708 research outputs found

    A Study of the Refugees Welcome Movement in Malmö - Opportunity structures, Mobilisation and Framing

    Get PDF
    This study examines the Refugees Welcome Movement campaign in Malmö between the period September 2015 and June 2016. The purpose of this study derives from the identification of a knowledge gap of descriptive, as well as analytical accounts that conceptualises the many and long withstanding occurrences of collective action within Social movement theory. This study aims therefore to tackle this knowledge gap in its quest to firstly, describe the Refugees Welcome Movement campaign along the following dimensions: Claim making, repertoire of collective action and its networks and organisational base. Secondly, with the help of an integrated theoretical model composed of cultural and structural factors analyse, and explain (i) the emergence of the Refugees Welcome Movement campaign, (ii) and the developments of the campaign over time. This study’s finds that the campaign can be defined as a segmented and pluralist campaign, which not the least is shown in the number of organisations that have taken part, multiple types of claim making and the broad and varied repertoire of collective action. The study also highlights the key role of organisations in the camping, as well as virtual and social networks. This study finally analyses and concludes on the explanatory value of cultural and structural factors in explaining the emergence of the Refugees Welcome Movement campaign in Malmö and the identified progressions within the campaign

    Nordic Defense Cooperation: Prospects for expanding the endeavor

    Get PDF
    The debate on Nordic defense cooperation has surged in the recent year as a result from a perceived shift in the security environment. The study focuses on the five Nordic states; all of them committed to different security communities and yet engaged in cooperative measures with each other. With the question of exploring the prerequisites for a possible deepening of the Nordic defense cooperation, this study adopting the concepts security and identity, will utilize the theoretical ideas of Emmanuel Adler and Michael Barnett on security communities by performing a qualitative content analysis of the Nordic countries’ defense policies. The analysis is performed through a constructed coding scheme where eleven questions has been created and then applied onto the policies. The results show that the prerequisites for a deepening of the Nordic defense cooperation heavily rest on their commonalties in culture, views on democracy, rule of law and aspirations in the region concerning their security policies. All countries are committed to a future development but differ to some extent as to how such cooperation ought to take and in their perceptions on security-issues

    Modelling of Heavy Vehicle Transmission Synchronizer using Constrained Lagrangian Formalism

    Get PDF
    Robust and efficient synchronizers are keys elements to ensure good gear shift in heavy vehicles. In order to improve existing as well as develop new synchronizers, efficient simulation tools are needed. In this contribution, a mechanical system with 5 degrees of freedom modelling a generic synchronizer consisting of engaging sleeve, synchronizer ring and gearwheel are considered. Due to the design of the different components and their interactions the synchronizing process is described in terms of different steps or phases; presynchronization, main synchronization, blocker transition and engagement. The four main phases are further divided into sub-phases. To study the whole process in a unified manner, Constrained Lagrangian Formalism (CLF) turns out to be a suitable method in which the interactions between components (sleeve, synchronizer ring and gearwheel) are described by unilateral or/and bilateral constraints imposed on generalized coordinates of the system during different phases. Using CLF a mathematical model of a generic synchronizer is developed and represented by the system of differential-algebraic equations. Kinematics and kinetics of the generic synchronizer are modelled for each sub-phase. The sleeve is considered as a master and the gearwheel is considered as a slave. The statement of the dynamics problem for a generic synchronizer is given and the numerical algorithm is implemented in Matlab for solving the differential-algebraic equations resulting from CLF. The generic synchronizer computational model is adapted to available experimental setup and validated using obtained measurement data. Sensitivity of the synchronization time is studied varying the cone angle, coefficient of dry friction and sleeve force. Effect of driveline vibrations on synchronization performance is also studied

