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Altmetri och vetenskaplig kommunikation : En enkätstudie bland svenska UH-bibliotek / Altmetrics and scholarly communication : A survey study among Swedish University libraryNordfeldt, Liza January 1900 (has links)
Altmetrics is a relatively new metric system compared to traditional bibliometric methods. The purpose of this bachelor thesis was to conduct a cross-sectional study of the altmetric usage in Swedish university libraries and to see if and how they use altmetrics and how it can benefit the scholarly communication between academic librarians and scholars. The research questions are;• Do Swedish university libraries use altmetrics, and if so, how? • How do the librarians experience the attitude from the researchers, regarding their opinions about altmetrics? • How can altmetric tools be an aid in the scholarly communication and what is altmetrics advantages and disadvantages according to the librarians?A survey was sent out to all universities in Sweden and their main libraries. For theoretical framework the concepts Technologies of Control and Technologies of Narcissism together with the concept Cognitive Authority were used. The results show that altmetrics is a tool that the academic libraries are familiar with but few are actually using. The scholars and PhD students think that altmetrics is something than can be used for “fun”, to see their own impact but not for evaluating. The librarians see altmetric as a tool that is a complement to traditional citations and not something that will replace it. Altmetrics can show a broader and faster impact but the altmetric data is unreliable and more studies have to be done.
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Alternative media : Empowerment in individuals in totalitarian societies.Tehrani, Ali January 2012 (has links)
My thesis explores changes in media technologies and the way alternative media affect the dynamics of power in totalitarian societies. How totalitarian states respond to these media trends and the security importance of the information coming from the inside of the totalitarian territory are the main interests of my essay. My primary sources in this research are Animal Farm, a novella by George Orwell; the film The Lives of Others (2006) by Florian Henckel von Donnersmarck; and the recently published novel, The Revisionists, by Thomas Mullen. My primary goals in this essay are firstly to argue that the social and political conditions presented in these works match definitions of totalitarian societies. Using my secondary sources, I introduce the main characteristics of totalitarian societies and highlight their mechanism in my primary sources. Secondly, I investigate the role of media in such societies along with technological changes that have added new items to security concerns. Besides reading the reflections of reality in fictional presentations in some cases, I give examples from the 21st century world that we are living in and argue that it is an extension of the conditions presented in Animal Farm and The Lives of Others.
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The inclusion and exclusion of Somali communities as seen through the publicness of space in Nairobi and Stockholm / Ett perspektiv på inkludering och exkludering av Somaliska migranter sett genom rummets offentlighet i Nairobi och StockholmBürgi, Julia January 2018 (has links)
The neighborhoods of Eastleigh in Nairobi, Kenya and Rinkeby in Stockholm, Sweden are both home to Somali populations that have burgeoned over the last 25 years. While situated in vastly different urban contexts, the Somali communities in each location have needs related to public space, particularly when considering their status in both places as a minority group that is often marginalized by Kenyan and Swedish societies. By examining the experiences of each of these two communities in public space and the level of publicness they experience, we can see how the Somali community can be made to feel included or excluded within each city. Using Setha Low’s framework of categorical activities that contribute to a flourishing society, the publicness of spaces in each location is investigated. In addition, the study explores the ways in which publicness is under threat in both places through the means of technologies of control. The resistance to such technologies is argued as symbolic of the fight for inclusion within Kenyan and Swedish society.
