. The methods are further evaluated with experiments and the results clearly describes that the proposed methods are useful and efficient compared to existing methods. The paper also stress that profile cloning in Facebook is not only possible but also fairly easy to perform.

  • 5.
    Clementson, Martin
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Augustsson, John
    User Study of Quantized MIP Level Data In Normal Mapping Techniques2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

     The standard MIP mapping technique halves the resolution of textures for each level of the MIP chain. In this thesis the bits per pixel(bpp) is reduced as well. Normal maps are generally used with MIP maps, and todays industry standard for these are usually 24 bpp.The reduction is simulated as there is currently no support for the lower bpp in GPU hardware.

    Objectives: To render images of normal mapped objects with decreasing bpp for each level in a MIP chain and evaluate these against the standard MIP mapping technique using a subjective user study and an objective image comparison method.

    Methods: A custom software is implemented to render the images with quantized normal maps manually placed in a MIP chain. For the subjective experiment a 2AFC test is used, and the objective part consists of a PDIFF test for the images.

    Results: The results indicate that as the MIP level is increased and the bpp is lowered, users can increasingly see a difference.

    Conclusions: The results show that participants can see a difference as the bpp is reduced, which indicates normal mapping as not suitable for this method, however further study is required before this technique can be dismissed as an applicable method

  • 6.
    Erik, Wikström
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Expected Damage of Projectile-Like Spell Effects in Games2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background. Many video games make use of particle effects to portray magic abilities known as spells. Different spells may have large variation in behaviour and colour. Aside from their different appearance, the spells often deal a different amount of damage.

    Objectives. The aim of this paper is to evaluate how velocity, scale, and direction, as well as the colour orange and blue affect the expected damage of a projectile-like spell.Methods. A perceptual experiment with a 2AFC was conducted where participants compared various spells with different values of velocity, scale, direction, and colour. The participants were asked to select the spell that they expect to deal the most damage.

    Results. Scale had a larger impact on the expected damage of a spell than velocity. The largest and fastest spells with an added sinus based direction in the x-axis were expected to cause the most damage. However, the difference between these spells and the largest and fastest spells without the added direction was not found to be statistically significant. The orange spells were rated as more damage causing in all cases compared to the blue spells. The difference between the blue and orange preference in two of these cases were however not large enough to be statistically significant.

    Conclusions. The results showed that the visual attributes of a particle-based spell affect its perceived damage with the scale having a greater impact than velocity and orange being the colour most often associated with higher damage. The effect of an added direction could not be evaluated due the result from the direction spells not being statistically significant.

  • 7.
    Fricker, Samuel
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Maksimov, Yuliyan
    Fachhochschule Nordwestschweiz, CHE.
    Pricing of data products in data marketplaces2017In: Lecture Notes in Business Information Processing / [ed] Werder K.,Ojala A.,Holmstrom Olsson H., Springer Verlag , 2017, Vol. 304, p. 49-66Conference paper (Refereed)
    Abstract [en]

    Mobile computing and the Internet of Things promises massive amounts of data for big data analytic and machine learning. A data sharing economy is needed to make that data available for companies that wish to develop smart systems and services. While digital markets for trading data are emerging, there is no consolidated understanding of how to price data products and thus offer data vendors incentives for sharing data. This paper uses a combined keyword search and snowballing approach to systematically review the literature on the pricing of data products that are to be offered on marketplaces. The results give insights into the maturity and character of data pricing. They enable practitioners to select a pricing approach suitable for their situation and researchers to extend and mature data pricing as a topic. © Springer International Publishing AG 2017.

  • 8.
    Frid Kastrati, Mattias
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Goswami, Prashant
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Selective rasterized ray-traced reflections on the GPU2016In: Eurographics Proceedings STAG 2016 / [ed] Andrea Giachetti and Silvia Biasotti and Marco Tarini, Eurographics - European Association for Computer Graphics, 2016Conference paper (Refereed)
    Abstract [en]

    Ray-tracing achieves impressive effects such as realistic reflections on complex surfaces but is also more computationally expensive than classic rasterization. Rasterized ray-tracing methods can accelerate ray-tracing by taking advantage of the massive parallelization available in the rasterization pipeline on the GPU. In this paper, we propose a selective rasterized raytracing method that optimizes the rasterized ray-tracing by selectively allocating computational resources to reflective regions in the image. Our experiments suggest that the method can speed-up the computation by up to 4 times and also reduce the memory footprint by almost 66% without affecting the image quality. We demonstrate the effectiveness of our method using complex scenes and animations.

  • 9.
    Hu, Yan
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Sundstedt, Veronica
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Exploring Biometrics as an Evaluation Technique for Digital Game Addiction Prevention2018In: Journal of Behavioral Addictions, ISSN 2062-5871, E-ISSN 2063-5303, Vol. 7, p. 15-15Article in journal (Other academic)
  • 10.
    Jerčić, Petar
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Sennersten, Charlotte
    CSIRO Mineral Resources, AUS.
    Lindley, Craig
    Intelligent Sensing and Systems Laboratory, CSIRO ICT Centre, AUS .
    Modeling cognitive load and physiological arousal through pupil diameter and heart rate2018In: Multimedia tools and applications, ISSN 1380-7501, E-ISSN 1573-7721Article in journal (Refereed)
    Abstract [en]

    This study investigates individuals’ cognitive load processing abilities while engaged on a decision-making task in serious games, to explore how a substantial cognitive load dominates over the physiological arousal effect on pupil diameter. A serious game was presented to the participants, which displayed the on–line biofeedback based on physiological measurements of arousal. In such dynamic decision-making environment, the pupil diameter was analyzed in relation to the heart rate, to evaluate if the former could be a useful measure of cognitive abilities of individuals. As pupil might reflect both cognitive activity and physiological arousal, the pupillary response will show an arousal effect only when the cognitive demands of the situation are minimal. Evidence shows that in a situation where a substantial level of cognitive activity is required, only that activity will be observable on the pupil diameter, dominating over the physiological arousal effect indicated by the pupillary response. It is suggested that it might be possible to design serious games tailored to the cognitive abilities of an individual player, using the proposed physiological measurements to observe the moment when such dominance occurs. © 2018, The Author(s).

