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  • 201. Ahlund, Claes
    Stig Dagerman som lyriker i "Birgitta svit"1996In: Samlaren: tidskrift, ISSN 0348-6133, Vol. 1996, p. 28-50Article in journal (Refereed)
  • 202. Ahlund, Claes
    Strindberg och sekelskiftets fysionomi: dekadens och nydaning i Götiska rummen och Svarta fanor2002In: On the threshold: new studies in Nordic literature / [ed] Janet Garton and Michael Robinson, Norwich: Norvik Press, 2002, p. 490-Chapter in book (Other academic)
  • 203.
    Ahlund, Claes
    Mid Sweden University, Faculty of Human Sciences, Department of Humanities.
    Tyrannen, riksföreståndaren och diktatorn: K. G. Ossiannilsson som fascistisk diktare2006In: Tidskrift för litteraturvetenskap, ISSN 1104-0556, no 2, p. 27-53Article in journal (Refereed)
  • 204.
    Ahlund, Claes
    Mid Sweden University, Faculty of Human Sciences, Department of Humanities.
    "Under späkelsernas gissel. Karlfeldt och kriget"2008In: Edda. Nordisk tidsskrift for litteraturforskning, ISSN 0013-0818, E-ISSN 1500-1989, Vol. 95, no 3, p. 234-248Article in journal (Refereed)
    Abstract [en]

     

    The war poetry of Erik Axel Karlfeldt (1864-1931) is a neglected part of the poet's work. The aim of this article is to discuss three poems from Flora och Bellona (1918): "Det röda korset" ("The Red Cross"), "Svart Jul" ("Black Christmas") and "En pesthymn" ("A Hymn of Pestilence"). Attention is paid to the ideological level of the poems, but also to their poetic structure. The poems are related to Peter Hallberg's discussion of Karlfeldt's archaistic imagery, to Esaias Tegnér's "Svea", but also to the contemporary political poetry of outspoken nationalists and socialists. Compared to the explicit political poetry, Karlfeldt's poetry is complex, often ambivalent in its criticism of both belligerents and alternately displaying despair and optimism. "En pesthymn" can be seen as a turning point, mirroring the outbreak in 1918 of the Finnish Civil War. In this poem, the ambivalent moral judgements of the poet's preceding war poetry are replaced by unequivocal political support for the "Whites".

     

     

     

     

  • 205. Ahlund, Claes
    et al.
    Landgren, Bengt
    Från etableringsfas till konsolidering: svensk akademisk litteraturundervisning 1890-19462003Book (Other academic)
  • 206.
    Ahlén, Emelie
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Social Work.
    Rahmani, Shermineh
    Mid Sweden University, Faculty of Human Sciences, Department of Social Work.
    Hur unga utlandsfödda invandrare blir bemötta i det svenska samhället.: En kvalitativ och kvantitativ studie om diskriminering och rasism2010Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sammanfattning: Ungdomar med utländsk bakgrund har enligt tidigare studier sämre förutsättning i skolan, arbeten och inom rättsväsendet, på grund av diskriminering. Syftet med denna uppsats har varit att ta reda på hur unga utlandsfödda ungdomar blir bemötta i det svenska samhället, samt att se om det finns vissa specifika mönster till varför det uppstår diskriminering i bland annat skolan. Till vår undersökning använde vi oss av teorier om - diskriminering och rasism, som används i analysen av det empiriska materialet. Vår utgångspunkt i uppsatsen har varit att ta reda på varför diskriminering och rasism sker i samhället. Vi hade ett antal frågeställningar som kan ses nedan, som besvarats i arbetet.

    • Hur blir invandrarungdomar bemötta i det svenska samhället utifrån deras etniska bakgrund?
    • Spelar ungdomarnas genus någon roll i hur de blir bemötta i det offentliga samhället?
    • Finns det skillnader mellan ungdomar med olika bakgrund beroende på deras vilken världsdel de kommer ifrån?
    • Påverkar ungdomarnas socioekonomiska och kulturella bakgrund, hur de blir bemötta i det svenska samhället?

           För att besvara dessa frågeställningar, delade vi ut enkäter till 42 ungdomar i en mellan stor stad i åldrarna 16 – 24 år i olika skolor. När resultatet av enkäterna var sammanställda valde vi att ha en fokusgrupp med fyra deltagande som hade deltagit i enkätundersökningen. Syftet med att ha en fokusgrupp var att få en fördjupad kunskap om vissa svar kring rasism och diskriminering. Vårt resultat i studien visade att ungdomar med utländsk bakgrund, blir diskriminerade ute i samhället utav skolan, polisen, socialtjänsten, i affärer, på arbetsplatser samt på andra platser i samhället som till exempel på bussen. Dessa slutsatser stärktes och jämfördes sedan med tidigare forskning i en analysdel, samt en avslutad diskussion.

