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  • 251. Adimurthi,
    et al.
    Tintarev, Kyril
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och tillämpad matematik.
    On a version of Trudinger-Moser inequality with Möbius shift invariance2010Ingår i: Calculus of Variations and Partial Differential Equations, ISSN 0944-2669, E-ISSN 1432-0835, Vol. 39, nr 1-2, s. 203-212Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper raises a question about the optimal critical nonlinearity for the Sobolev space in two dimensions, connected to loss of compactness, and discusses the pertinent concentration compactness framework. We study properties of the improved version of the Trudinger-Moser inequality on the open unit disk B subset of R-2, recently proved by Mancini and Sandeep [g], (Arxiv 0910.0971). Unlike the original Trudinger-Moser inequality, this inequality is invariant with respect to the Mobius automorphisms of the unit disk, and as such is a closer analogy of the critical nonlinearity integral |u|(2)* in the higher dimension than the original Trudinger-Moser nonlinearity.

  • 252. Adimurthi, no first name
    et al.
    Tintarev, Cyril
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori.
    On compactness in the Trudinger-Moser inequality2014Ingår i: Annali della Scuola Normale Superiore di Pisa (Classe Scienze), Serie V, ISSN 0391-173X, E-ISSN 2036-2145, Vol. 13, nr 2, s. 399-416Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We show that the Moser functional J(u) = integral Omega(e(4 pi u2) - 1) dx on the set B = {u is an element of H-0(1)(Omega) : parallel to del u parallel to(2) <= 1}, where Omega subset of R-2 is a bounded domain, fails to be weakly continuous only in the following exceptional case. Define g(s)w(r) = s(-1/2)w(r(s)) for s > 0. If u(k) -> u in B while lim inf J(u(k)) > J(u), then, with some s(k) -> 0, u(k) = g(sk) [(2 pi)(-1/2) min {1, log1/vertical bar x vertical bar}], up to translations and up to a remainder vanishing in the Sobolev norm. In other words, the weak continuity fails only on translations of concentrating Moser functions. The proof is based on a profile decomposition similar to that of Solimini [16], but with different concentration operators, pertinent to the two-dimensional case.

  • 253.
    Adinda, Akram
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Edström, August
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Isaksson, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    McLeod, Tyson
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    An online marketplace to help reduce the wastage of Swedish wool2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det produceras över 1800 ton ull i Sverige varje år, endast 300 används. Detta projektarbete bestod av att skapa en webbtjänst i form av en köp- och säljmarknad som underlättar den svenska ullhandeln, samt sprider information angående svinnet. Själva köp- och säljmarknaden består av ett flertal sektioner. Tjänsten är utformad utifrån resultat av kontextuella undersökningar samt enkäter som bidrar till en mer användarvänlig upplevelse. På marknadsplatsen finner man bland annat en karta som illusterar för användaren var ull finns tillgängligt.

    Det övergripande målet med projektarbetet var att minska svinnet av svensk ull samt dess negativa effekter på miljön. Detta genom att underlätta handeln av lokalproducerad ull samt förebygga problem som den subjektivitet som kan uppstå vid försäljning, vilket i sig kan ses som en följd av avsaknaden av ett klassificeringssystem. Projektet resulterade i en väl fungerande webbtjänst med stöd för handel av ull.

  • 254.
    Adinugroho, Sigit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Calving Events Detection and Quantification from Time-lapse Images: A Case Study of Tunabreen Glacier, Svalbard2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A fully automated method for detecting and measuring calving regions of a glacier is an important tool to gather massive statistical data of calving events. A new framework to achieve the goals is presented in this thesis. First, time-lapse images are registered to the first image in the set. Registration process makes use of the M-Estimator Sample Consensus (MSAC) method to estimate a transformation model that relates a pair of Speeded-Up Robust Features (SURF). Then, the terminus of a glacier is separated from other objects by a semi-automatic Chan-vese level-set segmentation. After that, calving regions in a terminus are detected as a combined difference of Local Binary Patterns (LBP) of two successive images. Clustered points that form a difference image are transformed into polygons representing changed regions by applying the &#945;-shape method. Finally, the areas of changed regions are estimated by the pixel scaling method. The results highlight the performance of the method under normal conditions and reveal the impact of various weather conditions to the performance of the method.

  • 255. Adinugroho, Sigit
    et al.
    Vallot, Dorothée
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Westrin, Pontus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Strand, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Calving events detection and quantification from time-lapse images in Tunabreen glacier2015Ingår i: Proc. 9th International Conference on Information & Communication Technology and Systems, Piscataway, NJ: IEEE , 2015, s. 61-65Konferensbidrag (Refereegranskat)
  • 256.
    Adle, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen.
    Framtagning av metod för analys av livslängdsdata2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Husqvarna AB has as of today an extensive research and development department.This department serves to control the active product as well as the upcoming ones.The way that is done is through two different sets of tests. The first one being a longterm endurance test with aimed to unveil the durability of a product. Second and finalsort of test is a more one dimensional one. The aim is to determine different specificunits of interest like for example Newton (N).

    Today the R&D department has a great knowledge within normal distributed data andsomewhat less when it comes to the opposite, so called none normal distributed data.When endurance is of interest the likelihood of that to be of the latter sort is morecommon than not. For now no complete method has been appointed to make iteasier to process a situation of this kind. Studying ever unique case individually, bylooking at the data, has been the way to go. This causes an inconsistency in theanalysis and makes it purely based on which individual that has done it. Lastly it mayalso, unintentionally, ignore the large picture of how a product has progressed.

    To solve these problems this thesis work was put together to propose and conduct amethod. To form this method was an ongoing process throughout the whole thesisperiod. Ideas and thoughts were put forward to be reviewed and discussed. After aseries of tweaks to steer it towards the overall goal the method was finalized. Themethod that was put forward was firmly tested. Also a wide laboration in what themethod actually meant was done.