  • 11.
    Karlsson, Christoffer
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies. 1987.
    The performance impact from processing clipped triangles in state-of-the-art games.2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background. Modern game applications pressures hardware to its limits, and affects how graphics hardware and APIs are designed. In games, rendering geometry plays a vital role, and the implementation of optimization techniques, such as view frustum culling, is generally necessary to meet the quality expected by the customers. Failing to optimize a game application can potentially lead to higher system requirements or less quality in terms of visual effects and content. Many optimization techniques, and studies of the performance of such techniques exist. However, no research was found where the utilization of computational resources in the GPU, in state-of-the-art games, was analyzed.

    Objectives. The aim of this thesis was to investigate the potential problem of commercial game applications wasting computational resources. Specifically, the focus was set on the triangle data processed in the geometry stage of the graphics pipeline, and the amount of triangles discarded through clipping.

    Methods. The objectives were met by conducting a case study and an empirical data analysis of the amount triangles and entire draw calls that were discarded through clipping, as well as the vertex data size and the time spent on processing these triangles, in eight games. The data was collected using Triangelplockaren, a tool which collects the triangle data that reaches the rasterizer stage. This data was then analyzed and discussed through relational findings in the results.

    Results. The results produced consisted of 30 captures of benchmark and gameplay sessions. The average of each captured session was used to make observations and to draw conclusions.

    Conclusions. This study showed evidence of noteworthy amounts of data being processed in the GPU which is discarded through clipping later in the graphics pipeline. This was seen in all of the game applications included in this study. While it was impossible to draw conclusions regarding the direct impact on performance, it was safe to say that the performance relative to the geometry processed was significant in each of the analyzed cases, and in many cases extreme.

  • 12.
    Karlsson, Christoffer
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Schachtschabel, Lukas
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Legible Tone Mapping: An evaluation of text processed by tone mapping operators2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Context. Tone mapping operators (TMO) are designed to reduce the dynamicrange of high dynamic range images so that they can be presented onstandard dynamic range display devices. Many operators focus on creatingperceptually similar images.

    Objectives. This thesis aims to investigate how dierent TMOs reproducephotographed text. The underlying reason being to test the contrast reproductionof each TMO.

    Methods. An experiment has been performed in order to investigate thelegibility of photographed and tone mapped text. A user study was conducted,in which 18 respondents partook, where respondents were to ratehow much of the text in each photograph that they found to be legible.

    Results. Due to low participation, the results of the experiment are mostlyinconclusive. However, some tendencies have been observed and analyzedand they fall in line with previous work within the area.

    Conclusions. The main conclusion that can be drawn from the results isthat the TMO presented by Kuang [11] is rated as better than the TMOsby Fattal [7] and Kim and Kautz [10].

  • 13.
    Karlsson, Julia
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Using graphical attributes to influence the perception of safety in a 3D environment2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Context. Most games make use of graphics to create an environment that fits the mood they wish to convey. To use a game's graphical attributes such as colour, shape and texture to their utmost ability, knowing how these are perceived could help.

    Objective. This paper tries to determine how graphical attributes such as colour, texture, and shapes affect the perceived safety of a path inside a 3d environment.

    Method. To reach the objective, an experiment was conducted with 20 participants. The experiment was a two-alternative forced-choice (2AFC) test of 38 pairs of images, where each pair contained two versions of a tunnel entrance scene rendered using different graphical attributes. Each difference was based around either colour (warm and cold colour schemes), shape (round, wide, angular and thin), or texture (rugged, neutral and sterile).

    Results. The experiment generated results that varied compared to the expected results. For instance, the wider shapes were seen as safer compared to the thinner shapes, as was the same result with rounder shapes being perceived safer than angular shapes. Although a few preferred the cold colour scheme, the warmer colour scheme was seen as safer by the majority. While expected to be perceived as less safe than neutral textures but more than the rugged ones, the sterile texture was actually most commonly seen as safe.

    Conclusions. The main conclusion that was made is that colour, texture and shape can be applied to change the perception of safety in a scene. However, when opposing attributes are used in combination, the result might be based on how dominant the attribute is. The dominance of the graphical attributes could be an interesting topic for future work.

  • 14.
    Khambhammettu, Mahith
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Persson, Marie
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Analyzing a Decision Support System for Resource Planning and Surgery Scheduling2016In: Procedia Computer Science / [ed] Martinho R.,Rijo R.,Cruz-Cunha M.M.,Bjorn-Andersen N.,Quintela Varajao J.E., Elsevier, 2016, Vol. 100, p. 532-538Conference paper (Refereed)
    Abstract [en]

    This study aims to propose a decision support system based on optimization modelling for operating room resource planning and sequence dependent scheduling of surgery operations. We conduct a simulation experiment using real world data collected from the local hospital to evaluate the proposed model. The obtained results are compared with real surgery schedules, planned at the local hospital. The experiment shows that the efficiency of schedules produced by the proposed model are significantly improved, in terms of less surgery turnover time, increased utilization of operating rooms and minimized make-span, compared to the real schedules. Moreover, the proposed optimization based decision support system enables analysis of surgery scheduling in relation to resource planning.