  • 207.
    Ahmad, Hana
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Social Work.
    Zouari, Bouchra
    Mid Sweden University, Faculty of Human Sciences, Department of Social Work.
    Kvinnlig köönsstympning i Sverige - En kvalitativ studie om Socialtjänstens arbete mot kvinnlig köönsstympning2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 208.
    Ahmad, Helin
    Mid Sweden University, Faculty of Human Sciences, Department of Social Work.
    Familjebehandlingsarbete med dysfunktionella familjer och med barnet i fokus2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Studiens syfte var att undersöka och förstå vad en dysfunktionell familj är enligt familjebehandlare samt hur familjebehandlingsarbete fungerar med dysfunktionella familjer och med barnet i fokus. Studien är kvalitativ och den datainsamlingsmetod som har använts är semistrukturerade intervjuer. I studien intervjuades fem familjebehandlare. Det empiriska materialet har analyserats genom en innehållsanalys. Studiens resultat är uppdelad i tre olika teman, vilka är definition av en dysfunktionell familj, arbetsmetoder samt barns bästa. I resultatet framkom det att alla familjebehandlarna är överens om att alla familjer som de kommer i kontakt med i sitt dagliga arbete är dysfunktionella familjer. Kortfattat beskriver behandlarna att dysfunktionella familjer är familjer där något inte fungerar som det ska samt där barnet i familjen inte får sina behov tillgodosedda. Vidare i resultatet framkom det att olika typer av samtal med familjer är en mycket central arbetsmetod inom familjebehandling. I resultatet framkom det även att familjebehandlarna inte kommer i kontakt med barnet lika mycket som med föräldrarna i sitt arbete. Familjebehandlarna försöker dock vara medvetna om att det är för barnets skull som de utför sitt arbete samt att de hela tiden arbetar efter barnets behov och inte efter föräldrarnas behov.

  • 209.
    Ahmad, Jawad
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Andersson, Henrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Screen Printed Piezoresistive Sensors for Monitoring Pressure Distribution in Wheelchair2018In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748Article in journal (Refereed)
    Abstract [en]

    Prolonged sitting inadequacies cause pressure ulcer to many individuals, especially to disadvantaged with reduced mobility. The measurement of distributed pressure and detection of irregular sitting postures is essential for preventing the risk of developing pressure ulcer. In this paper, a pressure sensing system capable of recognizing sitting postures by means of measuring interface pressure through printed pressure sensors is presented. A thin and flexible large area sensor is screen-printed using silver flake and carbon particle inks and comprises 16 sensing elements. For the evaluation of practical usability, the sensor characterization is carried out by conducting stability, repeatability, drift and bending tests. The performance of the sensor is checked under varying environmental conditions. Sitting posture detection accuracy above 80 % is achieved using a classification algorithm for four different sitting postures. Pressure distribution is monitored at a scanning rate of 10 Hz. A low power and small form factor of read-out electronics enables a compact packaging inside the seat cushion. The presented sensor design targets smart wheelchairs, but it is extendable to much larger areas, for example to be used in beds. The proposed sensing system would be of a great assistance for caregivers and health professionals.

  • 210.
    Ahmad, Jawad
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Andersson, Henrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Sitting Posture Recognition using Screen Printed Large Area Pressure Sensors2017In: Proceedings of IEEE Sensors, IEEE, 2017, p. 232-234Conference paper (Refereed)
    Abstract [en]

    In the biomedical sector, pressure sensors exhibit an important role towards monitoring and recognition of sitting posture for wheelchair users, which is helpful for pressure ulcer prevention and cure.  In this paper, a flexible and inexpensive screen printed large area pressure sensing system is presented. The large area sensor comprise three layers, is able to cancel-out false pressure detection, and achieves a sitting classification accuracy over 80 percent. The sensor matrix contains 16 sensors distributed over an area of 23.5 cm × 21.5 cm and the pressure points are monitored at a scanning rate of 77 Hz. The sensor system provides wireless communication and a Windows based GUI is developed that allows real-time presentation of pressure data by means of a pressure map. The presented sensor design targets smart wheelchairs but is suitable for any low cost and high throughput pressure distribution monitoring systems. 

  • 211.
    Ahmad, Naeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Modelling and optimization of sky surveillance visual sensor network2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    A Visual Sensor Network (VSN) is a distributed system of a largenumber of camera sensor nodes. The main components of a camera sensornode are image sensor, embedded processor, wireless transceiver and energysupply. The major difference between a VSN and an ordinary sensor networkis that a VSN generates two dimensional data in the form of an image, whichcan be exploited in many useful applications. Some of the potentialapplication examples of VSNs include environment monitoring, surveillance,structural monitoring, traffic monitoring, and industrial automation.However, the VSNs also raise new challenges. They generate large amount ofdata which require higher processing powers, large bandwidth requirementsand more energy resources but the main constraint is that the VSN nodes arelimited in these resources.This research focuses on the development of a VSN model to track thelarge birds such as Golden Eagle in the sky. The model explores a number ofcamera sensors along with optics such as lens of suitable focal length whichensures a minimum required resolution of a bird, flying at the highestaltitude. The combination of a camera sensor and a lens formulate amonitoring node. The camera node model is used to optimize the placementof the nodes for full coverage of a given area above a required lower altitude.The model also presents the solution to minimize the cost (number of sensornodes) to fully cover a given area between the two required extremes, higherand lower altitudes, in terms of camera sensor, lens focal length, camera nodeplacement and actual number of nodes for sky surveillance.The area covered by a VSN can be increased by increasing the highermonitoring altitude and/or decreasing the lower monitoring altitude.However, it also increases the cost of the VSN. The desirable objective is toincrease the covered area but decrease the cost. This objective is achieved byusing optimization techniques to design a heterogeneous VSN. The core ideais to divide a given monitoring range of altitudes into a number of sub-rangesof altitudes. The sub-ranges of monitoring altitudes are covered by individualsub VSNs, the VSN1 covers the lower sub-range of altitudes, the VSN2 coversthe next higher sub-range of altitudes and so on, such that a minimum cost isused to monitor a given area.To verify the concepts, developed to design the VSN model, and theoptimization techniques to decrease the VSN cost, the measurements areperformed with actual cameras and optics. The laptop machines are used withthe camera nodes as data storage and analysis platforms. The area coverage ismeasured at the desired lower altitude limits of homogeneous as well asheterogeneous VSNs and verified for 100% coverage. Similarly, the minimumresolution is measured at the desired higher altitude limits of homogeneous aswell as heterogeneous VSNs to ensure that the models are able to track thebird at these highest altitudes.