    UpphovsrÀttsligt skydd för videospel - bland paragrafer, pixlar och polygoner

    Get PDF
    The Swedish and international video game industry have grown the last few years. An expanding video game industry relies on protection of intellectual property and copyright. The purpose of this paper is to examine how the Swedish national copyright of video games is formed. The purpose of this paper is also to analyse if the Swedish national copyright of video games is effective and satisfying and also analyse if the copyright of video games can be improved. A video game has to be a “creation” due to the Swedish copyright act (SFS 1960:729) standard to be protected. A creation has to be the result of a creator’s own intellectual creation. The protection of technological measures to prevent or restrict acts not authorised by the right holders is also instituted in the copyright of video games and is important in the battle against piracy. The copyright of computer programs origins from the Directive 2009/24. The protection of computer programs applies on source and object code, which means that the ideas behind the program are not protected. Due to the interpretation of the ECJ, neither the interface nor the functions of the program are subject to copyright. According to Swedish case law video games are protected as computer programs. The ECJ has interpreted Directive 2001/29 to be applicable instead of the Directive 2009/24 in the C-355/12 Nintendo case because video games has it’s own creative value and cannot be reduced to the code solely. Cinematographic works, or audio-visual works, are protected by copyright. Video games and movies share attributes because video games contain motion pictures. The term “audio-visual works” is defined as motion pictures and a result of intellectual creative work. In case law from the Swedish Supreme court, case NJA 2000 s. 580, the copyright protection of cinematographic works was not applicable on video games. According to the court a video game was not purchased to be viewed, but to be played. The Swedish Market court came to the opposite conclusion in case MD 2011:29, and applied the rules derived from the Directive 2001/24. As mentioned, the ECJ ruled that the graphics and motion pictures in a video game can be protected under the rules of Directive 2001/24 and not only reduced to the code solely (C-355/12 Nintendo). This means that video games are protected both as a computer program and as a cinematographic work. This is problematic because it is hard to determine which rules are applicable in any given situation. A solution to this problem is to introduce video games as an own category of works in the Swedish copyright act.Den svenska och internationella spelbranschen har vĂ€xt under de senaste Ă„ren. En större och viktigare spelbransch Ă€r ocksĂ„ behov av immaterialrĂ€ttsligt skydd och spel skyddas först och frĂ€mst genom upphovsrĂ€tten. Syftet med den hĂ€r uppsatsen Ă€r att utreda hur skyddet för videospel Ă€r utformat i den svenska nationella upphovsrĂ€tten. Syftet Ă€r ocksĂ„ att analysera det nuvarande skyddet och ta stĂ€llning till om det Ă€r tillfredstĂ€llande och effektivt samt analysera om skyddet skulle kunna förbĂ€ttras. För att ett spel ska skyddas upphovsrĂ€ttsligt krĂ€vs det att det Ă€r ett verk enligt upphovsrĂ€ttslagen. Spelet ska dĂ€rför vara ett resultat av en upphovsmans egna intellektuella skapelse. Det finns ocksĂ„ ett skydd för tekniska Ă„tgĂ€rder vilket har betydelse för videospel eftersom det Ă€r en viktig del i kampen mot piratkopiering. Skyddet för datorprogram bygger först och frĂ€mst pĂ„ reglerna som införts genom det EU-rĂ€ttsliga datorprogramdirektivet. Skyddet för datorprogram avser den objekt- och kĂ€llkod som datorprogram bestĂ„r av. De idĂ©erna som stĂ„r bakom datorprogrammet skyddas inte. Enligt EU-domstolens tolkning av direktivet skyddas inte heller ett datorprograms grĂ€nssnitt eller programfunktioner. Det har framkommit i praxis att videospel skyddas som datorprogram. Videospel bestĂ„r av kod och att videospel skyddas som ett datorprogram framkom i NJA 2000 s. 580. EU-domstolen har dock kommit fram till att videospel har ett eget kreativt vĂ€rde som inte enbart kan reduceras till programkoden. I C-355/12 tillĂ€mpade EU-domstolen infosocdirektivet framför datorprogramdirektivet. Filmverk, eller audiovisuella verk, skyddas ocksĂ„ upphovsrĂ€ttsligt och ett videospel bestĂ„r av rörliga bilder som pĂ„minner om filmverk. Med begreppet audiovisuella verk avses verk som bestĂ„r av rörliga bilder som Ă€r en upphovsmans egna intellektuella skapelse. Enligt HD:s resonemang i NJA 2000 s. 580 omfattas inte videospel av skyddet för filmverk. Det berodde bl.a. pĂ„ att videospel inte anskaffas för att Ă„ses utan för att spelas. I fallet MD 2011:29 kom marknadsdomstolen fram till motsatsen, och menade att videospel kunde anses vara filmverk. EU-domstolen har kommit fram till att spel inte enbart kan reduceras till programkoden och att grafiken och de rörliga bilderna kan ha skydd enligt infosocdirektivet. Det betyder alltsĂ„ att videospel bĂ„de har skyddats som datorprogram och som filmverk vilket gör att olika regler kan tillĂ€mpas pĂ„ spel. Det Ă€r problematiskt att det Ă€r svĂ„rt att avgöra vilka regler som ska tillĂ€mpas. Ett förslag Ă€r att införa videospel som egen verkskategori i URL

