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  • 1.
    Aarts, Marcel
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Using Kinect to interact with presentation software2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    Imagination Studios is a company specialized in motion capturing and animation. Part of their daily business is working at trade shows where they have a booth to keep close contact with existing customers and also to find new ones. However, usually only two to three people will be working at the booth, and frequently, these people will be in meetings with potential customers. During a time like this, nobody is free to attend to other people checking out the booth. This can result in a potential loss of a new customer. This project seeks a way to alleviate that problem.The idea behind this project was to create an application that trade show visitors can interact with in a playful and innovative way while also giving them a feel of what Imagination Studios is all about while looking for information about the company. To do this it was decided to let users interact with the system by using a Microsoft Kinect. The Kinect allows for easy implementation of a user interface based on motion capturing while also being very cost effective. A new user interface was to be designed as well, without copying already existing solutions and without simply expanding a traditional UI with new elements. To achieve this several design sketches were made, and the most interesting ones were then turned into storyboards. These were then used to decide on the final design, which was then elaborated on by use of video sketches and a collage in Adobe Photoshop.Several tools were used during the actual implementation. For the actual visualization and graphical design, the Unreal Engine 3 in combination with UDK was decided upon. To connect Kinect and Unreal Engine 3, a third party addon called NIUI which makes use of the open source SDK OpenNI was used. For ease of debugging and programming in Unrealscript, the programming language used by the Unreal Engine 3, an addon for Microsoft Visual Studio 2010 called nFringe (Pixel Mine, Inc., 2010) was used.

    Fulltekst (pdf)
    fulltext
  • 2.
    Abbas, M.
    et al.
    University Pretoria, South Africa.
    De La Sen, M.
    University of the Basque Country, Spain.
    Nazir, Talat
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Common Fixed Points of Generalized Rational Type Cocyclic Mappings in Multiplicative Metric Spaces2015Inngår i: Discrete dynamics in nature and society, ISSN 1026-0226, E-ISSN 1607-887X, Vol. 2015, artikkel-id 532725Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this paper is to present fixed point result of mappings satisfying a generalized rational contractive condition in the setup of multiplicative metric spaces. As an application, we obtain a common fixed point of a pair of weakly compatible mappings. Some common fixed point results of pair of rational contractive types mappings involved in cocyclic representation of a nonempty subset of a multiplicative metric space are also obtained. Some examples are presented to support the results proved herein. Our results generalize and extend various results in the existing literature.

  • 3.
    Abbas, M.
    et al.
    Ton Duc Thang University, Ho Chi Minh City, Viet Nam.
    Nazir, Talat
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Popović, B.
    University of Kragujevac, Serbia.
    Radenović, S.
    University of Belgrade, Serbia.
    On Weakly Commuting Set-Valued Mappings on a Domain of Sets Endowed with Directed Graph2017Inngår i: Results in Mathematics, ISSN 1422-6383, Vol. 71, nr 3-4, s. 1277-1295Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this paper is to present coincidence and common fixed point results of set-valued mappings satisfying certain generalized graphic F-contractive conditions on a family of sets endowed with a graph. It is worth mentioning that these results are obtained without appealing to any form of continuity of mappings involved herein. Some examples are presented to support the results proved in this paper. Our results unify, generalize and extend various comparable results in the existing literature. © 2016, Springer International Publishing.

  • 4.
    Abbas, Muhammad
    et al.
    RISE Res Inst Sweden, Västerås, Sweden..
    Ferrari, Alessio
    CNR, ISTI, Pisa, Italy..
    Shatnawi, Anas
    Berger Levrault, Montpellier, France..
    Enoiu, Eduard Paul
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Saadatmand, Mehrdad
    RISE Res Inst Sweden, Västerås, Sweden..
    Sundmark, Daniel
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Correction to: On the relationship between similar requirements and similar software A case study in the railway domain (Jan, 10.1007/s00766-021-00370-4, 2022)2022Inngår i: Requirements Engineering, ISSN 0947-3602, E-ISSN 1432-010X, Vol. 27, nr 3, s. 399-399Artikkel i tidsskrift (Fagfellevurdert)
  • 5.
    Abbas, Mujahid
    et al.
    Ton Duc Thang Univ, Ho Chi Minh City, Vietnam..
    Nazir, Talat
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Lampert, Tatjana Aleksic
    Fac Sci, Dept Math, Radoja Domanovica 12, Kragujevac 34000, Serbia.
    Radenovic, Stojan
    State Univ Novi Pazar, Serbia..
    Common fixed points of set-valued F-contraction mappings on domain of sets endowed with directed graph2017Inngår i: Computational and Applied Mathemathics, ISSN 0101-8205, Vol. 36, nr 4, s. 1607-1622Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this paper is to present common fixed point results of set-valued graphic F-contraction mappings on a family of sets endowed with a graph. Some examples are presented to support the results proved herein. Our results unify, generalize and extend various results in the existing literature.

  • 6.
    Abbaspour Asadollah, Sara
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Cyberattacks: Modeling, Analysis, and Mitigation2022Inngår i: Proceedings - 2022 6th International Conference on Computer, Software and Modeling: ICCSM 2022, Institute of Electrical and Electronics Engineers Inc. , 2022, s. 80-84Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Industrial cybersecurity has risen as an important topic of research nowadays. The heavy connectivity by the Internet of Things (IoT) and the growth of cyberattacks against industrial assets cause this risen and attract attention to the cybersecurity field. While fostering current software applications and use-cases, the ubiquitous access to the Internet has also exposed operational technologies to new and challenging security threats that need to be addressed. As the number of attacks increases, their visibility decreases. An attack can modify the Cyber-Physical Systems (CPSs) quality to avoid proper quality assessment. They can disrupt the system design process and adversely affect a product’s design purpose. This working progress paper presents our approach to modeling, analyzing, and mitigating cyberattacks in CPS. We model the normal behavior of the application as well as cyberattacks with the help of Microsoft Security Development Lifecycle (SDL) and threat modeling approach (STRIDE). Then verify the application and attacks model using a model checking tool and propose mitigation strategies to decrease the risk of vulnerabilities. The results can be used to improve the system design to overcome the vulnerabilities.

  • 7.
    Abbaspour Asadollah, Sara
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Sundmark, Daniel
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Eldh, S.
    Ericsson AB, Stockholm, Sweden.
    Hansson, Hans
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Concurrency bugs in open source software: a case study2017Inngår i: Journal of Internet Services and Applications, ISSN 1867-4828, E-ISSN 1869-0238, Vol. 8, nr 1, artikkel-id 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Concurrent programming puts demands on software debugging and testing, as concurrent software may exhibit problems not present in sequential software, e.g., deadlocks and race conditions. In aiming to increase efficiency and effectiveness of debugging and bug-fixing for concurrent software, a deep understanding of concurrency bugs, their frequency and fixing-times would be helpful. Similarly, to design effective tools and techniques for testing and debugging concurrent software, understanding the differences between non-concurrency and concurrency bugs in real-word software would be useful. This paper presents an empirical study focusing on understanding the differences and similarities between concurrency bugs and other bugs, as well as the differences among various concurrency bug types in terms of their severity and their fixing time, and reproducibility. Our basis is a comprehensive analysis of bug reports covering several generations of five open source software projects. The analysis involves a total of 11860 bug reports from the last decade, including 351 reports related to concurrency bugs. We found that concurrency bugs are different from other bugs in terms of their fixing time and severity while they are similar in terms of reproducibility. Our findings shed light on concurrency bugs and could thereby influence future design and development of concurrent software, their debugging and testing, as well as related tools.