  • 15.
    Komu, Miika
    et al.
    Ericsson Res, FIN.
    Morabito, Roberto
    Ericsson Res, FIN.
    Kauppinen, Tero
    Ericsson Res, FIN.
    Kjallman, Jimmy
    Ericsson Res, FIN.
    Yao, Yong
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Power Consumption in Remote Gaming: an Empirical Evaluation2016In: 2016 IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    The thin-client approach for gaming is becoming more popular. For instance, Nvidia Shield, Valve Steam and Shinra technologies have offerings based on the concept. In remote cloud gaming, the game is being executed and processed in the cloud while the user receives a video and audio stream of the game, in a very similar way as with remote desktop clients. At the same time, clouds are moving towards the end-users as "edge clouds" with different standardization bodies, such Open Mobile Edge Cloud and Open Fog Consortium, giving momentum for the efforts. Were remote gaming approaches to utilize edge clouds, the games could be played without installing any infrastructure at the homes of end-users while keeping network delays to the latency-sensitive games low. While waiting for such edge-cloud deployments to substantiate, even regional clouds could be utilized for the purpose. In such environments, remote cloud gaming can already now be utilized by game companies as an alternative to traditional download-and-install games in order to support, e.g., anti-piracy protection. While the incentives for the game companies are relatively clear, the end-user experience has been investigated mainly from the viewpoint of latency. In this paper, we fill a research gap related to energy efficiency by showing that mobile phone users can save between 12 and 32 % power by utilizing remote gaming instead of playing with a native app. Our prototype is based on GamingAnywhere open-source software for which we have also integrated a gamepad for easier controls. We show power measurements both with a 2D and 3D games, and also additional measurements with a smart TV-stick.

  • 16.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    BTH Newsletter on Science Publishing and Information about Research Funding: December 20162016Other (Other (popular science, discussion, etc.))
  • 17.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    BTH Newsletter on Science Publishing and Information about research funding: December 20172017Other (Other (popular science, discussion, etc.))
  • 18.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    BTH Newsletter on Science Publishing and Information about Research Funding: June 20162016Other (Other (popular science, discussion, etc.))
  • 19.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    BTH Newsletter on Science Publishing and Information about research funding: June 20172017Other (Other (popular science, discussion, etc.))
  • 20.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    BTH Newsletter on Science Publishing and Information about research funding: March 20172017Other (Other (popular science, discussion, etc.))
  • 21.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    BTH newsletter on science Publishing and Information about Research Funding: September 20162016Other (Other (popular science, discussion, etc.))
  • 22.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    BTH Newsletter on Science Publishing and Information about research funding: September 20172017Other (Other (popular science, discussion, etc.))
  • 23.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    Hur ser forskningssamarbetet ut på BTH?: Samförfattarskap, nyckelord, tidskrifter och organisationer2016Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Jag med hjälp av data från ISI Web of Science mellan åren 2013-mars 2016 samt data från vår egen publiceringsdatabas under samma tidsperiod, gjort visualiseringar av samförfattande, nyckelord och citerade tidskrifter samt medförfattares affilieringar för att få ledtrådar hur forskningssamarbete och -publiceringar ser ut den aktuella perioden.

  • 24.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    Statistik över nedladdade fulltextfiler och mest besökta publikationer i BTHs DiVA-databas juni-nov. 20152015Other (Other (popular science, discussion, etc.))
  • 25.
    Linde, Peter
    et al.
    Blekinge Institute of Technology, The Library.
    Ahnström, Eva-Lisa
    Blekinge Institute of Technology, The Library.
    BTH Newsletter on Science Publishing and Information about Research Funding: March 20162016Other (Other (popular science, discussion, etc.))
  • 26.
    Linde, Peter
    et al.
    Blekinge Institute of Technology, The Library.
    Eva-Lisa, Ahnström
    Blekinge Institute of Technology, The Library.
    BTH Newsletter on Science Publishing and Information about research funding: December 20152015Other (Other (popular science, discussion, etc.))
  • 27.
    Liu, Fengming
    et al.
    Shandong Normal University, CHI.
    Zhu, Xiaoqian
    Shandong Normal University, CHI.
    Hu, Yuxi
    UC Davis, USA.
    Ren, Lehua
    Shandong Normal University, CHI.
    Johnson, Henric
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    A cloud theory-based trust computing model in social networks2017In: Entropy, ISSN 1099-4300, Vol. 19, no 1, article id 11Article in journal (Refereed)
    Abstract [en]

    How to develop a trust management model and then to efficiently control and manage nodes is an important issue in the scope of social network security. In this paper, a trust management model based on a cloud model is proposed. The cloud model uses a specific computation operator to achieve the transformation from qualitative concepts to quantitative computation. Additionally, this can also be used to effectively express the fuzziness, randomness and the relationship between them of the subjective trust. The node trust is divided into reputation trust and transaction trust. In addition, evaluation methods are designed, respectively. Firstly, the two-dimension trust cloud evaluation model is designed based on node's comprehensive and trading experience to determine the reputation trust. The expected value reflects the average trust status of nodes. Then, entropy and hyper-entropy are used to describe the uncertainty of trust. Secondly, the calculation methods of the proposed direct transaction trust and the recommendation transaction trust involve comprehensively computation of the transaction trust of each node. Then, the choosing strategies were designed for node to trade based on trust cloud. Finally, the results of a simulation experiment in P2P network file sharing on an experimental platform directly reflect the objectivity, accuracy and robustness of the proposed model, and could also effectively identify the malicious or unreliable service nodes in the system. In addition, this can be used to promote the service reliability of the nodes with high credibility, by which the stability of the whole network is improved. © 2016 by the authors.

