umu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
1 - 50 av 50
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Ahlgren, Per
    et al.
    Department of e-Resources, University Library, Stockholm University.
    Colliander, Cristian
    Umeå universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Persson, Olle
    Umeå universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Field normalized citation rates, field normalized journal impact and Norwegian weights for allocation of university research funds2012Ingår i: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 92, nr 2, s. 767-780Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We compared three different bibliometric evaluation approaches: two citationbased approaches and one based on manual classification of publishing channels into quality levels. Publication data for two universities was used, and we worked with two levels of analysis: article and department. For the article level, we investigated the predictive power of field normalized citation rates and field normalized journal impact with respect to journal level. The results for the article level show that evaluation of journals based on citation impact correlate rather well with manual classification of journals into quality levels. However, the prediction from field normalized citation rates to journal level was only marginally better than random guessing. At the department level, we studied three different indicators in the context of research fund allocation within universities and the extent to which the three indicators produce different distributions of research funds. It turned out that the three distributions of relative indicator values were very similar, which in turn yields that the corresponding distributions of hypothetical research funds would be very similar.

  • 2.
    Anani, Adi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    M-learning in review: Technology, standard and evaluation2008Ingår i: Journal of Communication and Computer, ISSN 1548-7709, Vol. 5, nr 11, s. 1-6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nowadays E-learning as a form of learning depending on networks and computer devices has been expanding by leaps and bounds. As a special kind of E-learning, M-learning (mobile learning) aims at the use of mobile devices anywhere at anytime by anybody. In this paper, the technologies to develop a M-learning system is deeply analyzed according to the layer model at first. Secondly, from the view of application, the standardization in M-learning is researched in order to accelerate the development and popularization of M-learning. Finally, quality estimation of M-learning system is discussed from the view of QoE (quality of experiences). The experience form end-user is the sole effective norm to judge the result of M-learning technology. It is no doubt that technologies, standardization and evaluation will play very important parts in the course of M-learning development.

  • 3.
    Bensch, Suna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Freund, Rudolf
    Hirvensalo, Mika
    Otto, Friedrich
    Non-Classical Models of Automata and Applications VI Preface2016Ingår i: Fundamenta Informaticae, ISSN 0169-2968, E-ISSN 1875-8681, Vol. 148, nr 3-4, s. I-IIArtikel i tidskrift (Övrigt vetenskapligt)
  • 4.
    Bermell, Måns
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Identification of Problem Gambling via Recurrent Neural Networks: Predicting self-exclusion due to problem gambling within the remote gambling sector by means of recurrent neural networks2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Under recent years the gambling industry has been moving towards providing their customer the possibility to gamble online instead of visiting a physical location. Aggressive marketing, fast growth and a multitude of actors within the market have resulted in a spike of customers who have developed a gambling problem. Decision makers are trying to fight back by regulating markets in order to make the companies take responsibility and work towards preventing these problems. One method of working proactively in this regards is to identify vulnerable customers before they develop a destructive habit.

    In this work a novel method of predicting customers that have a higher risk in regards to gambling-related problems is explored. More concretely, a recurrent neural network with long short-term memory cells is created to process raw behaviour data that are aggregated on a daily basis to classify them as high-risk or not. Supervised training is used in order to learn from historical data, where the usage of permanent self-exclusions due to gambling related problems defines problem gamblers. The work consists of: obtain a local optimal configuration of the network which enhances the performance for identifying problem gam- blers who favour the casino section over sports section, and analyze the model to provide insights in the field.

    This project was carried out together with LeoVegas Mobile Gaming Group. The group offers both online casino games and sports booking in a number of countries in Europe. This collaboration made both data and expertise within the industry accessible to perform this work. The company currently have a model in production to perform these predictions, but want to explore other approaches.

    The model that has been developed showed a significant increase in performance compared to the one that is currently used at the company. Specifically, the precision and recall which are two metrics important for a two class classification model, increased by 37% and 21% respectively. Using raw time series data, instead of aggregated data increased the responsiveness regarding customers change in behaviour over time. The model also scaled better with more history compared to the current model, which could be a result of the nature of a recurrent network compared to the current model used.

  • 5.
    Bohlin, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Toward higher-order network models2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Complex systems play an essential role in our daily lives. These systems consist of many connected components that interact with each other. Consider, for example, society with billions of collaborating individuals, the stock market with numerous buyers and sellers that trade equities, or communication infrastructures with billions of phones, computers and satellites.

    The key to understanding complex systems is to understand the interaction patterns between their components - their networks. To create the network, we need data from the system and a model that organizes the given data in a network representation. Today's increasing availability of data and improved computational capacity for analyzing networks have created great opportunities for the network approach to further prosper. However, increasingly rich data also gives rise to new challenges that question the effectiveness of the conventional approach to modeling data as a network. In this thesis, we explore those challenges and provide methods for simplifying and highlighting important interaction patterns in network models that make use of richer data.

    Using data from real-world complex systems, we first show that conventional network modeling can provide valuable insights about the function of the underlying system. To explore the impact of using richer data in the network representation, we then expand the analysis for higher-order models of networks and show why we need to go beyond conventional models when there is data that allows us to do so. In addition, we also present a new framework for higher-order network modeling and analysis. We find that network models that capture richer data can provide more accurate representations of many real-world complex systems.

  • 6.
    Buckland, Philip I.
    et al.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet. Umeå universitet, Humanistiska fakulteten, Humlab.
    Buckland, Paul C.
    BugsCEP, an entomological database twenty-five years on2014Ingår i: Antenna (Journal of the Royal Entomological Society), ISSN 0140-1890, Vol. 38, nr 1, s. 21-28Artikel i tidskrift (Refereegranskat)
  • 7.
    Buckland, Philip I.
    et al.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Eriksson, Erik J.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Palm, Fredrik
    Umeå universitet, Humanistiska fakulteten, Humlab.
    SEAD - The Strategic Environmental Archaeology Database: Progress Report Spring 20142014Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report provides an overview of the progress and results of the VR:KFI infrastructure projects 2007-7494 and (825-)2010-5976. It should be considered as a status report in an on-going long-term research infrastructure development project.

  • 8.
    Buckland, Philip I.
    et al.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Sjölander, Mattias
    Blombocken avslöjar forntiden: Databaser.2017Ingår i: Populär arkeologi, ISSN 0281-014, nr 5, s. 28-31Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Databaser. Fossila insekter och förkolnade fröer kan ge mycket information om de miljöer som människor har levt i och kan liksom annan biologisk information tjäna arkeologi

  • 9.
    Colliander, Cristian
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Ahlgren, Per
    Department of e-Resources, University Library, Stockholm University.
    Experimental comparison of first and second-order similarities in a scientometric context2012Ingår i: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 90, nr 2, s. 675-685Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The measurement of similarity between objects plays a role in several scientific areas. In this article, we deal with document–document similarity in a scientometric context. We compare experimentally, using a large dataset, first-order with second-order similarities with respect to the overall quality of partitions of the dataset, where the partitions are obtained on the basis of optimizing weighted modularity. The quality of a partition is defined in terms of textual coherence. The results show that the second-order approach consistently outperforms the first-order approach. Each difference between the two approaches in overall partition quality values is significant at the 0.01 level.