  • 8.
    Abbaspour, Sara
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Engineering Department, University of Qom, Iran.
    Fotouhi, F.
    Engineering Department, University of Qom, Iran.
    Sedaghatbaf, A.
    RISE Research Institutes of Sweden, Sweden.
    Fotouhi, Hossein
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Vahabi, Maryam
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. ABB Corporate Research, Sweden.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    A comparative analysis of hybrid deep learning models for human activity recognition2020Inngår i: Sensors, E-ISSN 1424-8220, Vol. 20, nr 19, s. 1-14, artikkel-id 5707Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent advances in artificial intelligence and machine learning (ML) led to effective methods and tools for analyzing the human behavior. Human Activity Recognition (HAR) is one of the fields that has seen an explosive research interest among the ML community due to its wide range of applications. HAR is one of the most helpful technology tools to support the elderly’s daily life and to help people suffering from cognitive disorders, Parkinson’s disease, dementia, etc. It is also very useful in areas such as transportation, robotics and sports. Deep learning (DL) is a branch of ML based on complex Artificial Neural Networks (ANNs) that has demonstrated a high level of accuracy and performance in HAR. Convolutional Neural Networks (CNNs) and Recurrent Neural Networks (RNNs) are two types of DL models widely used in the recent years to address the HAR problem. The purpose of this paper is to investigate the effectiveness of their integration in recognizing daily activities, e.g., walking. We analyze four hybrid models that integrate CNNs with four powerful RNNs, i.e., LSTMs, BiLSTMs, GRUs and BiGRUs. The outcomes of our experiments on the PAMAP2 dataset indicate that our proposed hybrid models achieve an outstanding level of performance with respect to several indicative measures, e.g., F-score, accuracy, sensitivity, and specificity. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

  • 9.
    Abdi, Somayeh
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Task Offloading in Edge-cloud Computing using a Q-Learning Algorithm2024Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Task offloading is a prominent problem in edge−cloud computing, as it aims to utilize the limited capacityof fog servers and cloud resources to satisfy the QoS requirements of tasks, such as meeting their deadlines.This paper formulates the task offloading problem as a nonlinear mathematical programming model to maximizethe number of independent IoT tasks that meet their deadlines and to minimize the deadline violationtime of tasks that cannot meet their deadlines. This paper proposes two Q-learning algorithms to solve theformulated problem. The performance of the proposed algorithms is experimentally evaluated with respect toseveral algorithms. The evaluation results demonstrate that the proposed Q-learning algorithms perform wellin meeting task deadlines and reducing the total deadline violation time.

  • 10.
    Abdullah, Syed Md Jakaria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Virtual Clustered-based Multiprocessor Scheduling in Linux Kernel2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Recent advancements of multiprocessor architectures have led to increasing use of multiprocessors in real-time embedded systems. The two most popular real-time scheduling approaches in multiprocessors are global and partitioned scheduling. Cluster based multiprocessor scheduling can be seen as a hybrid approach combining benefits of both partitioned and global scheduling. Virtual clustering further enhances it by providing dynamic cluster resource allocation duringrun-time and applying hierarchical scheduling to ensure temporal isolation between different software components. Over the years, the study of virtual clustered-based multiprocessor scheduling has been limited to theoretical analysis. In this thesis, we implemented a Virtual-Clustered Hierarchical Scheduling Framework (VC-HSF) in Linux without modifying the base Linux kernel. This work includes complete design, implementation and experimentation of this framework in a multiprocessor platform. Our main contributions are twofold: (i) to the best of our knowledge, our work is the first implementation of any virtual-clustered real-time multiprocessor scheduling in an operating system, (ii) our design and implementation gives practical insights about challenges of implementing any virtual-clustered algorithms for real-time scheduling.

    Fulltekst (pdf)
    VC-HSF Thesis
  • 11.
    Abdulle, Assyr
    et al.
    Institute of Mathematics, Ecole Polytechnique Federale de Lausanne, Switzerland.
    Arjmand, Doghonay
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Paganoni, Edoardo
    Institute of Mathematics, Ecole Polytechnique Federale de Lausanne, Switzerland.
    A parabolic local problem with exponential decay of the resonance error for numerical homogenization2021Inngår i: Mathematical Models and Methods in Applied Sciences, ISSN 0218-2025, Vol. 31, nr 13, artikkel-id 2733-2772Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper aims at an accurate and efficient computation of effective quantities, e.g., the homogenized coefficients for approximating the solutions to partial differential equations with oscillatory coefficients. Typical multiscale methods are based on a micro-macro coupling, where the macromodel describes the coarse scale behaviour, and the micro model is solved only locally to upscale the effective quantities, which are missing in the macro model. The fact that the micro problems are solved over small domains within the entire macroscopic domain, implies imposing artificial boundary conditions on the boundary of the microscopic domains. A naive treatment of these artificial boundary conditions leads to a first order error in ε/δ, where ε < δ represents the characteristic length ofthe small scale oscillations and δ^d is the size of micro domain. This error dominates all other errors originating from the discretization of the macro and the micro problems, and its reduction is a main issue in today’s engineering multiscale computations. The objective of the present work is to analyse a parabolic approach, first announced in [A. Abdulle,D. Arjmand, E. Paganoni, C. R. Acad. Sci. Paris, Ser. I, 2019], for computing the homogenized coefficients with arbitrarily high convergence rates in ε/δ. The analysis covers the setting of periodic microstructure,and numerical simulations are provided to verify the theoretical findings for more general settings, e.g. non-periodic micro structures.

  • 12.
    Abdulle, Assyr
    et al.
    École polytechnique fédérale de Lausanne, Switzerland.
    Arjmand, Doghonay
    École polytechnique fédérale de Lausanne, Switzerland.
    Paganoni, Edoardo
    École polytechnique fédérale de Lausanne, Switzerland.
    Exponential decay of the resonance error in numerical homogenization via parabolic and elliptic cell problems2019Inngår i: Comptes rendus. Mathematique, ISSN 1631-073X, E-ISSN 1778-3569, Vol. 357, nr 6, s. 545-551Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents two new approaches for finding the homogenized coefficients of multiscale elliptic PDEs. Standard approaches for computing the homogenized coefficients suffer from the so-called resonance error, originating from a mismatch between the true and the computational boundary conditions. Our new methods, based on solutions of parabolic and elliptic cell problems, result in an exponential decay of the resonance error.