  • 28.
    Lopez-Rojas, Edgar
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Elmir, Ahmad
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Axelsson, Stefan
    Norges Teknisk-Naturvitenskapelige Universitet, NOR.
    Paysim: A financial mobile money simulator for fraud detection2016In: 28th European Modeling and Simulation Symposium, EMSS 2016 / [ed] Bruzzone A.G.,Jimenez E.,Louca L.S.,Zhang L.,Longo F., Dime University of Genoa , 2016, p. 249-255Conference paper (Refereed)
    Abstract [en]

    The lack of legitimate datasets on mobile money transactions to perform research on in the domain of fraud detection is a big problem today in the scientific community. Part of the problem is the intrinsic private nature of financial transactions, that leads to no public available data sets. This will leave the researchers with the burden of first harnessing the dataset before performing the actual research on it. This paper propose an approach to such a problem that we named the PaySim simulator. PaySim is a financial simulator that simulates mobile money transactions based on an original dataset. In this paper, we present a solution to ultimately yield the possibility to simulate mobile money transactions in such a way that they become similar to the original dataset. With technology frameworks such as Agent-Based simulation techniques, and the application of mathematical statistics, we show in this paper that the simulated data can be as prudent as the original dataset for research.

  • 29.
    Ma, Liyao
    et al.
    University of Jinan, CHN .
    Sun, Bin
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Han, Chunyan
    University of Jinan, CHN .
    Training Instance Random Sampling Based Evidential Classification Forest Algorithms2018In: 2018 21st International Conference on Information Fusion, FUSION 2018, Institute of Electrical and Electronics Engineers Inc. , 2018, p. 883-888Conference paper (Refereed)
    Abstract [en]

    Modelling and handling epistemic uncertainty with belief function theory, different ways to learn classification forests from evidential training data are explored. In this paper, multiple base classifiers are learned on uncertain training subsets generated by training instance random sampling approach. For base classifier learning, with the tool of evidential likelihood function, gini impurity intervals of uncertain datasets are calculated for attribute splitting and consonant mass functions of labels are generated for leaf node prediction. The construction of gini impurity based belief binary classification tree is proposed and then compared with C4.5 belief classification tree. For base classifier combination strategy, both evidence combination method for consonant mass function outputs and majority voting method for precise label outputs are discussed. The performances of different proposed algorithms are compared and analysed with experiments on VCI Balance scale dataset. © 2018 ISIF

  • 30.
    Martin, Eva Garcia
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Lavesson, Niklas
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Doroud, Mina
    Twitter Inc, San Francisco, CA USA..
    Hashtags and followers: An experimental study of the online social network Twitter2016In: SOCIAL NETWORK ANALYSIS AND MINING, ISSN 1869-5450, Vol. 6, no 1, article id UNSP 12Article in journal (Refereed)
    Abstract [en]

    We have conducted an analysis of data from 502,891 Twitter users and focused on investigating the potential correlation between hashtags and the increase of followers to determine whether the addition of hashtags to tweets produces new followers. We have designed an experiment with two groups of users: one tweeting with random hashtags and one tweeting without hashtags. The results showed that there is a correlation between hashtags and followers: on average, users tweeting with hashtags increased their followers by 2.88, while users tweeting without hashtags increased 0.88 followers. We present a simple, reproducible approach to extract and analyze Twitter user data for this and similar purposes.

  • 31.
    Mehri, Vida. A.
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Tutschku, Kurt
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Privacy and trust in cloud-based marketplaces for AI and data resources2017In: IFIP Advances in Information and Communication Technology, Springer New York LLC , 2017, Vol. 505, p. 223-225Conference paper (Refereed)
    Abstract [en]

    The processing of the huge amounts of information from the Internet of Things (IoT) has become challenging. Artificial Intelligence (AI) techniques have been developed to handle this task efficiently. However, they require annotated data sets for training, while manual preprocessing of the data sets is costly. The H2020 project “Bonseyes” has suggested a “Market Place for AI”, where the stakeholders can engage trustfully in business around AI resources and data sets. The MP permits trading of resources that have high privacy requirements (e.g. data sets containing patient medical information) as well as ones with low requirements (e.g. fuel consumption of cars) for the sake of its generality. In this abstract we review trust and privacy definitions and provide a first requirement analysis for them with regards to Cloud-based Market Places (CMPs). The comparison of definitions and requirements allows for the identification of the research gap that will be addressed by the main authors PhD project. © IFIP International Federation for Information Processing 2017.

  • 32.
    Moraes, Ana Louiza Dallora
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Eivazzadeh, Shahryar
    Blekinge Institute of Technology, Faculty of Engineering, Department of Health.
    Mendes, Emilia
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Sanmartin Berglund, Johan
    Blekinge Institute of Technology, Faculty of Engineering, Department of Health.
    Anderberg, Peter
    Blekinge Institute of Technology, Faculty of Engineering, Department of Health.
    Prognosis of Dementia Employing Machine Learning and Microsimulation Techniques: A Systematic Literature Review2016In: Procedia Computer Science / [ed] Martinho R.,Rijo R.,Cruz-Cunha M.M.,Bjorn-Andersen N.,Quintela Varajao J.E., Elsevier, 2016, Vol. 100, p. 480-488Conference paper (Refereed)
    Abstract [en]

    OBJECTIVE: The objective of this paper is to investigate the goals and variables employed in the machine learning and microsimulation studies for the prognosis of dementia. METHOD: According to preset protocols, the Pubmed, Socups and Web of Science databases were searched to find studies that matched the defined inclusion/exclusion criteria, and then its references were checked for new studies. A quality checklist assessed the selected studies, and removed the low quality ones. The remaining ones (included set) had their data extracted and summarized. RESULTS: The summary of the data of the 37 included studies showed that the most common goal of the selected studies was the prediction of the conversion from mild cognitive impairment to Alzheimer's Disease, for studies that used machine learning, and cost estimation for the microsimulation ones. About the variables, neuroimaging was the most frequent used. CONCLUSIONS: The systematic literature review showed clear trends in prognosis of dementia research in what concerns machine learning techniques and microsimulation.