    The result was a method to be applied on none normal distributed data. This methodhas three parts. The first being the report where everything is embraced. The secondpart is a short manual for an operator to use. Last part is an example where themethod is put to use.

  • 257.
    Adler, Jeremy
    et al.
    Uppsala universitet, Science for Life Laboratory, SciLifeLab. Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi.
    Sintorn, Ida-Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Strand, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Parmryd, Ingela
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Conventional analysis of movement on non-flat surfaces like the plasma membrane makes Brownian motion appear anomalous2019Ingår i: Communications Biology, ISSN 2399-3642, Vol. 2, artikel-id 12Artikel i tidskrift (Refereegranskat)
  • 258.
    Adlertz, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Implementing a New Register Allocator for the Server Compiler in the Java HotSpot Virtual Machine2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The Java HotSpot Virtual Machine currently uses two Just In Time compilers to increase the performance of Java code in execution. The client and server compilers, as they are named, serve slightly different purposes. The client compiler produces code fast, while the server compiler produces code of greater quality. Both are important, because in a runtime environment there is a tradeoff between compiling and executing code. However, maintaining two separate compilers leads to increased maintenance and code duplication. An important part of the compiler is the register allocator which has high impact on the quality of the produced code. The register allocator decides which local variables and temporary values that should reside in physical registers during execution. This thesis presents the implementation of a second register allocator in the server compiler. The purpose is to make the server compiler more flexible, allowing it to produce code fast or produce code of greater quality. This would be a major step towards making the client compiler redundant. The new register allocator is based on an algorithm called the linear scan algorithm, which is also used in the client compiler. The implementation shows that the time spent on register allocation in the server compiler can be greatly reduced with an average reduction of 60 to 70% when running the SPECjvm2008 benchmarks. However, while the new implementation, in most benchmarks, is slower than the register allocator in the client compiler, concrete suggestions on how to improve the speed of the new register allocator are presented. Looking at performance, the implementation is not yet in line the with the client compiler, which in most benchmarks produces code that performs 10 to 25% better. The implementation does, however, have good potential in reaching that performance by implementing additional performance improvements described in this thesis. The benchmark data shows that, while the new implementation looks promising, additional work is needed to reach the same compilation speed and performance as the register allocator in the client compiler. Also, other phases in the server compiler, such as certain optimization phases, also need to be optional and adjustable to further reduce the compilation time.

  • 259.
    Adolfsson, Hampus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Adolfsson, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Wang, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    A Web Application for Daily Staff Coordination in Hospital Care2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Stress och tunga arbetsbördor hör till vardagen för den som jobbar inom svensk sjukvård, och problemet förvärras ytterligare av den rådande bristen på kvalificerad personal. Däri uppstår ett behov av verktyg som lätter på personalens belastning. Denna rapport presenterar en prototyp av en webbapplikation för dygnsmässig schemaläggning av personal, anpassad för barnoperationsavdelningen vid Uppsala akademiska sjukhus. Målet med projektet var att leverera en flexiblare digital lösning för avdelningens samordning av personal. Två fundamentala egenskaper hos applikationen var att den skulle vara enkel att använda samt visa upp informationen tydligt och med få missförstånd. Den resulterande prototypen uppfyllde kraven på användbarhet, med undantag för ett antal specifika problem, och förbättrade läsbarheten i jämförelse med det tidigare systemet. Det finns dock viss möjlighet för förbättring vad gäller effektiviteten uppgifter kan genomföras med.

  • 260.
    Adwent, Ann-Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datalogi.
    Shared IT Service Center i kommuner2012Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    To be able to maintain an adequate IT

    service for various users and needs,

    more municipalities are looking at the

    possibility for mergers of local IT

    departments. One solution for merging

    multiple services/functions and creating

    synergy opportunities is called Shared

    Service Center (SSC). The concept of SSC

    is that the administrative service

    itself becomes a core activity within

    the organization. The aim of this thesis

    is to provide municipalities who are

    considering a merging of their local IT

    departments with recommendations on how

    to design the Shared IT Service Center.

    Recommendations are outlined based on an

    analysis of IT-management literature,

    reports and by conducting a study on

    three ongoing collaborations.

    The conclusions drawn from the study

    suggest guidelines for the design of a

    Shared IT Service Center for

    municipalities. These are as following:

    Create a vision associated with a

    specific and structured target state.

    Identify needs for different target

    groups in municipalities and set a

    common standard.

    Create a clear and practical model/SLA

    appearance of the cooperation and

    agreement.

    Ensure the individual municipalities

    commissioning skills in order to not

    lose it in the context of a common IT

    operation.

    Find an organization that is democratic

    for member municipalities and

    facilitates long-term partnership.

    Specify the operation and maintenance so

    that it can be regulated and controlled

    Establish a common help desk.

    Establish a common standard and

    consolidated infrastructure before the

    introduction of a common technology platform.

  • 261.
    Afridi Asad, Hameed
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Development of Microwave sensor and Android Application for monitoringlong bone defects2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Fractures of the long bones are one of the most common injuries. Long bone are always at risk for fractures and require careful treatment to avoid the human disabilities. Microwave technology is using to development of biomedical sensors for detecting and monitoring bone defects. Microwave are electromagnetic (EM) radiation with frequencies between 300MHz and 300 GHz. The microwave technology is used in wireless networking and communication systems, wireless security systems, remote sensing and medical application. The main purpose of this thesis is to investigate rectangular microstrip patch antenna for monitoring long bone defects. A narrow band microwave antenna will be designed, then validate the antenna using measurement. Design an application for mobile, where physicians can easily see the patient’s measurement in a graph form,healing process and physicians can analyze the patient’s health condition.

