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  • 351. Alexanderson, K
    et al.
    von Knorring, M
    Parmander, M
    Tyrkkö, Arja
    Karlstad University, Faculty of Social and Life Sciences, Department of Social Studies.
    Hälso- och sjukvårdens ledning och styrning av arbetet med patienters sjukskrivning2007Report (Refereed)
  • 352.
    Alexandersson, Birgitta
    Karlstad University, Faculty of Arts and Education. Karlstad University.
    Tid för återhämtning: Ett möte mellan flyktingbarn och FMT-metoden2010Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I detta examensarbete beskriver jag FMT – Funktionsinriktad MusikTerapi. Mitt syfte har varit att undersöka om denna ickeverbala metod, kan stödja utvecklingen för flyktingbarn som ännu inte tillgodogjort sig det svenska språket. De fyra barnen, som alla går i förberedelseklass, visar olika symtom på traumatisk stress som kan härledas till deras erfarenheter av krig.

    Examensarbetet inleds med en historisk tillbakablick på musikterapi i allmänhet. Sedan beskrivs FMT-metoden ingående. Jag redogör för olika erfarenheter av att vara flykting och vad det innebär att gå i en förberedelseklass. Därefter följer en bakgrundsbeskrivning av barnen och arbetet med metoden, samt en avslutande del som grundar sig på de erfarenheter och slutsatser som jag har kommit fram till.

    Mina studier visar att FMT är en användbar metod för att stärka och utveckla funktioner hos barn, där erfarenheter av krig kommit att hämma individens fortsatta utveckling.

  • 353.
    Alexandersson, Jenny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Förändring av layout och produktionsflöde: Med fokus på förbättringar och struktur i produktionen2018Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This project has been implemented as a degree of Bachelor of Science in Innovation and Design at the Faculty of Health, Science and Technology at the University of Karlstad. The project started in November 2017 and continued to May 2018.

    The most of the work has been performed on the company KD: Solskydd AB in Degerfors. The main task of this project was to develop a new flow-oriented factory layout, to one of the departments in the company. The work included many observations and interviews, it was a big part of the specification and preliminary study. The analysis part of the project was to investigate the possibilities to a better flow in the production and opportunities for improvement in the factory. The methods that were used in this project were establish in Lean.

    From the product development process strategy have a project can be formed and performed. The process has been adapted to this project.

    Ten separate ideas of layouts were made. Each idea fulfilled the specification different. A group of selected co-workers from the compony and some of the persons in the board of the company, got a presentation of the ten ideas. The group discussed the separate ideas from the information they have of the ideas, from that they select one of the layout ideas. To be the one!

    A simulation of the new layout was performed in Karlstad Lean Factory. Nine employees from the company participated in the simulation. The simulation helped the co-workers to see improvements in the production flow.

    In the end of the project investigated the possibilities to more improvement areas in the company, with help from Lean.

  • 354.
    Alexandersson, Linnea
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Language, Literature and Intercultural Studies.
    Motiverande uppgifter i matematikboken: En kvalitativ studie om egenskaper i matematikuppgifter som elever i årskurs 2 finner motiverande.2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Research shows that students largely work individually in math books and a lot of literature suggests that students' interest in mathematics decreases with age. As the source for the choice of my research is an interest in how the tasks and information in the textbook contributes to student motivation and desire to learn mathematics. One way to examine this is to find out what students think about the information in the mathematics textbooks by allowing them to describe the characteristics of the data that they are motivated by. The survey will contribute to the knowledge about the types of tasks which, according to the students, is more motivating to them than others. It provides a knowledge that teachers can weigh into their choice of textbooks and other teaching resources. The purpose of the study is to examine the characteristics of mathematic tasks students in second grade will find motivating. The information contained in the students' regular teaching materials and students' stories or descriptions are the starting point for the study. My research question is: what characterizes mathematic tasks that students experience that is motivating to learn math? The research strategy and research design is qualitative study. Information collected from interviews at a certain time. Of the result and the analysis I have concluded that what characterizes a motivating task is based on the difficulty of the tasks.

  • 355.
    Alexandersson, Lisa
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Nursing.
    Dahlström, Monica
    Karlstad University, Faculty of Social and Life Sciences, Department of Nursing.
    Distriktssköterskans erfarenhet av att vårda tillsammans med närstående: resurs eller börda?: En litteraturstudie2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Introduction: District nurses meet informal caregivers of different ages, family constellations and in diverse contexts such as health care centers, child health care centre, home care and school health care. In the home, informal caregivers care a large part of the care provider's nursing and healthcare. In addition to family members, there may also be friends who are close to the care recipient. The aim: To describe the district nurse's experiences of caring together with informal caregivers. Method: The method used was a literature study with manifest content analysis. 14 articles were included in the essay analysis. Results: Six categories emerged: building relationships (subcategory: trust and trust), good communication, cooperation (subcategory: involvement of close relatives), support and accessibility, lack of communication (subcategory: conflicts of interests), factors in the family. These categories are summarized in two themes: informal caregivers as resource and informal caregivers as a burden. Conclusion: The results of the study show that the district nurse's experience of caring with informal caregivers is that it can both be a resource and a burden. The district nurses experience is that informal caregivers are a resource if they are included. The results show that the relationship between the nurse and informal caregivers is important for the cooperation and planning of the patient's care in the absence of the district nurse. District nurses need to raise awareness for the encounter with informal caregivers and patients who have other cultural beliefs and lifestyles than their own.

  • 356.
    Alexandersson, Lisa
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Nursing.
    Thörnqvist, Jenny
    Karlstad University, Faculty of Social and Life Sciences, Department of Nursing.
    Livskvalitet hos kvinnor som överlevt bröstcancer: En litteraturstudie2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 357.
    Alexandersson, Natalie
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Educational Studies.
    Den fria lekens betydelse: Förskollärares tankar kring den fria lekens betydelse för barns sociala kompetens2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim with this paper is to study four preschool teachers' attitude towards free play and social skills and how they define social skills in the free play. The methods I have used are studying relevant research and literature covering this field of studies. I have also conducted an interview with the, above mentioned, preschool teachers.