  • 33.
    Oliveira, Pedro Almir
    et al.
    Federal Institute of Maranhão (IFMA), BRA.
    Santos Neto, Pedro
    Universidade Federal do Piaui, BRA.
    Britto, Ricardo
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Rabêlo, Ricardo De Andrade Lira
    Universidade Federal do Piaui, BRA.
    Braga, Ronyerison
    Universidade Federal do Piaui, BRA.
    Souza, Matheus
    Universidade Federal do Piaui, BRA.
    CIaaS: computational intelligence as a service with Athena2018In: Computer languages, systems & structures, ISSN 1477-8424, E-ISSN 1873-6866, Vol. 54, p. 95-118Article in journal (Refereed)
    Abstract [en]

    Computational Intelligence (CI) is a sub-branch of Artificial Intelligence (AI) that focus on studying adaptive mechanisms to enable intelligent behavior in complex environments. CI techniques have been successful in solving complex problems in many different knowledge areas. However, despite their usefulness, developing solutions based on CI techniques is not a trivial activity, since it involves the codification/adaptation of algorithms to specific context and problems. In this paper, we present and validate through a quasi-experiment a new paradigm to develop CI-based solutions using a more mature version of Athena (2.0): Computational Intelligence as a Service (CIaaS). Using this tool, both researchers and practitioners can design and evaluate CI-based solutions by dragging and dropping components in a visual environment, in a cloud-based platform. The results of the quasi-experiment suggest that our approach can help researchers to design and evaluate CI-based systems in a simple, reliable and fast way. © 2018 Elsevier Ltd

  • 34. Peltonen, L.-M.
    et al.
    Alhuwail, D.
    Ali, S.
    Badger, M.K.
    Eler, G.J.
    Georgsson, Mattias
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Islam, T.
    Jeon, E.
    Jung, H.
    Kuo, C.-H.
    Lewis, A.
    Pruinelli, L.
    Ronquillo, C.
    Sarmiento, R.F.
    Sommer, J.
    Tayaben, J.L.
    Topaz, M.
    Current trends in nursing informatics: Results of an international survey2016In: Studies in Health Technology and Informatics / [ed] Sermeus W.,Weber P.,Procter P.M., IOS Press, 2016, Vol. 225, p. 938-939Conference paper (Refereed)
    Abstract [en]

    Nursing informatics (NI) can help provide effective and safe healthcare. This study aimed to describe current research trends in NI. In the summer 2015, the IMIA-NI Students Working Group created and distributed an online international survey of the current NI trends. A total of 402 responses were submitted from 44 countries. We identified a top five NI research areas: standardized terminologies, mobile health, clinical decision support, patient safety and big data research. NI research funding was considered to be difficult to acquire by the respondents. Overall, current NI research on education, clinical practice, administration and theory is still scarce, with theory being the least common. Further research is needed to explain the impact of these trends and the needs from clinical practice. © 2016 IMIA and IOS Press.

  • 35.
    Petersson Forsberg, Lena
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Spatial Planning.
    Eriksen, Sara
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Could mixed AC/DC power systems support more sustainable communities?2016In: 2016 1st International Conference on Sustainable Green Buildings and Communities, SGBC 2016, Institute of Electrical and Electronics Engineers Inc. , 2016Conference paper (Refereed)
    Abstract [en]

    The main contribution of this paper is to challenge the current understanding in Swedish spatial planning of power systems being, inherently, alternating current (AC) systems. We propose two areas for piloting local direct current (DC) systems as a way of introducing the concept of mixed AC/DC power systems with the aim of supporting more (self-)sustainable local communities. One is local recreational areas, so called 'green spaces' in urban planning. The other is eHealth, when it involves spatial planning and building, or rebuilding existing living space, for supporting healthcare provision in the patient's own home. The paper discusses how mixed AC/DC power systems might be introduced into the current planning discourse and practice in Sweden as part of the necessary reconceptualization of what sustainability means in spatial planning. The paper is based on the authors' previous and on-going research, in spatial planning and eHealth respectively, and has been inspired by the on-going research and development at IIT-M on robust and affordable local DC solutions for Indian households. It is an early-stage exploratory paper based on a recently initiated interdisciplinary dialogue between computer scientists and spatial planning researchers at Blekinge Institute of Technology, Sweden, about green infrastructuring for a more sustainable society. © 2016 IEEE.

  • 36.
    Pettersson, Erik
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Social Interaction with Real-time Facial Motion Capture2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Context. Social interaction between player avatars is one of the fundamentals of online multiplayer games, where text- and voice chat is used as standard methods for communication. To express emotions, players have the option to use emotes, which are text-based commands to play animations of the player’s avatar.

    Objectives. This study investigates if real-time facial capture could be preferred and more realistic, compared to typing emote commands to play facial animations when expressing emotions to other players.

    Methods. By using two methods for social interaction between players, a user study with 24 participants was conducted in a private conference room. An experiment was created where each participant tested the two methods to perform facial expressions, one consisting of typing emote commands, the other by performing with the calibrated participant’s face in real-time, with a web camera. Each participant performed and ranked the realism of each facial expression, in a survey for each method. A final survey could then determine the method that each participant had greater performance with and the method that was preferred the most.