  • 10.
    Dubois, Mathieu
    et al.
    NeuroSpin, I2BM, CEA.
    Hadj-Selem, Fouad
    NeuroSpin, I2BM, CEA.
    Löfstedt, Tommy
    NeuroSpin, I2BM, CEA.
    Perrot, Matthieu
    Centre d'Acquisition et de Traitement des Images (CATI).
    Fischer, Clara
    Centre d'Acquisition et de Traitement des Images (CATI).
    Frouin, Vincent
    NeuroSpin, I2BM, CEA.
    Duchesnay, Edouard
    NeuroSpin, I2BM, CEA.
    Predictive support recovery with TV-Elastic Net penalty and logistic regression: An application to structural MRI2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The use of machine-learning in neuroimaging offers new perspectives in early diagnosis and prognosis of brain diseases. Although such multivariate methods can capture complex relationships in the data, traditional approaches provide irregular (l12 penalty) or scattered (l1 penalty) predictive pattern with a very limited relevance. A penalty like Total Variation (TV) that exploits the natural 3D structure of the images can increase the spatial coherence of the weight map. However, TV penalization leads to non-smooth optimization problems that are hard to minimize. We propose an optimization framework that minimizes any combination of l1, l2, and TV penalties while preserving the exact l1 penalty. This algorithm uses Nesterov's smoothing technique to approximate the TV penalty with a smooth function such that the loss and the penalties are minimized with an exact accelerated proximal gradient algorithm. We propose an original continuation algorithm that uses successively smaller values of the smoothing parameter to reach a prescribed precision while achieving the best possible convergence rate. This algorithm can be used with other losses or penalties. The algorithm is applied on a classification problem on the ADNI dataset. We observe that the TV penalty does not necessarily improve the prediction but provides a major breakthrough in terms of support recovery of the predictive brain regions.

  • 11.
    Eriksson, Anton
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Interactive visualization of community structure in complex networks2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Several applied sciences model system dynamics with networks. Since networks often contain thousands or millions of nodes and links, researchers have developed methods that reveal and high- light their essential structures. One such method developed by researchers in IceLab uses information theory to compress descrip- tions of network flows with memory based on paths rather than links and identify hierarchically nested modules with long flow persistence times. However, current visualization tools for navigat- ing and exploring nested modules build on obsolete software that requires plugins and cannot handle such memory networks.

    Drawing from ideas in cartography, this thesis presents a pow- erful visualization method that enables researchers to analyze and explore modular decompositions of any network. The resulting application uses an efficient graph layout algorithm adapted with a simulation based on information flow. Like in a topographic map, zooming into the map successively reveals more detailed commu- nity structures and network features in a continuous fashion.

  • 12.
    Eriksson, John
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Inloggning på trådlöst nätverk vid Umeå Stadsbibliotek2015Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Examensarbetet gick ut på att projektera en lösning där biblioteksanvändare vid Umeå kommuns stadsbibliotek ska kunna logga in på det trådlösa nätverket med hjälp av deras lånekort och ett lösenord eller PIN-kod. Lösningen ska även ta hänsyn till gäster som saknar bibliotekskort och erbjuda dem en tillfällig inloggning. Den projekterade lösningen gick ut på att använda befintlig hårdvara vid Umeå kommun samt outnyttjade funktioner i de befintliga servrarna. Den framtagna lösningen har även testats och skulle inom en snar framtid kunna implementeras.

  • 13.
    Eriksson Krutrök, Moa
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Lindgren, Simon
    Umeå universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Continued contexts of terror: analyzing temporal patterns of hashtag co-occurrence as discursive articulations2018Ingår i: Social Media + Society, ISSN 2056-3051, E-ISSN 2056-3051, Vol. 4, nr 4, artikel-id 2056305118813649Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study looks at how terror attacks are rendered discursively meaningful on social media through the concurrent use and reiteration of terror hashtags, which were created following previous incidents of terror. The article focuses on 12 terror attacks in Europe in 2015-2017 and their relating hashtags on Twitter, to see how various combinations of these were reused and co-articulated in tweets posted in relation to subsequent attacks. Through social network analysis of co-occurring hashtags in about 3 million tweets, in combination with close readings of a smaller sample, this study aims to analyze both the networks of hashtags in relation to terror attacks as well as the discursive process of hashtag co-articulation. The study shows that the patterns by which attack hashtags are reused and co-articulated depend on both temporal and contextual differences.

  • 14.
    Eriksson, Maria
    Umeå universitet, Humanistiska fakulteten, Institutionen för kultur- och medievetenskaper.
    Close Reading Big Data: The Echo Nest and the Production of (Rotten) Music Metadata2016Ingår i: First Monday, ISSN 1396-0466, E-ISSN 1396-0466, Vol. 21, nr 7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Digital music distribution is increasingly powered by automated mechanisms that continuously capture, sort and analyze large amounts of Web-based data. This paper traces the historical development of music metadata management and its ties to the growing of the field of ‘big data’ knowledge production. In particular, it explores the data catching mechanisms enabled by the Spotify-owned company The Echo Nest, and provides a close reading of parts of the company’s collection and analysis of data regarding musicians. Doing so, it reveals evidence of the ways in which trivial, random, and unintentional data enters into the data steams that power today’s digital music distribution. The presence of such curious data needs to be understood as a central part of contemporary algorithmic knowledge production, and calls for a need to re-conceptualize both (digital) musical artifacts and (digital) musical expertize.

  • 15.
    Forsman, Mona
    et al.
    Department of Forest Resource Management, Swedish University of Agricultural Sciences.
    Börlin, Niclas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Holmgren, Johan
    Department of Forest Resource Management, Swedish University of Agricultural Sciences.
    Estimation of tree stem attributes using terrestrial photogrammetry2012Ingår i: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Copernicus Gesellschaft , 2012, s. B5-261-B5-265Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The objective of this work was to create a method to measure stem attributes of standing trees on field plots in the forest using terrestrial photogrammetry. The primary attributes of interest are the position and the diameter at breast height (DBH).

    The developed method creates point clouds from image from three or more calibrated cameras attached to a calibrated rig. SIFT features in multiple images in combination with epipolar line filtering are used to make high quality matching in images with large amounts of similar features and many occlusions. After projection of the point cloud to a simulated ground plane, RANSAC filtering is applied, followed by circle fitting to the remaining points.

    To evaluate the algorithm, a camera rig of five Canon digital system cameras with a baseline of 123 cm and up to 40 cm offset in height was constructed. The rig was used in a field campaign at the Remningstorp forest test area in southern Sweden. Ground truth was collected manually by surveying and manual measurements.