    The study indicates that the preschool teachers shared the conception that the free play is of importance for children to develop social skills. Children learn many social skills by free play. The study also confirms that the preschool teachers are very important for the development of social skills among children by supporting and stimulating the free play and by their attitudes towards both children and other adults.

  • 358.
    Alexandersson, Sanna
    et al.
    Karlstad University.
    Balldin, Annika
    Karlstad University.
    Ambulanssjuksköterskans upplevelse av hur och varför hot- och våldssituationer kan påverka omvårdnaden2013Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 359.
    Alexandersson (Weimers), Jenny
    Karlstad University.
    Styrningsrationalitet i svenska kommuner - en fråga om ideologi?: En komparativ studie om sambandet mellan ideologi och styrningsrationalitet2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This paper is about if municipal council's ideology affect steering in the municipalities of Vellinge and Fagertsa. Vellinge has for a long time been governed by Sweden's conservative party Moderaterna. Fagersta has for a long time been governed by Sweden's left party Vänsterpartiet. The main question of the paper to be answered is as follows:

    Is there a relation between the steering in municipalities and the ideology of the governing parties?

    The hypothesis is that there is a connection between what ideology the party that governs has and how the municipalities are being governed. The question is being answered by an idea analysis. Two ideal types are being used to compare the two steering alternatives New Puplic Management and Traditional Bureucracy with the two municipalities. The conclusion is that there is a connection though it is rather weak. It is also clear that the steering is being affected not only by the governing parties ideology but also by the state. This explanation is supported by the theory employed in the paper.

    Keywords: Styrningsrationalitet, New Public Management, Traditional Bureucracy, Kommuner

  • 360.
    Alexandra, Guseva
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Educational Studies.
    Att organisera för lärande: En studie av samband mellan gruppens ålderssammansättning och förutsättningar för barns lärande i förskolan2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to investigate whether there are some patterns and connections between the teachers’ experiences of the conditions for children’s learning and age settings at preschool groups. The study is quantitative, and a web survey is used to collect the data from the teachers. The study includes all preschools in a municipality in Värmland, Sweden. 144 preschool teachers from 55 municipal preschool groups participated in the study. Following age settings are represented in the study: same-age preschool groups, groups with children between 1-3 years old, groups with children between 3-5 years old and groups with children between 1-5 years old.

    The study is based on interactionistic theories, which means that the preschool is examined from various interacting aspects and dimensions. Conditions for children’s learning are seen in the study in relation to preschool quality, which is a complex phenomenon constituted in the interaction between dimensions of structure, process, and outcome. The study focuses on age setting as a structural aspect of preschool quality and following aspects of process quality: organizing of the pedagogical environment, teachers’ approach to organizing of daily activities and teachers’ interplay with children

    The results of the study show that there are important differences between groups with different age settings regarding organizing of the pedagogical environment and interplay between teachers and children. However, these differences are rather ambiguous and can be explained by other aspects and factors such as group’size, children’s age, and pedagogical approach. Therefore, age setting as such is not the key to preschool quality but must be seen in relation to other aspects and dimensions.

  • 361.
    alexson, malin
    Karlstad University, Faculty of Arts and Education.
    Elevperspektiv på viktiga faktorer hos vårdläraren för ökad studiemotivation.2010Independent thesis Basic level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
  • 362.
    Alfalk, Marjut
    et al.
    Karlstad University.
    Wäseby, Anna
    Karlstad University.
    Skolsköterskans arbete vid övervikt hos barn och ungdomar: Integrerad litteraturstudie2013Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 363.
    Alfredsson, Alexandra
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Business Administration.
    Augustsson, Alexandra
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Business Administration.
    Kraven på revision: är professionellt uppträdande det som räknas?2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Auditors in Sweden are supervised by the Swedish Supervisory Board of Public Accountants (SSBPA). This board also handles the consequences following a breach of professional and statutory rules. In a study from 2010 by Thomas Carrington, he came to the conclusion that an accountant’s professional appearance is the most important factor to the SSBPA when evaluating an auditor’s wrongdoings. Following the corporate scandals at the start of the 21st century, the supervision of auditors has tightened through the adoption of new laws and an increase in demand on auditors and audit quality. Because of the new laws and the increased demands it is of interest to study the disciplinary cases published by the SSBPA to see if any changes have eventuated. The question formulation regards the changes in demands on sufficient audit by the SSBPA. Moreover, it includes the question if the professional appearance of the auditor is still what matters the most when evaluating sufficient audit. We have read all the completed disciplinary cases between 2007 and 2012. The cases have been classified as errors and, just like with Carrington’s study, the errors have been divided in to two categories; process- or professional appearance errors. To get a deeper understanding of the subject at hand we have researched what auditing is, how it is conducted and the definition of auditing quality. Furthermore, we have investigated the work process of the SSBPA as well as acquired knowledge about the audit process and the auditor’s professional appearance.

    When comparing this study with the study by Carrington, some differences and similarities have become apparent. One of the differences noticed is that it is enough to err in only one of the two categories to get the harshest consequence; withdrawal of the license, whereas Carrington found that in most cases the auditor has to err in both. In addition, when studying the disciplinary cases published by the SSBPA we discovered that the process errors have increased while the professional appearance errors have decreased. A similarity between the two studies is that most cases will have a milder consequence than withdrawal of license, namely warning or reminder.

    In conclusion, we have found that the SSBPA has tightened the demands on a sufficient audit and this is based on the corporate scandals leading to a stricter legislative and a more tightened supervision of auditors. Finally, it is established that an auditor’s professional appearance is no longer the most important factor when evaluating sufficient audit. 