    Wind turbine drive train vibration with focus on gear dynamics under nondeterministic loads

    Get PDF
    In present-day, the engineering challenge around a drive train design for a wind turbine is not only to enhancesystem reliability but also to reduce the turbine top mass. These requirements together with the trend of upscaling affect many system characteristics and parameters. The proposed contribution presents a model tostudy torsional drive train vibration dynamics of a generic indirect drive multi-MW wind turbine. The mainfocus lies on developing a fully parameterized computational model of a multi-stage gearbox which fulfillsthe requirement of a proper gear dynamic representation appropriate for multibody formalism as well asthe requirement to be computationally efficient. Two different strategies for modeling the gear contact arestudied and compared in time domain. An analysis of a multi-stage gearbox together with a generator load and a turbine specific nondeterministic excitation was carried out. It is believed that the obtained results will help designer to improve drive train components and to enhance wind turbine reliability and cost efficiency

    Vibration dynamics in non-linear dual mass flywheels for heavy-duty trucks

    Get PDF
    A non-linear model for simulations of a dual mass flywheel (DMF) for heavy-duty applications is proposed. The model includes internal clearances and friction. LuGre friction model is used, which depends on normal force, relative velocity between the two surfaces and an internal deflection variable. Measurements on the DMF are performed in a test rig and the test rig properties are analysed. The correlation shows that the general behaviour of the DMF is reproduced by the proposed simulation model. The viscous part of the friction is dominant for the analysed cases with zero mean torque, and a conventional Coulomb friction model would not suffice for this application. Near resonances, the model also shows a high sensitivity to internal clearances and spring stiffness. This indicates that correlation could be improved further if the static stiffness was measured with good accuracy for the relevant range of deflection angles

    Wind turbine drive train vibration with focus on gear dynamics under nondeterministic loads

    Get PDF
    In present-day, the engineering challenge around a drive train design for a wind turbine is not only to enhancesystem reliability but also to reduce the turbine top mass. These requirements together with the trend of upscaling affect many system characteristics and parameters. The proposed contribution presents a model tostudy torsional drive train vibration dynamics of a generic indirect drive multi-MW wind turbine. The mainfocus lies on developing a fully parameterized computational model of a multi-stage gearbox which fulfillsthe requirement of a proper gear dynamic representation appropriate for multibody formalism as well asthe requirement to be computationally efficient. Two different strategies for modeling the gear contact arestudied and compared in time domain. An analysis of a multi-stage gearbox together with a generator load and a turbine specific nondeterministic excitation was carried out. It is believed that the obtained results will help designer to improve drive train components and to enhance wind turbine reliability and cost efficiency