    Initial results show estimated tree stem diameters within 10% of the ground truth. This suggest that terrestrial photogrammetry is a viable method to measure tree stem diameters on circular field plots.

  • 16.
    Hegner, Stephen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A model of independence and overlap for transactions on database schemata2010Ingår i: Advances in Databases and Information Systems, 14th East European Conference, Proceedings / [ed] Barbara Catania, Mirjana Ivanovic, and Bernhard Thalheim, Springer Berlin/Heidelberg, 2010, s. 204-218Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traditional models of support for concurrent transactions invariably rely upon a notion of serializability, which involves not only complex scheduling, but also primitives (such as locks) for requiring transactions to wait, as well for aborting a transaction and forcing it to re-run. For batch transactions, this approach is often the most reasonable. On the other hand, for interactive transactions, only a very limited amount of waiting and aborting is tolerable, and so minimizing their occurrence, even at the cost of increased analysis of the transactions themselves, is warranted. In this work, a systematic study of independence for transactions, without any explicit serialization, is initiated. Each transaction operates on a view of the main schema, and each such view is partitioned into a write region and a read-only region. For a set of transactions to run concurrently, their views may overlap only on their read-only regions. These regions need not be specified explicitly; rather, they are defined naturally using a component-based model of the main schema. Furthermore, when two transactions do conflict, because their views overlap on write regions, the precise point of conflict is immediately identified. To illustrate the utility of the framework, the case of relational schemata governed by the most common types of constraints in practice -- functional and foreign-key dependencies -- is developed in detail.

  • 17.
    Holme, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Temporal networks2014Ingår i: Encyclopedia of Social Network Analysis and Mining / [ed] Reda Alhajj, Jon Rokne, Springer-Verlag New York, 2014, s. 2119-2128Kapitel i bok, del av antologi (Refereegranskat)
  • 18.
    Holme, Petter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Liljeros, Fredrik
    Birth and death of links control disease spreading in empirical contact networks2014Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, s. 4999-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate what structural aspects of a collection of twelve empirical temporal networks of human contacts are important to disease spreading. We scan the entire parameter spaces of the two canonical models of infectious disease epidemiology-the Susceptible-Infectious-Susceptible (SIS) and Susceptible-Infectious-Removed (SIR) models. The results from these simulations are compared to reference data where we eliminate structures in the interevent intervals, the time to the first contact in the data, or the time from the last contact to the end of the sampling. The picture we find is that the birth and death of links, and the total number of contacts over a link, are essential to predict outbreaks. On the other hand, the exact times of contacts between the beginning and end, or the interevent interval distribution, do not matter much. In other words, a simplified picture of these empirical data sets that suffices for epidemiological purposes is that links are born, is active with some intensity, and die.

  • 19.
    Holme, Petter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Department of Energy Science, Sungkyunkwan University, Suwon, Korea; Department of Sociology, Stockholm University.
    Takaguchi, Taro
    Time evolution of predictability of epidemics on networks2015Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 91, nr 4, artikel-id 042811Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Epidemic outbreaks of new pathogens, or known pathogens in new populations, cause a great deal of fear because they are hard to predict. For theoretical models of disease spreading, on the other hand, quantities characterizing the outbreak converge to deterministic functions of time. Our goal in this paper is to shed some light on this apparent discrepancy. We measure the diversity of (and, thus, the predictability of) outbreak sizes and extinction times as functions of time given different scenarios of the amount of information available. Under the assumption of perfect information-i.e., knowing the state of each individual with respect to the disease-the predictability decreases exponentially, or faster, with time. The decay is slowest for intermediate values of the per-contact transmission probability. With a weaker assumption on the information available, assuming that we know only the fraction of currently infectious, recovered, or susceptible individuals, the predictability also decreases exponentially most of the time. There are, however, some peculiar regions in this scenario where the predictability decreases. In other words, to predict its final size with a given accuracy, we would need increasingly more information about the outbreak.

  • 20. Huang, Xiao-Yu
    et al.
    Xiang, Xian-Hong
    Li, Wubin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Chen, Kang
    Cai, Wen-Xue
    Li, Lei
    Matrix Factorization for Evolution Data2014Ingår i: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, s. 525398-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study a matrix factorization problem, that is, to find two factor matrices U and V such that R approximate to U-T x V, where R is a matrix composed of the values of the objects O-1, O-2, ... , O-n at consecutive time points T-1, T-2, ... , T-t. We first present MAFED, a constrained optimization model for this problem, which straightforwardly performs factorization on R. Then based on the interplay of the data in U,V, and R, a probabilistic graphical model using the same optimization objects is constructed, in which structural dependencies of the data in these matrices are revealed. Finally, we present a fitting algorithm to solve the proposed MAFED model, which produces the desired factorization. Empirical studies on real-world datasets demonstrate that our approach outperforms the state-of-the-art comparison algorithms.

  • 21.
    Johansson, Alexander
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Performance analysis of lattice based post-quantum secure cryptography with Java2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Efficient quantum computers will break most of today’s public-key cryptosystems. Therefore, the National Institute of Standards and Technology (NIST) calls for proposals to standardise one or more quantum-secure cryptographic schemes. Eventually, banks must adopt the standardised schemes, but little is known about how efficient such an implementation would be in Java, one of the standard programming languages for banks. In this thesis, we test and evaluate a post-quantum secure encryption scheme known as FrodoKEM, which is based on a hard lattice problem known as Learning With Errors (LWE). We found that a post-quantum secure encryption version of FrodoKEM provides strong theoretical security regarding the criteria given by NIST, and is also sufficiently fast for key generation, encryption and decryption. These results imply that it could be possible to implement these types of post-quantum secure algorithms in high-level programming languages such as Java, demonstrating that we no longer are limited to use low-level languages such as C. Consequently, we can easier and cheaper implement post-quantum secure cryptography.

  • 22.
    Johansson, Kristoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Utveckling av insticksprogram för DigiSign2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    DigiSign är en webbapplikation skapad av företaget Omegapoint som används för att styra så kallade”Digital Signage” skärmar och hantera innehållet skärmarna ska visa. Applikationen saknar en funktion föratt kunna skapa egna mallar. Målet med detta projekt är att utveckla ett insticksprogram för DigiSign därdet är möjligt att skapa egna mallar som underlättar användningen av DigiSign för kunderna.Denna rapport beskriver utvecklingen av insticksprogrammet samt hur integrering med DigiSignapplikationen gått till. Insticksprogrammet som konstruerats är skapat med Microsoft ASP.NET Web formsoch JavaScript.Arbetet under detta projekt har varit uppdelat i tre olika faser, förstudie, utveckling av användargränssnittoch integrering av insticksprogrammet i DigiSign. I förstudien så undersöktes det vilka tekniker som kundetänkas att användas, hur konkurrerande produkter fungerade samt planering av projektet genomfördes.När valet av teknik bestämts så gjordes det en instudering av de tekniker där erfarenhet saknades. Efter endiskussion med företaget där parterna kommit överens om vilka krav och funktioner insticksprogrammetskulle innefatta gjorts så påbörjades utvecklingen av insticksprogrammet. Resultatet av projektet blev ettinsticksprogram som underlättar för kunderna genom att de själva kan skapa mallar för sina bildspel.