  • 364.
    Alfredsson, Alexandra
    et al.
    Karlstad University.
    Augustsson, Alexandra
    Karlstad University.
    Kraven på tillräcklig revision: är professionellt uppträdande det som räknas?2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 365.
    Alfredsson, Antonia
    Karlstad University.
    Läkemedelsorsakade förgiftningar i Sveringe: Trender, riskgrupp och tillgång2013Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 366.
    Alfredsson, Elin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Health Sciences.
    Axelsson, Emma
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Health Sciences.
    Att leva med fatigue vid cancersjukdom- ur ett patientperspektiv: En litteraturstudie2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

     Introduktion: Cancer är den andra vanligaste dödsorsaken i Sverige. Cancer drabbar alla åldersgrupper men är vanligare bland äldre. De tre vanligaste behandlingsmetoderna för cancer är strålning, cytostatika och kirurgi. Den vanligaste biverkningen är cancerrelaterad fatigue. Livskvalitet som påverkas definieras som en individs inställning till livet i relation till deras mål, förväntningar, normer och bekymmer. Syfte: Syftet med studien var att belysa patienters upplevelser av cancerrelaterad fatigue och hur den påverkar deras livssituation samt livskvalitet. Metod: Litteraturstudien genomfördes enligt Polit och Becks (2017) nio steg. Tio vetenskapliga artiklar valdes ut efter sökningar gjorda i databaserna CINAHL och PubMed, dessa artiklar presenteras i en artikelmatris (bilaga 1). Artiklarna som användes till studiens resultatdel var fem stycken kvantitativa, fyra stycken kvalitativa och en med mixad metod. Resultat: Utifrån det insamlade materialet utarbetades fem teman som svarade på patienternas upplevelser av cancerrelaterad fatigue och hur livssituationen påverkas samt livskvalitet. Dessa fem teman var värdelöshet/hopplöshet, ensamhet/inte känna sig förstådd, orkeslöshet/kroppslig svaghet, irritation/frustration, och förståelse/acceptans. Slutats: Cancerrelaterad fatigue påverkar patienternas hela tillvaro och hur det upplever olika aspekter i livet. De upplever en förändrad livssituation och att livskvaliteten påverkas negativt. Cancerrelaterad fatigue är ett symtom som påverkar alla patienter på något vis men alla drabbas inte lika hårt. Cancerrelaterad fatigue kan ses som ett holistiskt fenomen med mycket stor komplexitet. 

  • 367.
    Alfredsson, Emelie
    Karlstad University, Faculty of Social and Life Sciences. Karlstad University.
    Ett Förändrat Ledarskap?: En studie av EU:s ledarskap sett ur ett institutionellt perspektiv, kopplat till internationella miljöförhandlingar2010Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Political Science, level III thesis

    Spring semester 2010

    Author: Emelie Alfredsson

    Supervisor: Tomas Mitander

    "A Changed Leadership? - A study of the EU leadership from a institutional standpoint, related to multilateral environmental negotiations"

    The EU has for a relatively long time considered itself a leader in the environmental policy area as a whole as well as in multilateral environmental negotiations. This study attempts to classify and identify the European leadership with the purpose of relating it to the institutional framework of the Union. The treaties of the European Union decide its ability to act and its institutions the right to engage in different policy areas, the environmental area being the focus of this study. With the recent ratification of the Lisbon treaty this study aims to make out if the type of leadership the Union showed during the Kyoto negotiations has changed with the new treaty, into a new type during the COP-15 meeting in Copenhagen. The results shows that the Union has kept the same type of leadership despite the change in treaties, though with great potential of changing leadership if or when the new reforms of the new treaty are better implemented. This result points to the fact that institutional changes have a small effect on the EU leadership and that other factors such as ability to unite the member countries may play a bigger role.

    Keywords: EU, leadership, multilateral environmental negotiations, Copenhagen, Kyoto

  • 368.
    Alfredsson, Jannie
    Karlstad University, Faculty of Social and Life Sciences.
    Downshifting: Hur påverkas miljön och klimatet av downshifting? På vilka sätt kan småbarnsföräldrars inre välmående påverkas av downshifting?2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 369.
    Alfredsson, Johan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Law.
    Försäkringstjänst i samband med leasing: Underordnad eller separat tjänst i mervärdesskattehänseende?2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 370.
    Alfredsson, Johan
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Business Administration.
    Larsson, Jakob
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Business Administration.
    Skatteverkets kommunikation med medborgarna2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 371.
    Alfredsson, Lottie
    et al.
    Karlstad University, Faculty of Technology and Science.
    Christenson, Sara
    Karlstad University, Faculty of Technology and Science.
    Supplier Selection & Quality Expectations: Development of a Simple Supplier Evaluation Tool in a Norwegian Ventilation Systems Company2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today’s competitive market, survival and response to customer needs and

    expectations are enabled through high-quality products for low costs – quality

    products provided by suppliers fulfilling today’s quality-requirements for a low

    price. Companies have until recent years selected suppliers only according to a

    pricing structure, leaving other criteria’s, such as quality, behind.

    The purpose of this master thesis is therefore to investigate quality aspects that

    must be considered from a supplier evaluation perspective and design a simple

    evaluation tool for first-time supplier selections. Both new and existing

    suppliers will be tested with the tool according to information given during a

    case study made at Flexit AS, a Norwegian ventilation-systems company

    looking to introduce a structured approach for selecting suppliers.

    Through an extensive literature- and empirical study, where a survey, of which

    evaluation criteria’s to be included in the evaluation tool, was conducted

    together with several both semi-structured and unstructured interviews, a

    foundation for the design of the tool was presented.

    Quality management systems and quality performance measurements, such as

    rejection rate and delivery precision, are considered as fundamental aspects to

    consider when assessing a supplier. Acceptance levels of approval are set

    according to in-house objectives. If any evaluation tool including quality

    should be usable, an in-house quality system must therefore first be

    implemented by the in-house company – a notable improvement

    recommended to the case company.

    The design of the tool given from the thesis provides the evaluator with an

    opportunity to visualize and compare existing suppliers according to five

    criteria’s including cost, together with an additional spreadsheet for evaluation

    of new suppliers put forward as a foundation and an indicator if new suppliers

    are considering quality on a basic level.