  • 212.
    Ahmad, Naeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Modelling, optimization and design of visual sensor networks for sky surveillance2013Doctoral thesis, comprehensive summary (Other academic)
  • 213.
    Ahmad, Naeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Khursheed, Khursheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Model, placement optimization and verification of a sky surveillance visual sensor network2013In: International Journal of Space-Based and Situated Computing (IJSSC), ISSN 2044-4893, E-ISSN 2044-4907, Vol. 3, no 3, p. 125-135Article in journal (Refereed)
    Abstract [en]

    A visual sensor network (VSN) is a distributed system of a large number of camera nodes, which generates two dimensional data. This paper presents a model of a VSN to track large birds, such as golden eagle, in the sky. The model optimises the placement of camera nodes in VSN. A camera node is modelled as a function of lens focal length and camera sensor. The VSN provides full coverage between two altitude limits. The model can be used to minimise the number of sensor nodes for any given camera sensor, by exploring the focal lengths that fulfils both the full coverage and minimum object size requirement. For the case of large bird surveillance, 100% coverage is achieved for relevant altitudes using 20 camera nodes per km² for the investigated camera sensors. A real VSN is designed and measurements of VSN parameters are performed. The results obtained verify the VSN model.

  • 214.
    Ahmad, Naeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Khursheed, Khursheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Solution space exploration of volumetric surveillance using a general taxonomy2013In: Proceedings of SPIE - The International Society for Optical Engineering / [ed] Daniel J. Henry, 2013, p. Art. no. 871317-Conference paper (Refereed)
    Abstract [en]

    Visual surveillance systems provide real time monitoring of the events or the environment. The availability of low cost sensors and processors has increased the number of possible applications of these kinds of systems. However, designing an optimized visual surveillance system for a given application is a challenging task, which often becomes a unique design task for each system. Moreover, the choice of components for a given surveillance application out of a wide spectrum of available alternatives is not an easy job. In this paper, we propose to use a general surveillance taxonomy as a base to structure the analysis and development of surveillance systems. We demonstrate the proposed taxonomy for designing a volumetric surveillance system for monitoring the movement of eagles in wind parks aiming to avoid their collision with wind mills. The analysis of the problem is performed based on taxonomy and behavioral and implementation models are identified to formulate the solution space for the problem. Moreover, we show that there is a need for generalized volumetric optimization methods for camera deployment.

  • 215.
    Ahmad, Naeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Khursheed, Khursheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Cost Optimization of a Sky Surveillance Visual Sensor Network2012In: Proceedings of SPIE - The International Society for Optical Engineering, Belgium: SPIE - International Society for Optical Engineering, 2012, p. Art. no. 84370U-Conference paper (Refereed)
    Abstract [en]

    A Visual Sensor Network (VSN) is a network of spatially distributed cameras. The primary difference between VSN and other type of sensor network is the nature and volume of information. A VSN generally consists of cameras, communication, storage and central computer, where image data from multiple cameras is processed and fused. In this paper, we use optimization techniques to reduce the cost as derived by a model of a VSN to track large birds, such as Golden Eagle, in the sky. The core idea is to divide a given monitoring range of altitudes into a number of sub-ranges of altitudes. The sub-ranges of altitudes are monitored by individual VSNs, VSN1 monitors lower range, VSN2 monitors next higher and so on, such that a minimum cost is used to monitor a given area. The VSNs may use similar or different types of cameras but different optical components, thus, forming a heterogeneous network.  We have calculated the cost required to cover a given area by considering an altitudes range as single element and also by dividing it into sub-ranges. To cover a given area with given altitudes range, with a single VSN requires 694 camera nodes in comparison to dividing this range into sub-ranges of altitudes, which requires only 96 nodes, which is 86% reduction in the cost.

  • 216.
    Ahmad, Naeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Khursheed, Khursheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Modeling and Verification of a Heterogeneous Sky Surveillance Visual Sensor Network2013In: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, p. Art. id. 490489-Article in journal (Refereed)
    Abstract [en]

    A visual sensor network (VSN) is a distributed system of a large number of camera nodes and has useful applications in many areas. The primary difference between a VSN and an ordinary scalar sensor network is the nature and volume of the information. In contrast to scalar sensor networks, a VSN generates two-dimensional data in the form of images. In this paper, we design a heterogeneous VSN to reduce the implementation cost required for the surveillance of a given area between two altitude limits. The VSN is designed by combining three sub-VSNs, which results in a heterogeneous VSN. Measurements are performed to verify full coverage and minimum achieved object image resolution at the lower and higher altitudes, respectively, for each sub-VSN. Verification of the sub-VSNs also verifies the full coverage of the heterogeneous VSN, between the given altitudes limits. Results show that the heterogeneous VSN is very effective to decrease the implementation cost required for the coverage of a given area. More than 70% decrease in cost is achieved by using a heterogeneous VSN to cover a given area, in comparison to homogeneous VSN. © 2013 Naeem Ahmad et al.

  • 217.
    Ahmad, Naeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Khursheed, Khursheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Model and placement optimization of a sky surveillance visual sensor network2011In: Proceedings - 2011 International Conference on Broadband and Wireless Computing, Communication and Applications, BWCCA 2011, IEEE Computer Society, 2011, p. 357-362Conference paper (Refereed)
    Abstract [en]

    Visual Sensor Networks (VSNs) are networks which generate two dimensional data. The major difference between VSN and ordinary sensor network is the large amount of data. In VSN, a large number of camera nodes form a distributed system which can be deployed in many potential applications. In this paper we present a model of the physical parameters of a visual sensor network to track large birds, such as Golden Eagle, in the sky. The developed model is used to optimize the placement of the camera nodes in the VSN. A camera node is modeled as a function of its field of view, which is derived by the combination of the lens focal length and camera sensor. From the field of view and resolution of the sensor, a model for full coverage between two altitude limits has been developed. We show that the model can be used to minimize the number of sensor nodes for any given camera sensor, by exploring the focal lengths that both give full coverage and meet the minimum object size requirement. For the case of large bird surveillance we achieve 100% coverage for relevant altitudes using 20 camera nodes per km2 for the investigated camera sensors.