  • 23.
    Jäger, Gerold
    Christian-Albrechts-Universität Kiel.
    The Theory of Tolerances with Applications to the Traveling Salesman Problem2011Övrigt (Refereegranskat)
  • 24.
    Jäger, Gerold
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    An Optimal Strategy for Static Black-Peg Mastermind with Three Pegs2018Ingår i: SAGT: International Symposium on Algorithmic Game Theory: 11th International Symposium, SAGT 2018, Beijing, China, September 11-14, 2018, Proceedings / [ed] Xiaotie Deng, Springer, 2018, Vol. 11059, s. 261-266Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mastermind is a famous game played by a codebreaker against a codemaker. We investigate its static (also called non-adaptive) black-peg variant. Given c colors and p pegs, the codemaker has to choose a secret, a p-tuple of c colors, and the codebreaker asks a set of questions all at once. Like the secret, a question is a p-tuple of c colors. The codemaker then tells the codebreaker how many pegs in each question are correct in position and color. Then the codebreaker has one final question to find the secret. His aim is to use as few of questions as possible. Our main result is an optimal strategy for the codebreaker for p=3 pegs and an arbitrary number c of colors using ⌊3c/2⌋+1questions.

    A reformulation of our result is that the metric dimension of ℤn×ℤn×ℤnis equal to ⌊3n/2⌋.

  • 25.
    Karlsson, Lars
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kjelgaard Mikkelsen, Carl Christian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Negative stride in the column-major format makes sense and has useful applications2017Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Two lower triangular or two upper triangular matrices of the same size can be stored with minimal memory footprint. If both positive and negative strides are used, then both matrices can be accessed as if they were stored in regular column-major format.

  • 26.
    Kashian, Alireza
    et al.
    Dept. of Infrastructure Engineering, University of Melbourne, Parkville, Australia.
    Rajabifard, Abbas
    Dept. of Infrastructure Engineering, University of Melbourne, Parkville, Australia.
    Chen, Yiqun
    Dept. of Infrastructure Engineering, University of Melbourne, Parkville, Australia.
    Richter, Kai-Florian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    OSM POI Analyzer: A Platform for Assessing Position of POIs in OpenStreetMap2017Ingår i: ISPRS Geospatial Week 2017 / [ed] D. Li, J. Gong, B. Yang, H. Wu, L. Wu, Z. Gui, X. Cheng, H. Wu, S. Li, R. Lindenbergh, J. Boehm, M. Rutzinger, W. Yao, M. Weinmann, Z. Kang, K. Khoshelham, M. Peter, L. Díaz-Vilariño, W. Shi, B. Lu, H. Abdulmuttalib, M. R. Delavar, T. Balz, B. Osmanoglu, F. Rocca, U. Sörgel, J. Zhang, P. Li, S. Du, L. Zhao, X. Lin, K. Qin, C. Kang, X. Li, C. Chen, R. Li, G. Qiao, H. Wu, and C. Heipke, 2017, Vol. XLII-2/W7, s. 497-504Konferensbidrag (Refereegranskat)
    Abstract [en]

     In recent years, more and increased participation in Volunteered Geographical Information (VGI) projects provides enough data coverage for most places around the world for ordinary mapping and navigation purposes, however, the positional credibility of contributed data becomes more and more important to bring a long-term trust in VGI data. Today, it is hard to draw a definite traditional boundary between the authoritative map producers and the public map consumers and we observe that more and more volunteers are joining crowdsourcing activities for collecting geodata, which might result in higher rates of man-made mistakes in open map projects such as OpenStreetMap. While there are some methods for monitoring the accuracy and consistency of the created data, there is still a lack of advanced systems to automatically discover misplaced objects on the map. One feature type which is contributed daily to OSM is Point of Interest (POI). In order to understand how likely it is that a newly added POI represents a genuine real-world feature scientific means to calculate a probability of such a POI existing at that specific position is needed. This paper reports on a new analytic tool which dives into OSM data and finds co-existence patterns between one specific POI and its surrounding objects such as roads, parks and buildings. The platform uses a distance-based classification technique to find relationships among objects and tries to identify the high-frequency association patterns among each category of objects. Using such method, for each newly added POI, a probabilistic score would be generated, and the low scored POIs can be highlighted for editors for a manual check. The same scoring method can be used for existing registered POIs to check if they are located correctly. For a sample study, this paper reports on the evaluation of 800 pre-registered ATMs in Paris with associated scores to understand how outliers and fake entries could be detected automatically.

  • 27.
    Kashian, Alireza
    et al.
    University of Melbourne, Australia.
    Rajabifard, Abbas
    University of Melbourne, Australia.
    Richter, Kai-Florian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Chen, Yiqun
    University of Melbourne, Australia.
    Automatic analysis of positional plausibility for points of interest in OpenStreetMap using coexistence patterns2019Ingår i: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 33, nr 7, s. 1420-1443Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the past decade, Volunteered Geographic Information (VGI) has emerged as a new source of geographic information, making it a cheap and universal competitor to existing authoritative data sources. The growing popularity of VGI platforms, such as OpenStreetMap (OSM), would trigger malicious activities such as vandalism or spam. Similarly, wrong entries by unexperienced contributors adds to the complexities and directly impact the reliability of such databases. While there are some existing methods and tools for monitoring OSM data quality, there is still a lack of advanced mechanisms for automatic validation. This paper presents a new recommender tool which evaluates the positional plausibility of incoming POI registrations in OSM by generating near real-time validation scores. Similar to machine learning techniques, the tool discovers, stores and reapplies binary distance-based coexistence patterns between one specific POI and its surrounding objects. To clarify the idea, basic concepts about analysing coexistence patterns including design methodology and algorithms are covered in this context. Furthermore, the results of two case studies are presented to demonstrate the analytical power and reliability of the proposed technique. The encouraging results of this new recommendation tool elevates the need for developing reliable quality assurance systems in OSM and other VGI projects.

  • 28.
    Kohler, Timothy A.
    et al.
    Department of Anthropology, Washington State University, Pullman, USA.
    Buckland, Philip I.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier.
    Kintigh, K. W.
    School of Human Evolution and Social Change, Arizona State University, Tempe, USA.
    Bocinsky, R. K.
    Crow Canyon Archaeological Center, Cortez, USA; Montana Climate Office, University of Montana, Missoula, USA; Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, USA.
    Brin, A.
    Center for Digital Antiquity, Arizona State University, Tempe, USA.
    Gillreath-Brown, A.
    Department of Anthropology, Washington State University, Pullman, USA.
    Ludäscher, B.
    School of Information Sciences, University of Illinois at Urbana-Champaign, USA; National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, USA.
    McPhillips, T. M.
    School of Information Sciences, University of Illinois at Urbana-Champaign, USA.
    Opitz, R.
    School of Humanities, University of Glasgow, UK.
    Terstriep, J.
    National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, USA.
    Paleodata for and from archaeology2018Ingår i: PAGES Magazine, ISSN 2411-9180, Vol. 26, nr 2, s. 68-69Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Archaeology depends on, and generates, proxy paleoclimatic and paleoenvironmental data. We review various initiatives, most quite recent, by which archaeologists seek to make these data more readily discoverable and useful, to facilitate the cumulation of research.