    Results. The results showed that there was a difference of realism between facial expressions in both methods, where happiness was the most realistic. Disgust and sadness were however poorly rated when expressing these with the face. There was no difference of realism between the methods and which method participants preferred the most. There was however a difference in each participant’s performance with the two methods, where typing emote commands had higher performance.

    Conclusions. The results show that there is no difference of realism and preference, in typing emote commands to play facial animations and performing facial expressions in real-time with the face. There was, however, a difference in performing each method, where performing facial expressions with the face was the lowest. This confirms that the real-time facial capture technology needs improvements, to fully recognize and track the facial features of the human face.

  • 37. Roberts, Kirk
    et al.
    Boland, Mary Regina
    Pruinelli, Lisiane
    Dcruz, Jina
    Berry, Andrew
    Georgsson, Mattias
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Hazen, Rebecca
    Sarmiento, Raymond F
    Backonja, Uba
    Yu, Kun-Hsing
    Jiang, Yun
    Brennan, Patricia Flatley
    Biomedical informatics advancing the national health agenda: the AMIA 2015 year-in-review in clinical and consumer informatics.2017In: JAMIA Journal of the American Medical Informatics Association, ISSN 1067-5027, E-ISSN 1527-974X, Vol. E1, p. E185-E190Article in journal (Refereed)
    Abstract [en]

    The field of biomedical informatics experienced a productive 2015 in terms of research. In order to highlight the accomplishments of that research, elicit trends, and identify shortcomings at a macro level, a 19-person team conducted an extensive review of the literature in clinical and consumer informatics. The result of this process included a year-in-review presentation at the American Medical Informatics Association Annual Symposium and a written report (see supplemental data). Key findings are detailed in the report and summarized here. This article organizes the clinical and consumer health informatics research from 2015 under 3 themes: the electronic health record (EHR), the learning health system (LHS), and consumer engagement. Key findings include the following: (1) There are significant advances in establishing policies for EHR feature implementation, but increased interoperability is necessary for these to gain traction. (2) Decision support systems improve practice behaviors, but evidence of their impact on clinical outcomes is still lacking. (3) Progress in natural language processing (NLP) suggests that we are approaching but have not yet achieved truly interactive NLP systems. (4) Prediction models are becoming more robust but remain hampered by the lack of interoperable clinical data records. (5) Consumers can and will use mobile applications for improved engagement, yet EHR integration remains elusive.

  • 38.
    Santos, Beatriz Sousa
    et al.
    Universidade de Aveiro, PRT.
    Dischler, Jean Michel
    Universite de Strasbourg, FRA.
    Adzhiev, Valery
    Bournemouth University, GBR.
    Anderson, Eike Falk
    Bournemouth University, GBR.
    Ferko, Andrej
    Comenius University, SVK.
    Fryazinov, Oleg
    Bournemouth University, GBR.
    Ilčík, Martin
    Technische Universitat Wien, AUT.
    Ilčíková, Ivana
    Comenius University, SVK.
    Slavik, Pavel
    Ceske vysoke uceni technicke v Praze, CZE.
    Sundstedt, Veronica
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Svobodova, Liba
    Ceske vysoke uceni technicke v Praze, CZE.
    Wimmer, Michael
    Technische Universitat Wien, AUT.
    Zara, Jiri
    Ceske vysoke uceni technicke v Praze, CZE.
    Distinctive Approaches to Computer Graphics Education2018In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 7, no 1, p. 403-412Article in journal (Refereed)
    Abstract [en]

    This paper presents the latest advances and research in Computer Graphics education in a nutshell. It is concerned with topics that were presented at the Education Track of the Eurographics Conference held in Lisbon in 2016. We describe works corresponding to approaches to Computer Graphics education that are unconventional in some way and attempt to tackle unsolved problems and challenges regarding the role of arts in computer graphics education, the role of research-oriented activities in undergraduate education and the interaction among different areas of Computer Graphics, as well as their application to courses or extra-curricular activities. We present related works addressing these topics and report experiences, successes and issues in implementing the approaches. © 2017 The Eurographics Association and John Wiley & Sons Ltd.

  • 39. Shao, Borong
    et al.
    Lavesson, Niklas
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Boeva, Veselka
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Shahzad, Raja Khurram
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    A mixture-of-experts approach for gene regulatory network inference2016In: INTERNATIONAL JOURNAL OF DATA MINING AND BIOINFORMATICS, ISSN 1748-5673, Vol. 14, no 3, p. 258-275Article in journal (Refereed)
    Abstract [en]

    Gene regulatory network (GRN) inference is an important problem in bioinformatics. Many machine learning methods have been applied to increase the inference accuracy. Ensemble learning methods are shown in DREAM3 and DREAM5 challenges to yield a higher inference accuracy than individual algorithms. However, no ensemble method has been proposed to take advantage of the complementarity among existing algorithms from the perspective of network motifs. We propose an ensemble method based on the principle of Mixture-of-Experts ensemble learning. The method can quantitatively evaluate the accuracy of individual algorithms on predicting each type of the network motifs and assign weights to the algorithms accordingly. The individual predictions are then used to generate the ensemble prediction. By performing controlled experiments and statistical tests, the proposed ensemble method is shown to yield a significantly higher accuracy than the generic average ranking method used in the DREAM5 challenge. In addition, a new type of network motif is found in GRN, the inclusion of which can increase the accuracy of the proposed method significantly.