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Ultrasonic Spot Welding of Thin Walled Fibre-Reinforced ThermoplasticsTutunjian, Shahan 28 July 2021 (has links)
Das Ultraschall-Punktschweißen von faserverstärkten thermoplastischen Kunststoffen hat in der letzten Zeit bei Forschern in der Luftfahrt- und Automobilindustrie großes Interesse hervorgerufen. Es bietet eine effiziente Lösung zum Verbinden großer thermoplastischer Verbundbauteile durch Punktschweißen mit einem hohen Automatisierungsgrad. In der vorliegenden Arbeit wurde eine neue Technik zum Fokussieren der Ultraschallschwingungsenergie an der gewünschten Fügestelle zwischen zwei Fügepartnern aus thermoplastischen Verbundlaminaten untersucht. Bei diesem untersuchten Verfahren waren keine zusätzlichen Energierichtungsgeber zwischen den Fügepartnern erforderlich, um die Vibrationsenergie zu fokussieren. Es wurde festgestellt, dass es durch Schweißen der Laminate zwischen einer Sonotrode und einem Amboss möglich war, eine lokalisierte Wärme durch Reibung zu erzeugen in dem die Sonotrode eine größere Kontaktfläche mit dem Laminat als mit dem Amboss aufwies. In der Anfangsphase des Schweißens wurden die Grenzflächenschichten durch die reibungsverursachte Erwärmung abgeschwächt. Folglich zentrierte sich die zyklische Verformung in diesen abgeschwächten Grenzflächen. Die Annahme des Vorhandenseins der Reibung und ihres Einflusses auf die Wärmeerzeugung wurde mittels mechanischer FEM-Analyse untersucht. Die mikroskopische Analyse des Schweißpunktes lieferte schließlich den Beweis für die Schmelzauslösung an einem Ring um den Schweißpunkt und das anschließende Punktwachstum. Um die räumliche Verteilung der Temperatur und ihre zeitliche Entwicklung in der Schweißzone während des Ultraschallschweißprozesses besser zu verstehen, wurde das thermische Problem numerisch modelliert. Zur Verifizierung der mathematischen Modelle wurden die berechneten Zeitverläufe der Temperatur im Schweißpunktzentrum mit den experimentell ermittelten Werten unter vergleichbaren Bedingungen gegenübergestellt. Es wurde festgestellt, dass nach einer bestimmten Schweißzeit die Temperatur im Schweißzentrum plötzlich anstieg und das Polymer an der Schweißstelle überhitzt und die Zersetzung begann. Es wurde beobachtet, dass der Zeitverlauf der verbrauchten Leistungskurve durch das Schweißgerät einem ähnlichen Muster folgte, wie der Zeitverlauf der Temperatur in der Schweißpunktmitte. Basierend auf dieser Beobachtung wurde ein Steuerungssystem entwickelt. Die zeitliche Ableitung der Schweißleistung wurde in Echtzeit überwacht. Sobald ein kritischer Wert überschritten wurde, wurde die Ultraschallschwingungsamplitude aktiv durch einen Mikrocontroller eingestellt. Bei diesem Ansatz wurde die Temperatur im Schweißpunkt indirekt gesteuert, um während der gesamten Schweißdauer in einem optimalen Bereich zu bleiben. Die Ergebnisse des gesteuerten Schweißprozesses wurden mittels Temperaturmessungen und Computertomographie bewertet. Aus der Studie wurde der Schluss gezogen, dass das leistungsgesteuerte Ultraschall-Punktschweißverfahren eine effiziente und stabile Methode zum automatischen Verbinden von faserverstärkten thermoplastischen Teilen ist.:1 Introduction
1.1 Motivation
1.2 State of the Art
1.3 Statement of the Theses and Methods
2 Theoretical Background
2.1 Ultrasonic Welder
2.1.1 Ultrasonic Stack
2.1.2 Working Principle of the Ultrasonic Welder
2.2 Viscoelasticity
2.2.1 Viscoelasticity of Continuous Fibre-Reinforced Laminates
2.2.2 Viscoelastic Heating of CFRTP during the DUS Welding
2.3 Frictional heating at the Weld Interface during the DUS Welding
2.4 Fusion Mechanism during the USW
2.4.1 Contact of the Matrix at the Weld Interface
2.4.2 Healing of the Weld Interface through Autohesion
3 Experimental Analysis of the DUS Process
3.1 Experimental Setup
3.2 Experimental Procedure, Results and Discussions
3.2.1 Weld Progress and Formation Analysis
3.2.2 The Influence of the Amplitude and Static Force on the DUS
3.2.3 Computed Tomography Analysis of the DUS Welded Spots
3.2.4 Influence of the Weld Parameters on the Weld Force at Break
3.2.5 Influence of the Main Process Variables on the Weld Strength
4 Process Modelling and Simulation
4.1 Dynamic Mechanical 3D Finite Element Analysis
4.1.1 Woven Fabric Laminate Models
4.1.2 Laminate Properties and Meshing
4.1.3 FEM Analysis Procedure
4.1.4 Results of the Dynamic Analysis
4.2 Numerical Analysis of the Temperature Temporal and Spatial Development
4.2.1 The Numerical Method
4.2.2 Matrix Loss Modulus Calculation at the Welding Frequency
4.2.3 Model Validation
4.2.4 Analysis of the Spatial and Temporal development of the Temperature
4.2.5 Influence of Uncontrollable Factors on the DUS Process
5 Logical Control Method and Industrialisation
5.1 Process Controlling Hypothesis
5.2 Control System and Instruments
5.3 Experimental Procedure for Analysing the Control System
5.4 Analysis of the Controlled DUS Process