  • 13.
    Abdumuminov, Shuhrat
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation.
    Esteky, David Emanuel
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation.
    Black-Litterman Model: Practical Asset Allocation Model Beyond Traditional Mean-Variance2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This paper consolidates and compares the applicability and practicality of Black-Litterman model versus traditional Markowitz Mean-Variance model. Although well-known model such as Mean-Variance is academically sound and popular, it is rarely used among asset managers due to its deficiencies. To put the discussion into context we shed light on the improvement made by Fisher Black and Robert Litterman by putting the performance and practicality of both Black- Litterman and Markowitz Mean-Variance models into test. We will illustrate detailed mathematical derivations of how the models are constructed and bring clarity and profound understanding of the intuition behind the models. We generate two different portfolios, composing data from 10-Swedish equities over the course of 10-year period and respectively select 30-days Swedish Treasury Bill as a risk-free rate. The resulting portfolios orientate our discussion towards the better comparison of the performance and applicability of these two models and we will theoretically and geometrically illustrate the differences. Finally, based on extracted results of the performance of both models we demonstrate the superiority and practicality of Black-Litterman model, which in our particular case outperform traditional Mean- Variance model.

    Fulltekst (pdf)
    fulltext
  • 14.
    Abed Jaser, Zaid
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Al-Braichi, Osamah Haitham Sabhan
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Measuring Test Coverage in Embedded Software Development Branches2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Most of the hardware products today, especially those that people interact with, are controlled by software. There are many devices with inbuilt software which many people do not bother to notice. Software may be critical in terms of strict quality requirements due to failures which enable risks of endangering the production and more importantly the lives of people. The testing team of Westermo Network Technologies AB faced a challenge with not being able to identify the coverage of tested cases in software. Identifying the coverage of total executed test cases enables the possibility of knowing the potential future quality of a software. By reaching such a stage a software will likely not suffer from failures due to higher quality, therefore the lives of people and the production at stake will not get harmed. The essential problem is that test cases are both tested and skipped, which makes it more difficult for the company to identify what has been actually tested and skipped. The purpose of this thesis is to identify and calculate the coverage of test cases, the process was mainly to understand the essence in the identification of executed test cases. The ethical aspect of putting people's lives at stake is what inspired us to investigate software failures. Software is typically tested before a release, therefore our investigation was to research testing process of software. When investigating test result over many days and test systems we developed a coverage calculator system which helps Westermo to decide and determine the release of tested software, either the software test result is acceptable for a release or not.

    Fulltekst (pdf)
    fulltext
  • 15.
    Abedini, Ayda
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation.
    Halm, Martina
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation.
    Att vara eller att icke vara rädd för programmering: En kvalitativ studie om några lärares attityd till programmering och införandet av programmering som centralt innehåll i teknikämnet i läroplanen.2018Independent thesis Advanced level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Syftet med denna studie var att få en inblick i några lärares attityd till programmering och införandet av programmering som centralt innehåll i läroplanen. Studien är inriktad inom teknikämnet i mellanstadiet då programmering är aktuellt från och med 2018 i läroplanen. Genom intervjuer med några lärare har vi kommit fram till att majoriteten ställer sig positivt till införandet av programmering i kursplanen. De lärare som ställde sig positivt till detta hade även en del erfarenhet kring programmering. En grund till den positiva attityden är att lärarna har framtiden i åtanke då det kommer krävas mer kunskaper inom digitala verktyg och programmering.

    Fulltekst (pdf)
    Programmering i skolan
  • 16.
    Abedini, M.
    et al.
    Department of Industrial Engineering, Iran University of Science and Technology, Tehran, Iran.
    Ahmadzadeh, Farzaneh
    Mälardalens högskola, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Noorossana, R.
    Department of Industrial Engineering, Iran University of Science and Technology, Tehran, Iran.
    Customer credit scoring using a hybrid data mining approach2016Inngår i: Kybernetes, ISSN 0368-492X, E-ISSN 1758-7883, Vol. 45, nr 10, s. 1576-1588Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: A crucial decision in financial services is how to classify credit or loan applicants into good and bad applicants. The purpose of this paper is to propose a four-stage hybrid data mining approach to support the decision-making process. Design/methodology/approach: The approach is inspired by the bagging ensemble learning method and proposes a new voting method, namely two-level majority voting in the last stage. First some training subsets are generated. Then some different base classifiers are tuned and afterward some ensemble methods are applied to strengthen tuned classifiers. Finally, two-level majority voting schemes help the approach to achieve more accuracy. Findings: A comparison of results shows the proposed model outperforms powerful single classifiers such as multilayer perceptron (MLP), support vector machine, logistic regression (LR). In addition, it is more accurate than ensemble learning methods such as bagging-LR or rotation forest (RF)-MLP. The model outperforms single classifiers in terms of type I and II errors; it is close to some ensemble approaches such as bagging-LR and RF-MLP but fails to outperform them in terms of type I and II errors. Moreover, majority voting in the final stage provides more reliable results. Practical implications: The study concludes the approach would be beneficial for banks, credit card companies and other credit provider organisations. Originality/value: A novel four stages hybrid approach inspired by bagging ensemble method proposed. Moreover the two-level majority voting in two different schemes in the last stage provides more accuracy. An integrated evaluation criterion for classification errors provides an enhanced insight for error comparisons.

  • 17.
    Abelli, Björn
    Mälardalens högskola, Ekonomihögskolan.
    Directing and Enacting the Information System2007Inngår i: Advances in Information Systems Development: New Methods and Practice for the Networked Society, Volume 2, Issue PART 2, 2007, s. 13-23Konferansepaper (Fagfellevurdert)
  • 18.
    Abelli, Björn
    Mälardalens högskola, Ekonomihögskolan.
    Enacting the e-Society2006Inngår i: Proceedings of the IADIS International Conference e-Society 2006, 2006, s. 285-298Konferansepaper (Fagfellevurdert)
  • 19.
    Abelli, Björn
    Mälardalens högskola, Ekonomihögskolan.
    Programmeringens grunder - med exempel i C#2004Bok (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Detta är en lärobok i grundläggande programmering. Den fokuserar på att lära ut det som är gemensamt för de flesta programmeringsspråk – de grundläggande elementen och programkonstruktionerna och hur dessa relaterar till varandra, oberoende av språket. Vilket språk programmet skrivs i måste vara underordnat den uppgift programmet skall lösa. Boken går därför igenom grunderna i strukturerad programmering och visar otaliga exempel i såväl flödesdiagram, strukturdiagram, pseudokod som i källkod. I slutet av boken finns kapitel som går igenom grunderna även i objektorienterad programmering.

    Boken tonar ner inlärningen av ett specifikt programmeringsspråk, men i slutändan måste program ändå skrivas i något språk. Exemplen är skrivna i C# som har slagit igenom som ett praktiskt programmeringsspråk på mycket kort tid och redan börjat göra sitt intåg i högskolekurser i programmering.