  • 262.
    Afsarmanesh Tehrani, Nazanin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Clustering Multilayer Networks2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Detecting community structure is an important methodology to study complex networks. Community detection methods can be divided into two main categories: partitioning methods and overlapping clustering methods. In partitioning methods, each node can belong to at most one community while overlapping clustering methods allow communities with overlapping nodes as well. Community detection is not only a problem in single networks today, but also in multilayer networks where several networks with the same participants are considered at the same time. In recent years, several methods have been proposed for recognizing communities in multilayer networks; however, none of these methods finds overlapping communities. On the other hand, in many types of systems, this approach is not realistic. For example, in social networks, individuals communicate with different groups of people, like friends, colleagues, and family, and this determine overlaps between communities, while they also communicate through several networks like Facebook, Twitter, etc. The overall purpose of this study was to introduce a method for finding overlapping communities in multilayer networks. The proposed method is an extension of the popular Clique Percolation Method (CPM) for simple networks. It has been shown that the structure of communities is dependent on the definition of cliques in multilayer networks which are the smallest components of communities in CPM, and therefore, several types of communities can be defined based on different definitions of cliques. As the most conventional definition of communities, it is necessary for all nodes to be densely connected in single networks to form a community in the multilayer network. In the last part of the thesis, a method has been proposed for finding these types of communities in multilayer networks.

  • 263. Agarwal, M
    et al.
    Stoica, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åhgren, P
    Common factor estimation and two applications in signal prosessing2004Ingår i: Signal Processing, Vol. 84, s. 421-429Artikel i tidskrift (Refereegranskat)
  • 264. Agarwala, Sunita
    et al.
    Nandi, Debashis
    Kumar, Abhishek
    Dhara, Ashis Kumar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Thakur, Sumitra Basu
    Sadhu, Anup
    Bhadra, Ashok Kumar
    Automated segmentation of lung field in HRCT images using active shape model2017Ingår i: Proc. 37th Region 10 Conference, IEEE, 2017, s. 2516-2520Konferensbidrag (Refereegranskat)
  • 265.
    Agerberg, Gösta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Solving the Vehicle Routing Problem: using Search-based Methods and PDDL2013Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this project the optimization of transport planning has been studied. The approach was that smaller transport companies do not have the capability to fully optimize their transports. Their transport optimization is performed at a company level, meaning that the end result might be optimal for their company, but that potential for further optimization exists.

    The idea was to build a collaboration of transport companies, and then to optimize the transports globally within the collaboration. The intent was for the collaboration to perform the same driving assignments but at a lower cost, by using fewer vehicles and drivers, or travel shorter distance, or both combined. This should be achieved by planning the assignments in a smarter way, for example using a company's empty return journey to perform an assignment for another company.

    Due to the complexity of these types of problems, called Vehicle Routing Problem (VRP), shown to be NP-complete, search methods are often used. In this project the method of choice was a PDDL-based planner called LPG-td. It uses enforced hill-climbing together with a best-first search to find feasible solutions. The method was tested for scaling, performance versus another method and against time, as well as together with a real-life based problem.

    The results showed that LPG-td might not be a suitable candidate to solve the problem considered in this project. The solutions found for the collaboration were worse than for the sum of individual solutions, and used more computational time. Since the solution for the collaboration at most should be equal to the sum of individual solutions, in theory, this meant that the planner failed.

  • 266. Agerholm, Troels
    et al.
    Mazorchuk, Volodymyr
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Algebra, geometri och logik.
    On selfadjoint functors satisfying polynomial relations2011Ingår i: Journal of Algebra, ISSN 0021-8693, E-ISSN 1090-266X, Vol. 330, nr 1, s. 448-467Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study selfadjoint functors acting on categories of finite dimensional modules over finite dimensional algebras with an emphasis on functors satisfying some polynomial relations. Selfadjoint functors satisfying several easy relations, in particular, idempotents and square roots of a sum of identity functors. are classified. We also describe various natural constructions for new actions using external direct sums, external tensor products. Serre subcategories, quotients and centralizer subalgebras.

  • 267.
    Agnarsson, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Simulation of a radar in Flames: a ray based radar model2013Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this report a radar model is modeled and implemented in a simulation framework

    called Flames. The focus is to investigate how and if electromagnetic waves emitted

    from the radar antenna can be simulated by different methods and how these

    methods can be implemented to work in real-time simulations. The radar model

    developed in this report is based on ray tracing and ray propagation techniques

    developed by the author. The model considers varying refractive indices that

    describes both standard atmospheres and atmospheres where ducting occur.

    Preparatory studies are also made to model ground reflection by ray tracing

    techniques. Other simulation techniques, such as the Finite-Difference Time-Domain

    method and the Split-Step Parabolic Equation method, are furthermore considered

    for radar simulation applications. The results show that ray tracing in conjunction

    with geometrical optics is a valid method for simulating electromagnetic waves in

    simple atmosphere models.