  • 218.
    Ahmad, Naeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    A taxonomy of visual surveillance systems2013Report (Other academic)
    Abstract [en]

    The increased security risk in society and the availability of low cost sensors and processors has expedited the research in surveillance systems. Visual surveillance systems provide real time monitoring of the environment. Designing an optimized surveillance system for a given application is a challenging task. Moreover, the choice of components for a given surveillance application out of a wide spectrum of available products is not an easy job.

     

    In this report, we formulate a taxonomy to ease the design and classification of surveillance systems by combining their main features. The taxonomy is based on three main models: behavioral model, implementation model, and actuation model. The behavioral model helps to understand the behavior of a surveillance problem. The model is a set of functions such as detection, positioning, identification, tracking, and content handling. The behavioral model can be used to pinpoint the functions which are necessary for a particular situation. The implementation model structures the decisions which are necessary to implement the surveillance functions, recognized by the behavioral model. It is a set of constructs such as sensor type, node connectivity and node fixture. The actuation model is responsible for taking precautionary measures when a surveillance system detects some abnormal situation.

     

    A number of surveillance systems are investigated and analyzed on the basis of developed taxonomy. The taxonomy is general enough to handle a vast range of surveillance systems. It has organized the core features of surveillance systems at one place. It may be considered an important tool when designing surveillance systems. The designers can use this tool to design surveillance systems with reduced effort, cost, and time.

  • 219.
    Ahmad, Nisar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Design and Implementation of a High Frequency Flyback Converter2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The power supply designers choose flyback topology due to its promising features of design simplicity, cost effectiveness and multiple outputs handling capability. The designed product based on flyback topology should be smaller in size, cost effective and energy efficient. Similarly, designers focus on reducing the circuit losses while operating at high frequencies that affect the converter efficiency and performance. Based on the above circumstances, an energy efficient open loop high frequency flyback converter is designed and operated in MHz frequency region using step down multilayer PCB planar transformer. The maximum efficiency of 84.75% is observed and maximum output power level reached is 22.8W. To overcome the switching losses, quasi-resonant soft switching technique is adopted and a high voltage CoolMOS power transistor is used.

  • 220.
    Ahmad, Shabir
    et al.
    Jeju National University, Jeju, South Korea.
    Hussain, Ishfaq
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Fayaz, Muhammad
    Jeju National University, Jeju, South Korea.
    Kim, Do-Hyeun
    Jeju National University, Jeju, South Korea.
    A Distributed Approach towards Improved Dissemination Protocol for Smooth Handover in MediaSense IoT Platform2018In: Processes, ISSN 2227-9717, E-ISSN 1099-5862, Vol. 6, no 5, article id 46Article in journal (Refereed)
    Abstract [en]

    Recently, the Internet has been utilized by many applications to convey time-sensitive messages. The persistently expanding Internet coverage and its easy accessibility have offered to ascend to a problem which was once regarded as not essential to contemplate. Nowadays, the Internet has been utilized by many applications to convey time-sensitive messages. Wireless access points have widely been used but these access points have limitations regarding area coverage. So for covering a wider space, various access points need to be introduced. Therefore, when the user moves to some other place, the devices expected to switch between access points. Packet loss amid the handovers is a trivial issue. MediaSense is an Internet of Things distributed architecture enabling the development of the IoT application faster. It deals with this trivial handover issue by utilizing a protocol called Distributed Context eXchange Protocol. However, this protocol is centralized in nature and also suffers in a scenario when both sender and receiver address change simultaneously. This paper presents a mechanism to deal with this scenario and presents a distributed solution to deal with this issue within the MediaSense platform. The proposed protocol improves dissemination using retransmission mechanism to diminish packet loss. The proposed protocol has been delineated with a proof of concept chat application and the outcomes have indicated a significant improvement in terms of packet loss.

  • 221.
    Ahmad, Waqas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Interpreting Plenoptic Images as Multi-View Sequences for Improved Compression2017Data set
    Abstract [en]

    The paper is written in the response to ICIP 2017, Grand challenge on plenoptic image compression. The input image format and compression rates set out by the competition are followed to estimate the results.

  • 222.
    Ahmad, Waqas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Interpreting Plenoptic Images as Multi-View Sequences for Improved Compression2017In: ICIP 2017, IEEE, 2017, p. 4557-4561Conference paper (Refereed)
    Abstract [en]

    Over the last decade, advancements in optical devices have made it possible for new novel image acquisition technologies to appear. Angular information for each spatial point is acquired in addition to the spatial information of the scene that enables 3D scene reconstruction and various post-processing effects. Current generation of plenoptic cameras spatially multiplex the angular information, which implies an increase in image resolution to retain the level of spatial information gathered by conventional cameras. In this work, the resulting plenoptic image is interpreted as a multi-view sequence that is efficiently compressed using the multi-view extension of high efficiency video coding (MV-HEVC). A novel two dimensional weighted prediction and rate allocation scheme is proposed to adopt the HEVC compression structure to the plenoptic image properties. The proposed coding approach is a response to ICIP 2017 Grand Challenge: Light field Image Coding. The proposed scheme outperforms all ICME contestants, and improves on the JPEG-anchor of ICME with an average PSNR gain of 7.5 dB and the HEVC-anchor of ICIP 2017 Grand Challenge with an average PSNR gain of 2.4 dB.