  • 372.
    Alfredsson, Patrik
    et al.
    Karlstad University, Faculty of Technology and Science.
    Haeffner, Fredric
    Karlstad University, Faculty of Technology and Science.
    Åtgärdsförslag för erosionsskador i Kölaälv2006Independent thesis Basic level (professional degree), 15 points / 22,5 hpStudent thesis
  • 373.
    Alfredsson, Simone
    et al.
    Karlstad University.
    Elvén, Lotta
    Karlstad University.
    Investeringskalkylering: En benchmarking av Volvo Construction Equipment2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Uppsatsen innefattar en intern benchmarking för Volvo Construction Equipment, Arvika, Hallsberg, Eskilstuna och Braås. En kartläggning utifrån intervjuer ska göras över de investeringskalkyleringsmetoder som används i dagsläget. Syftet är att arbeta fram en mall för investeringar inom Operations Sweden, där samtliga involverade använder samma beräkningsmetoder och parametrar i sina bedömningar.

    Volvo Construction Equipment tillverkar anläggningsmaskiner. De fyra fabrikerna bildar tillsammans gemenskapen Operations Sweden. Inom Operations Sweden tas beslut om ett investeringsprojekt ska genomföras eller ej. Beslutet tas av en ledningsgrupp. Innan uppstarten av Operations Sweden togs fler beslut på lokal nivå. Vid investeringskalkyleringen, som är en del i ett investeringsprojekt, uppstår skillnader både i hur man ska gå tillväga och vilka inputs som bör användas. Operations Sweden efterfrågar ett mer lättförståeligt utbildningsmaterial för hur investeringskalkyleringen skall gå till och en lathund som beskriver beräkningssätt, för- och nackdelar och de fallgropar som finns för respektive investeringskalkyleringsmetod.

    Som ett resultat av intervjuerna upptäcktes att de som arbetar som projektledare oftast har en civilingenjörsexamen. Förkunskaper inom ekonomi är knappa vilket kan försvåra tillämpningen och förståelsen för investeringskalkyleringsarbetet. Ett utbildningsmaterial utarbetades utifrån intervjuerna där det framkom hur arbetssätten skiljde sig och var svårigheter fanns. Utbildningsmaterialet ska bidra till att alla projektledare inom Operations Sweden arbetar på ett enhetligt sätt vid investeringskalkyleringen och att alla ska ha tillräcklig kunskap om de olika investeringskalkyleringsmetoderna.

  • 374.
    Alfredsson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    A Case Study of Recent Mifare Classic Field Deployments From an (In-)Security Perspective2013In: Proceedings of the 21st International Conference on Software, Telecommunications and Computer Networks (SoftCOM 2013), Split, Croatia: FESB, University of Split , 2013Conference paper (Refereed)
    Abstract [en]

    Mifare Classic is a very popular near-field communication technology that provides a shared-key, access-controlled, storage. Although the authentication protocol of Mifare Classic is compromised since half a decade, systems are still being deployed based on this technology, e.g. for access control systems and for public transport ticketing. By using commodity hardware, such as NFC enabled smartphones, by passing the security measures in some cases only require the installation and operation of a smartphone app. To this end, we present case studies of a number of recent Mifare Classic systems deployed during the last year, to serve as an illustration of practical security problems and to raise awareness thereof among NFC technology buyers and system implementors.

  • 375.
    Alfredsson, Stefan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    A Cross-Layer Perspective on Transport Protocol Performance in Wireless Networks2012Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Communication by wireless technologies has seen a tremendous growth in the last decades. Mobile phone technology and wireless broadband solutions are rapidly replacing the last-hop wireline connectivity for telephones and Internet access.  Research has, however, shown that Internet traffic can experience a performance degradation over wireless compared to wired networks.  The inherent properties of radio communication lead to a higher degree of unreliability, compared to communication by wire or fiber.  This can result in an increased amount of transmission errors, packet loss, delay and delay variations, which in turn affect the performance of the main Internet transport protocols TCP and UDP.  This dissertation examines the cross-layer relationship between wireless transmission and the resulting performance on the transport layer. To this end, experimental evaluations of TCP and UDP over a wireless 4G downlink system proposal are performed.  The experiment results show, in a holistic scenario, that link-level adaptive modulation, channel prediction, fast persistent link retransmissions, and channel scheduling, enables the transport protocols TCP and UDP to perform well and utilize the wireless link efficiently.  Further, a novel approach is proposed where a modified TCP receiver can choose to accept packets that are corrupted by bit errors. Results from network emulation experiments indicate that by accepting and acknowledging even small amounts of corrupted data, a much higher throughput can be maintained compared to standard TCP.

  • 376.
    Alfredsson, Stefan
    Karlstad University, Division for Information Technology.
    TCP in Wireless Networks: Challenges, Optimizations and Evaluations2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents research on transport layer behavior in wireless networks. As the Internet is expanding its reach to include mobile devices, it has become apparent that some of the original design assumptions for the dominant transport protocol, TCP, are approaching their limits. A key feature of TCP is the congestion control algorithm, constructed with the assumption that packet loss is normally very low, and that packet loss therefore is a sign of network congestion. This holds true for wired networks, but for mobile wireless networks non-congestion related packet loss may appear. The varying signal power inherent with mobility and handover between base-stations are two example causes of such packet loss. This thesis provides an overview of the challenges for TCP in wireless networks together with a compilation of a number of suggested TCP optimizations for these environments. A TCP modification called TCP-L is proposed. It allows an application to increase its performance, in environments where residual bit errors normally give a degraded throughput, by making a reliability tradeoff. The performance of TCP-L is experimentally evaluated with an implementation in the Linux kernel. The transport layer performance in a 4G scenario is also experimentally investigated, focusing on the impact of the link layer design and its parameterization. Further, for emulation-based protocol evaluations, controlled packet loss and bit error generation is shown to be an important aspect.