  • 268.
    Agrawal, M
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. AUTOMATIC CONTROL.
    Stoica, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Besson, O
    Åhgren, P
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Estimation of nominal directions of arrival and angular spreads of distributed sources2003Ingår i: Signal Processing, Vol. 83, s. 1833-1838Artikel i tidskrift (Refereegranskat)
  • 269.
    Agrawal, Prerna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Tool And Algorithms for Rapid Source Term Prediction (RASTEP) Based on Bayesian Belief Networks2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In case of an accident in a nuclear power plant (NPP), the fast and cor-rect identification of the NPP state that would give a prediction of a possible radioactive release presents a major challenge to both nuclear power plants and regulators. Such prediction is important so that correct and timely decisions and measures are taken to mitigate accident consequences, such as evacuation of people from areas around the power plant. Recent research work [2][3] proposes analyzing the NPP using the Bayesian Belief Network models as a solution to this problem. A BBN is a graphical model that represents any entity with a set of connected nodes. These nodes represent the random variables and the connections between the nodes represent the conditional dependencies between them [7]. However, the BBN models alone are not suitable for use in off-site locations under high stress conditions by people who are not experts. Hence there arises a need for an interface that would –– - Be easy to operate by non-experts under high stress situations with incomplete knowledge of the plant state. - Provide the more detailed information about the network that is not easy for users to read out from the BBN itself. - Provide good graphical displays of the radioactive release predictions and other statistics of the network. One such tool is developed as a part of this master thesis project. The contribution is twofold –– - Analyzing the user requirements, designing the architecture and development of the tool. - Design and implementation of the algorithms for extracting additional information from the network which is not easy to read out while working directly with the BBN. This kind of information helps the user to take some decisions with entering the observations when the user is not a BBN expert. For instance, it helps the user to know which nodes are important to answer and which nodes can be left out. This also helps the user to interpret the intermediate state of the BBN model of the plant. The tool and the algorithms were evaluated by an expert user in order to assess them based on ease of use, value of the analysis output and the processing time. This project work was carried forward in collaboration with Swedish Radiation Safety Authority (SSM) [8]. SSM is already assessing the tool with the goal to obtain fast and independent predictions of radioactive releases based on plant observations.

  • 270.
    Agrens, Rudolfs Eriks
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Sensor Network for Real-TimeAir Quality Measurement2018Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this research, a sensor network for air quality measurement is developed. There is a need for air quality assessment in rapidly developing urban areas. Prolonged real-time monitoring can provide a direct feedback on how increasing traffic and construction work affect air quality. Measures can then be taken to mitigate pollution, reducing health hazards and maintaining the standard of air quality in all areas of the city. A low-cost sensor node is required to be able to cover a larger area using more sensor nodes. Methods for measuring humidity, temperature, particle concentration, as well as the gasses carbon monoxide, nitrogen dioxide and ozone were investigated and a sensor node designed by choosing suitable sensors. Field-testing of the sensor nodes was performed in the center of Uppsala city in collaboration with Uppsala Kommun and Uppsala Stadsteater. The commercially available Air Quality Egg was used as a reference method for sensor calibration and verification of measurement accuracy. The results show that the readings match the reference method well. Even low gas concentrations can be measured with good accuracy. There is future interest from Uppsala Kommun to expand the sensor network for measurements in other areas than the city center.

  • 271. Aguero, Juan Carlos
    et al.
    Goodwin, Graham
    Söderström, Torsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Yuz, Juan
    Sampled Data Errors in Variables Systems.2009Ingår i: SYSID 2009, IFAC 15th Symposium on System Identification, Saint-Malo, France, July 6-8, 2009., 2009Konferensbidrag (Refereegranskat)
  • 272. Agüero, Juan C.
    et al.
    Godoy, Boris I.
    Goodwin, Graham C.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Scenario-based EM identification for FIR systems having quantized output data2009Ingår i: Proc. 15th IFAC Symposium on System Identification, International Federation of Automatic Control , 2009, s. 66-71Konferensbidrag (Refereegranskat)
  • 273. Agüero, Juan C.
    et al.
    Goodwin, Graham C.
    Lau, Katrina
    Wang, Meng
    Silva, Eduardo I.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Three-degree of freedom adaptive power control for CDMA cellular systems2009Ingår i: Proc. 28th Global Telecommunications Conference, IEEE Communications Society, 2009, s. 2793-2798Konferensbidrag (Refereegranskat)
  • 274.
    Ahani, Ghafour
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Yuan, Di
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    BS-assisted Task Offloading for D2D Networks with Presence of User Mobility2019Ingår i: 2019 IEEE 89TH VEHICULAR TECHNOLOGY CONFERENCE (VTC2019-SPRING), IEEE , 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Task offloading is a key component in mobile edge computing. Offloading a task to a remote server takes communication and networking resources. An alternative is device-to-device (D2D) offloading, where a task of a device is offloaded to some device having computational resource available. The latter requires that the devices are within the range of each other, first for task collection, and later for result gathering. Hence, in mobility scenarios, the performance of D2D offloading will suffer if the contact rates between the devices are low. We enhance the setup to base station (BS) assisted D2D offloading, namely, a BS can act as a relay for task distribution or result collection. However, this would imply additional consumption of wireless resources. The associated cost and the improvement in completion time of task offloading compose a fundamental trade-off. For the resulting optimization problem, we mathematically prove the complexity, and propose an algorithm using Lagrangian duality. The simulation results demonstrate not only that the algorithm has close-to-optimal performance, but also provide structural insights of the optimal trade-off.

  • 275.
    Ahani, Ghafour
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Yuan, Di
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    On optimal proactive and retention-aware caching with user mobility2018Ingår i: 2018 IEEE 88th Vehicular Technology Conference (VTC-Fall), IEEE, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Caching popular contents at edge devices is an effective solution to alleviate the burden of the backhaul networks. Earlier investigations commonly neglected the storage cost in caching. More recently, retention-aware caching, where both the downloading cost and storage cost are accounted for, is attracting attention. Motivated by this, we address proactive and retention-aware caching problem with the presence of user mobility, optimizing the sum of the two types of costs. More precisely, a cost-optimal caching problem for vehicle-to-vehicle networks is formulated with joint consideration of the impact of the number of vehicles, cache size, storage cost, and content request probability. This is a combinatorial optimization problem. However, we derive a stream of analytical results and they together lead to an algorithm that guarantees global optimum with polynomial-time complexity. Numerical results show significant improvements in comparison to popular caching and random caching.