  • 223.
    Ahmad, Waqas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Towards a generic compression solution for densely and sparsely sampled light field data2018In: Proceedings of 24TH IEEE International Conference On Image Processing, 2018Conference paper (Refereed)
    Abstract [en]

    Light field (LF) acquisition technologies capture the spatial and angular information present in scenes. The angular information paves the way for various post-processing applications such as scene reconstruction, refocusing, and synthetic aperture. The light field is usually captured by a single plenoptic camera or by multiple traditional cameras. The former captures a dense LF, while the latter captures a sparse LF. This paper presents a generic compression scheme that efficiently compresses both densely and sparsely sampled LFs. A plenoptic image is converted into sub-aperture images, and each sub-aperture image is interpreted as a frame of a multiview sequence. In comparison, each view of the multi-camera system is treated as a frame of a multi-view sequence. The multi-view extension of high efficiency video coding (MVHEVC) is used to encode the pseudo multi-view sequence.This paper proposes an adaptive prediction and rate allocation scheme that efficiently compresses LF data irrespective of the acquisition technology used.

  • 224.
    Ahmad, Waqas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Palmieri, Luca
    Christian-Albrechts-Universität, Kiel, Germany.
    Koch, Reinhard
    Christian-Albrechts-Universität, Kiel, Germany.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Matching Light Field Datasets From Plenoptic Cameras 1.0 And 2.02018In: Proceedings of the 2018 3DTV Conference, 2018, article id 8478611Conference paper (Refereed)
    Abstract [en]

    The capturing of angular and spatial information of the scene using single camera is made possible by new emerging technology referred to as plenoptic camera. Both angular and spatial information, enable various post-processing applications, e.g. refocusing, synthetic aperture, super-resolution, and 3D scene reconstruction. In the past, multiple traditional cameras were used to capture the angular and spatial information of the scene. However, recently with the advancement in optical technology, plenoptic cameras have been introduced to capture the scene information. In a plenoptic camera, a lenslet array is placed between the main lens and the image sensor that allows multiplexing of the spatial and angular information onto a single image, also referred to as plenoptic image. The placement of the lenslet array relative to the main lens and the image sensor, results in two different optical design sof a plenoptic camera, also referred to as plenoptic 1.0 and plenoptic 2.0. In this work, we present a novel dataset captured with plenoptic 1.0 (Lytro Illum) and plenoptic 2.0(Raytrix R29) cameras for the same scenes under the same conditions. The dataset provides the benchmark contents for various research and development activities for plenoptic images.

  • 225.
    Ahmad, Waqas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Palmieri, Luca
    University of Padova, Italy.
    Koch, Reinhard
    Christian-Albrechts-University of Kiel, Germany.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    The Plenoptic Dataset2018Data set
    Abstract [en]

    The dataset is captured using two different plenoptic cameras, namely Illum from Lytro (based on plenoptic 1.0 model) and R29 from Raytrix (based on plenoptic 2.0 model). The scenes selected for the dataset were captured under controlled conditions. The cameras were mounted onto a multi-camera rig that was mechanically controlled to move the cameras with millimeter precision. In this way, both cameras captured the scene from the same viewpoint.

  • 226.
    Ahmad, Waqas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Compression scheme for sparsely sampled light field data based on pseudo multi-view sequences2018In: Proceedings of SPIE - The International Society for Optical Engineering, 2018, Vol. 10679, article id 106790MConference paper (Refereed)
    Abstract [en]

    With the advent of light field acquisition technologies, the captured information of the scene is enriched by having both angular and spatial information. The captured information provides additional capabilities in the post processing stage, e.g. refocusing, 3D scene reconstruction, synthetic aperture etc. Light field capturing devices are classified in two categories. In the first category, a single plenoptic camera is used to capture a densely sampled light field, and in second category, multiple traditional cameras are used to capture a sparsely sampled light field. In both cases, the size of captured data increases with the additional angular information. The recent call for proposal related to compression of light field data by JPEG, also called “JPEG Pleno”, reflects the need of a new and efficient light field compression solution. In this paper, we propose a compression solution for sparsely sampled light field data. In a multi-camera system, each view depicts the scene from a single perspective. We propose to interpret each single view as a frame of pseudo video sequence. In this way, complete MxN views of multi-camera system are treated as M pseudo video sequences, where each pseudo video sequence contains N frames. The central pseudo video sequence is taken as base View and first frame in all the pseudo video sequences is taken as base Picture Order Count (POC). The frame contained in base view and base POC is labeled as base frame. The remaining frames are divided into three predictor levels. Frames placed in each successive level can take prediction from previously encoded frames. However, the frames assigned with last prediction level are not used for prediction of other frames. Moreover, the rate-allocation for each frame is performed by taking into account its predictor level, its frame distance and view wise decoding distance relative to the base frame. The multi-view extension of high efficiency video coding (MV-HEVC) is used to compress the pseudo multi-view sequences. The MV-HEVC compression standard enables the frames to take prediction in both direction (horizontal and vertical d), and MV-HEVC parameters are used to implement the proposed 2D prediction and rate allocation scheme. A subset of four light field images from Stanford dataset are compressed, using the proposed compression scheme on four bitrates in order to cover the low to high bit-rates scenarios. The comparison is made with state-of-art reference encoder HEVC and its real-time implementation X265. The 17x17 grid is converted into a single pseudo sequence of 289 frames by following the order explained in JPEG Pleno call for proposal and given as input to the both reference schemes. The rate distortion analysis shows that the proposed compression scheme outperforms both reference schemes in all tested bitrate scenarios for all test images. The average BD-PSNR gain is 1.36 dB over HEVC and 2.15 dB over X265.