  • 40.
    Silvander, Johan
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Wilson, Magnus
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Wnuk, Krzysztof
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Encouraging Business Flexibility by Improved Context Descriptions2017In: Proceedings of the Seventh International Symposium on Business Modeling and Software Design / [ed] Boris Shishkov, SciTePress, 2017, Vol. 1, p. 225-228Conference paper (Refereed)
    Abstract [en]

    Business-driven software architectures are emerging and gaining importance for many industries. As softwareintensive solutions continue to be more complex and operate in rapidly changing environments, there is a pressure for increased business flexibility realized by more efficient software architecture mechanisms to keep up with the necessary speed of change. We investigate how improved context descriptions could be implemented in software components, and support important software development practices like business modeling and requirement engineering. This paper proposes context descriptions as an architectural support for improving the connection between business flexibility and software components. We provide initial results regarding software architectural mechanisms which can support context descriptions as well as the context description’s support for business-driven software architecture, and the business flexibility demanded by the business ecosystems.

  • 41.
    Sjöblom, Mattias
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Investigating Gaze Attraction to Bottom-Up Visual Features for Visual Aids in Games2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Context. Video games usually have visual aids guiding the players in 3D-environments. The designers need to know which visual feature is the most effective in attracting a player's gaze and what features are preferred by players as visual aid.

    Objectives. This study investigates which feature of the bottom-upvisual attention process attracts the gaze faster.

    Methods. With the use of the Tobii T60 eye tracking system, a user study with 32 participants was conducted in a controlled environment. An experiment was created where each participant looked at a slideshow consisting of 18 pictures with 8 objects on each picture. One object per picture had a bottom-up visual feature applied that made it stand out as different. Video games often have a goal or a task and to connect the experiment to video games a goal was set. This goal was to find the object with the visual feature applied. The eye tracker measured the gaze while the participant was trying to find the object. A survey to determine which visual feature was preferredby the players was also made.

    Results. The result showed that colour was the visual feature with the shortest time to attract attention. It was closely followed by intensity,motion and a pulsating highlight. Small size had the longest attraction time. Results also showed that the preferred visual feature for visual aid by the players was intensity and the least preferred was orientation.

    Conclusions. The results show that visual features with contrast changes in the texture seems to draw attention faster, with colour the fastest, than changes on the object itself. These features were also the most preferred as visual aid by the players with intensity the most preferred. If this study was done on a larger scale within a 3D-environment, this experiment could show promise to help designers in decisions regarding visual aid in video games.

  • 42.
    Sundstedt, Veronica
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Navarro, Diego
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Mautner, Julian
    Stillalive Studios, SWE.
    Possibilities and challenges with eye tracking in video games and virtual reality applications2016In: SA 2016 - SIGGRAPH ASIA 2016 Courses, Association for Computing Machinery (ACM), 2016, article id a17Conference paper (Refereed)
    Abstract [en]

    Due to an increase in affordable, reliable and non-intrusive eye trackers the technology has recently been used by the video game industry. This course offers participants the opportunity to get an update on research and developments in gaze-based interaction techniques in combination with other sensors. The course consists of three parts: (1) a review of eye tracking analysis and interaction in video games and virtual reality applications, (2) possibilities and challenges with gaze-based interaction, and (3) lessons learned from developing a commercial video game application using eye tracking along with alternative virtual reality technologies. This course is relevant for everyone who is interested in developing games that use eye tracking as an interaction device. The content is suitable for beginners or experienced delegates who want to learn more about the state of the art and future possibilities in eye tracking combined with other sensors as interaction devices. We believe that games and virtual reality applications have just started to incorporate these new techniques and further research and developments are needed in order to evaluate novel ways to enhance gameplay.

  • 43.
    Sveinsdottir, Thordis
    et al.
    Trilateral Research and Consulting, GBR.
    Wessels, Bridgette
    University of Sheffield, GBR.
    Smallwood, Rod
    University of Sheffield, GBR.
    Linde, Peter
    Blekinge Institute of Technology, The Library.
    Kala, Vasso
    National Centre of Medical Documentation, GRC.
    Tsoukala, Victoria
    National Hellenic Research Foundation, GRC.
    Sondervan, Jeroen
    University of Amsterdam, NLD.
    Policy recommendations for Open Access to research data in Europe-Stakeholder values and ecosystems2014In: Information Services and Use, ISSN 0167-5265, E-ISSN 1875-8789, Vol. 34, no 3-4, p. 331-333Article in journal (Refereed)
    Abstract [en]

    RECODE will leverage existing networks, communities and projects to address challenges within the open access and data dissemination and preservation sector, and produce policy recommendations for open access to research data based on existing good practice. The open access to research data sector includes several different networks, initiatives, projects and communities that are fragmented by discipline, geography, stakeholder category (publishers, academics, repositories, etc.) as well as other boundaries. Many of these organisations are already addressing key barriers to open access to research data, such as stakeholder fragmentation, technical and infrastructural issues, ethical and legal issues, and state and institutional policy fragmentation. However, these organisations are often working in isolation or with limited contact with one another. RECODE will provide a space for European stakeholders interested in open access to research data to work together to provide common solutions for these issues. RECODE will culminate in a series of over-arching policy recommendations for a policy framework to support open access to European research data targeted at different stakeholders and policy-makers (http://www.recodeproject.eu). © 2014-IOS Press and the authors.