  • 276.
    Ahgren, P
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Stoica, P
    High-resolution frequency analysis with small data record2000Ingår i: ELECTRONICS LETTERS, ISSN 0013-5194, Vol. 36, nr 20, s. 1745-1747Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a paper published recently Samant and Shearman discuss several techniques for performing spectral analysis using short data records to overcome the problem of caller ID identification. They fail, however, to mention the nonlinear least squares (NLS) me

  • 277.
    Ahgren, Per
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Jakobsson, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    A study of doubletalk detection performance in the presence of acoustic echo path changes2006Ingår i: IEEE transactions on consumer electronics, ISSN 0098-3063, E-ISSN 1558-4127, Vol. 52, nr 2, s. 515-522Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An efficient and well-performing double-talk detection (DTD) algorithm is a vital part of a practically working acoustic echo canceller. However, recent algorithms are typically evaluated using a static time-invariant room acoustic impulse response, omitting a proper treatment of the case when the acoustic path is changing. In this work, we introduce a common framework to objectively evaluate how path changes affect the DTD performance. Via extensive numerical simulations, we conclude that the main factor in acoustic path changes affecting the DTD performance for some of the more common DTD algorithms is variations in the damping of the acoustic path.

  • 278.
    Ahlberg, Daniel
    et al.
    Stockholm Univ, Dept Math, S-10691 Stockholm, Sweden.
    Deijfen, Maria
    Stockholm Univ, Dept Math, S-10691 Stockholm, Sweden.
    Janson, Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori.
    Competing first passage percolation on random graphs with finite variance degrees2019Ingår i: Random structures & algorithms (Print), ISSN 1042-9832, E-ISSN 1098-2418, Vol. 55, nr 3, s. 545-559Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the growth of two competing infection types on graphs generated by the configuration model with a given degree sequence. Starting from two vertices chosen uniformly at random, the infection types spread via the edges in the graph in that an uninfected vertex becomes type 1 (2) infected at rate lambda(1) (lambda(2)) times the number of nearest neighbors of type 1 (2). Assuming (essentially) that the degree of a randomly chosen vertex has finite second moment, we show that if lambda(1) = lambda(2), then the fraction of vertices that are ultimately infected by type 1 converges to a continuous random variable V is an element of (0,1), as the number of vertices tends to infinity. Both infection types hence occupy a positive (random) fraction of the vertices. If lambda(1) not equal lambda(2), on the other hand, then the type with the larger intensity occupies all but a vanishing fraction of the vertices. Our results apply also to a uniformly chosen simple graph with the given degree sequence.

  • 279.
    Ahlberg, Daniel
    et al.
    Stockholm Univ, Dept Math, SE-10691 Stockholm, Sweden.
    Griffiths, Simon
    PUC Rio, Dept Matemat, BR-22451900 Gavea, RJ, Brazil.
    Janson, Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori.
    Morris, Robert
    Inst Nacl Matemat Pura & Aplicada, Estr Dona Castorina 110, BR-22460320 Rio De Janeiro, Brazil.
    Competition in growth and urns2019Ingår i: Random structures & algorithms (Print), ISSN 1042-9832, E-ISSN 1098-2418, Vol. 54, nr 2, s. 211-227Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study survival among two competing types in two settings: a planar growth model related to two-neighbor bootstrap percolation, and a system of urns with graph-based interactions. In the planar growth model, uncolored sites are given a color at rate 0, 1 or infinity, depending on whether they have zero, one, or at least two neighbors of that color. In the urn scheme, each vertex of a graph G has an associated urn containing some number of either blue or red balls ( but not both). At each time step, a ball is chosen uniformly at random from all those currently present in the system, a ball of the same color is added to each neighboring urn, and balls in the same urn but of different colors annihilate on a one-for-one basis. We show that, for every connected graph G and every initial configuration, only one color survives almost surely. As a corollary, we deduce that in the two-type growth model on Z(2), one of the colors only infects a finite number of sites with probability one. We also discuss generalizations to higher dimensions and multi-type processes, and list a number of open problems and conjectures.

  • 280.
    Ahlberg, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori. Uppsala Univ, Dept Math, SE-75106 Uppsala, Sweden..
    Griffiths, Simon
    Univ Oxford, Dept Stat, Oxford OX1 3TG, England..
    Morris, Robert
    IMPA, Rio De Janeiro, RJ, Brazil..
    Tassion, Vincent
    Univ Geneva, Dept Math, Geneva, Switzerland..
    Quenched Voronoi percolation2016Ingår i: Advances in Mathematics, ISSN 0001-8708, E-ISSN 1090-2082, Vol. 286, s. 889-911Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We prove that the probability of crossing a large square in quenched Voronoi percolation converges to 1/2 at criticality, confirming a conjecture of Benjamini, Kalai and Schramm from 1999. The main new tools are a quenched version of the box-crossing property for Voronoi percolation at criticality, and an Efron Stein type bound on the variance of the probability of the crossing event in terms of the sum of the squares of the influences. As a corollary of the proof, we moreover obtain that the quenched crossing event at criticality is almost surely noise sensitive.