    I första hand är boken avsedd för nybörjare i programmering på högskolenivå, som vill lära sig programmeringens grunder.

  • 20.
    Abelli, Björn
    et al.
    Mälardalens högskola, Ekonomihögskolan.
    Révay, Péter
    Mälardalens högskola, Ekonomihögskolan.
    To Be or Not To Be Computer Based2004Inngår i: Proceedings of microCAD 2004, 2004, s. 1-8Konferansepaper (Fagfellevurdert)
  • 21.
    Abola, Benard
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Perturbed Markov Chains with Damping Component and Information Networks2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis brings together three thematic topics, PageRank of evolving tree graphs, stopping criteria for ranks and perturbed Markov chains with damping component. The commonality in these topics is their focus on ranking problems in information networks. In the fields of science and engineering, information networks are interesting from both practical and theoretical perspectives. The fascinating property of networks is their applicability in analysing broad spectrum of problems and well established mathematical objects. One of the most common algorithms in networks' analysis is PageRank. It was developed for web pages’ ranking and now serves as a tool for identifying important vertices as well as studying characteristics of real-world systems in several areas of applications. Despite numerous successes of the algorithm in real life, the analysis of information networks is still challenging. Specifically, when the system experiences changes in vertices /edges or it is not strongly connected or when a damping stochastic matrix and a damping factor are added to an information matrix. For these reasons, extending existing or developing methods to understand such complex networks is necessary.

    Chapter 2 of this thesis focuses on information networks with no bidirectional interaction. They are commonly encountered in ecological systems, number theory and security systems. We consider certain specific changes in a network and describe how the corresponding information matrix can be updated as well as PageRank scores. Specifically, we consider the graph partitioned into levels of vertices and describe how PageRank is updated as the network evolves.

    In Chapter 3, we review different stopping criteria used in solving a linear system of equations and investigate each stopping criterion against some classical iterative methods. Also, we explore whether clustering algorithms may be used as stopping criteria.

    Chapter 4 focuses on perturbed Markov chains commonly used for the description of information networks. In such models, the transition matrix of an information Markov chain is usually regularised and approximated by a stochastic (Google type) matrix. Stationary distribution of the stochastic matrix is equivalent to PageRank, which is very important for ranking of vertices in information networks. Determining stationary probabilities and related characteristics of singularly perturbed Markov chains is complicated; leave alone the choice of regularisation parameter. We use the procedure of artificial regeneration for the perturbed Markov chain with the matrix of transition probabilities and coupling methods. We obtain ergodic theorems, in the form of asymptotic relations. We also derive explicit upper bounds for the rate of convergence in ergodic relations. Finally, we illustrate these results with numerical examples.

    Fulltekst (pdf)
    fulltext
  • 22.
    Abola, Benard
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Biganda, Pitos
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam,Tanzania.
    Engström, Christopher
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Anguzu, Collins
    Department of Mathematics, Makerere University, Kampala, Uganda.
    Mango, John Magero
    Department of Mathematics, Makerere University, Kampala, Uganda.
    Kakuba, Gudwin
    Department of Mathematics, Makerere University, Kampala, Uganda.
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    A Variant of Updating Page Rank in Evolving Tree graphs2019Inngår i: Proceedings of 18th Applied Stochastic Models and Data Analysis International Conference with the Demographics 2019 Workshop, Florence, Italy: 11-14 June, 2019 / [ed] Christos H. Skiadas, ISAST: International Society for the Advancement of Science and Technology , 2019, s. 31-49Konferansepaper (Fagfellevurdert)
    Abstract [en]

    PageRank update refers to the process of computing new PageRank values after change(s) (addition or removal of links/vertices) has occurred in real life networks. The purpose of the updating is to avoid recalculating the values from scratch. To efficiently carry out the update, we consider PageRank as the expected number of visits to target vertex if multiple random walks are performed, starting at each vertex once and weighing each of these walks by a weight value. Hence, it might be looked at as updating non-normalised PageRank. In the proposed approach, a scaled adjacency matrix is sequentially updated after every change and the levels of the vertices being updated as well. This enables sets of internal and sink vertices dependent on their roots or parents, thus vector-vector product can be performed sequentially since there are no infinite steps from one vertex to the other.

  • 23.
    Abola, Benard
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Biganda, Pitos
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam,Tanzania.
    Engström, Christopher
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Mango, John Magero
    Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Kakuba, Godwin
    Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    A Variant of Updating PageRank in Evolving Tree Graphs2021Inngår i: Applied Modeling Techniques and Data Analysis 1: Computational Data Analysis Methods and Tools / [ed] Yannis Dimotikalis, Alex Karagrigoriou, Christina Parpoula, Christos H. Skiadas, John Wiley & Sons, Inc. Hoboken, NJ, USA , 2021, Vol. 7, s. 3-22Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    A PageRank update refers to the process of computing new PageRank valuesafter a change(s) (addition or removal of links/vertices) has occurred in real-lifenetworks. The purpose of updating is to avoid re-calculating the values from scratch.To efficiently carry out the update, we consider PageRank to be the expected numberof visits to a target vertex if multiple random walks are performed, starting at eachvertex once and weighing each of these walks by a weight value. Hence, it mightbe looked at as updating a non-normalized PageRank. We focus on networks of treegraphs and propose an approach to sequentially update a scaled adjacency matrix afterevery change, as well as the levels of the vertices. In this way, we can update thePageRank of affected vertices by their corresponding levels.

  • 24.
    Abola, Benard
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Biganda, Pitos
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam,Tanzania.
    Engström, Christopher
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Mango, John Magero
    Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Kakuba, Godwin
    Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    PageRank in evolving tree graphs2018Inngår i: Stochastic Processes and Applications: SPAS2017, Västerås and Stockholm, Sweden, October 4-6, 2017 / [ed] Sergei Silvestrov, Anatoliy Malyarenko, Milica Rančić, Springer, 2018, Vol. 271, s. 375-390Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    In this article, we study how PageRank can be updated in an evolving tree graph. We are interested in finding how ranks of the graph can be updated simultaneously and effectively using previous ranks without resorting to iterative methods such as the Jacobi or Power method. We demonstrate and discuss how PageRank can be updated when a leaf is added to a tree, at least one leaf is added to a vertex with at least one outgoing edge, an edge added to vertices at the same level and forward edge is added in a tree graph. The results of this paper provide new insights and applications of standard partitioning of vertices of the graph into levels using breadth-first search algorithm. Then, one determines PageRanks as the expected numbers of random walk starting from any vertex in the graph. We noted that time complexity of the proposed method is linear, which is quite good. Also, it is important to point out that the types of vertex play essential role in updating of PageRank.

  • 25.
    Abola, Benard
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Makerere University, Kampala, Uganda.
    Biganda, Pitos
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam,Tanzania.
    Engström, Christopher
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Mango, John Magero
    Makerere University, Kampala, Uganda.
    Kakuba, Godwin
    Makerere University, Kampala, Uganda.
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Updating of PageRank in Evolving Tree graphs2020Inngår i: Data Analysis and Applications 3: Computational, Classification, Financial, Statistical and Stochastic Methods / [ed] A. Makrides, A. Karagrigoriou, C.H. Skiadas, John Wiley & Sons, 2020, s. 35-51Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Summary Updating PageRank refers to a process of computing new PageRank values after changes have occurred in a graph. The main goal of the updating is to avoid recalculating the values from scratch. This chapter focuses on updating PageRank of an evolving tree graph when a vertex and an edge are added sequentially. It describes how to maintain level structures when a cycle is created and investigates the practical and theoretical efficiency to update PageRanks for an evolving graph with many cycles. The chapter discusses the convergence of the power method applied to stochastic complement of Google matrix when a feedback vertex set is used. It also demonstrates that the partition by feedback vertex set improves asymptotic convergence of power method in updating PageRank in a network with cyclic components.

  • 26.
    Abola, Benard
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Biganda, Pitos
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam,Tanzania.
    Engström, Christopher
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Evaluation of Stopping Criteria for Ranks in Solving Linear Systems2019Inngår i: Data Analysis and Applications 1: Clustering and Regression, Modeling‐estimating, Forecasting and Data Mining, Volume 2 / [ed] Christos H. Skiadas, James R. Bozeman, John Wiley & Sons, 2019, Chapter 10, s. 137-152Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Bioinformatics, internet search engines (web pages) and social networks are some of the examples with large and high sparsity matrices. For some of these systems, only the actual ranks of the solution vector is interesting rather than the vector itself. In this case, it is desirable that the stopping criterion reflects the error in ranks rather than the residual vector that might have a lower convergence. This chapter evaluates stopping criteria on Jacobi, successive over relaxation (SOR) and power series iterative schemes. Numerical experiments were performed and results show that Kendall's correlation coefficient gives good stopping criterion of ranks for linear system of equations. The chapter focuses on the termination criterion as means of obtaining good ranks. It outlines some studies carried out on stopping criteria in solving the linear system.

  • 27.
    Abola, Benard
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Biganda, Pitos
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam,Tanzania.
    Silvestrov, Dmitrii
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Stockholm University, Sweden.
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Mango, John
    Department of Mathematics, Makerere University, Kampala, Uganda.
    Kakuba, Gudwin
    Department of Mathematics, Makerere University, Kampala, Uganda.
    Nonlinearly  Perturbed Markov Chains  and  Information Networks2019Inngår i: Proceedings of 18th Applied Stochastic Models and Data Analysis International Conference with the Demographics 2019 Workshop, Florence, Italy: 11-14 June, 2019 / [ed] Christos H. Skiadas, ISAST: International Society for the Advancement of Science and Technology , 2019, s. 51-79Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper is devoted to studies of perturbed Markov chains commonly used for description of information networks. In such models, the matrix of transition probabilities for the corresponding Markov chain is usually regularised by adding  a special damping matrix multiplied by a small damping (perturbation) parameter ε. In this paper, we present results of the detailed perturbation analysis of Markov chains with damping component and numerical experiments supporting and illustrating the results of this perturbation analysis.

  • 28.
    Abola, Benard
    et al.
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Biganda, Pitos
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam,Tanzania.
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Silvestrov, Dmitrii
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik. Stockholm University, Sweden.
    Engström, Christopher
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    Mango, John Magero
    Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Kakuba, Godwin
    Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Chapter 2. Nonlinearly Perturbed Markov Chains and Information Networks2021Inngår i: Applied Modeling Techniques and Data Analysis 1: Computational Data Analysis Methods and Tools / [ed] Yannis Dimotikalis, Alex Karagrigoriou, Christina Parpoula, Christos H. Skiadas, Hoboken, NJ: John Wiley & Sons, 2021, s. 23-55Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    This chapter is devoted to studies of perturbed Markov chains, commonly used for the description of information networks. In such models, the matrix of transition probabilities for the corresponding Markov chain is usually regularized by adding aspecial damping matrix, multiplied by a small damping (perturbation) parameter ε. In this chapter, we present the results of detailed perturbation analysis of Markov chains with damping component and numerical experiments supporting and illustrating the results of this perturbation analysis.

  • 29.
    Aboradan, Anas
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik.
    Landing, Josef
    Mälardalens universitet, Akademin för innovation, design och teknik.
    Finding Bad Smells in natural language Test Specifications Using NALABS2022Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Tests are important artifacts in the software development process. Testing activities such as test automation, test maintenance, and test suite optimization mainly rely on an in-depth understanding of test specifications. The manual process of writing testspecifications in natural language can create many different quality issues such as ambiguous, incomplete, redundant, or inconsistent test cases. Nowadays, the concept of test smells is proposed by several researchers to be used as indicators of low-qualityattributes in test specifications. Quality assurance processes for test specifications often rely on manual reviews to detect these smells. The manual process of detecting these smells is considered time consuming and costly. However, there is currently no work that implements a comprehensive quality model that classifies and identifies these smells by using a systematic strategy. As a result, there is a need for machine-supported analytical measures that decrease the time and effort needed to detect these smells manually, especially when it comes to reviewing and validating large test specifications.This study aims to investigate which natural language smell metrics implemented in NALABS can be found in test specifications and to measure the sufficiency of those smellmetrics. It also aims to extend these smell metrics by exploring, proposing, or combining with new bad smell metrics to cover more aspects of natural language test quality. The results of the study show that the smell metrics exists in real-world test specifications and can uncover many potential quality issues by assisting test designers in identifying certain types of quality issues pertaining to for example the understandability and complexity of test specifications. Moreover, the results show thatthe list of smell metrics implemented in NALABS is incomplete and can be extended to cover more aspects of test quality.

    Fulltekst (pdf)
    fulltext
  • 30.
    Abrahamsson, Henrik
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Internet Traffic Management2008Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 31.
    Abrahamsson, Henrik
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Network overload avoidance by traffic engineering and content caching2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The Internet traffic volume continues to grow at a great rate, now driven by video and TV distribution. For network operators it is important to avoid congestion in the network, and to meet service level agreements with their customers.  This thesis presents work on two methods operators can use to reduce links loads in their networks: traffic engineering and content caching.

    This thesis studies access patterns for TV and video and the potential for caching.  The investigation is done both using simulation and by analysis of logs from a large TV-on-Demand system over four months.

    The results show that there is a small set of programs that account for a large fraction of the requests and that a comparatively small local cache can be used to significantly reduce the peak link loads during prime time. The investigation also demonstrates how the popularity of programs changes over time and shows that the access pattern in a TV-on-Demand system very much depends on the content type.

    For traffic engineering the objective is to avoid congestion in the network and to make better use of available resources by adapting the routing to the current traffic situation. The main challenge for traffic engineering in IP networks is to cope with the dynamics of Internet traffic demands.

    This thesis proposes L-balanced routings that route the traffic on the shortest paths possible but make sure that no link is utilised to more than a given level L. L-balanced routing gives efficient routing of traffic and controlled spare capacity to handle unpredictable changes in traffic.  We present an L-balanced routing algorithm and a heuristic search method for finding L-balanced weight settings for the legacy routing protocols OSPF and IS-IS. We show that the search and the resulting weight settings work well in real network scenarios.

    Fulltekst (pdf)
    fulltext
  • 32.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science, Kista, Sweden.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Caching for IPTV distribution with time-shift2013Inngår i: 2013 International Conference on Computing, Networking and Communications, ICNC 2013, IEEE , 2013, s. 916-921Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Today video and TV distribution dominate Internet traffic and the increasing demand for high-bandwidth multimedia services puts pressure on Internet service providers. In this paper we simulate TV distribution with time-shift and investigate the effect of introducing a local cache close to the viewers. We study what impact TV program popularity, program set size, cache replacement policy and other factors have on the caching efficiency. The simulation results show that introducing a local cache close to the viewers significantly reduces the network load from TV-on-Demand services. By caching 4% of the program volume we can decrease the peak load during prime time by almost 50%. We also show that the TV program type and how program popularity changes over time can have a big influence on cache hit ratios and the resulting link loads

  • 33.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Simulation of IPTV caching strategies2010Inngår i: Proceedings of the 2010 International Symposium on Performance Evaluation of Computer and Telecommunication Systems, 2010, s. 187-193Konferansepaper (Fagfellevurdert)
    Abstract [en]

    IPTV, where television is distributed over the Internet Protocol in a single operator network, has become popular and widespread. Many telecom and broadband companies have become TV providers and distribute TV channels using multicast over their backbone networks. IPTV also means an evolution to time-shifted television where viewers now often can choose to watch the programs at any time. However, distributing individual TV streams to each viewer requires a lot of bandwidth and is a big challenge for TV operators. In this paper we present an empirical IPTV workload model, simulate IPTV distribution with time-shift, and show that local caching can limit the bandwidth requirements significantly.

  • 34.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science, Kista, Sweden.
    Nordmark, Mattias
    TeliaSonera AB, Stockholm, Sweden .
    Program popularity and viewer behaviour in a large TV-on-Demand system2012Inngår i: IMC '12 Proceedings of the 2012 ACM conference on Internet measurement conference, New York: ACM , 2012, s. 199-210Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Today increasingly large volumes of TV and video are distributed over IP-networks and over the Internet. It is therefore essential for traffic and cache management to understand TV program popularity and access patterns in real networks.

    In this paper we study access patterns in a large TV-on-Demand system over four months. We study user behaviour and program popularity and its impact on caching. The demand varies a lot in daily and weekly cycles. There are large peaks in demand, especially on Friday and Saturday evenings, that need to be handled.

    We see that the cacheability, the share of requests that are not first-time requests, is very high. Furthermore, there is a small set of programs that account for a large fraction of the requests. We also find that the share of requests for the top most popular programs grows during prime time, and the change rate among them decreases. This is important for caching. The cache hit ratio increases during prime time when the demand is the highest, and aching makes the biggest difference when it matters most.

    We also study the popularity (in terms of number of requests and rank) of individual programs and how that changes over time. Also, we see that the type of programs offered determines what the access pattern will look like.

  • 35. Abramov, V.
    et al.
    Paal, E.Tallinn University of Technology.Silvestrov, Sergei D.Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.Stolin, A.Chalmers University of Techology.
    Proceedings of the 3rd Baltic-Nordic Workshop “Algebra, Geometry, and Mathematical Physics”2008Konferanseproceedings (Fagfellevurdert)
  • 36. Abramov, Viktor
    et al.
    Paal, Eugen
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation.
    Stolin, Alexander
    Preface [Special issue devoted to the 4th Baltic-Nordic Workshop “Algebra, Geometry and Mathematical Physics”]2010Inngår i: Proceedings of the Estonian Academy of Sciences, ISSN 1736-6046, E-ISSN 1736-7530, Vol. 59, nr 4Artikkel i tidsskrift (Fagfellevurdert)
  • 37.
    Abramov, Viktor
    et al.
    University of Tartu, Estonia.
    Silvestrov, Sergei
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, Utbildningsvetenskap och Matematik.
    3-Hom-Lie Algebras Based on σ-Derivation and Involution2020Inngår i: Advances in Applied Clifford Algebras, ISSN 0188-7009, E-ISSN 1661-4909, Vol. 30, nr 3, artikkel-id 45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We show that, having a Hom-Lie algebra and an element of its dual vector space that satisfies certain conditions, one can construct a ternary totally skew-symmetric bracket and prove that this ternary bracket satisfies the Hom-Filippov-Jacobi identity, i.e. this ternary bracket determines the structure of 3-Hom-Lie algebra on the vector space of a Hom-Lie algebra. Then we apply this construction to two Hom-Lie algebras constructed on an associative, commutative algebra using σ-derivation and involution, and we obtain two 3-Hom-Lie algebras.

  • 38.
    Abukhader, Rami
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Kakoore, Samer
    Mälardalens högskola, Akademin för innovation, design och teknik.
    ARTIFICIAL INTELLIGENCE FOR VERTICAL FARMING – CONTROLLING THE FOOD PRODUCTION2021Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The Covid-19 crisis has highlighted the vulnerability of access to food and the need for local and circular food supply chains in urban environments. Nowadays, Indoor Vertical Farming has been increased in large cities and started deploying Artificial Intelligence to control vegetations remotely. This thesis aims to monitor and control the vertical farm by scheduling the farming activities by solving a newly proposed Job-shop scheduling problem to enhance food productivity. The Job-shop scheduling problem is one of the best-known optimization problems as the execution of an operation may depend on the completion of another operation running at the same time. This paper presents an efficient method based on genetic algorithms developed to solve the proposed scheduling problem. To efficiently solve the problem, a determination of the assignment of operations to the processors and the order of each operation so that the execution time is minimized. An adaptive penalty function is designed so that the algorithm can search in both feasible and infeasible regions of the solution space. The results show the effectiveness of the proposed algorithm and how it can be applied for monitoring the farm remotely.

    Fulltekst (pdf)
    ARTIFICIAL INTELLIGENCE FOR VERTICAL FARMING
  • 39.
    Acheampong, Archibold Nana
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation.
    Analyzing the "True" Delta, Gamma and Vega of European Swaptions in Black-76 and Bachelier Models Using Python2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Option pricing models such as the Black-76, Bachelier and Stochastic Alpha Beta Rho (SABR) models define delta, gamma and vega using the forward rate as the underlying instrument. In terms of options on swaps, this underlying instrument is the forward swap rate, which is the market fixed rate on the swap. This work employs the Black-76 and Bachelier models to determine delta, gamma and vega of a European swaption, but rather uses the swap value as the underlying instrument. We use data in our implementation and the work is done in the python programming language. 

    Our results yielded relatively higher absolute delta values than those implied by the conventional Black-76 and Bachelier models. This means that our method yields relatively higher sensitivity of the swaption value to small changes in underlying asset value. It also means higher trading volumes of the swap contract to hedge against small changes in the value of the underlying swap using our method. It was also observed from our gamma values that both our method and the conventional Black-76 and Bachelier models can provide better sensitivities, relative to each other, to big changes in the underlying swap value. This, however, depends on the choice of strike rate. Further, our work produced comparatively lower absolute vega values, hence, lower sensitivity to changing implied volatility. To be able to use volatility values in both the normal and log-normal sense, we converted from normal to log-normal volatilities. This was achieved numerically using the Newton Raphson method implemented in python. 

    Changes in swap value and volatility were mimicked using basis point additions and subtractions of certain parameter values, specifically, floating rates, forward rate and volatility values. Each basis point adjustment in the necessary parameter yielded a different delta, gamma or vega value. Since the swap value or volatility can change multiple times within a specific time period, it was observed that there can exist a series of delta, gamma and vega values within a specific period of time.

  • 40.
    Acheampong, Isaac
    Mälardalens högskola, Institutionen för matematik och fysik.
    Java Applet for the Pricing of Exotic Options by Monte-Carlo Simulations in a Levy market with Stochastic Volatility2006Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    FULLTEXT01
  • 41.
    Achrenius, William
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Bergman Törnkvist, Martin
    Mälardalens högskola, Akademin för innovation, design och teknik.
    GRAPH GENERATION ALGORITHMS FOR THE GRADE DECISION CANVAS2018Independent thesis Basic level (degree of Bachelor), 12 hpOppgave
    Abstract [en]

    Development in the field of software architecture, from the early days in the mid-80’s, has been significant. From purely technical descriptions to decision based architectural knowledge, software architecture has seen fundamental changes to its methodologies and techniques. Architectural knowledge is a resource that is managed and stored by companies, this resource is valuable because it can be reused and analysed to improve future development. Companies today are interested in the reasoning behind the software architecture. This reasoning is mainly formulated through the architectural decisions made during development. For architectural decisions to be easier to analyse they need to be stored in a way that enables use of common analytical tools so that comparisons between decisions are consistent and relevant. Additionally, it is also important to have enough data, which leads us to the problem that, preferably, all the individual architectural knowledge cases must be structured and stored. To do this we present a tool that uses graph generation algorithms to generate architectural knowledge as graphs based on an architectural decision canvas called GRADE. This enables multiple decision cases to be encoded through graphs that can be used to analyse relationships and balances between different architectural knowledge elements represented through nodes and edges within a graph.

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  • 42.
    Achuthan, Krishnashree
    et al.
    Amrita Vishwa Vidyapeetham, Amrita Ctr Cybersecur Syst & Networks, Kollam, Kerala, India..
    Ramesh, Maneesha V.
    Amrita Vishwa Vidyapeetham, Amrita Ctr Int Programs, Kollam, Kerala, India..
    Punnekkat, Sasikumar
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Raman, Raghu
    Amrita Vishwa Vidyapeetham, Ctr Res Adv Technol Educ, Kollam, Kerala, India..
    Internationalizing Engineering Education With Phased Study Programs: India-European Experience2014Inngår i: 2014 IEEE FRONTIERS IN EDUCATION CONFERENCE (FIE), IEEE , 2014, s. 295-301Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Most of the critical challenges seen in the past decades have impacted citizens in a global way. Given shrinking resources, educationists find preparing students for the global market place a formidable challenge. Hence exposing students to multi-lateral educational initiatives are critical to their growth, understanding and future contributions. This paper focuses on European Union's Erasmus Mundus programs, involving academic cooperation amongst international universities in engineering programs. A phased undergraduate engineering program with multiple specializations is analyzed within this context. Based on their performance at the end of first phase, selected students were provided opportunities using scholarship to pursue completion of their degree requirements at various European universities. This paper will elaborate the impact of differing pedagogical interventions, language and cultural differences amongst these countries on students in diverse engineering disciplines. The data presented is based on on the feedback analysis from Eramus Mundus students (N = 121) that underwent the mobility programs. The findings have given important insights into the structure of the initiative and implications for academia and education policy makers for internationalizing engineering education. These included considering digital interventions such as MOOCs (Massive Open Online Courses) and Virtual Laboratory (VL) initiatives for systemic reorganization of engineering education.

  • 43.
    Adach, Malina
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Hänninen, Kaj
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Lundqvist, Kristina
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    A Combined Security Ontology based on the Unified Foundational Ontology2022Inngår i: Proceedings - 16th IEEE International Conference on Semantic Computing, ICSC 2022, Institute of Electrical and Electronics Engineers Inc. , 2022, s. 187-194Konferansepaper (Fagfellevurdert)
    Abstract [en]

    While ontology comparison and alignment have been extensively researched in the last decade, there are still some challenges to these disciplines, such as incomplete ontologies, those that cover only a portion of a domain, and differences in domain modeling due to varying viewpoints. Although the literature has compared ontological concepts from the same domain, comparisons of concepts from different domains (e.g., security and safety) remain unexplored. To compare the concepts of security and safety domains, a security ontology must first be created to bridge the gap between these domains. Therefore, this paper presents a Combined Security Ontology (CSO) based on the Unified Foundational Ontology (UFO) that could be compared to or aligned with other ontologies. This CSO includes the core ontological concepts and their respective relationships that had been extracted through a previous systematic literature review. The CSO concepts and their relationships were mapped to the UFO to get a common terminology that facilitates to bridge the gap between the security and safety domains. Since the proposed CSO is based on the UFO, it could be compared to or aligned with other ontologies from different domains.

  • 44.
    Adach, Malina
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Hänninen, Kaj
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Lundqvist, Kristina
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Concepts and Relationships in Safety and Security Ontologies: A Comparative Study2022Inngår i: 2022 6th International Conference on System Reliability and Safety, ICSRS 2022, Institute of Electrical and Electronics Engineers Inc. , 2022, s. 357-364Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Safety and security ontologies quickly become essential support for integrating heterogeneous knowledge from various sources. Today, there is little standardization of ontologies and almost no discussion of how to compare concepts and their relationships, establish a general approach to create relationships or model them in general. However, concepts with similar names are not semantically similar or compatible in some cases. In this case, the problem of correspondence arises among the concepts and relationships found in the ontologies. To solve this problem, a comparison between the Hazard Ontology (HO) and the Combined Security Ontology (CSO) is proposed, in which the value of equivalence between their concepts and their relationships was extracted and analyzed. Although the HO covers the concepts related to the safety domain and the CSO includes securityrelated concepts, both are based on the Unified Foundational Ontology (UFO). For this study, HO and CSO were compared, and the results were summarized in the form of comparison tables. Our main contribution involves the comparisons among the concepts in HO and CSO to identify equivalences and differences between the two. Due to the increasing number of ontologies, their mapping, merging, and alignment are primary challenges in bridging the gaps that exist between the safety and security domains. 

  • 45.
    Adach, Malina
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Hänninen, Kaj
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Lundqvist, Kristina
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Security Ontologies: A Systematic Literature Review2022Inngår i: Lecture Notes In Computer Science: 26th International Conference on Enterprise Design, Operations, and Computing, EDOC 2022, Springer Science and Business Media Deutschland GmbH , 2022, s. 36-53Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Security ontologies have been developed to facilitate the organization and management of security knowledge. A comparison and evaluation of how these ontologies relate to one another is challenging due to their structure, size, complexity, and level of expressiveness. Differences between ontologies can be found on both the ontological and linguistic levels, resulting in errors and inconsistencies (i.e., different concept hierarchies, types of concepts, definitions) when comparing and aligning them. Moreover, many concepts related to security ontologies have not been thoroughly explored and do not fully meet security standards. By using standards, we can ensure that concepts and definitions are unified and coherent. In this study, we address these deficiencies by reviewing existing security ontologies to identify core concepts and relationships. The primary objective of the systematic literature review is to identify core concepts and relationships that are used to describe security issues. We further analyse and map these core concepts and relationships to five security standards (i.e., NIST SP 800-160, NIST SP 800-30 rev.1, NIST SP 800-27 rev.A, ISO/IEC 27001 and NISTIR 8053). As a contribution, this paper provides a set of core concepts and relationships that comply with the standards mentioned above and allow for a new security ontology to be developed.

  • 46.
    Addazi, Lorenzo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Cicchetti, Antonio
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Systematic Evaluation of Model Comparison Algorithms using Model Generation2020Inngår i: Journal of Object Technology, E-ISSN 1660-1769, Vol. 19, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Model-Driven Engineering promotes the migration from code-centric to model-based software development. Systems consist of model collections integrating different concerns and perspectives, while semi-automated model transformations analyse quality attributes and generate executable code combining the information from these. Raising the abstraction level to models requires appropriate management technologies supporting the various software development activities. Among these, model comparison represents one of the most challenging tasks and plays an essential role in various modelling activities. Its hardness led researchers to propose a multitude of approaches adopting different approximation strategies and exploiting specific knowledge of the involved models. In this respect, almost no support is provided for the systematic evaluation of comparison approaches against specific scenarios and modelling practices, namely benchmarks. In this article we propose Benji, a framework for the automated generation of model comparison benchmarks. In particular, by giving a set of difference patterns and an initial model, users can generate model manipulation scenarios resulting from the application of the patterns on the model. The generation support provided by the framework obeys specific design principles that are considered as essential properties for the systematic evaluation of model comparison solutions, and are inherited from the general principles coming from evidence-based software engineering. The framework is validated through representative scenarios of model comparison benchmark generations.

  • 47.
    Addazi, Lorenzo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Cicchetti, Antonio
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Using Benji to systematically evaluate model comparison algorithms2020Inngår i: Proceedings - 23rd ACM/IEEE International Conference on Model Driven Engineering Languages and Systems, MODELS-C 2020 - Companion Proceedings, Association for Computing Machinery, Inc , 2020, s. 56-60Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Model comparison is a critical task in model-driven engineering. Its correctness enables an effective management of model evolution, synchronisation, and even other tasks, such as model transformation testing. The literature is rich as concerns comparison algorithms approaches, however the same cannot be said for their systematic evaluation. In this paper we present Benji, a tool for the generation of model comparison benchmarks. In particular, Benji provides domain-specific languages to design experiments in terms of input models and possible manipulations, and based on those generates corresponding benchmark cases. In this way, the experiment specification can be exploited as a systematic way to evaluate available comparison algorithms against the problem under study.

  • 48.
    Addazi, Lorenzo
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ciccozzi, Federico
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Blended graphical and textual modelling for UML profiles: A proof-of-concept implementation and experiment2021Inngår i: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 175, artikkel-id 110912Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Domain-specific modelling languages defined by extending or constraining the Unified Modelling Language (UML) through the profiling mechanism have historically relied on graphical notations to maximise human understanding and facilitate communication among stakeholders. Other notations, such as text-, form-, or table-based are, however, often preferred for specific modelling purposes, due to the nature of a specific domain or the available tooling, or for personal preference. Currently, the state of the art support for UML-based languages provides an almost completely detached, or even entirely mutually exclusive, use of graphical and textual modelling. This becomes inadequate when dealing with the development of modern systems carried out by heterogeneous stakeholders. Our intuition is that a modelling framework based on seamless blended multi-notations can disclose several benefits, among which: flexible separation of concerns, multi-view modelling based on multiple notations, convenient text-based editing operations (inside and outside the modelling environment), and eventually faster modelling activities. In this paper we report on: (i) a proof-of-concept implementation of a framework for UML and profiles modelling using blended textual and graphical notations, and (ii) an experiment on the framework, which eventually shows that blended multi-notation modelling performs better than standard single-notation modelling.

  • 49.
    ADENIYA, Abdel Tariq
    Mälardalens högskola, Akademin för utbildning, kultur och kommunikation.
    MARGIN VALUATION ADJUSTMENT of an INTEREST RATE SWAP2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    After the last financial crisis, regulators started to strengthen the measures to reduce the risk on the financial market by requiring margin to be posted. In addition to the Variation Margin that reflects the daily change in market value of the contracts, Initial Margin has to be posted to compensate the fluctuation of the collateral value. The Margin Valuation Adjustment (MVA) represents the funding price of the initial margin that has to be calculated. The numerical calculation of the MVA is a real challenge as it requires to run a Monte Carlo simulation inside another Monte Carlo simulation. However, alternative formula could be used to approximate the result of the MVA. This thesis highlights the essential notion about the MVA and the available tools to calculate its value.

  • 50.
    Adlerteg, Amalia
    Mälardalens universitet, Akademin för utbildning, kultur och kommunikation.
    Solving the Gleason Problem using Partition of Unity2023Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The Gleason problem has been proven to be a complicated issue to tackle. In this thesiswe will conclude that a domain, Ω ⊂ R𝑛, has Gleason 𝑅-property at any point 𝑝 ∈ Ω, where 𝑅(Ω) ⊂ 𝐶(Ω) is the ring of functions that are real analytic in 𝑝. First, we investigate function spaces and give them fitting norms. Afterwards, we build a bump function that is then used to construct a smooth partition of unity on R𝑛. Finally, we show that some of the functionspaces, introduced earlier, have the Gleason property. Ultimately, we use our smooth partition of unity in order to prove that the statement above holds for domains in R2. Subsequently, with the same reasoning one can prove that the statement also holds for domains Ω ⊂ R𝑛.

    Fulltekst (pdf)
    fulltext
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