  • 227.
    Ahmad, Waqas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Vagharshakyan, Suren
    Tampere University of Technology, Finland.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gotchev, Atanas
    Tampere University of Technology, Finland.
    Bregovic, Robert
    Tampere University of Technology, Finland.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Shearlet Transform Based Prediction Scheme for Light Field Compression2018Conference paper (Refereed)
    Abstract [en]

    Light field acquisition technologies capture angular and spatial information ofthe scene. The spatial and angular information enables various post processingapplications, e.g. 3D scene reconstruction, refocusing, synthetic aperture etc at theexpense of an increased data size. In this paper, we present a novel prediction tool forcompression of light field data acquired with multiple camera system. The captured lightfield (LF) can be described using two plane parametrization as, L(u, v, s, t), where (u, v)represents each view image plane coordinates and (s, t) represents the coordinates of thecapturing plane. In the proposed scheme, the captured LF is uniformly decimated by afactor d in both directions (in s and t coordinates), resulting in a sparse set of views alsoreferred to as key views. The key views are converted into a pseudo video sequence andcompressed using high efficiency video coding (HEVC). The shearlet transform basedreconstruction approach, presented in [1], is used at the decoder side to predict thedecimated views with the help of the key views.Four LF images (Truck, Bunny from Stanford dataset, Set2 and Set9 from High DensityCamera Array dataset) are used in the experiments. Input LF views are converted into apseudo video sequence and compressed with HEVC to serve as anchor. Rate distortionanalysis shows the average PSNR gain of 0.98 dB over the anchor scheme. Moreover, inlow bit-rates, the compression efficiency of the proposed scheme is higher compared tothe anchor and on the other hand the performance of the anchor is better in high bit-rates.Different compression response of the proposed and anchor scheme is a consequence oftheir utilization of input information. In the high bit-rate scenario, high quality residualinformation enables the anchor to achieve efficient compression. On the contrary, theshearlet transform relies on key views to predict the decimated views withoutincorporating residual information. Hence, it has inherit reconstruction error. In the lowbit-rate scenario, the bit budget of the proposed compression scheme allows the encoderto achieve high quality for the key views. The HEVC anchor scheme distributes the samebit budget among all the input LF views that results in degradation of the overall visualquality. The sensitivity of human vision system toward compression artifacts in low-bitratecases favours the proposed compression scheme over the anchor scheme.

  • 228.
    Ahmed, Leila
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Hälsofrämjande ledarskap ur anställdas perspektiv: - En kvalitativ intervjustudie2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 229.
    Ahmed, Lisa
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Science Education and Mathematics.
    Lärarstyrd lek i matematikundervisningen: Dess möjligheter och begränsningar för elevens lärande.2018Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Avsikten med min studie är att veta hur lärarstyrd lek påverkar matematikundervisningen samt se vilka möjligheter och begränsningar som metoden lärarstyrd lek har. För detta syfte har jag intervjuat ett antal lärare om detta arbetssätt, hur de planerar för en undervisning som bygger på lärarstyrd lek, vad de menar med lärarstyrd lek, vilka möjligheter och begränsningar de ser samt om de märker att de stimulerar eleven i matematikundervisningen med den lärarstyrda leken.Det resultatet som jag ser i min studie är att i huvudsak anser samtliga pedagoger att det finns en positiv påverkan på lärandet när lärarstyrd lek genomförs i undervisningen. De pekar på några begränsande faktorer som tidsbrist, höga arbetsbelastning, problem med elevers sociala sampel. Trots att arbetssättet möter vissa utmaningar så bedömer samtliga pedagoger att lärarstyrd lek i matematikundervisningen ökar elevens motivation i lärandet och gör ämnet roligt och intressant.

  • 230.
    Ahmed Shire, F Sagal
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Healthcare professional´s experience of promoting maternal mental health: a qualitative study in Saudi Arabia.2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 231.
    Ahmetgjekaj, Fatmir
    Mid Sweden University, Faculty of Human Sciences, Department of Humanities.
    New age i massmediernas tid och rum2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 232.
    Ahnelöv, Malin
    Mid Sweden University, Faculty of Human Sciences, Department of Tourism Studies and Geography.
    När millenniegenerationen väljer Airbnb: En kvalitativ fallstudie av Stockholm2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 233.
    Ahola, Paulina
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Social Work.
    Holm, Yvonne
    Mid Sweden University, Faculty of Human Sciences, Department of Social Work.
    "Jag går inte och väntar på något mirakel, jag är väl zombie på mitt vis" - En kvalitativ studie om äldres syn på psykisk ohälsa och sin psykosociala situation2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 234.
    Ahonen, Mikko
    University of Tampere.
    Designing an Information System for Open Innovation – Bridging the Gap between Individual and Organisational Creativity2011Doctoral thesis, monograph (Other academic)
    Abstract [en]