  • 281.
    Ahlberg, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori. Inst Nacl Matemat Pura & Aplicada, Estr Dona Castorina 110, BR-22460320 Rio De Janeiro, Brazil.;Uppsala Univ, Dept Math, SE-75106 Uppsala, Sweden..
    Steif, Jeffrey E.
    Univ Gothenburg, Chalmers Univ Technol, Math Sci, SE-41296 Gothenburg, Sweden..
    Pete, Gabor
    Hungarian Acad Sci, Renyi Inst, 13-15 Realtanoda U, H-1053 Budapest, Hungary.;Budapest Univ Technol & Econ, Inst Math, 1 Egry Jozsef U, H-1111 Budapest, Hungary..
    Scaling limits for the threshold window: When does a monotone Boolean function flip its outcome?2017Ingår i: Annales de l'I.H.P. Probabilites et statistiques, ISSN 0246-0203, E-ISSN 1778-7017, Vol. 53, nr 4, s. 2135-2161Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Consider a monotone Boolean function f : {0, 1}(n) -> {0, 1} and the canonical monotone coupling {eta(p) : p is an element of [0, 1]} of an element in {0, 1}(n) chosen according to product measure with intensity p is an element of [0, 1]. The random point p is an element of [0, 1] where f (eta(p)) flips from 0 to 1 is often concentrated near a particular point, thus exhibiting a threshold phenomenon. For a sequence of such Boolean functions, we peer closely into this threshold window and consider, for large n, the limiting distribution (properly normalized to be nondegenerate) of this random point where the Boolean function switches from being 0 to 1. We determine this distribution for a number of the Boolean functions which are typically studied and pay particular attention to the functions corresponding to iterated majority and percolation crossings. It turns out that these limiting distributions have quite varying behavior. In fact, we show that any nondegenerate probability measure on R arises in this way for some sequence of Boolean functions.

  • 282.
    Ahlberg, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori. Inst Matematica Pura & Aplicada, Estr Dona Castorina 110, BR-22460320 Rio De Janeiro, Brazil.
    Tassion, Vincent
    Univ Geneva, 2-4 Rue Lievre, CH-1211 Geneva, Switzerland.
    Teixeira, Augusto
    Inst Matematica Pura & Aplicada, Estr Dona Castorina 110, BR-22460320 Rio De Janeiro, Brazil.
    Sharpness of the phase transition for continuum percolation in R22018Ingår i: Probability theory and related fields, ISSN 0178-8051, E-ISSN 1432-2064, Vol. 172, nr 1-2, s. 525-581Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the phase transition of random radii Poisson Boolean percolation: Around each point of a planar Poisson point process, we draw a disc of random radius, independently for each point. The behavior of this process is well understood when the radii are uniformly bounded from above. In this article, we investigate this process for unbounded (and possibly heavy tailed) radii distributions. Under mild assumptions on the radius distribution, we show that both the vacant and occupied sets undergo a phase transition at the same critical parameter.c. Moreover, For. <.c, the vacant set has a unique unbounded connected component and we give precise bounds on the one-arm probability for the occupied set, depending on the radius distribution. At criticality, we establish the box-crossing property, implying that no unbounded component can be found, neither in the occupied nor the vacant sets. We provide a polynomial decay for the probability of the one-arm events, under sharp conditions on the distribution of the radius. For. >.c, the occupied set has a unique unbounded component and we prove that the one-arm probability for the vacant decays exponentially fast. The techniques we develop in this article can be applied to other models such as the Poisson Voronoi and confetti percolation.

  • 283.
    Ahlberg, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori. Inst Nacl Matemat Pura & Aplicada, Rio De Janeiro, RJ, Brazil;Stockholm Univ, Dept Math, SE-10691 Stockholm, Sweden;Stockholm Univ, Dept Math, SE-10691 Stockholm, Sweden.
    Tykesson, Johan
    Chalmers Univ Technol, Dept Math, SE-41296 Gothenburg, Sweden;Univ Gothenburg, Gothenburg, Sweden.
    Gilbert´s disc model with geostatical marking2018Ingår i: Advances in Applied Probability, ISSN 0001-8678, E-ISSN 1475-6064, Vol. 50, nr 4, s. 1075-1094Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study a variant of Gilbert's disc model, in which discs are positioned at the points of a Poisson process in R-2 with radii determined by an underlying stationary and ergodic random field phi: R-2 -> [0, infinity), independent of the Poisson process. This setting, in which the random field is independent of the point process, is often referred to as geostatistical marking. We examine how typical properties of interest in stochastic geometry and percolation theory, such as coverage probabilities and the existence of long-range connections, differ between Gilbert's model with radii given by some random field and Gilbert's model with radii assigned independently, but with the same marginal distribution. Among our main observations we find that complete coverage of R(2 )does not necessarily happen simultaneously, and that the spatial dependence induced by the random field may both increase as well as decrease the critical threshold for percolation.

  • 284.
    Ahlberg, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen.
    Studier av mätdataregistrering för JAS 39 Gripen2002Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 285. Ahlberg, Ragnar
    et al.
    Gustafsson, Bertil
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för teknisk databehandling. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Numerisk analys.
    A note on parallel algorithms for partial differential equations1984Ingår i: Parallel Computing: 83, Amsterdam, The Netherlands: Elsevier Science , 1984, s. 93-98Konferensbidrag (Refereegranskat)
  • 286.
    Ahlbom, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Quadratic Programming Modelsin Strategic Sourcing Optimization2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Strategic sourcing allows for optimizing purchases on a large scale.Depending on the requirements of the client and the offers provided forthem, finding an optimal or even a near-optimal solution can become computationally hard. Mixed integer programming (MIP), where theproblem is modeled as a set of linear expressions with an objectivefunction for which an optimal solution results in a minimum objectivevalue, is particularly suitable for finding competitive results. However, given the research and improvements continually being made for quadratic programming (QP), which allows for objective functions with quadratic expressions as well, comparing runtimes and objective values for finding optimal and approximate solutions is advised: for hard problems, applying the correct methods may decrease runtimes by severalorders of magnitude. In this report, comparisons between MIP and QPmodels used in four different problems with three different solverswere made, measuring both optimization and approximation performance interms of runtimes and objective values. Experiments showed that while QP holds an advantage over MIP in some cases, it is not consistentlyefficient enough to provide a significant improvement in comparison with, for example, using a different solver.