5.5 Control System Validation and Industrialisation
5.6 Automation of the Ultrasonic Spot Welding Process
6 Summary and Outlook
6.1 Conclusions
6.2 Outlook
References
Appendix / The ultrasonic spot welding of fibre-reinforced thermoplastic composites has recently received strong interest among researchers mainly in the fields of aerospace and automotive industries. It offers an efficient solution to join large thermoplastic composite parts through the spot welding approach with a high level of automation. In this study, a new technique for focusing the ultrasonic vibration energy at the desired spot between two mating thermoplastic composite laminates was investigated. In this method, no additional energy directing protrusions between the weldments were required to focus the vibration energy. It was found that by welding the laminates amid an ultrasonic sonotrode and an anvil in which the prior had a larger contact surface with the laminate as the latter, it was possible to generate a localised frictional heating. In the initial phase of the welding, the frictional heating softened the interfacial layers and thus caused the focusing of the strain energy in the weld spot centre. The assumption for the presence of the friction and its influence on the heat generation was investigated by means of finite element method analysis. Microscopic analysis of the weld spot delivered the proof for the melt initiation at a ring around the weld spot and subsequent inwards growth of the weld spot. In order to gain a better understanding of the temperature spatial distribution and its temporal development in the weld zone during the ultrasonic welding process, the thermal problem was analysed using the explicit finite difference method. The mathematical model was verified through a comparison between the calculated temperature curves and the experimentally obtained counterparts. It was found that after a certain weld duration the temperature in the weld centre underwent a sudden increase and caused the overheating and decomposition of the polymer in the weld spot. It was observed that the time trace of the consumed power curve by the welder followed a similar pattern as the time trace of the temperature in the weld spot centre. Based on this observation, a control system was developed accordingly. The time derivative of the weld power was monitored in real time and as soon as it exceeded a critical value, the ultrasonic vibration amplitude was actively adjusted through a microcontroller. In this approach, the temperature in the weld spot was indirectly controlled to remain within an adequate range throughout the welding duration. The results of the controlled welding process were evaluated by means of temperature measurements and computed tomography scans. It was concluded from the study that the power-controlled differential ultrasonic spot welding process could be an efficient method to fusion bond the fibre-reinforced thermoplastic parts in an automated manner.:1 Introduction
1.1 Motivation
1.2 State of the Art
1.3 Statement of the Theses and Methods
2 Theoretical Background
2.1 Ultrasonic Welder
2.1.1 Ultrasonic Stack
2.1.2 Working Principle of the Ultrasonic Welder
2.2 Viscoelasticity
2.2.1 Viscoelasticity of Continuous Fibre-Reinforced Laminates
2.2.2 Viscoelastic Heating of CFRTP during the DUS Welding
2.3 Frictional heating at the Weld Interface during the DUS Welding
2.4 Fusion Mechanism during the USW
2.4.1 Contact of the Matrix at the Weld Interface
2.4.2 Healing of the Weld Interface through Autohesion
3 Experimental Analysis of the DUS Process
3.1 Experimental Setup
3.2 Experimental Procedure, Results and Discussions
3.2.1 Weld Progress and Formation Analysis
3.2.2 The Influence of the Amplitude and Static Force on the DUS
3.2.3 Computed Tomography Analysis of the DUS Welded Spots
3.2.4 Influence of the Weld Parameters on the Weld Force at Break
3.2.5 Influence of the Main Process Variables on the Weld Strength
4 Process Modelling and Simulation
4.1 Dynamic Mechanical 3D Finite Element Analysis
4.1.1 Woven Fabric Laminate Models
4.1.2 Laminate Properties and Meshing
4.1.3 FEM Analysis Procedure
4.1.4 Results of the Dynamic Analysis
4.2 Numerical Analysis of the Temperature Temporal and Spatial Development
4.2.1 The Numerical Method
4.2.2 Matrix Loss Modulus Calculation at the Welding Frequency
4.2.3 Model Validation
4.2.4 Analysis of the Spatial and Temporal development of the Temperature
4.2.5 Influence of Uncontrollable Factors on the DUS Process
5 Logical Control Method and Industrialisation
5.1 Process Controlling Hypothesis
5.2 Control System and Instruments
5.3 Experimental Procedure for Analysing the Control System
5.4 Analysis of the Controlled DUS Process
5.5 Control System Validation and Industrialisation
5.6 Automation of the Ultrasonic Spot Welding Process
6 Summary and Outlook
6.1 Conclusions
6.2 Outlook
References
Appendix
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