  • 29.
    Larsson, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Koncept för datorhantering2015Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Rapporten innehåller information gällande förbättring av en existerande arbetsprocess på ett specifikt företag. Det handlar om hur ett eventuellt datorhanteringssystem skulle kunna effektivisera det nuvarande arbetet. Rapporten innehåller även en idé om hur mängden papper i hanteringen av datorerna skulle kunna minskas.Innehållet består av tankar, funderingar, analyser och konceptbilder på hur ett system skulle kunna se ut.

  • 30.
    Lee, Sungmin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Rocha, Luis E C
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Liljeros, Fredrik
    Stockholm University.
    Holme, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Exploiting Temporal Network Structures of Human Interaction to Effectively Immunize Populations2012Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 5, s. e36439-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Decreasing the number of people who must be vaccinated to immunize a community against an infectious disease could both save resources and decrease outbreak sizes. A key to reaching such a lower threshold of immunization is to find and vaccinate people who, through their behavior, are more likely than average to become infected and to spread the disease further. Fortunately, the very behavior that makes these people important to vaccinate can help us to localize them. Earlier studies have shown that one can use previous contacts to find people that are central in static contact networks. However, real contact patterns are not static. In this paper, we investigate if there is additional information in the temporal contact structure for vaccination protocols to exploit. We answer this affirmative by proposing two immunization methods that exploit temporal correlations and showing that these methods outperform a benchmark static-network protocol in four empirical contact datasets under various epidemic scenarios. Both methods rely only on obtainable, local information, and can be implemented in practice. For the datasets directly related to contact patterns of potential disease spreading (of sexually-transmitted and nosocomial infections respectively), the most efficient protocol is to sample people at random and vaccinate their latest contacts. The network datasets are temporal, which enables us to make more realistic evaluations than earlier studies—we use only information about the past for the purpose of vaccination, and about the future to simulate disease outbreaks. Using analytically tractable models, we identify two temporal structures that explain how the protocols earn their efficiency in the empirical data. This paper is a first step towards real vaccination protocols that exploit temporal-network structure—future work is needed both to characterize the structure of real contact sequences and to devise immunization methods that exploit these.

  • 31.
    Lorido-Botran, Tania
    et al.
    University of Deusto.
    Huerta, Sergio
    University of Deusto.
    Tomás, Luis
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Sanz, Borja
    University of Deusto.
    An unsupervised approach to online noisy-neighbor detection in cloud data centers2017Ingår i: Expert systems with applications, ISSN 0957-4174, E-ISSN 1873-6793, Vol. 89, s. 188-204Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Resource sharing is an inherent characteristic of cloud data centers. Virtual Machines (VMs) and/or Containers that are co-located in the same physical server often compete for resources leading to interference. The noisy neighbor’s effect refers to an anomaly caused by a VM/container limiting resources accessed by another one. Our main contribution is an online, lightweight and application-agnostic solution for anomaly detection, that follows an unsupervised approach. It is based on comparing models for different lags: Dirichlet Process Gaussian Mixture Models to characterize the resource usage profile of the application, and distance measures to score the similarity among models. An alarm is raised when there is an abrupt change in short-term lag (i.e. high distance score for short-term models), while the long-term state remains constant. We test the algorithm for different cloud workloads: websites, periodic batch applications, Spark-based applications, and Memcached server. We are able to detect anomalies in the CPU and memory resource usage with up to 82–96% accuracy (recall) depending on the scenario. Compared to other baseline methods, our approach is able to detect anomalies successfully, while raising low number of false positives, even in the case of applications with unusual normal behavior (e.g. periodic). Experiments show that our proposed algorithm is a lightweight and effective solution to detect noisy neighbor effect without any historical info about the application, that could also be potentially applied to other kind of anomalies.

  • 32.
    Lugnegård, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Designhögskolan vid Umeå universitet.
    Finding missing people: Hur kan man effektivisera arbete med att söka efter försvunna personer?2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Finding missing people and obtaining an overview of complex emergencies is very demanding and requires costly resources. I have on a few occasions sought after my grandfather, who, when he got Alzheimer, liked to go for a stroll at night (!) when my grandmother was sleeping. Those kind of situations are very stressful, especially a cold winter night. During my first 25 years I was part of a dedicated outdoor culture with countless ski trips, mountain hikes, mountain bike trips and many hours in primarily Swedish nature. It happened on a few occasions that we came in contact with people who worked with rescue operations in this type of environment. It could be about hikers who strayed away or been injured in the inaccessible nature, lost skiers in the mountain massifs around Riksgränsen, berry pickers in the Västerbotten forests etc. There are many examples of this type of situations and it's reflections on these scenarios and similar current problem which is the basis for this project.  

    Every year, about 7000 people are reported missing in Sweden. Of these remains about 30-35 vanished. Globally, the figure is huge. Earthquakes, floods and other hit by natural occurs despite various preventive measures. There are many occasions where the search, reconnaissance and location of individuals as well as physical problems play a critical role, but where human capacity seldom is sufficient. Search party chains (organized by organisations like Missing People) requires significant human resources and costs precious time, police helicopter reconnaissance is economically very costly, not environmentally friendly and involves a significant margin of error. With these statements as background, I would look at the possibility of creating a thorough design solution that contributes to people in need can be located, provided security and helped significantly faster than today without requiring significant resources.

    With this as a backdrop, I wanted to create a concept that would contribute to that more people were found and could be saved. Through an extensive research of how a rescue operation is conducted, interviews with police and Missing People, as well as observations during actual operations, I identified a few main problem areas that my concept generation would center around.

    Together with my sponsor, we wanted to create something that can best be described as a robotic eagle with hyper vision, long flight time and a positive association for the victim.

    The result is Aetos (Greek for eagle). A modular drone-system with innovative features to handle with long flights and demanding rescue missions. Thanks to an aerodynamic shape and a remote-controlled system Aetos requires minimal resources to create overview and help in locating the missing person. We want to save lives, and it can Aetos that.