  • 44.
    Tran, Hung
    et al.
    Mälardalens högskola, SWE.
    Kaddoum, Georges
    Universite du Quebec a Montreal, CAN.
    Gagnon, Francois
    Universite du Quebec a Montreal, CAN.
    Sibomana, Louis
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Cognitive radio network with secrecy and interference constraints2017In: Physical Communication, ISSN 1874-4907, Vol. 22, p. 32-41Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate the physical-layer security of a secure communication in single-input multiple-output (SIMO) cognitive radio networks (CRNs) in the presence of two eavesdroppers. In particular, both primary user (PU) and secondary user (SU) share the same spectrum, but they face with different eavesdroppers who are equipped with multiple antennas. In order to protect the PU communication from the interference of the SU and the risks of eavesdropping, the SU must have a reasonable adaptive transmission power which is set on the basis of channel state information, interference and security constraints of the PU. Accordingly, an upper bound and lower bound for the SU transmission power are derived. Furthermore, a power allocation policy, which is calculated on the convex combination of the upper and lower bound of the SU transmission power, is proposed. On this basis, we investigate the impact of the PU transmission power and channel mean gains on the security and system performance of the SU. Closed-form expressions for the outage probability, probability of non-zero secrecy capacity, and secrecy outage probability are obtained. Interestingly, our results show that the strong channel mean gain of the PU transmitter to the PU's eavesdropper in the primary network can enhance the SU performance.

  • 45.
    Törn, Johan
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies.
    Comparison Between Two DifferentScreen Space Ambient OcclusionTechniques2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Context. In this project a comparison between two screen space ambientocclusion techniques are presented. The techniques are Scalable AO (SAO)and Multiresolution SSAO (MSSAO) since they both are techniques thatuse mipmaps to accelerate their calculations.

    Objectives. The aim is to see how big the difference is between the resultsof these two techniques and a golden reference that is an object space raytraced texture that is created with mental ray in Maya and how long timethe computation takes.

    Methods. The comparisons between the AO textures that these techniquesproduce and the golden references are performed using Structural SimilarityIndex (SSIM) and Perceptual Image Difference (PDIFF).

    Results. On the lowest resolution, both techniques execute in about thesame time on average, except that SAO with the shortest distance is faster.The only effect caused by the shorter distance, in this case, is that moresamples are taken in higher resolution mipmap levels than when longerdistances are used. The MSSAO achieved a better SSIM value meaningthat MSSAO is more similar to the golden reference than SAO. As theresolution increases the SSIM value between both techniques become moresimilar with SAO getting a better value and MSSAO getting slightly worse,while the execution time for MSSAO has larger increases than SAO.

    Conclusions. It is concluded that MSSAO is better than SAO in lowerresolution while SAO is better in larger resolution. I would recommendthat SAO is used for indoor scenes where there are not many small geometryparts close to each other that should occlude each other. MSSAO shouldbe used for outdoor scenes with a lot of vegetation which has many smallgeometry parts close to each other that should occlude. At higher resolution,MSSAO takes longer computational time as compared with SAO, while atlower resolution the computational time is similar.

  • 46.
    Wen, Wei
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Back to basics: Towards novel computation and arrangement of spatial sensory in images2016In: Acta Polytechnica, ISSN 1210-2709, Vol. 56, no 5, p. 409-416Article in journal (Refereed)
    Abstract [en]

    The current camera has made a huge progress in the sensor resolution and the low-luminance performance. However, we are still far from having an optimal camera as powerful as our eye is. The study of the evolution process of our visual system indicates attention to two major issues: the form and the density of the sensor. High contrast and optimal sampling properties of our visual spatial arrangement are related directly to the densely hexagonal form. In this paper, we propose a novel software-based method to create images on a compact dense hexagonal grid, derived from a simulated square sensor array by a virtual increase of the fill factor and a half a pixel shifting. After that, the orbit functions are proposed for a hexagonal image processing. The results show it is possible to achieve image processing operations in the orbit domain and the generated hexagonal images are superior, in detection of curvature edges, to the square images. We believe that the orbit domain image processing has a great potential to be the standard processing for hexagonal images.

  • 47.
    Wen, Wei
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Creative Technologies. Blekinge Institute of Technology, Faculty of Computing, Department of Technology and Aesthetics.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Technology and Aesthetics.
    Virtual deformable image sensors: Towards to a general framework for image sensors with flexible grids and forms2018In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 6, article id 1856Article in journal (Refereed)
    Abstract [en]

    Our vision system has a combination of different sensor arrangements from hexagonal to elliptical ones. Inspired from this variation in type of arrangements we propose a general framework by which it becomes feasible to create virtual deformable sensor arrangements. In the framework for a certain sensor arrangement a configuration of three optional variables are used which includes the structure of arrangement, the pixel form and the gap factor. We show that the histogram of gradient orientations of a certain sensor arrangement has a specific distribution (called ANCHOR) which is obtained by using at least two generated images of the configuration. The results showed that ANCHORs change their patterns by the change of arrangement structure. In this relation pixel size changes have 10-fold more impact on ANCHORs than gap factor changes. A set of 23 images; randomly chosen from a database of 1805 images, are used in the evaluation where each image generates twenty-five different images based on the sensor configuration. The robustness of ANCHORs properties is verified by computing ANCHORs for totally 575 images with different sensor configurations. We believe by using the framework and ANCHOR it becomes feasible to plan a sensor arrangement in the relation to a specific application and its requirements where the sensor arrangement can be planed even as combination of different ANCHORs. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.

  • 48.
    Wiaderek, Krzysztof
    et al.
    Institute of Computer and Information Sciences, POL.
    Rutkowska, Danuta
    Institute of Computer and Information Sciences, POL.
    Rakus-Andersson, Elisabeth
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
    Image retrieval by use of linguistic description in databases2018In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Springer Verlag , 2018, Vol. 10842, p. 92-103Conference paper (Refereed)
    Abstract [en]

    In this paper, a new method of image retrieval is proposed. This concerns retrieving color digital images from a database that contains a specific linguistic description considered within the theory of fuzzy granulation and computing with words. The linguistic description is generated by use of the CIE chromaticity color model. The image retrieval is performed in different way depending on users’ knowledge about the color image. Specific database queries can be formulated for the image retrieval. © Springer International Publishing AG, part of Springer Nature 2018.

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