  • 287.
    Ahlén, Oscar Ahlén
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Klassificering av läkemedelshandlingar med hjälp av maskininlärning2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Handlingar kopplade till processer för godkännande och övervakning av läkemedel är mycket centrala dokument för läkemedelsmyndigheters dagliga arbete. Att ersätta manuell hantering av dessa handlingar med maskinella klassificeringssystem är en tänkbar metod för att effektivisera och kvalitetssäkra denna verksamhet. I detta arbete undersöktes möjligheten att klassificera 4750 utvalda handlingar från 10 kategorier med maskininlärning genom ett pilotprojekt på Läkemedelsverket. Maskininlärningsalgoritmer i fokus var Naive Bayes (NB), K-Nearest Neighbors (K-NN) och Support Vector Machines (SVM) och deras prestanda tillsammans med komplexitetsreducering av utvald data utvärderades. Resultatet visade på en generellt hög och jämförbar klassificeringsprestanda mellan algoritmerna där SVM hade en högsta träffsäkerhet på nästan 98%. Dessa höga siffror förklarades av en hög grad av separation i träningsdata och en större mängd handlingar och kategorier behöver utvärderas i framtida försök. Resultatet indikerar ändå på att utförligare experiment och potentiell applicering av maskininlärning mot denna domän är mycket lovande.

  • 288. Ahlford, Marianne
    et al.
    Andersson, Martin
    Blomquist, Hanna
    Ekström, Magnus
    Ericsson, Lars
    Gumbel, Johannes
    Holmgren, Anna
    Holmberg, Petter
    Kia, Leonard
    Lindström, Anton
    Lyrberg, Magnus
    Mahmoudi, Shaman
    Nolin, Bengt
    Sundien, Jesper
    Wallentin, Henrik
    Gällmo, Olle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Datorteknik.
    Hessel, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Datorteknik.
    Mokrushin, Leonid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Datorteknik.
    Pettersson, Paul
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik. Datorteknik.
    Uppsala Underdogs - A Robot Soccer Project2006Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    In this paper, we describe the four-legged soccer team Uppsala Underdogs developed by a group of 4th year computer science students at Uppsala University during the fall of 2004. The project is based on the experience from two similar previous projects. This year the emphasis of the project has been on distribution of data and on support for evaluation and reconfiguration of strategies. To support data distribution, a middleware has been developed, which implements a replication algorithm and provides a clean interface for the other software modules (or behaviors). To enable easy reconfiguration of strategies, an automata-based graphical description language has been developed, which can be compiled into code that uses the database and the lower level modules, such as tactics and positioning, to make decisions and control the robot. In addition, a graphical simulator has been developed in which the strategies can be evaluated.

  • 289.
    Ahlgren, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för datorteknik. Swedish Institute of Computer Science.
    Improving Computer Communication Performance by Reducing Memory Bandwidth Consumption1997Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 290.
    Ahlgren, Bengt
    et al.
    SICS.
    Björkman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Gunningberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    The applicability of integrated layer processing1998Ingår i: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 16, nr 3, s. 317-331Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we review previous work on the applicability and performance of integrated layer processing (ILP). ILP has been shown to clearly improve computer communication performance when integrating simple data manipulation functions, but the situati

  • 291.
    Ahlgren, Bengt
    et al.
    SICS .
    Björkman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Gunningberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Towards predictable ILP performance controlling communication buffer cache effects1996Ingår i: Australian Computer Journal, ISSN 0004-8917, Vol. 28, nr 2, s. 66-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cache memory behaviour is becoming more and more important as the speed of CPUs is increasing faster than the speed of memories. The operation of caches are statistical which means that the system level performance becomes unpredictable. In this paper we

  • 292.
    Ahlgren, Bengt
    et al.
    SICS.
    Gunningberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Moldeklev, Kjersti
    Telenor Research.
    Increasing communication performance with a minimal-copy data path supporting ILP and ALF1996Ingår i: Journal of High Speed Networks, ISSN 0926-6801, E-ISSN 1875-8940, Vol. 5, nr 2, s. 203-214Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many current implementations of communication subsystems on workstation class computers transfer communication data to and from primary memory several times. This is due to software copying between user and operating system address spaces, presentation la

  • 293. Ahlgren, Bengt
    et al.
    Hidell, Markus
    Ngai, Edith C.-H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Internet of Things for smart cities: Interoperability and open data2016Ingår i: IEEE Internet Computing, ISSN 1089-7801, E-ISSN 1941-0131, Vol. 20, nr 6, s. 52-56Artikel i tidskrift (Refereegranskat)
  • 294.
    Ahlgren, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi.
    Resursoptimering för restauranger2018Självständigt arbete på grundnivå (kandidatexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    An optimization of reservation systems for tables in the restaurant industry. The optimization is aimed at maximizing the number of guests as well as placing guests at the optimal tables based on the prevailing conditions.

  • 295.
    Ahlkrona, Josefin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för beräkningsvetenskap. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Numerisk analys.
    Computational Ice Sheet Dynamics: Error control and efficiency2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Ice sheets, such as the Greenland Ice Sheet or Antarctic Ice Sheet, have a fundamental impact on landscape formation, the global climate system, and on sea level rise. The slow, creeping flow of ice can be represented by a non-linear version of the Stokes equations, which treat ice as a non-Newtonian, viscous fluid. Large spatial domains combined with long time spans and complexities such as a non-linear rheology, make ice sheet simulations computationally challenging. The topic of this thesis is the efficiency and error control of large simulations, both in the sense of mathematical modelling and numerical algorithms. In the first part of the thesis, approximative models based on perturbation expansions are studied. Due to a thick boundary layer near the ice surface, some classical assumptions are inaccurate and the higher order model called the Second Order Shallow Ice Approximation (SOSIA) yields large errors. In the second part of the thesis, the Ice Sheet Coupled Approximation Level (ISCAL) method is developed and implemented into the finite element ice sheet model Elmer/Ice. The ISCAL method combines the Shallow Ice Approximation (SIA) and Shelfy Stream Approximation (SSA) with the full Stokes model, such that the Stokes equations are only solved in areas where both the SIA and SSA is inaccurate. Where and when the SIA and SSA is applicable is decided automatically and dynamically based on estimates of the modeling error. The ISCAL method provides a significant speed-up compared to the Stokes model. The third contribution of this thesis is the introduction of Radial Basis Function (RBF) methods in glaciology. Advantages of RBF methods in comparison to finite element methods or finite difference methods are demonstrated.