  • 33.
    Mankevich, Vasili
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för informatik.
    Managing Innovation Networks: Exploring Coopetition Dynamics in Innovation Ecosystems2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Companies increasingly rely on external partners when starting their innovation initiatives. Emergent innovation ecosystems of heterogeneous actors proved to be successful in leveraging combined competence for the creation of the new ventures. However, constantly changing environment of simultaneous competition and cooperation – coopetition, presents a challenge for the ecosystem management. Drawing on the network orchestration and coopetition research, I analyze management practices and coopetition dynamics in the digital creative industry in Northern Sweden. Based on the analysis, I offer two main contributions. First, I provide a detailed account of innovation ecosystem orchestration within the digital creative industry, including its chronological evolution and the challenges related to it. Second, the application of coopetition notion to the innovation ecosystem context brings forward tensions that should be further scrutinized in order to develop better management practices for such innovation networks. 

  • 34.
    Mollevik, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Evaluation of strategies for pedestrian guidance using commodity smartphones2016Ingår i: 2016 10th International Conference on Next Generation Mobile Applications, Security and Technologies (NGMAST), 2016, s. 41-46Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the user evaluation of two strategies for guiding pedestrians. This work is based on a hands free, eyes free scenario explored by SpaceBook [1], using cheap Android phones. The first model described is a comparatively simple purely reactive model [2]. The second is using more involved techniques including prediction of future positions and scheduling [3]. The paper describes both models discussing identified problems with them. It then goes on to describe our evaluation procedure and the results of the evaluation.

  • 35.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Guerrero, Esteban
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Baskar, Jayalakshmi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Deliberative Argumentation for Smart Environments2014Ingår i: PRIMA 2014: Principles and Practice of Multi-Agent Systems / [ed] Hoa Khanh Dam, Jeremy Pitt, Yang Xu, Guido Governatori, Takayuki Ito, Springer International Publishing , 2014, s. 141-149Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, an argumentation-based deliberative approach for fusing contextual information obtained from heterogeneous sources using a multi-agent system is introduced. The system is characterized by three different agents: an Environment Agent, an Activity Agent and a Coach Agent. These agents consider data from heterogenous sources of data. As a method for aggregating data and supporting decision-making, so-called agreement rules are instrumental in the argumentation-based deliberative method. The aggregation rules will be associated to specific beliefs related to the services of each agent.

  • 36.
    Nilsson Sjöström, Dennis
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    A Mathematical Model of Hacking the 2016 US Presidential Election2018Självständigt arbete på avancerad nivå (masterexamen), 300 hpStudentuppsats (Examensarbete)
    Abstract [en]

    After the 2016 US presidential election, allegations were published that the electronic voting machines used throughout the US could have been manipulated.These claims arose due to the reported attacks by Department of Homeland Security toward voter registration databases. The US is more vulnerable against these types of attacks since electronic voting machines is the most prevalent method for voting. To reduce election costs, other countries are also considering replacing paper ballots with electronic voting machines. This, however, imposes a risk. By attacking the electronic voting machines, an attacker could change the outcome of an election. A well-executed attack would be designed to be highly successful, but at the same time the risk for detection would be low. The question evaluated in this paper is whether such an attack would be possible and if so, how much it would cost to execute.

    This paper presents a mathematical model of the 2016 US presidential election.The model is based on voting machine equipment data and pollingdata. The model is used to simulate how rational attackers would maximize their effect on the election and minimize their effort by hacking voting machines. By using polls, it was possible to determine the effort needed to change the outcome of the 2016 US presidential election and thus estimate the costs. Based on the model, the estimated cost to hack the 2016US presidential election would amount to at least ten million dollars. The results show that these attacks are possible by attacking only one manufacturer of electronic voting machines. Hence, the use of electronic voting machines poses too much of a risk for democracy, and paper ballots should still be considered for elections. This kind of model can be implemented on the elections of other countries that use electronic voting machines.

  • 37.
    Ohst, Jan
    et al.
    Koblenz, Germany.
    Liljeros, Fredrik
    Stockholm, Sweden .
    Stenhem, Mikael
    Stockholm, Sweden .
    Holme, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Stockholm, Sweden; Suwon, Korea .
    The network positions of methicillin resistant Staphylococcus aureus affected units in a regional healthcare system2014Ingår i: EPJ Data Science, ISSN 2193-1127, Vol. 3, nr 1, artikel-id 29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We studied a dataset of care episodes in a regional Swedish hospital system. We followed how 2,314,477 patients moved between 8,507 units (hospital wards and outpatient clinics) over seven years. The data also included information on the date when patients tested positive with methicillin resistant Staphylococcus aureus. To simplify the complex flow of patients, we represented it as a network of units, where two units were connected if a patient moved from one unit to another, without visiting a third unit in between. From this network, we characterized the typical network position of units with a high prevalence of methicillin resistant Staphylococcus aureus, and how the patient’s location in the network changed upon testing positive. On average, units with medium values of the analyzed centrality measures had the highest average prevalence. We saw a weak effect of the hospital system’s response to the patient testing positive - after a positive test, the patient moved to units with a lower centrality measured as degree (i.e. number of links to other units) and in addition, the average duration of the care episodes became longer. The network of units was too random to be a strong predictor of the presence of methicillin resistantStaphylococcus aureus - would it be more regular, one could probably both identify and control outbreaks better. The migration of the positive patients with within the healthcare system, however, helps decreasing the outbreak sizes.

  • 38.
    Per, Ahlgren
    et al.
    Uppsala University, Department of Statistics, Sweden.
    Yunwei, Chen
    Scientometrics & Evaluation Research Center (SERC), Chengdu Library and Information Center of Chinese Academy of Sciences, Chengdu, China.
    Colliander, Cristian
    Umeå universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Umeå universitet, Umeå universitetsbibliotek (UB).
    Jan van Eck, Nees
    Centre for Science and Technology Studies, Leiden University. The Netherlands.
    Community Detection Using Citation Relations and Textual Similarities in a Large Set of PubMed Publications2019Ingår i: Proceedings of the 17th International Conference on Scientometrics & Informetrics / [ed] Giuseppe Catalano, Cinzia Daraio, Martina Gregori, Henk F. Moed and Giancarlo Ruocco, International Society for Scientometrics and Informetrics , 2019, Vol. 1, s. 1380-1392Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this contribution, the effects of enhancing direct citations, with respect to publication-publication relatedness measurement, by indirect citation relations (bibliographic coupling and co-citation) and text relations on clustering accuracy are analyzed. In total, we investigate six approaches. In one of these, direct citations are enhanced by both bibliographic coupling and co-citation, whereas text relations are used to enhance direct citations in another approach. In addition to an approach based on direct citations only, we include in the study, for comparison reasons, each approach that is involved in the enhancement of direct citations. For the evaluation of the approaches, we use a methodology proposed by earlier research. However, the used evaluation criterion is based on MeSH, arguable the most sophisticated item-level classification scheme available. The results show that the co-citation approach has the worst performance, and that the direct citations approach is outperformed by the other four investigated approaches. An approach in which direct citations are enhanced by the BM25 textual relatedness measure has the best performance, followed by the approach that combines direct citations with bibliographic coupling and co-citation. The latter performs slightly better than the bibliographic coupling approach, which in turn has a better performance than the BM25 approach.