  • 377.
    Alfredsson, Stefan
    et al.
    Karlstad University, Division for Information Technology.
    Brunstrom, Anna
    Karlstad University, Division for Information Technology.
    Bit Error Tolerant Multimedia Transport2004In: Perspectives on Multimedia: Communication, Media and Information Technology, Chichester: John Wiley & Sons, 2004, p. 175-191Chapter in book (Other academic)
  • 378.
    Alfredsson, Stefan
    et al.
    Karlstad University, Division for Information Technology.
    Brunstrom, Anna
    Karlstad University, Division for Information Technology.
    TCP-L: Allowing Bit Errors in Wireless TCP2003In: Proceedings of the 12th IST Summit on Mobile and Wireless Communications: Enabling a Pervasive Wireless World / [ed] Atílio Gameiro, Institute for Operations Research and the Management Sciences (INFORMS), 2003, p. 149-154Conference paper (Refereed)
    Abstract [en]

    This paper presents a technique to improve the performance of TCP and the utilization of wireless networks.Wireless links exhibit high rates of bit errors, compared to communication over wireline or fiber. Since TCP cannotseparate packet losses due to bit errors versus congestion,all losses are treated as signs of congestion and congestionavoidance is initiated. This paper explores the possibility of accepting TCP packets with an erroneous checksum, toimprove network performance for those applications that can tolerate bit errors. Since errors may be in the TCP header aswell as the payload, the possibility of recovering the headeris discussed. An algorithm for this recovery is also presented.Experiments with an implementation have been performed,which show that large improvements in throughput can beachieved, depending on link and error characteristics.

  • 379.
    Alfredsson, Stefan
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Division for Information Technology.
    Brunstrom, Anna
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Division for Information Technology.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    A 4G Link Level Emulator for Transport Protocol Evaluation2004In: Proceedings of The Second Swedish National Computer Networking Workshop (SNCNW), 2004, p. 19-23Conference paper (Refereed)
    Abstract [en]

    This paper presents a wireless link and networkemulator, based upon the "Wireless IP" 4G system proposalfrom Uppsala University and partners. In wireless fading down-links (base to terminals) link-level frames are scheduled andthe transmission is adapted on a fast time scale. With fastlink adaptation and fast link level retransmission, the fading properties of wireless links can to a large extent be counteractedat the physical and link layers. A purpose of the emulatoris to investigate the resulting interaction with transport layer protocols. The emulator is built on Internet technologies, andis installed as a gateway between communicating hosts. The paper gives an overview of the emulator design, and presentspreliminary experiments with three different TCP variants. The results illustrate the functionality of the emulator by showing theeffect of changing link layer parameters on the different TCP variants.

  • 380.
    Alfredsson, Stefan
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunstrom, Anna
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    Cross-layer analysis of TCP performance in a 4G system2007In: Proceedings of the 15th International Conference on Software, Telecommunications and Computer Networks, IEEE Computer Society, 2007Conference paper (Refereed)
    Abstract [en]

    This paper presents results from an experimental study of TCP in a wireless 4G evaluation system. Test-bed results on transport layer performance are presented and analyzed in relation to several link layer aspects. The aspects investigated are the impact of channel prediction errors, channel scheduling, delay, and adaptive modulation switch level, on TCP performance. The paper contributes a cross-layer analysis of the interaction between symbol modulation levels, different scheduling strategies, channel prediction errors and the resulting frame retransmissions effect on TCP. The paper also shows that highly persistent ARQ with fast link retransmissions do not interact negatively with the TCP retransmission timer even for short round trip delays.

  • 381.
    Alfredsson, Stefan
    et al.
    Karlstad University, Division for Information Technology. Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunstrom, Anna
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Division for Information Technology.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    Emulation and Validation of a 4G System Proposal2005In: Proceedings of RadioVetenskap och Kommunikation 2005: Volume II, 2005, p. 357-362Conference paper (Refereed)
    Abstract [en]

    This paper presents a wireless link and network emulator,along with experiments and validation against the "Wireless IP" 4G system proposal from Uppsala University and partners. In wireless fading downlinks (base to terminals) link-level frames are scheduled and the transmission is adapted on a fast time scale. With fast link adaptation and fast link level retransmission, the fading properties of wireless links can to a large extent be counteracted at thephysical and link layers. The emulator has been used to experimentally investigate the resulting interaction between the transport layer and the link layer. The paper gives an overview of the emulator design, and presents experimental results with three different TCP variants in combination with various link layer characteristics.

  • 382.
    Alfredsson, Stefan
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunstrom, Anna
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    Impact of 4G Wireless Link Configurations on VoIP Network Performance2008In: Proceedings of the 2008 IEEE International Symposium on Wireless Communication Systems, IEEE Communications Society, 2008, p. 708-712Conference paper (Refereed)
    Abstract [en]

    The performance of applications in wireless networks is partly dependent upon the link configuration. Link characteristics varies with frame retransmission persistency, link frame retransmission delay, adaptive modulation strategies, coding, and more. The link configuration and channel conditions can lead to packet loss, delay and delay variations, which impact different applications in different ways. A bulk transfer application may tolerate delays to a large extent, while packet loss is undesirable. On the other hand, real-time interactive applications are sensitive to delay and delay variations, but may tolerate packet loss to a certain extent. This paper contributes a study of the effect of link frame retransmission persistency and delay on packet loss and latency for real-time interactive applications. The results indicate that a reliable retransmission mechanism with fast link retransmissions in the range of 2-8 ms is sufficient to provide an upper delay bound of 50 ms over the wireless link, which is well within the delay budget of voice over IP applications.

  • 383.
    Alfredsson, Stefan
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Brunstrom, Anna
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Mikael, Sternad
    Signaler och System, Uppsala universitet.
    Transport Protocol Performance over 4G Links: Emulation Methodology and Results2006In: Proceedings of the International Symposium on Wireless Communication Systems (ISWCS), IEEE Computer Society, 2006, p. 327-332Conference paper (Refereed)
    Abstract [en]

    This paper presents a wireless link and network emulator for the "Wireless IP" 4G system proposal from Uppsala University and partners. In wireless fading downlinks (base to terminals) link-level frames are scheduled and the transmission is adapted on a fast time scale. With fast link adaptation and fast link level retransmission, the fading properties of wireless links can to a large extent be counteracted at the physical and link layers. The emulator has been used to experimentally investigate the resulting interaction between the transport layer and the physical/link layer in such a downlink. The paper introduces the Wireless IP system, describes the emulator design and implementation, and presents experimental results with TCP in combination with various physical/link layer parameters. The impact of link layer ARQ persistency, adaptive modulation, prediction errors and simple scheduling are all considered.