    Delarbeten
    1. A numerical study of scaling relations for non-Newtonian thin-film flows with applications in ice sheet modelling
    Öppna denna publikation i ny flik eller fönster >>A numerical study of scaling relations for non-Newtonian thin-film flows with applications in ice sheet modelling
    2013 (Engelska)Ingår i: Quarterly Journal of Mechanics and Applied Mathematics, ISSN 0033-5614, E-ISSN 1464-3855, Vol. 66, s. 417-435Artikel i tidskrift (Refereegranskat) Published
    Nationell ämneskategori
    Beräkningsmatematik
    Identifikatorer
    urn:nbn:se:uu:diva-205727 (URN)10.1093/qjmam/hbt009 (DOI)000327457200001 ()
    Projekt
    eSSENCE
    Tillgänglig från: 2013-08-09 Skapad: 2013-08-22 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
    2. Accuracy of the zeroth- and second-order shallow-ice approximation: numerical and theoretical results
    Öppna denna publikation i ny flik eller fönster >>Accuracy of the zeroth- and second-order shallow-ice approximation: numerical and theoretical results
    2013 (Engelska)Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 6, s. 2135-2152Artikel i tidskrift (Refereegranskat) Published
    Nationell ämneskategori
    Beräkningsmatematik
    Identifikatorer
    urn:nbn:se:uu:diva-213571 (URN)10.5194/gmd-6-2135-2013 (DOI)000329050500017 ()
    Projekt
    eSSENCE
    Tillgänglig från: 2013-12-19 Skapad: 2013-12-28 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
    3. Dynamically coupling the non-linear Stokes equations with the shallow ice approximation in glaciology: Description and first applications of the ISCAL method
    Öppna denna publikation i ny flik eller fönster >>Dynamically coupling the non-linear Stokes equations with the shallow ice approximation in glaciology: Description and first applications of the ISCAL method
    2016 (Engelska)Ingår i: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 308, s. 1-19Artikel i tidskrift (Refereegranskat) Published
    Nationell ämneskategori
    Beräkningsmatematik
    Identifikatorer
    urn:nbn:se:uu:diva-269822 (URN)10.1016/j.jcp.2015.12.025 (DOI)000369086700001 ()
    Projekt
    eSSENCE
    Tillgänglig från: 2015-12-17 Skapad: 2015-12-18 Senast uppdaterad: 2017-12-01Bibliografiskt granskad
    4. The ISCAL method and the grounding line: Combining the Stokes equations with the Shallow Ice Approximation and Shelfy Stream Approximation
    Öppna denna publikation i ny flik eller fönster >>The ISCAL method and the grounding line: Combining the Stokes equations with the Shallow Ice Approximation and Shelfy Stream Approximation
    2016 (Engelska)Rapport (Övrigt vetenskapligt)
    Serie
    Technical report / Department of Information Technology, Uppsala University, ISSN 1404-3203 ; 2016-006
    Nationell ämneskategori
    Beräkningsmatematik
    Identifikatorer
    urn:nbn:se:uu:diva-283438 (URN)
    Projekt
    eSSENCE
    Tillgänglig från: 2016-04-19 Skapad: 2016-04-13 Senast uppdaterad: 2016-05-16Bibliografiskt granskad
    5. A meshfree approach to non-Newtonian free surface ice flow: Application to the Haut Glacier d'Arolla
    Öppna denna publikation i ny flik eller fönster >>A meshfree approach to non-Newtonian free surface ice flow: Application to the Haut Glacier d'Arolla
    2016 (Engelska)Rapport (Övrigt vetenskapligt)
    Serie
    Technical report / Department of Information Technology, Uppsala University, ISSN 1404-3203 ; 2016-005
    Nationell ämneskategori
    Beräkningsmatematik
    Identifikatorer
    urn:nbn:se:uu:diva-283437 (URN)
    Projekt
    eSSENCE
    Tillgänglig från: 2016-04-19 Skapad: 2016-04-13 Senast uppdaterad: 2016-05-16Bibliografiskt granskad
  • 296.
    Ahlkrona, Josefin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för teknisk databehandling.
    Implementing Higher Order Dynamics into the Ice Sheet Model SICOPOLIS2011Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Ice sheet modeling is an important tool both for reconstructing past ice sheets and predicting their future evolution, but is complex and computationally costly. It involves modeling a system including the ice sheet, ice shelves and ice streams, which all have different dynamical behavior. The governing equations are non-linear, and to capture a full glacial cycle more than 100,000 years need to be simulated. To reduce the problem size, approximations of the equations are introduced. The most common approximation, the Shallow Ice Approximation (SIA), works well in the ice bulk but fails in e.g. the modeling of ice streams and the ice sheet/ice shelf coupling. In recent years more accurate models, so-called higher order models, have been constructed to address these problems. However, these models are generally constructed in an ad hoc fashion, lacking rigor. In this thesis, so-called Second Order Shallow Ice Approximation (SOSIA) equations for pressure, vertical shear stress and velocity are implemented into the ice sheet model SICOPOLIS. The SOSIA is a rigorous model derived by Baral in 1999 [3]. The numerical solution for a simple model problem is compared to an analytical solution, and benchmark experiments, comparing the model to other higher order models, are carried out. The numerical and analytical solution agree well, but the results regarding vertical shear stress and velocity differ from other models. It is concluded that there are problems with the model implemented, most likely in the treatment of the relation between stress and strain rate.