  • 39.
    Richter, Kai-Florian
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Horned, Arvid
    Umeå University.
    Karlsson, Kristoffer
    Umeå University.
    Icon-based Navigation2018Ingår i: Geospatial Technologies for All: short papers, posters and poster abstracts of the 21th AGILE Conference on Geographic Information Science / [ed] Mansourian, A., Pilesjö, P., Harrie, L., von Lammeren, R, Lund: Lund University , 2018, artikel-id 86Konferensbidrag (Refereegranskat)
    Abstract [en]

    Icon-based navigation uses a minimalist approach to mobile navigation assistance by offering navigators only icon displays representing landmark objects at waypoints along a route in an indoor environment. In this paper, we motivate this new concept and its usefulness, present a first prototype implementation exploring the concept, and results of an initial empirical evaluation. While results are not fully conclusive, they point to the potential of this kind of navigation assistance.

  • 40.
    Rieppo, Lassi
    et al.
    Department of Physics, University of Kuopio, Kuopio, Finland; BioMater Centre, University of Kuopio, Kuopio, Finland.
    Saarakkala, Simo
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Närhi, Tommi
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Holopainen, Jaakko
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Biosciences, University of Kuopio, Kuopio, Finland.
    Helminen, Heikki
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Jurvelin, Jukka
    Department of Physics, University of Kuopio, Kuopio, Finland; BioMater Centre, University of Kuopio, Kuopio, Finland.
    Rieppo, Jarno
    BioMater Centre, University of Kuopio, Kuopio, Finland; Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Quantitative analysis of spatial proteoglycan content in articular cartilage with Fourier transform infrared imaging spectroscopy: Critical evaluation of analysis methods and specificity of the parameters.2010Ingår i: Microscopy research and technique (Print), ISSN 1059-910X, E-ISSN 1097-0029, Vol. 73, nr 5, s. 503-512, artikel-id 19839035Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVE: To evaluate the specificity of the current Fourier transform infrared imaging spectroscopy (FT-IRIS) methods for the determination of depthwise proteoglycan (PG) content in articular cartilage (AC). In addition, curve fitting was applied to study whether the specificity of FT-IRIS parameters for PG determination could be improved.

    METHODS: Two sample groups from the steer AC were prepared for the study (n = 8 samples/group). In the first group, chondroitinase ABC enzyme was used to degrade the PGs from the superficial cartilage, while the samples in the second group served as the controls. Samples were examined with FT-IRIS and analyzed using previously reported direct absorption spectrum techniques and multivariate methods and, in comparison, by curve fitting. Safranin O-stained sections were measured with digital densitometry to obtain a reference for depthwise PG distribution.

    RESULTS: Carbohydrate region-based absorption spectrum methods showed a statistically weaker correlation with the PG reference distributions than the results of the curve fitting (subpeak located approximately at 1,060 cm(-1)). Furthermore, the shape of the depthwise profiles obtained using the curve fitting was more similar to the reference profiles than with the direct absorption spectrum analysis.

    CONCLUSIONS: Results suggest that the current FT-IRIS methods for PG analysis lack the specificity for quantitative measurement of PGs in AC. The curve fitting approach demonstrated that it is possible to improve the specificity of the PG analysis. However, the findings of the present study suggest that further development of the FT-IRIS analysis techniques is still needed.

  • 41.
    Sjöström, Tomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Discrete time variational mechanics of multidomain systems: Applications to coupled electronic, hydraulic, and multibody systems2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Idag finns det få simulatorer för icke-släta multidomän kretsar som bygger på tidsdiskretisering av Lagranges ekvationer.

    Huvudmålet är att visa att det är möjligt att använda en semi-implicit, parameter fri icke-slät diskret lösare för att simulera kretsar med tidssteg proportionella mot systemens tidsskalor.

    Detta visas genom att implementera olika typer av elektriska, mekaniska och hydrauliska komponenter samt att visa att komponenterna är stabila och har rätt beteende när systemet simuleras av en modifierad block pivot lösare.

    Simulerings resultaten visar att icke-släta Newton metoder med styckvis-linjära komponenter och komplementära villkor är tillräkligt för att simulera brytande komponponenter i de simulerande kretsarna.

  • 42.
    Sutherland, Alexander
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bensch, Suna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Inferring Robot Actions from Verbal Commands Using Shallow Semantic Parsing2015Ingår i: ICAI 2015: Proceedings of the 2015 International Conference on Artificial Intelligence, 2015, s. 28-34Konferensbidrag (Refereegranskat)
  • 43.
    Söderström, Ulrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    HD video communication at very low bitrates2009Ingår i: Recent Advances in Multimedia Signal Processing and Communications / [ed] Mislav Grgic, Kresimir Delac, Mohammed Ghanbari, Berlin, Heidelberg: Springer Berlin/Heidelberg, 2009, s. 295-314Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    This chapter describes compression of facial video, i.e., video where the face or head-and-shoulders of a person is the important information. This kind of video is used for communication between people and HD quality of this video makes it much more useful. When it is wearable so that the user is free to move it becomes an even more appealing application.

  • 44.
    Thrash, Tyler
    et al.
    University of Zürich, Switzerland.
    Lanini-Maggi, Sara
    University of Zürich, Switzerland.
    Fabrikant, Sara I.
    University of Zürich, Switzerland.
    Bertel, Sven
    Hochschule Flensburg, Germany.
    Brügger, Annina
    University of Zürich, Switzerland.
    Credé, Sascha
    University of Zürich, Switzerland.
    Do, Cao Tri
    University of Zürich / ETH Zürich, Switzerland.
    Gartner, Georg
    TU Wien, Austria.
    Huang, Haosheng
    University of Zürich, Switzerland.
    Münzer, Stefan
    Universität Mannheim, Germany.
    Richter, Kai-Florian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    The Future of Geographic Information Displays from GIScience, Cartographic, and Cognitive Science Perspectives2019Ingår i: 14th International Conference on Spatial Information Theory / [ed] Sabine Timpf, Christoph Schlieder, Markus Kattenbeck, Bernd Ludwig and Kathleen Stewart, Dagstuhl, Germany, 2019, Vol. 142, s. 19:1-19:11Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the development of modern geovisual analytics tools, several researchers have emphasized the importance of understanding users' cognitive, perceptual, and affective tendencies for supporting spatial decisions with geographic information displays (GIDs). However, most recent technological developments have focused on support for navigation in terms of efficiency and effectiveness while neglecting the importance of spatial learning. In the present paper, we will envision the future of GIDs that also support spatial learning in the context of large-scale navigation. Specifically, we will illustrate the manner in which GIDs have been (in the past) and might be (in the future) designed to be context-responsive, personalized, and supportive for active spatial learning from three different perspectives (i.e., GIScience, cartography, and cognitive science). We will also explain why this approach is essential for preventing the technological infantilizing of society (i.e., the reduction of our capacity to make decisions without technological assistance). Although these issues are common to nearly all emerging digital technologies, we argue that these issues become especially relevant in consideration of a person's current and future locations.