  • 384.
    Alfredsson, Stefan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Del Giudice, Giacomo
    Politecnico di Bari, Italy.
    Garcia, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Brunstrom, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    De Cicco, Luca
    Ecole superieure d'Electricite, France; Politecnico di Bari, Italy.
    Mascolo, Saverio
    Politecnico di Bari, Italy.
    Impact of TCP Congestion Control on Bufferbloat in Cellular Networks2013In: Proceedings of the 14th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM 2013) / [ed] Angelos Lazaris, Balaji Rengarajan, IEEE Press, 2013Conference paper (Refereed)
    Abstract [en]

    The existence of excessively large and too filled network buffers, known as bufferbloat, has recently gained attention as a major performance problem for delay-sensitive applications. One important network scenario where bufferbloat may occur is cellular networks.

    This paper investigates the interaction between TCP congestion control and buffering in cellular networks. Extensive measurements have been performed in commercial 3G, 3.5G and 4G cellular networks, with a mix of long and short TCP flows using the CUBIC, NewReno and Westwood+ congestion control algorithms. The results show that the completion times of short flows increase significantly when concurrent long flow traffic is introduced. This is caused by increased buffer occupancy from the long flows. In addition, for 3G and 3.5G the completion times are shown to depend significantly on the congestion control algorithms used for the background flows, with CUBIC leading to significantly larger completion times.

  • 385.
    Alfredsson, Stefan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Del Giudice, Giacomo
    Politecnico di Bari, Italy.
    Garcia, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Brunstrom, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    De Cicco, Luca
    Ecole superieure d'Electricite, France; Politecnico di Bari, Italy.
    Mascolo, Saverio
    Politecnico di Bari, Italy.
    Observations of Bufferbloat in Swedish Cellular Networks2013In: Proceedings of the 9th Swedish National Computer Networking Workshop (SNCNW 2013) / [ed] Bengt Ahlgren, 2013Conference paper (Refereed)
  • 386.
    Alfredsson, Svante
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Konceptutveckling av transportlösning för kaffeutrustning till event2016Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    This thesis is done during the spring semester 2016 for the Bachelor of Science in Innovation and Design programme at Karlstad University. The mission of the thesis was provided by the company 3TEMP AB in Arvika.

    In order to serve large quantities of coffee at big events, festivals and fairs a powerful coffee machine is required. Due to its size the machine is difficult handle during transport. This project is about finding a solution that makes the transport of the coffee machine and its related equipment safer and easier to handle during transportation between events.

    The goal of the project was to find a possible solution that makes the transportation of the equipment more efficient and ergonomic. In order to find as many ideas as possible the design process has been used. This includes a research followed by an ideation, concept development and concept evaluation. The project ended with one concept presented in the form of a layout design in CAD together with assembly drawings, sketches and a model.

    In this project interviews and observations has been done together with the people who transport coffee equipment on a daily basis. The results of the observations were later compared with the recommended lifting weight for manual lifting tasks using NOISH lifting equation. In the event business different types of vehicles are used to transport equipment at the event areas. Everything from ATVs and snowmobiles to tractors and caterpillar vehicles are used. In the project there has been a search for a common denominator between those vehicles.

    During the project benchmarking of similar products has also been done to find inspiration for new ideas. To further evaluate the concepts an examination of laws and regulations for transportation of equipment in traffic and off-road has been done.

    The equipment also has to withstand long distance transport by rail, road, sea and air. To meet these requirements interviews were made with the company MariTerm AB who works with educating in cargo securing of goods for worldwide shipment.

  • 387.
    Alfsson, Diana
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Language, Literature and Intercultural Studies.
    Mobbning i litteraturen - då och nu: Skillnader och likheter i beskrivningen av mobbning idag och för 60 år sedan2016Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    This essay is a comparative study of two youth novels with bullying as a motif. The novels are Vi kallar honom Anna by Peter Pohl and Gilla Hata Horan by Johanna Nilsson. Bullying at school is an ever present problem for students, teachers, parents and school management. The society is obliged to provide a safe and equal environment where every student is included. The school system of today take actions to prevent bullying. I believe literature could play a part in that work. The purpose of the essay is to examine similarities and differences between the texts in how bullying is described 60 years ago, and the bullying that exists today and often takes place on the Internet. I also plan to use the result in literature classes. I have in my analysis used a comparative method, and biografic science where focus lies on what the author wants to say with the text.

    My analysis shows that the texts displays many situations that relates to science. There are many similarities and differences between the texts, but the biggest difference is the description of how teachers and management looked at bullying in the 1950s, compared to today. Another difference is the description of how bullying today takes place around the clock, compared with how bullying mainly took place during school time 50 years ago, differences that clearly is stated in the novels. Back in the day you knew who the persons that performed bullying was. Today you can be anonymous, which makes it hard to know who is behind it. Both authors have their own experiences from bullying with a time difference of 40-50 years. Despite the time gap bullying is described with essentially the same universal components in cause and effect.

    Keywords: Bullying, study of motifs, comparative, intertextuality

  • 388.
    Alfsson, Diana
    Karlstad University, Faculty of Arts and Education.
    Tappar ungdomarna standardspråket om chatt/ungdomsspråket används inom skolan?: En studie av chatt/ungdomsspråkets inverkan på skriftspråket2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 389.
    Alge, Petter
    Karlstad University.
    En skärgårdskommun på kryss mot framtiden: Framväxten av ett EU-projekt i Nynäshamns kommun. En fallstudie2013Student paper second term, 5 credits / 7,5 HE creditsStudent thesis
  • 390.
    Algervik, Robert
    Karlstad University, Faculty of Technology and Science, Avdelningen för matematik.
    Embedding Theorems for Mixed Norm Spaces and Applications2010Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis is devoted to the study of mixed norm spaces that arise in connection with embeddings of Sobolev and Besov type spaces. We study different structural, integrability, and smoothness properties of functions satisfying certain mixed norm conditions. Conditions of this type are determined by the behaviour of linear sections of functions. The work in this direction originates in a paper due to Gagliardo (1958), and was further developed by Fournier (1988), by Blei and Fournier (1989), and by Kolyada (2005).

    Here we continue these studies. We obtain some refinements of known embeddings for certain mixed norm spaces introduced by Gagliardo, and we study general properties of these spaces. In connection with these results, we consider a scale of intermediate mixed norm spaces, and prove intrinsic embeddings in this scale.

    We also consider more general, fully anisotropic, mixed norm spaces. Our main theorem states an embedding of these spaces to Lorentz spaces. Applying this result, we obtain sharp embedding theorems for anisotropic Sobolev-Besov spaces, and anisotropic fractional Sobolev spaces. The methods used are based on non-increasing rearrangements, and on estimates of sections of functions and sections of sets. We also study limiting relations between embeddings of spaces of different type. More exactly, mixed norm estimates enable us to get embedding constants with sharp asymptotic behaviour. This gives an extension of the results obtained for isotropic Besov spaces by Bourgain, Brezis, and Mironescu, and for anisotropic Besov spaces by Kolyada.

    We study also some basic properties (in particular the approximation properties) of special weak type spaces that play an important role in the construction of mixed norm spaces, and in the description of Sobolev type embeddings.

    In the last chapter, we study mixed norm spaces consisting of functions that have smooth sections. We prove embeddings of these spaces to Lorentz spaces. From this result, known properties of Sobolev-Liouville spaces follow.

  • 391.
    Algervik, Robert
    Karlstad University, Faculty of Technology and Science, Avdelningen för matematik.
    Embedding Theorems for Mixed Norm Spaces and Applications2008Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    This thesis is devoted to the study of mixed norm spaces that arise in connection with embeddings of Sobolev and Besov type spaces. The work in this direction originates in a paper due to Gagliardo (1958), and was continued by Fournier (1988) and by Kolyada (2005).

    We consider fully anisotropic mixed norm spaces. Our main theorem states an embedding of these spaces into Lorentz spaces. Applying this result, we obtain sharp embedding theorems for anisotropic fractional Sobolev spaces and anisotropic Sobolev-Besov spaces. The methods used are based on non-increasing rearrangements and on estimates of sections of functions and sections of sets. We also study limiting relations between embeddings of spaces of different type. More exactly, mixed norm estimates enable us to get embedding constants with sharp asymptotic behaviour. This gives an extension of the results obtained for isotropic Besov spaces $B_p^\alpha$ by Bourgain, Brezis, and Mironescu, and for Besov spaces $B^{\alpha_1,\dots,\alpha_n}_p$ by Kolyada.

    We study also some basic properties (in particular the approximation properties) of special weak type spaces that play an important role in the construction of mixed norm spaces and in the description of Sobolev type embeddings.

  • 392.
    Algervik, Robert
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mathematics.
    Kolyada, Viktor
    Karlstad University, Faculty of Technology and Science, Department of Mathematics.
    On Fournier-Gagliardo mixed norm spaces2011In: Annales Academiae Scientiarum Fennicae Mathematica, ISSN 1239-629X, Vol. 36, p. 493-508Article in journal (Refereed)
    Abstract [en]

    We study mixed norm spaces

    V (Rn)

    that arise in connection with embeddings of

    Sobolev spaces

    W

    1

    1

    (Rn). We prove embeddings of V (Rn)

    into Lorentz type spaces defined in terms

    of iterative rearrangements. Basing on these results, we introduce the scale of mixed norm spaces

    V

    p

    (Rn). We prove that V ½ V p

    and we discuss some questions related to this embedding.

  • 393.
    Algons, Madelene
    Karlstad University.
    Svenska som andraspråk på grundskolan: Ett ämne som kan integreras i svenskämnet?2013Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 394.
    Algurén, Caroline
    Karlstad University, Faculty of Social and Life Sciences.
    Om barn och sorg - hur kan vi vuxna se, förstå och hjälpa?: About children and grief - How can we as adultes see, understand and help?2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    Abstract

    To become a teacher it is important to have some knowledge about children’s grief. It is likely that you at least once will come in contact with a pupil who has lost a parent or a sibling. Than it’s important to know how we as adults/teachers can handle this problem. In this paper I have interviewed four different teachers who work at four different schools and they all have 25-30 years experience of their profession. I have asked them about children and grief. How can we as adults see, understand and help? How dose the school handle this situation?

    Do they follow a special crises plan? And how were the reactions from the pupils in crises?

    The literature shows that children’s grief can look different and it’s important too realise that.

    My main conclusion is that its important too talk about death even with small children. Every school is helped with having a crises plan, the teacher has an important role for child who has lost a relative. Sometimes the school is the only place were there are no hysterical, crying people and were everything is as it used to be.

    Keywords: reactions of grief, crisis plan in school, grief, dealing with grief in school

  • 395.
    Alho, Artur
    et al.
    Univ Lisbon, Ctr Math Anal Geometry & Dynam Syst, Inst Super Tecn, Av Rovisco Pais, P-1049001 Lisbon, Portugal..
    Carloni, Sante
    Univ Lisbon, Ctr Multidisciplinar Astrofis CENTRA, Inst Super Tecn, Av Rovisco Pais, P-1049001 Lisbon, Portugal..
    Uggla, Claes
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    On dynamical systems approaches and methods in f (R) cosmology2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 8, article id 064Article in journal (Refereed)
    Abstract [en]

    We discuss dynamical systems approaches and methods applied to flat Robertson Walker models in f(R)-gravity. We argue that a complete description of the solution space of a model requires a global state space analysis that motivates globally covering state space adapted variables. This is shown explicitly by an illustrative example, f(R) = R + alpha R-2, alpha > 0, for which we introduce new regular dynamical systems on global compactly extended state spaces for the Jordan and Einstein frames. This example also allows us to illustrate several local and global dynamical systems techniques involving, e.g., blow ups of nilpotent fixed points, center manifold analysis, averaging, and use of monotone functions. As a result of applying dynamical systems methods to globally state space adapted dynamical systems formulations, we obtain pictures of the entire solution spaces in both the Jordan and the Einstein frames. This shows, e.g., that due to the domain of the conformal transformation between the Jordan and Einstein frames, not all the solutions in the Jordan frame are completely contained in the Einstein frame. We also make comparisons with previous dynamical systems approaches to f (R) cosmology and discuss their advantages and disadvantages.