    History shows that those companies that continue to invest in their innovative capabilities during tough economic times are often those that prosper when growth returns. Recently, information systems (IS) have been harnessed to support innovation. Even with IS support, innovation campaigns and suggestion management systems often end up in failure. Employees and customers are reluctant to share their best ideas. Individuals interests, motivation, creativity and life-long learning are seldom adequately supported by companies. In the information systems research area there is very little research on creativity and creativity has traditionally been studied mainly within the decision support systems (DSS) research area. This DSS area has focused on rather mechanistic idea-generation processes lacking a focus on individuals and their creativity. Even in the emerging open innovation paradigm, individual and group levels have come in for little research. From these starting points, we became interested in ways to improve existing information systems and innovation practices. The research question here is: How to design an artefact to support learning and creativity within the open innovation paradigm. Since we are interested in building new artefacts, we will utilise design research methods, particularly the Design Science Research Methodology (DSRM) process model. Our three artefacts are the results of our work. The first artefact, the Mobile Personal Development Plan, is focused on extending development talks between an employer and employees within human resource management to support innovation. Curiosity and emerging interests are seen here as idea seeds and future competences. The second artefact, the iPortfolio, extends this with a life-long learning and problem-solving focus. The third artefact, the Brokering Platform for Open Innovation, finally focuses on collaboration with customers and crowds. The software development was time consuming in our work and only the first artefact is demonstrated as a functional software prototype. Our pilot in an SME company illustrates practical requirements and usability issues related to the software. Additionally, a Delphi study with international open innovation experts served to identify future related requirements. Given the lack of creativity research in the IS field, we claim that our work makes an appropriate contribution. To the design research literature our input is new usage cases of the previously mentioned DSRM process model. Our results apply to organisations, where the employees work in dispersed teams and need an information system to communicate their emerging ideas and interests for more systematic problem-solving. The managers in our study reported that there are plenty of ideas available, but the challenge is to ensure the commitment of external resources to the actual innovation building. The integration of learning into the innovation and problem-solving activity should be motivational. We therefore discuss human resource management in relation to creativity and innovation. Surprisingly, in our pilots we noticed difficulties in time management in mobile settings and the current health risk debate gradually changed our artefact design, so this work also provides a critical view on mobility and on the access anytime, anywhere phenomenon. Finally, we suggest improvements to existing innovation practices in organisations.

  • 235.
    Ahonen, Mikko
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Designing to archive open data – Case: ISERV e-services project.2017Conference paper (Refereed)
  • 236.
    Ahonen, Mikko
    et al.
    Institute of Environmental Health and Safety, Tallinn, Estonia.
    Koppel, Tarmo
    Tallinn University of Technology, Estonia.
    Voltage transients measurements and power line communication2016In: 2016 57th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON), IEEE, 2016, p. 1-4Conference paper (Refereed)
    Abstract [en]

    Power line communication (PLC) connects energy producers with energy consumers. In the European Union stricter guidelines are under development to limit disturbances in the 2-150 kHz frequency range, because devices utilising PLC do not work. This study measured voltage transients in 22 locations and identified sources for noise. Home environments and public buildings were measured. Measurements were conducted in the frequency range of 150 kHz-500 kHz (according to EN 55011 to EN 55022) and in the lower frequency range of 3 kHz to 95 kHz. Results indicate that voltage transients are generated mostly by switching mode power supplies, pumps, rectifiers, inverters and even low quality smart meters. Several of these devices exceeded PLC standard level, 122 dBμV. Additionally we demonstrate that basic power quality recordings do not provide enough information to mitigate PLC problems occurring within microseconds and frequency specific voltage transient measurements are needed.

  • 237. Ahonen-Jonnarth, U.
    et al.
    Van Hees, P.A.W.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Finlay, R.D.
    Organic acids produced by mycorrhizal Pinus sylvestris exposed to elevated aluminium and heavy metals concentrations2000In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 146, no 3, p. 557-567Article in journal (Refereed)
    Abstract [en]

    A cultivation method was developed to enable exposure of ectomycorrhizal plants with intact extramatrical mycelium to solutions containing different concentrations of aluminium or heavy metals. Pinus sylvestris seedlings colonized by Suillus variegatus (two isolates), Rhizopogon roseolus or Paxillus involutus (two isolates) were used. Seedlings were transferred to Petri dishes containing glass beads and exposed to elevated concentrations of Al, Cd, Cu, or Ni in two ways: immediately following transfer; and after allowing mycorrhizal seedlings to develop an extraradical mycelium that colonized the interface between the upper surface of the beads and the metal-containing solution. Production of organic acids in mycorrhizal and non-mycorrhizal systems was measured by withdrawing samples from the solution and analyzing by HPLC. In most experiments, levels of oxalic acid were significantly higher in mycorrhizal treatments than in non-mycorrhizal controls. The measured levels of organic acids were variable, but the results obtained suggest that production of oxalic acid is stimulated by exposure to elevated Al in mycorrhizal seedlings colonized by S. variegatus and R. roseolus. Elevated Al concentrations also increased oxalic acid production by non-mycorrhizal seedlings significantly in two of four Al experiments performed, but the measured concentrations were significantly lower than in corresponding mycorrhizal treatments in both cases. Malonic acid was found in the culture solution of non-mycorrhizal had P. involutus-colonized seedlings, but only trace amounts were found in S. variegatus or R. roseolus-infected seedlings. Citric, shikimic, lactic, acetic, propionic, fumaric, formic, iso-butyric and butyric acid were found in variable concentrations. Production of oxalic acid by seedlings ColoniZed by S. variegatus BL or P. involutus was not stimulated by exposure to 0.44 μM Cd or 17 μM Ni. Exposure to 0.157 mM CU in two separate experiments using P. involutus 87.017 and two strains of S. variegatus (BL and 159) appeared to stimulate production of oxalic acid irrespective of mycorrhizal status or species.