  • 45.
    Westin, Lars
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för regionalvetenskap (CERUM).
    Westin, Jonas
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för regionalvetenskap (CERUM).
    Planering av godstransporter på regional nivå: Modeller, verktyg och förvaltningspolitik2019Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Rapporten fokuserar på den kunskapsbrist som finns beträffande nuläget i det svenska gods­transport­nätverket på regional och lokal nivå. Det påverkar kommunikation och skapar osäkerhet i dialogen mellan aktörer inom transportplanering på regional och kommunal nivå. Som bakgrund diskuteras planeringsprocessen för gods­transporternas infrastruktur inom Trafikverket. Den relateras till planering på kommunal och regional nivå. Inom Trafikverket och dess föregångare har tyngdpunkten mellan nationell styrning och lokala förhandlingar varierat. Inom Trafikverket sker en förskjutning av fokus från nationell nivå till dialogprocesser med lokala planerare och näringsliv, från ”government” till ”governance”. Samtidigt är modell- och investeringskalkylsidan för åtgärder inom godstransporter mycket starkt nationellt fokuserad, med rötter i 1990-talets nationella produktivitetsproblematik. För godsplaneringen innebär det att representationen av de lokala och regionala godstransportnätverken är begränsad. Det skapar oklarheter i dialogprocesserna på regional och lokal nivå. Enskilda regioner har därför själva eller i samverkan med Trafikverket genomfört egna godsflödesenkäter och byggt regionala modeller. Några av dess presenteras i rapporten. Därpå diskuteras vilka verktyg och dataunderlag som behövs för att på ett bättre sätt stödja regional och lokal transportplanering för godstransporter.

  • 46.
    Wiberg, Charlotte
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för informatik.
    Webbanvändning inom resesektorn2007Ingår i: Turisten i upplevelseindustrin / [ed] Hanefors, Monica & Mosserg, Lena, Lund: Studentlitteratur AB, 2007Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 47. Williams, John W.
    et al.
    Grimm, Eric C.
    Blois, Jessica L.
    Charles, Donald F.
    Davis, Edward B.
    Goring, Simon J.
    Graham, Russell W.
    Smith, Alison J.
    Anderson, Michael
    Arroyo-Cabrales, Joaquin
    Ashworth, Allan C.
    Betancourt, Julio L.
    Bills, Brian W.
    Booth, Robert K.
    Buckland, Philip I.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Curry, B. Brandon
    Giesecke, Thomas
    Jackson, Stephen T.
    Latorre, Claudio
    Nichols, Jonathan
    Purdum, Timshel
    Roth, Robert E.
    Stryker, Michael
    Takahara, Hikaru
    The neotoma paleoecology database, a multiproxy, international, community-curated data resource2018Ingår i: Quaternary Research, ISSN 0033-5894, E-ISSN 1096-0287, Vol. 89, nr 1, s. 156-177Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Neotoma Paleoecology Database is a community-curated data resource that supports interdisciplinary global change research by enabling broad-scale studies of taxon and community diversity, distributions, and dynamics during the large environmental changes of the past. By consolidating many kinds of data into a common repository, Neotoma lowers costs of paleodata management, makes paleoecological data openly available, and offers a high-quality, curated resource. Neotoma’s distributed scientific governance model is flexible and scalable, with many open pathways for participation by new members, data contributors, stewards, and research communities. The Neotoma data model supports, or can be extended to support, any kind of paleoecological or paleoenvironmental data from sedimentary archives. Data additions to Neotoma are growing and now include >3.8 million observations, >17,000 datasets, and >9200 sites. Dataset types currently include fossil pollen, vertebrates, diatoms, ostracodes, macroinvertebrates, plant macrofossils, insects, testate amoebae, geochronological data, and the recently added organic biomarkers, stable isotopes, and specimen-level data. Multiple avenues exist to obtain Neotoma data, including the Explorer map-based interface, an application programming interface, the neotoma R package, and digital object identifiers. As the volume and variety of scientific data grow, community-curated data resources such as Neotoma have become foundational infrastructure for big data science.

  • 48. Wu, Jinsong
    et al.
    Bisio, Igor
    Gniady, Chris
    Hossain, Ekram
    Valla, Massimo
    Li, Haibo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    CONTEXT-AWARE NETWORKING AND COMMUNICATIONS: PART 12014Ingår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 52, nr 6, s. 14-15Artikel i tidskrift (Övrigt vetenskapligt)
  • 49.
    Yang, Binbin
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för informatik.
    Zisiadis, Miltiadis
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för informatik.
    Transmedia marketing: strengthening multiplatform user participation through storytelling2014Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The term transmedia storytelling describes an interactive narrative that exists in multiple platforms. This phenomenon allows active audience participation as a part of the narrative creation process. Part of the prior research on transmedia focuses on how to create a transmedia narrative. However there is a dearth of literature examining the merit that transmedia narratives create in Marketing. In order to answer the research question “How can transmedia storytelling be used to create value in marketing?” we conducted a multiple case study research in which we examined four marketing campaigns to reveal the transmedia elements in them. Using the approach of qualitative content analysis we applied a structured method according which we collected and ­­analysed the data from these campaigns. Our findings suggest that creating audience participation through transmedia storytelling in marketing campaigns for movies, products and services can be beneficial. By using different media, platforms and stimulating user participation, concepts such as brand extension and brand awareness are introduced to the audience with an alternative way. The aim of this thesis is to illustrate several ways of how transmedia can be a valuable asset to a marketing campaign through storytelling.

  • 50. Yousefnezhad, Narges
    et al.
    Madhikermi, Manik
    Främling, Kary
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    MeDI: Measurement-based Device Identification Framework for Internet of Things2018Ingår i: 2018 IEEE 16TH INTERNATIONAL CONFERENCE ON INDUSTRIAL INFORMATICS (INDIN), IEEE , 2018, s. 95-100Konferensbidrag (Refereegranskat)
    Abstract [en]

    IoT systems may provide information from different sensors that may reveal potentially confidential data, such as a person's presence or not. The primary question to address is how we can identify the sensors and other devices in a reliable way before receiving data from them and using or sharing it. In other words, we need to verify the identity of sensors and devices. A malicious device could claim that it is the legitimate sensor and trigger security problems. For instance, it might send false data about the environment, harmfully affecting the outputs and behavior of the system. For this purpose, using only primary identity values such as IP address, MAC address, and even the public-key cryptography key pair is not enough since IPs can be dynamic, MACs can be spoofed, and cryptography key pairs can be stolen. Therefore, the server requires supplementary security considerations such as contextual features to verify the device identity. This paper presents a measurement-based method to detect and alert false data reports during the reception process by means of sensor behavior. As a proof of concept, we develop a classification-based methodology for device identification, which can be implemented in a real IoT scenario.

1 - 50 av 50
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf