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  • 51.
    Abdul Hakim, Abdul Ali
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Energieffektivisering av ett flerbostadshus från miljonprogrammet: En fallstudie av Kungsfågelgatan 12 i Västerås2010Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Examensarbetet behandlar energieffektiviseringsåtgärder för ett flerbostadshus byggt under

    miljonprogrammet. Miljonprogrammet innebar kortfattat att man inom tioårsperioden 1965 till

    1975 byggde ca en miljon nya bostäder i Sverige. Anledningen till detta var dels bostadsbristen

    och dels låg standard på de befintliga bostäderna.

    Flerbostadshus från just miljonprogrammet valdes i detta examensarbete eftersom det är idag ett

    mycket aktuellt ämne med tanke på att dessa hus är allmän kända för hög energiförbrukning.

    Studier visar att möjligheten för energibesparing är stor inom bostadssektorn, detta gäller i hög

    grad för hus från miljonprogrammet.

    Miljonprogramshusen har nu stått i 35-45 år, och 40 år var deras uppskattade livstid då de

    byggdes. Dessa hus står nu därför inför omfattande renoveringar och det är därför viktig att göra

    rätt energibesparande åtgärder i samband med dessa renoveringar.

    Uppgiften till detta examensarbete blev i första hand att ta fram byggnadens energitekniska

    status idag och att sedan komma med några praktiska och tillämpbara förslag på åtgärder för

    minskad energianvändning.

    Energieffektiviseringsåtgärder som undersöktes var inre och yttre tilläggsisolering med 100 mm

    isolering, fönsterbyte, fönsterrenovering, tätning runt fönster och dörrar, inglasning av balkonger

    och värmeåtervinning med frånluftsvärmepump.

    Den relativa luftfuktigheten och temperaturen i väggkonstruktionen beräknades för den

    befintliga väggen samt med inre och yttre tilläggsisolering. Resultatet av fuktberäkningen visade

    tydligt att den yttre tilläggsisoleringen på både väggkonstruktioner – lättbetong och

    sandwichelement – är det bästa alternativen ur fuktsynpunkten.

    Alla undersökta energieffektiviseringsåtgärder tillsammans visade sig enligt beräkningarna

    minska byggnadens energianvändning från ca 167 kWh/m

    2 och år i dagläget till ca 90 kWh/m2

    och år efter att åtgärderna utförs. Detta avser energianvändning med definitionen i Boverkets

    Byggregler, alltså all köpt energi exklusive hushållsel.

    Slutsatsen efter beräkningarna visar att installering av frånluftsvärmepump är den bästa och

    effektivaste åtgärden för att spara energi. Med de här antagandena som gjorts så kommer 64500

    kWh/ år fjärrvärme att ersättas av 43000 kWh ”gratisvärme” och 21500 kWh el.

    Beräkningar visar att en yttre tilläggisolering samt fönsterbyte är näst mest effektivaste

    energibesparingsåtgärden. Det visade sig att yttre tilläggsisolering även är den säkraste åtgärden

    ur fuktsynpunkt.

    Tätning runt fönster och dörrar samt inglasning balkonger hade hjälpt något men inte i samma

    utsträckning som de övriga åtgärderna. Inglasning av balkonger är en dyr åtgärd och ger endast

    en mindre energibesparing.

  • 52.
    Abdul-Ahad, Amir Stefan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Cürüklü, Baran
    Mälardalen University, School of Innovation, Design and Engineering.
    Mahmoud, W. A.
    Al-Isra Private University, Amman, Jordan.
    Robust distance-based watermarking for digital image2008In: Proceedings of the 2008 International Conference on Security and Management, SAM 2008, 2008, p. 404-409Conference paper (Refereed)
    Abstract [en]

    In this paper, an algorithm is developed to invisibly watermark a cover object (color image) using watermark object (iconic image). The algorithm is based on the distances among the addresses of values of the cover object. These distances use to make the embedding. The order of manipulating these distances are specified by the values of the watermark data which is dealt with serially. The algorithm serves and achieves self encryption key. Each watermark object has its unique pattern of distances at different possible lengths of distance bits. This enhances the complexity of sequential embedding. The algorithm is tested using direct and single level and double level of Two-Dimensional Discrete Wavelet Transform (2D DWT) embeddings. Two important issues are addressed. Firstly is to achieve a high Peak Signal to Noise Ratio (PSNR). The ratio was found to increase with an increasing of distance bits. Secondly is that the watermarked object retains the same properties of cover object. The algorithm shows resisting and withstanding against the most important attacks. Some of these include the lossy compression, blurring, resize and some types of Noise.

  • 53. Abdul-Ahad, Amir Stefan
    et al.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Larsson, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Mahmoud, Waleed A.
    Robust Distance-Based Watermarking for Digital Video2008In: Proceedings of The Annual SIGRAD Conference, Stockholm, 2008Conference paper (Refereed)
  • 54.
    Abdul-Ahad, Amir Stefan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Çürüklü, Baran
    Mälardalen University, School of Innovation, Design and Engineering.
    Folke, Mia
    Mälardalen University, School of Innovation, Design and Engineering.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Indirect Wavelet-Based Cardio Arrhythmia Detection Algorithm2008In: Medicinteknikdagarna, Gothenburg, Sweden, 2008, p. 14-15Conference paper (Refereed)
  • 55.
    Abdul-Fattah, Amira
    Mälardalen University, School of Health, Care and Social Welfare.
    Att stå på egna ben: Upplevelser av att vara nyutbildad sjuksköterska2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien var att undersöka nyutbildade sjuksköterskors gemensamma upplevelser av att börja arbeta efter examen. Detta undersöktes genom åtta intervjupersoner varav två män och sex kvinnor, valdes ur ett handplockat urval och intervjuades utifrån en semistrukturerad intervju. Deltagarna intervjuades om sina unika upplevelser av att vara nyutbildade sjuksköterskor. Resultaten av en tematisk analys påvisade fyra kategorier, att känna osäkerhet, att känna stress, självständighet och att få stöd. Första kategorin bestod av subkategorierna ensamhet, att begå misstag, och kunskapsbrist. Andra kategorin hade subkategorierna oförmåga, tidsbrist, brist på stöd och att hantera svåra lägen. Tredje kategorin hade subkategorierna att känna självtillit, att bli stark och att få rutiner. Sista kategorin hade subkategorierna att få bekräftelse och feedback, att få uppskattning och bli vägledd. Studien kan ge bredare perspektiv på framtida studier gällande nyutbildade sjuksköterskors upplevelse av stress. Slutsatsen av studien är att nyutbildade sjuksköterskors upplevelser är individuella och kan vara både positiva och negativa.

  • 56.
    Abdul-Fattah, Doha
    et al.
    Mälardalen University, School of Health, Care and Social Welfare.
    Kamali, Parwa
    NÄR VARDAGEN FÖRÄNDRAS: - En litteraturstudie om vuxna personers upplevelser av att leva med diabetes typ 22017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: Type 2 diabetes is one of the most common diseases in Sweden. Living with type 2 diabetes affects the person’s daily life and life situation. Treatment of type 2 diabetes consists of the patients making lifestyle changes and self-care. Nurses have expressed a need for knowledge regarding how to support and educate patients with type 2 diabetes, in their self-care. Aim: To describe adult’s experiences of living with type 2 diabetes. Method: A qualitative literature study with descriptive approach. Results: The analysis resulted in two themes. The themes were loss of control over daily life, regain stability and hope in life. The persons experienced lack of knowledge about their disease, furthermore, they felt anxiety and anger. The persons experienced that they had difficulties adjusting their diet. After a certain period of illness, the people accepted and managed the disease and got support both from their families and from health care professionals. Conclusion: The care and education that patients with diabetes type 2 are offered need to be more individualized. This can ensure and help the patients with type 2 diabetes perform adequate self-care by their own preconditions, to maintain health and well-being.

  • 57.
    Abduljalil, Vian
    Mälardalen University, School of Innovation, Design and Engineering.
    Databasreplikering av kunddata i en DMZ miljö2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 58.
    Abdulkarem, Erivan
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Phothisingha, Suchada
    Mälardalen University, School of Education, Culture and Communication.
    Planerade och spontana musikaktiviteter i förskolan -          Hur förskollärare beskriver att de använder musik som ett redskap i barns utveckling och lärande.: Hur förskollärare beskriver att de använder musik som ett redskap i barns utveckling och lärande.2016Independent thesis Basic level (professional degree), 210 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien var att belysa hur förskollärare beskriver hur barn ges möjlighet att möta musik i förskolan. Semistrukturerade intervjuer med åtta förskollärare har genomförts på sex olika förskolor, för att fördjupa kunskapen om musikens funktion för förskolebarns utveckling samt förskollärares förhållningssätt kring barns spontana musikintressen. Resultatet visar att samtliga förskollärare i grunden hade en positiv relation till musik och var medvetna om musikens betydelse för barns utveckling. Å andra sidan visade det sig att flera av förskollärarna saknade medvetenhet om barns spontana musicerande och i stället lade fokus på den inplanerade verksamheten.

  • 59.
    Abdulla, Hana
    Mälardalen University, School of Health, Care and Social Welfare.
    FYSISK INAKTIVITET OCH STILLASITTANDE BLAND BARN OCH UNGA I GRUNDSKOLAN2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Children and youth inactivity and sedentary at school is increasing. This means that some of the students have a significant unhealthy lifestyle with physical inactivity, which in turn implies risks of suffering from various diseases, including obesity, type 2 diabetes and cardiovascular disease, all related to a sedentary lifestyle. To prevent illness, it is important that children and young people early get a positive attitude towards physical activity.

    The purpose of this study was to study the causes of child and adolescent physical inactivity in school, based on teachers 'and parents' perspectives.

    A qualitative research has been selected. To achieve the study objectives, the author has conducted seven semi-structured interviews, with an appropriate choice of five teachers and two parents with children in school. Data was analyzed with a manifest content analysis.

    The results show that teachers and parents felt that physical activity is a protective factor for children's health. There are several reasons for physical inactivity in students today, blah new technologies, various transportation facilities and family finances. Some measures that can reduce the physical inactivity, for example be to increase sports lesson 'time and by starting with children and young people's interest to make them feel joy in moving, which increases the interest in physical activity.

    The conclusion of this work is that children's movement is important for their health. Children and youth in elementary school in need of physical activity so that they feel good. Both schools and parents have a responsibility to promote children's physical activity so that they can preserve their health, before improving their learning ability, have more energy and to manage the school in a good way.

  • 60.
    Abdullah, Syed Md Jakaria
    Mälardalen University, School of Innovation, Design and Engineering.
    Virtual Clustered-based Multiprocessor Scheduling in Linux Kernel2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 61.
    Abdullah, Syed Md Jakaria
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Moghaddami Khalilzad, Nima
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards Implementation of Virtual-Clustered Multiprocessor Scheduling in Linux2013In: Proceedings of the 8th IEEE International Symposium on Industrial Embedded Systems, SIES 2013, 2013, p. 97-100Conference paper (Refereed)
    Abstract [en]

    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 and applying hierarchical scheduling techniques. Over the years, the study of virtual cluster scheduling has been limited to theoretical analysis. In this paper, we present our initial ideas about implementing virtual cluster scheduling in Linux. The purpose of this implementation is twofold: (i) we would like to demonstrate the feasibility of its implementation in an operating system, without modifying the kernel source code, (ii) we present practical insights on the overhead of implementing this framework.

  • 62.
    Abdullah, Tara
    Mälardalen University, School of Health, Care and Social Welfare.
    Nutritionsrelterade problem hos äldre patienter: En litteraturstudie ur ett sjuksköterskeperspektiv2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 63.
    Abdullahi, Beyar
    Mälardalen University, School of Innovation, Design and Engineering.
    Nyinflyttad: En analys av tidningen ”Nyinflyttad” som skickas till alla nya Arvikabor2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    This thesis aims to provide Arvika with a deeper insight into what their new residents think about the information they receive. Anyone moving to Arvika gets the magazine “Nyinflyttad/Recently moved in" sent home. The year 2011 Arvika had 1017 new residents, and they all got the same version of the magazine "Nyinflyttad/Recently moved in." A simpler version of the magazine hasn’t been made, although the municipality is aware that it is needed.

    The aim of my thesis is to see if the information that Arvika is sending to its new residents in meeting their information needs. 

    To get the answer on this question, I have examined data from the target group perspective. Through a focus group and various interviews, I have come up with a design proposal that is informative, clear and easy to read. I also think that my design proposal would benefit a much wider audience.

  • 64.
    Abdullahi Mohamed, Mohamed
    Mälardalen University, School of Sustainable Development of Society and Technology.
     GLP-1 REGULATES PROLIFERATION OF GLP-1 SECRETING CELLS THROUGH A FEEDBACK MECHANISM2010Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Background and aim:

    Diabetes mellitus (DM) is a chronic and progressive illness that affects all type of populations and ages. According to World health organization (WHO) by 2030 it will be 366 million people effected world wild. Many new drugs are Glucagon-like peptide-1 (GLP-1) based therapy for treatment of type 2diabetes. GLP-1 is released from the intestinal L-cells, and is a potent stimulator of glucose-dependent insulin secretion. The aim of this study was to investigate the effect of GLP-1 and its stable analogs on cell proliferation of GLP-1 secreting GLUTag cells.

    Material and methods:

    GluTag cells were incubated for 48h in DMEM medium containing (0.5% fetal bovine serum and 100 IU/ml penicillin and 100 μg/ml streptomycin and 3mM glucose concentration) in the present or absence of the agents. DNA synthesis was measured using 3H- thymidine incorporation and Ki67 antigen staining. Western blot were performed to investigate the present of GLP-1 receptor in GLUTag cells.

    Results/conclusions:

    These results suggest that GLP-1 regulates proliferation of the GLP-1-secreting cell through a feedback mechanism via its receptor. Since serum GLP-1 levels are decreased in type 2 diabetic patients, the effect of GLP-1 on the GLP-1-secreting cell proliferation suggested here provides a novel beneficial long-term effect of the incretin-based drugs in clinical practice i.e. through increase of the GLP-1-secreting cell mass, augmenting the incretin effect. In addition, the feedback mechanism action of GLP-1 reveals a new insight in regulation manner of the L-cell proliferation.

    GLP-1(7-36) increased cell proliferation in GLUTag cells, an effect which was blocked by the GLP-1 receptor antagonist exendin(9-39). The GLP-1 receptor was expressed in GluTag cells.

    Keywords:

    Incretin hormone, GLP-1, GLP-1 receptor, Exendin-4, Diabetes

  • 65.
    Abdulsalam Osman, Dana
    et al.
    Mälardalen University, School of Business, Society and Engineering.
    Hamad, Ivan
    Mälardalen University, School of Business, Society and Engineering.
    Hantering av styrande dokument: Hantering av styrande dokument i stora företag2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 66.
    Abdumuminov, Shuhrat
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Esteky, David Emanuel
    Mälardalen University, School of Education, Culture and Communication.
    Black-Litterman Model: Practical Asset Allocation Model Beyond Traditional Mean-Variance2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    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.

  • 67.
    Abecassis-Moedas, Celine
    et al.
    Univ Catolica Portuguesa, Catolica Lisbon Sch Business & Econ, Lisbon, Portugal.
    Ben Mahmoud-Jouini, Sihem
    HEC Paris, Innovat & Entrepreneurship Ctr, Paris, France.
    Dell'Era, Claudio
    Politecn Milan, Dept Management Econ & Ind Engn, Milan, Italy.
    Manceau, Delphine
    Univ Penn, Wharton Sch, Philadelphia.
    Verganti, Roberto
    Politecnico di Milano.
    Key resources and internationalization modes of creative knowledge-intensive business services: The case of design consultancies2012In: Creativity and Innovation Management, ISSN 0963-1690, E-ISSN 1467-8691, Vol. 21, no 3, p. 315-331Article in journal (Refereed)
    Abstract [en]

    In the knowledge economy, knowledge-intensive business services (KIBS) are a key driver for innovation and competitiveness. The internationalization of these businesses raises challenges given their specificities such as knowledge intensity, the importance of customer interaction and intimacy in service delivery. This paper focuses on design consultancies as a specific type of creative KIBS for which these characteristics are emphasized. The objective of this research is to analyse the resources leveraged by the firms to compete internationally. It is based on 11 case studies of design consultancies located in five different countries (France, Italy, Portugal, Spain and the UK) that were selected for their capacity to perform at the international level for several years. The paper advances three internationalization modes depending on contingent variables and focusing on specific resources that enable international competitiveness: star-based, process-based and glocality-based. In star-based creative KIBS, the individual designer has developed a reputation that attracts customers internationally, operating as a brand. In process-based creative KIBS, the reputation of a collective creative process attracts clients from other countries. In glocality-based creative KIBS, the geographical proximity obtained by opening international offices helps to develop a close understanding of the client through frequent interactions, and also to know the client's market well and to better understand local codes and signs. These modes complement those presented in the existing internationalization literature which takes the peculiarities of creative KIBS into consideration.

  • 68.
    Abed, Hadir Carmen
    Mälardalen University, School of Health, Care and Social Welfare.
    Utanförskapsarbete i en kommun: En kvalitativ studie om hur en kommun arbetar med utanförskapsfrågor2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There are differences in health between different groups in society. The differences can cause negative consequences for individuals and for the society. Young adults, immigrants, people with addiction problems, contributions dependent, people with diagnoses are currently outside the labor market who are more likely to end up in social exclusion. Individuals who are far from the labor market can affect their life situation, which usually has negative consequences. Work today is a central part of individuals lives that’s gives a sense of context and meaningfulness. The aim of the study is to analyse communal employees experience of work with exclusion. To answer the study’s purpose, a qualitative method was used, and semi-structured interviews were conducted with five communal employees who work with people in social exclusion in a communal in the middle of Sweden. The collected material has been analysed through a manifest content analysis. The results show that collaboration between different actors facilitates their ability to provide social support to individuals who are in exclusion. Social support was considered important in work with exclusion because it leads to positive factors. The communal employees highlighted that social context among vulnerable individuals is something that affects them to take part in the society and experience meaningfulness. A reasonable conclusion from the result is that communal employees work to increase the social context among vulnerable people who seek help thereby increasing social support. The participants have highlighted that their work with people is in social exclusion succeeds with the help of their collaboration with actors and authorities.

  • 69.
    Abedini, Ayda
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Halm, Martina
    Mälardalen University, School of Education, Culture and Communication.
    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 credits / 15 HE creditsStudent thesis
    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.

  • 70.
    Abedini, Ayda
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Halm, Martina
    Mälardalen University, School of Education, Culture and Communication.
    Digitalläsning eller traditionell läsning, vad fungerar bäst i klassrummet?: En studie om några elevers läsförståelse och attityd till digitalläsning i förhållande till traditionell läsning2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie var att studera hur några elevers läsförståelse och inställning är till digitalläsning i förhållande till traditionell läsning. Studien är inriktad inom svenskämnet och deltagare för denna studie gick i årkurs 5 och 6. Inom ramen för studien utfördes en enkätundersökning och ett läsförståelsetest. Slutsatsen av vår forskning är att de tillfrågade elevernas attityd till traditionell läsning är mer positiv än till digitalläsning. Vad gäller läsförståelsetestets resultat, pekar det på att traditionell läsning visade på högre resultat än läsning som skedde digitalt.

  • 71.
    Abedini, M.
    et al.
    Department of Industrial Engineering, Iran University of Science and Technology, Tehran, Iran.
    Ahmadzadeh, Farzaneh
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Noorossana, R.
    Department of Industrial Engineering, Iran University of Science and Technology, Tehran, Iran.
    Customer credit scoring using a hybrid data mining approach2016In: Kybernetes, ISSN 0368-492X, E-ISSN 1758-7883, Vol. 45, no 10, p. 1576-1588Article in journal (Refereed)
    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.

  • 72.
    Abelli, Björn
    Mälardalen University, School of Business.
    Directing and Enacting the Information System2007In: Advances in Information Systems Development: New Methods and Practice for the Networked Society, Volume 2, Issue PART 2, 2007, p. 13-23Conference paper (Refereed)
  • 73.
    Abelli, Björn
    Mälardalen University, School of Business.
    Enacting the e-Society2006In: Proceedings of the IADIS International Conference e-Society 2006, 2006, p. 285-298Conference paper (Refereed)
  • 74.
    Abelli, Björn
    Mälardalen University, School of Business.
    On Stage!: Playwriting, Directing and Enacting the Informing Processes.2007Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Within the discipline of information systems sometimes the conception of the main object is that the information system must be computer based. An example of an information system that is non-computer based is the scenic theatre performance. Input is the message or knowledge the participants of the theatre production want to pass over to the audience; output is the information and experiences the performance in itself mediates to the audience. This has been produced through a system development process; although the developers not always have been aware about what development model has been used.

    The dissertation combines some of the concepts found in theatre production with traditional system development concepts, and hence introduces new perspectives into the area of information systems. Some of the main findings in the study of theatre productions were the triplicity of a theatre production as a development process, an information system and an organization at the same time; the integrated relations of context, developers and users, which leads to spontaneous changes and overlaps of development roles; and the narrative and dramaturgical approach in the practical use of methods and techniques.

    These aspects should be useful also in development of other types of information systems, whether computer based or using other information technologies. The triplicity gives arguments to redefine each of these concepts.

    The generalizability of this approach has been validated through a second study, at a folk high school, which showed that models and concepts from theatre productions are possible to generalize to other information system areas than theatre, and that the borders of the organization coincides with the borders of the information system. Especially temporary organizations must be seen as ongoing, continuous development processes.

  • 75.
    Abelli, Björn
    Mälardalen University, School of Business.
    Programmeringens grunder - med exempel i C#2004Book (Other (popular science, discussion, etc.))
    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.

  • 76.
    Abelli, Björn
    Mälardalen University, School of Business.
    Theatre production : a system development process 2004Licentiate thesis, monograph (Other scientific)
  • 77.
    Abelli, Björn
    et al.
    Mälardalen University, School of Business.
    Révay, Péter
    Mälardalen University, School of Business.
    To Be or Not To Be Computer Based2004In: Proceedings of microCAD 2004, 2004, p. 1-8Conference paper (Refereed)
  • 78.
    Abelli Nordin, Camilla
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Lönnqvist, Rebecca
    Mälardalen University, School of Education, Culture and Communication.
    Samverkan i utvecklingssamtal: En studie om hur förskollärare och vårdnadshavare samverkar i utvecklingssamtalet på förskolan2016Independent thesis Basic level (professional degree), 210 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie var att ta reda på vad förskollärare och vårdnadshavare har för förväntningar och upplevelser av samverkan i utvecklingssamtal. Forskning visar att ett nära samarbete med hemmet höjer kvaliteten på förskolan, en bra kvalitativ förskola ger barnen bättre förutsättningar i det livslånga lärandet. Vi har intervjuat fyra förskollärare och fyra vårdnadshavare. Resultaten visade skillnader i vad förskollärare och vårdnadshavarna ser för syfte med utvecklingssamtalet. Vårdnadshavarna ser det ser det som ett tillfälle att i lugn och ro få prata om det enskilda barnet, dess utvecklig och trivsel, medan syftet för förskollärarna är att samverka runt barnet och förskoleverksamheten. Både vårdnadshavarna och förskollärare uttrycker att det är viktigt med en förtroendefull relation för att kunna mötas på ett bra sätt i alla samverkanssituationer. Slutsatsen av studien visar att förskollärarna anser att de allra flesta vårdnadshavare tycker att det är viktigt att delta i utvecklings- samtalen till skillnad från andra samverkansformer. Vårdnadshavarnas förväntningar och upplevelser tolkar vi också som positiva för de anser att den information de förväntat sig att få tillgodogörs och är relevant för dem och deras barn.

  • 79.
    ABGHARI, SHABNAM
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    FAKHOURI, REEF
    Mälardalen University, School of Sustainable Development of Society and Technology.
    The Relationship between Level of acculturation and Service Quality Perception: A Case study of Swedish Banks and Customers with Iranian and Iraqi cultural origins living in Sweden2009Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
  • 80.
    Abid, Ali
    et al.
    Mälardalen University, Department of Innovation, Design and Product Development. Mälardalen University, School of Innovation, Design and Engineering.
    Roback, Joel
    Mälardalen University, Department of Innovation, Design and Product Development.
    Produktutveckling för Cate & Nelson Design: Framtagning av möbel2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport behandlar examensarbete utfört för industridesignföretaget Cate & Nelson Design. Företaget ligger i Eskilstuna och jobbar i huvudsakligen med möbeldesign och inredningsprodukter. Projektgruppensuppgift har varit att ta fram en ny möbel för företaget och arbetet har omfattat utveckling av hela produkten från idé till prototyp.

  • 81.
    Abola, Benard
    et al.
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics. Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Biganda, Pitos
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam,Tanzania.
    Engström, Christopher
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    Mango, J. M.
    Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Kakuba, G.
    Department of Mathematics, School of Physical Sciences, Makerere University, Kampala, Uganda.
    Silvestrov, Sergei
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    PageRank in evolving tree graphs2018In: Stochastic Processes and Applications: SPAS2017, Västerås and Stockholm, Sweden, October 4-6, 2017 / [ed] Sergei Silvestrov, Anatoliy Malyarenko, Milica Rančić, Springer, 2018, Vol. 271, p. 375-390Chapter in book (Refereed)
    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.

  • 82.
    Abrahamsson, Alexandra
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Arbetsmiljöarbetet på SverigesBostadsrättsCentrum: Vad ändringarna i arbetsmiljölagen innebär2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This diploma work was performed because the company Sveriges BostadsrättsCentrum, with the abbreviation SBC, had a need to gain insight into how changes in the Work Environment Act and related regulations which took effect January 1, 2009 affecting their work with the work environment. The changes mean that the client may hand over his work environment responsibilities to a contractor and that he has to select so-called building work environment co-ordinators. At SBC they are working as representatives for tenant-owner's association when a construction is about to be carried out. The purpose was to ascertain how changes may affect the work at SBC. The diploma work intends to educate the staff at SBC how work with the work environment would look like if they met the regulatory requirements. The main issue that the diploma work deals with is whether SBC has the responsibility to select a building work environment co-ordinator for the planning and projecting before the contractor takes over responsibility for the work environment. Questions were answered by information from the Work Environment Act, AFS 1999:3 and other material from the Work Environment Authority. Two interviews with staff at the Work Environment Authority were also held. One of the conclusions drawn from the diploma work is that it’s the client who will select a building work environment co-ordinator for the planning and projecting. That should be done as soon as the planning and projecting has begun. The planning and projecting usually begins before the main contractor takes over responsibility for the work environment as the employee. It is not clear that SBC will take on the client’s responsibility to select a building work environment co-ordinator for the planning and projecting in the early planning, before the contractor takes on responsibility and there are several ways to do this.

  • 83.
    Abrahamsson, Anna
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Häkänen-Muhanga, Jenny
    Mälardalen University, School of Education, Culture and Communication.
    "Det kan sitta femton ungar och bara äta blåbär": En undersökning om hur förskollärare arbetar med utomhuspedagogik2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med undersökningen är att dels ta reda på hur förskollärare tänker kring utomhus­vistelsens syfte. Syftet är även att utifrån de ramfaktorer som finns i verksam­heten, undersöka hur förskollärare arbetar med utomhuspedagogik. En kvalita­tiv ansats med semistrukturerade intervjuer har genomförts med åtta informan­ter. Resultatet visar att förskollärare har olika syften med barns utomhusvis­telse, samt att olika ramfaktorer kan påverka förskollärares arbete med utomhuspedagogiken. Slutsatsen är att ett pedagogiskt respektive romantiskt synsätt genomsyrar förskollärares arbete med utomhuspedagogik, samt att det råder en viss omedvetenhet kring olika ramfaktorer och dess påverkan på arbetet med utomhuspedago­gik.   

  • 84.
    Abrahamsson, Anna
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Staaf, Malin
    Mälardalen University, School of Education, Culture and Communication.
    Språkutvecklande arbete i förskolans utomhusmiljö 2009Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med utvecklingsarbetet var att fördjupa oss i hur, vi som lärare, kan arbeta språkutvecklande samt stimulera förskolebarnens språkutveckling genom att använda oss av utomhusmiljön. Utvecklingsarbetet genomfördes på två förskolor i form av ett tema kring språkutveckling, med olika språkliga aktiviteter utomhus. Under temat visade barnen stort intresse och engagemang kring de samtal och aktiviteter som genomfördes, och deras åsikter belystes kontinuerligt. Resultatet visade att samtalet och samspelet, mellan lärare-barn och barn-barn, bör ligga till grund för språkutvecklande arbete utomhus. Vi ansåg att utomhusvistelsen gjorde aktiviteterna mer levande och innehållsrika.

  • 85.
    Abrahamsson, Carolina
    Mälardalen University, School of Education, Culture and Communication.
    Att komma till tals: Talad tid under engelsklektionen2012Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med min undersökning var att ta reda på hur mycket engelska som talas under fyra engelsklektioner i en årskurs 4, vad resten av tiden ägnades åt samt hur läraren stimulerar eleverna till tal. Jag har observerat fyra lektioner och genomfört en intervju med läraren för att ta reda på detta. Resultatet visar att det inte talas mycket engelska under lektionerna, utan tal på engelska utgör den minsta delen. Eleverna talar dock mer engelska än läraren, och för det mesta sker det i kör. Det är ett sätt som läraren använder för att stimulera eleverna till tal. Ett annat sätt är att de får tala i mindre grupper vilket skedde under en av lektionerna, och detta hade en positiv inverkan på resultatet. Den största delen av lektionerna utgjordes av svenskt tal, även om det till stor del var genom att de arbetade med att översätta engelska. De lyssnade även till engelska via filmer och cd-skivor och en av lektionerna ägnades delvis åt tyst arbete genom att de arbetade individuellt med stenciler.

  • 86.
    Abrahamsson, Caroline
    et al.
    Mälardalen University, School of Education, Culture and Communication.
    Carlsson, Linda
    Mälardalen University, School of Education, Culture and Communication.
    "Att lära barnen om livet": En studie om fostran i samverkan mellan hem och förskola2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Studien är gjord med syftet att få fördjupad kunskap om hur begreppet fostran och fostransuppdraget i förskolan förstås av vårdnadshavare och förskollärare. Till studiens undersökning har en kvalitativ forskningsmetod med semistrukturerade intervjuer använts. Resultatet visar att fostran är en central fråga för både vårdnadshavare, förskollärare och samhället i stort. Fostran handlar om att genom socialt samspel forma barn till väl fungerande medmänniskor.

  • 87.
    Abrahamsson, Caroline
    et al.
    Mälardalen University, School of Health, Care and Social Welfare.
    Jonsson, Eleonor
    Mälardalen University, School of Health, Care and Social Welfare.
    Samband mellan genetiska faktorer och korsbandsruptur - en litteraturöversikt.2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Personer med främre korsbandsruptur utgör en stor patientgrupp för en idrottsverksam sjukgymnast. Skadan är även vanlig hos hundar . Då hund och människa har likartad knäanatomi var det intressant att inkludera båda i samma studie. Alla bakomliggande faktorer till främre korsbandsruptur är inte helt utredda i dagsläget och detta gör det svårt att optimera preventiva åtgärder. En faktor som börjat utredas på senare år är den genetiska, dock inte i någon större utbredning. Syftet med denna uppsats var att sammanställa det aktuella kunskapsläget gällande ett eventuellt samband mellan genetiska faktorer och korsbandsruptur hos människa och hund. Detta studerades i en litteraturstudie, där data framför allt samlades in via vårdvetenskapliga och medicinska databaser. De 15 inkluderade artiklarna analyserades systematiskt genom hela processen och bevisvärde samt evidensstyrka värderades. Resultatet visar att det finns tydliga tecken på ett samband mellan genetiska faktorer och korsbandsruptur för människor. För hundar finns inte något tydligt samband. De granskade studierna visade ej signifikanta samband. Då det saknas studier med högt bevisvärde hos både människa och hund kan inte en stark slutsats dras. Därför behövs vidare forskning för att kunna bekräfta eller utesluta sambandet mellan genetiska faktorer och korsbandsruptur.

  • 88.
    Abrahamsson, Elin
    Mälardalen University, School of Education, Culture and Communication.
    Den pedagogiska måltiden: En kvalitativ studie om pedagogers och elevers tankar och uppfattningar kring måltiden i skolan2015Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sverige är, tillsammans med Finland och Estland, unikt i att servera avgiftsfria skolmåltider till alla elever. I Sverige har gratis skolmat serverats till elever i grundskolan sedan 1946, vilket gör att många av oss har en relation till skolmåltiden. Måltiden ska vara näringsriktig, men ska även fungera som ett pedagogiskt verktyg, och kallas därför för den pedagogiska måltiden. Syftet med studien har varit att undersöka på vilket sätt lärare och elever i grundskolans tidigare år kan tänkas uppfatta den s.k. pedagogiska måltiden. Genom kvalitativa intervjuer fick jag ta del av pedagogers och elevers tankar och åsikter om den pedagogiska måltiden. Jag ville även närmare undersöka vilka skillnader och likheter det fanns i pedagogernas och elevernas uppfattningar. Resultatet visade att det fanns många likheter i pedagogernas och elevernas uppfattningar om vad den pedagogiska måltiden handlade om. Måltiden sågs av pedagogerna som en del av deras pedagogiska uppdrag där de agerar som positiva förebilder. Slutsatsen var att den pedagogiska måltiden är ett komplext begrepp, där elever socialiseras in i den måltidskultur som finns i den svenska skolan, vilket kan skapa kulturkrockar i mötet med elever med annan kulturell bakgrund.

     

  • 89.
    Abrahamsson, H.
    et al.
    RISE, SICS, Germany.
    Abdesslem, F. B.
    RISE, SICS, Germany.
    Ahlgren, B.
    RISE, SICS, Germany.
    Brunstrom, A.
    Karlstad University, Sweden.
    Marsh, I.
    RISE, SICS, Germany.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Connected Vehicles in Cellular Networks: Multi-Access Versus Single-Access Performance2018In: TMA 2018 - Proceedings of the 2nd Network Traffic Measurement and Analysis Conference, Institute of Electrical and Electronics Engineers Inc. , 2018Conference paper (Refereed)
    Abstract [en]

    Connected vehicles can make roads traffic safer and more efficient, but require the mobile networks to handle time-critical applications. Using the MONROE mobile broadband measurement testbed we conduct a multi-access measurement study on buses. The objective is to understand what network performance connected vehicles can expect in today's mobile networks, in terms of transaction times and availability. The goal is also to understand to what extent access to several operators in parallel can improve communication performance. In our measurement experiments we repeatedly transfer warning messages from moving buses to a stationary server. We triplicate the messages and always perform three transactions in parallel over three different cellular operators. This creates a dataset with which we can compare the operators in an objective way and with which we can study the potential for multi-access. In this paper we use the triple-access dataset to evaluate single-access selection strategies, where one operator is chosen for each transaction. We show that if we have access to three operators and for each transaction choose the operator with best access technology and best signal quality then we can significantly improve availability and transaction times compared to the individual operators. The median transaction time improves with 6% compared to the best single operator and with 61% compared to the worst single operator. The 90-percentile transaction time improves with 23% compared to the best single operator and with 65% compared to the worst single operator.

  • 90.
    Abrahamsson, Henrik
    Mälardalen University, School of Innovation, Design and Engineering.
    Internet Traffic Management2008Licentiate thesis, comprehensive summary (Other scientific)
  • 91.
    Abrahamsson, Henrik
    Mälardalen University, School of Innovation, Design and Engineering.
    Network overload avoidance by traffic engineering and content caching2012Doctoral thesis, comprehensive summary (Other academic)
    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.

  • 92.
    Abrahamsson, Henrik
    et al.
    Swedish Inst of Computer Science, Kista, Sweden .
    Ahlgren, Bengt
    Swedish Inst of Computer Science, Kista, Sweden .
    Using Empirical Distributions to Characterize Web Client Traffic and to Generate Synthetic Traffic2000In: Conference Record / IEEE Global Telecommunications ConferenceVolume 1, 2000, 2000, p. 428-433Conference paper (Refereed)
    Abstract [en]

    We model a web client using empirical probability distributions for user clicks and transferred data sizes. By using a heuristic threshold value to distinguish user clicks in a packet trace we get a simple method for analyzing large packet traces in order to get information about user OFF times and amount of data transferred due to a user click. We derive the empirical probability distributions from the analysis of the packet trace. The heuristic is not perfect, but we believe it is good enough to produce a useful web client model. We use the empirical model to implement a web client traffic generator. The characteristics of the generated traffic is very close to the original packet trace, including self-similar properties.

  • 93.
    Abrahamsson, Henrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Ahlgren, Bengt
    SICS.
    Alonso, Juan
    Andersson, Anders
    SICS.
    Kreuger, Per
    SICS.
    A Multi Path Routing Algorithm for IP Networks Based on Flow Optimisation2002In: Proceedings of the Third International Workshop on Quality of Future Internet Services / [ed] Burkhard Stiller, Springer Berlin/Heidelberg, 2002, p. 135-144Conference paper (Refereed)
  • 94.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science, Kista, Sweden.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Caching for IPTV distribution with time-shift2013In: 2013 International Conference on Computing, Networking and Communications, ICNC 2013, IEEE , 2013, p. 916-921Conference paper (Refereed)
    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

  • 95.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Robust Traffic Engineering using L-balanced Weight-Settings in OSPF/IS-IS2009In: Proceedings of the 2009 6th International Conference on Broadband Communications, Networks and Systems, BROADNETS 2009, 2009Conference paper (Refereed)
    Abstract [en]

    Internet traffic volumes continue to grow at a great rate, now pushed by video and TV distribution in the networks. This brings up the need for traffic engineering mechanisms to better control the traffic. The objective of traffic engineering is to avoid congestion in the network and make good use of available resources by controlling and optimising the routing function. The challenge for traffic engineering in IP networks is to cope with the dynamics of Internet traffic demands. Today, the main alternative for intra-domain traffic engineering in IP networks is to use different methods for setting the weights in the routing protocols OSPF and IS-IS. In this paper we revisit the weight setting approach to traffic engineering but with focus on robustness. We propose I-balanced weight settings that route the traffic on the shortest paths possible but make sure that no link is utilised to more than a given level I. This gives efficient routing of traffic and controlled spare capacity to handle unpredictable changes in traffic. We present a heuristic search method for finding I-balanced weight settings and show that it works well in real network scenarios

  • 96.
    Abrahamsson, Henrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Robust Traffic Engineering using L-balanced Weight-Settings in OSPF/IS-IS2008Other (Other academic)
  • 97.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Simulation of IPTV caching strategies2010In: Proceedings of the 2010 International Symposium on Performance Evaluation of Computer and Telecommunication Systems, 2010, p. 187-193Conference paper (Refereed)
    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.

  • 98.
    Abrahamsson, Henrik
    et al.
    Swedish Institute of Computer Science, Kista, Sweden.
    Gunnar, Anders
    Swedish Institute of Computer Science, Kista, Sweden.
    Traffic Engineering in Ambient Networks: Challenges and Approaches2004Conference paper (Refereed)
  • 99.
    Abrahamsson, Henrik
    et al.
    SICS AB, Kista, Sweden .
    Hagsand, Olof
    Dynarc AB, Kista, Sweden .
    Marsh, Ian
    SICS AB, Kista, Sweden .
    TCP over High Speed Variable Capacity Links: A Simulation Study for Bandwidth Allocation2002In: Protocols for High Speed Networks Workshop, 2002, p. 117-129Conference paper (Refereed)
  • 100.
    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 system2012In: IMC '12 Proceedings of the 2012 ACM conference on Internet measurement conference, New York: ACM , 2012, p. 199-210Conference paper (Refereed)
    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.

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