    STRUCTURAL DYNAMICS OF A WIND TURBINE DRIVE TRAIN HIGH SPEED SUBSYSTEM: MATHEMATICAL MODELLING AND VALIDATION

    Get PDF
    The paper studies the dynamics of a wind turbine drive train high speed subsystem, both by modelling and experiments with focus on system torsional vibration and transient events which can reduce fatigue life of functional components (gearbox, bearings, shafts, couplings,others). A scaled down drive train high speed shaft test rig has been developed. Main components of the test rig are six-pole motor with variable frequency drive controller (up to 1000rpm), shafts’ disk coupling and flexible mounting structure representing gearbox housing with output high speed bearing. The test rig is equipped with measurement system comprising a set of accelerometers and displacement sensors, strain gauges and telemeter system, data acquisition hardware and software (SKFWindCon3.0). Mathematical and computational models of the test rig have been developed and went through validation tests. The system dynamic response is studied for different operational scenarios and structural parameters (run-shut down case with and without eccentric mass). The ultimate goal of the test rig is to get insight into interactionbetween internal dynamics of drive train mechanical and electrical functional components and to develop novel methods to detect, predict and prevent faults and failures in wind turbine drive trains arising due to misalignments and transient external loads

    Failure modes and optimal performance of a generic synchronizer

    Get PDF
    The gear shifting mechanism is a crucial part of the gearbox which transmits the torque from engine to wheels with different transmission ratio. For smooth and comfortable gear changing the gear shifting mechanism is still a challenge for the engineers to adapt the different driving situations. In case of heavy vehicles particularly under certain circumstances optimized performance by avoiding failure modes of the gear shifting mechanism is also a challenge. In this paper failure modes and optimized values of the system parameters are identified to contribute for this challenge. A model of the gear shifting mechanism is developed in GT-Suite software. Failure modes are identified via sensitivity analysis. Four system response characteristics are plotted against the time and used to identify the failure modes. Optimization routine of the GT-Suite is applied on the model by taking seven parameters into account as independent variables and synchronization time as an objective function. Percentage changes of the variables from their initial values are calculated and analyzed. Finding of optimal values of parameters of the gear shifting mechanism is valuable contribution to design reliable and efficient transmission system for automotive industry especially for heavy vehicles

    Mitigation of transient torque reversals in indirect drive wind turbine drivetrains

    Get PDF
    Bearing failure in wind turbine gearboxes is one of the significant sources of downtime. While it is well-known that bearing failures cause the largest downtime, the failure cause(s) is often elusive. The bearings are designed to satisfy their rolling contact fatigue (RCF) life. However, they often undergo sudden and rapid failure within a few years of operation. It is well-known that these premature failures are attributed to surface damages such as white surface flaking (WSF), white etching cracks (WECs) and axial cracks. In that regard, transient torque reversals (TTRs) in the drivetrain have emerged as one of the primary triggers of surface damage, as explained in this paper. The risk associated with TTRs motivates the need to mitigate TTRs arising in the drivetrain due to various transient events. This paper investigates three TTR mitigation methods. First, two existing devices, namely, the torsional tuned mass damper and the asymmetric torque limiter, are studied to demonstrate their TTR mitigation capabilities. Then, a novel idea of open-loop high-speed shaft mechanical brake control is proposed. The results presented here show that while the torsional tuned mass damper and the asymmetric torque limiter can improve the torsional vibration characteristics of the drivetrain, they cannot mitigate TTRs in terms of eliminating the bearing slip risk associated with TTRs. However, the novel approach proposed here can mitigate TTRs both in terms of improving the torque characteristic in the high-speed shaft and reducing the risk of bearing slip by actuating the high-speed shaft brake at the onset of the transient event. Furthermore, the control method is capable of mitigating TTRs with the mechanical limitations of a pneumatic actuator in terms of bandwidth and initial dead time applied to it. This novel approach allows the wind turbines to protect the gearbox bearings from TTRs using the existing hardware on the turbine
    • 

    corecore