  • 396.
    Alho, Artur
    et al.
    University of Lisbon, Portugal.
    Hell, Juliette
    Free University Berlin, Germany.
    Uggla, Claes
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Global dynamics and asymptotics for monomial scalar field potentials and perfect fluids2015In: Classical and quantum gravity, ISSN 0264-9381, E-ISSN 1361-6382, Vol. 32, no 14, article id 145005Article in journal (Refereed)
    Abstract [en]

    We consider a minimally coupled scalar field with a monomial potential and a perfect fluid in flat Friedmann-Lemaitre-Robertson-Walker cosmology. We apply local and global dynamical systems techniques to a new three-dimensional dynamical systems reformulation of the field equations on a compact state space. This leads to a visual global description of the solution space and asymptotic behavior. At late times we employ averaging techniques to prove statements about how the relationship between the equation of state of the fluid and the monomial exponent of the scalar field affects asymptotic source dominance and asymptotic manifest self-similarity breaking. We also situate the ’attractor’ solution in the three-dimensional state space and show that it corresponds to the one-dimensional unstable center manifold of a de Sitter fixed point, located on an unphysical boundary associated with the dynamics at early times. By deriving a center manifold expansion we obtain approximate expressions for the attractor solution. We subsequently improve the accuracy and range of the approximation by means of Pade approximants and compare with the slow-roll approximation. 

  • 397.
    Alho, Artur
    et al.
    Technical University of Lisbon, Portugal.
    Uggla, Claes
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Global dynamics and inflationary center manifold and slow-roll approximants2015In: Journal of Mathematical Physics, ISSN 0022-2488, E-ISSN 1089-7658, Vol. 56, no 1, article id 012502Article in journal (Refereed)
    Abstract [en]

    We consider the familiar problem of a minimally coupled scalar field with quadratic potential in flat Friedmann-Lemaître-Robertson-Walker cosmology to illustrate a number of techniques and tools, which can be applied to a wide range of scalar field potentials and problems in, e.g., modified gravity. We present a global and regular dynamical systems description that yields a global understanding of the solution space, including asymptotic features. We introduce dynamical systems techniques such as center manifold expansions and use Padé approximants to obtain improved approximations for the “attractor solution” at early times. We also show that future asymptotic behavior is associated with a limit cycle, which shows that manifest self-similarity is asymptotically broken toward the future and gives approximate expressions for this behavior. We then combine these results to obtain global approximations for the attractor solution, which, e.g., might be used in the context of global measures. In addition, we elucidate the connection between slow-roll based approximations and the attractor solution, and compare these approximations with the center manifold based approximants.

  • 398.
    Alho, Artur
    et al.
    Univ Lisbon, Inst Super Tecn, Ctr Math Anal Geometry & Dynam Syst, P-1049001 Lisbon, Portugal..
    Uggla, Claes
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Scalar field deformations of Lambda CDM cosmology2015In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 92, no 10, article id 103502Article in journal (Refereed)
    Abstract [en]

    This paper treats nonrelativistic matter and a scalar field phi with a monotonically decreasing potential minimally coupled to gravity in flat Friedmann-Lemaitre-Robertson-Walker cosmology. The field equations are reformulated as a three-dimensional dynamical system on an extended compact state space, complemented with cosmographic diagrams. A dynamical systems analysis provides global dynamical results describing possible asymptotic behavior. It is shown that one should impose global and asymptotic bounds on lambda = -V-1 dV/d phi to obtain viable cosmological models that continuously deform Lambda CDM cosmology. In particular we introduce a regularized inverse power-law potential as a simple specific example.

  • 399. Ali, A
    et al.
    Hoagg, J. B
    Mossberg, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Bernstein, D. S
    Growing window recursive quadratic optimization with variable regularization2010Conference paper (Refereed)
  • 400.
    Ali, Agha Rehmat
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Predicted Speed Control based on Fuzzy Logic for Belt Conveyors: Fuzzy Logic Control for Belt Conveyors2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In order to achieve energy savings for belt conveyor system, speed control provides one of the best solutions. Most of the traditional belt conveyors used in the industries are based on constant speed for all operational times. Due to the need and advancements in technology, Variable Frequency Drives (VFD) are employed in industries for a number of processes. Passive Speed Control was previously suggested for the proper utilization of VFD to make belt conveyor systems more power e- cient with increased life expectancy and reduced environmental eects including the noise reduction caused by constant speed of operation. Due to certain conditions and nature of operation of belt conveyor systems, it is not desirable to use Passive Speed control where feeding rate is random. Due to the extreme non-linearity of the random feeding rate, an Active speed control for VFD is desired which adjusts belt speed according to the material loading. In this thesis an Active Speed control for VFD is proposed that can achieve energy and cost ecient solutions for belt conveyor systems as well as avoiding half-lled belt operations. The aim of this thesis work is primarily to determine reliability and validity of Active Speed Control in terms of power savings. Besides achieving power savings, it is also necessary to check the economic feasibility. A detailed study is performed on the feasibility of Active Speed Control for random feeding rate according to industrial requirements. Due to the random and non-linearity of the material loading on the belt conveyor systems, a fuzzy logic algorithm is developed using the DIN 22101 model. The developed model achieves Active Speed Control based on the feeding rate and thereby optimizes the belt speed as required. This model also overcomes the risks of material spillage, overloading and sudden jerks caused due to unpredicted rise and fall during loading. The model conserves 20- 23% of the total power utilized compared to the conventional conveyor systems in use. However it is noticed that the peak power of conventional conveyor belt systems is up to 16% less compared to the proposed model. If implemented in dierent industries, based on the operational time and total consumption of electricity, the proposed Active speed control system is expected to achieve economic savings up to 10-12 % .

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