  • 238.
    Ahrling, Jane
    Mid Sweden University, Faculty of Human Sciences, Department of Humanities.
    A Feminist Reading of  The House of the Spirits,  Song of Solomon,  and  One Hundred Years of Solitude                            2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 239.
    Ahrling, Jane
    Mid Sweden University, Faculty of Human Sciences, Department of Humanities.
    A Feminist Reading of  The House of the Spirits,  Song of Solomon,  and  One Hundred Years of Solitude                            2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 240.
    Ahrne, Göran
    et al.
    Stockholms universitet. Sociologiska institutionen.
    Johansson, Roine
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Between Organizations1994In: Social organizations: Interaction inside, outside and between organizations, London: Sage Publications , 1994Chapter in book (Other scientific)
  • 241.
    Aimée Temahagari, Marie
    Mid Sweden University, Faculty of Human Sciences, Department of Nursing Sciences.
    FAKTORER SOM PÅVERKAR VÅRDPERSONALENS UTFÖRANDE AV MUNVÅRD HOS ÄLDRE PÅ SÄRSKILT BOENDE: En litteraturöverskikt2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 242.
    Ainegren, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Roller skis' rolling resistance and grip characteristics: influences on physiological and performance measures in cross-country skiers2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this thesis was to investigate roller ski characteristics; classical and freestyle roller skis’ rolling resistance coefficients (μR) and classical style roller skis’ static friction coefficients (μS), and to study the influence of different μR and μS on cross-country skiers’ performance and both physiological and biomechanical indices. The aim was also to study differences in skiing economy and efficiency between recreational skiers, female and male junior and senior elite cross-country skiers.The experiments showed that during a time period of 30 minutes of rolling on a treadmill (warm-up), μR decreased significantly (p<0.05) to about 60-65 % and 70-75 % of its initial value for freestyle and classical roller skis respectively. Also, there was a significant influence of normal force on μR, while different velocities and inclinations of the treadmill only resulted in small changes in μR.The study of the influence on physiological variables of a ~50 % change in μR showed that during submaximal steady rate exercise, external power, oxygen uptake, heart rate and blood lactate were significantly changed, while there were non-significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed and this occurred without a change in maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion was non-significant or small.The study of classical style roller skis μS showed values that were five to eight times more than the values of μS reported from on-snow skiing with grip-waxed cross-country skis.The subsequent physiological and biomechanical experiments with different μS showed a significantly lower skiing economy (~14 % higher v̇O2), higher heart rate, lower propulsive forces coming from the legs and shorter time to exhaustion (~30 %) when using a different type of roller ski with a μS similar to on-snow skiing, while there was no difference between tests when using different pairs of roller skis with a (similar) higher μS.The part of the thesis which focused on skiing economy and efficiency as a function of skill, age and gender, showed that the elite cross-country skiers had better skiing economy and higher gross efficiency (5-18 %) compared with the recreational skiers, and the senior elite had better economy and higher efficiency (4-5 %) than their junior counterparts, while no differences could be found between the genders.

  • 243.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Ainegren, Mats
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    The rolling resistances of roller skis and their effects on human performance during treadmill roller skiing2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical performance in a laboratory environment using classical and freestyle techniques on roller skis. For elite athletes the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance coefficient, µR, in order to allow correct comparisons between the results, as well as providing the opportunity to study work economy between different athletes, test occasions and core techniques.

    Thus, one of the aims of this thesis was to evaluate how roller skis’ µR is related to warm-up, mass, velocity and inclination of the treadmill. It was also necessary to investigate the methodological variability of the rolling resistance measurement system, RRMS, specially produced for the experiments, with a reproducibility study in order to indicate the validity and reliability of the results.

    The aim was also to study physiological responses to different µR during roller skiing with freestyle and classical roller skis and techniques on the treadmill as a case in which all measurements were carried out in stationary and comparable conditions.

    Finally, the aim was also to investigate the work economy of amateurs and female and male junior and senior cross-country skiers during treadmill roller skiing, i.e. as a function of skill, age and gender, including whether differences in body mass causes significant differences in external power per kg due to differences in the roller skis’ µR.

    The experiments showed that during a warm-up period of 30 minutes, µR decreased to about 60-65% and 70-75% of its initial value for freestyle and classical roller skis respectively. For another 30 minutes of rolling no significant change was found. Simultaneous measurements of roller ski temperature and mR showed that stabilized mR corresponds to a certain running temperature for a given normal force on the roller ski. The study of the influence on mR of normal force, velocity and inclination produced a significant influence of normal force on mR, while different velocities and inclinations of the treadmill only resulted in small changes in mR. The reproducibility study of the RRMS showed no significant differences between paired measurements with either classical or the freestyle roller skis.

    The study of the effects on physiological variables of ~50% change in µR,showed that during submaximal steady state exercise, external power, oxygen uptake, heart rate and blood lactate were significantly changed, while there were non significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed and this occurred without a significantly changed maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion was non significant or small.

    The final part of the thesis, which focused on work economy, found no significant difference between the four groups of elite competitors, i.e. between the two genders and between the junior and senior elite athletes. It was only the male amateurs who significantly differed among the five studied groups. The study also showed that the external power per kg was significantly different between the two genders due to differences in body mass and mR, i.e. the lighter female testing groups were roller skiing with a relatively heavier rolling resistance coefficient compared to the heavier testing groups of male participants.

  • 244.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Ainegren, Mats
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Roller ski rolling resistance and its effects on elite athletes’ performance2008In: ENGINEERING OF SPORT 7, VOL 2, 2008, Vol. 11, no 3, p. 393-400Conference paper (Refereed)
    Abstract [en]

    Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical fitness in a laboratory environment whilst performing classical and freestyle (skating) techniques on roller skis. For elite athletes the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance in order to allow the correct comparison between the results of different test occasions. In this study the roller skis’ rolling resistance has been measured using equipment on the ski-treadmill. The study investigates the influence of significant changes in rolling resistance on physiological variables. The results show that during submaximal exercise, heart rate, blood lactate, power and oxygen uptake are significantly changed by different rolling resistances, while there are no significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests show that time to exhaustion is significantly changed by different rolling resistances and this occurred without significant changes in maximal oxygen uptake and heart rate, and the influence on maximal power and ratings of perceived exertion were insignificant or small.

  • 245.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Ainegren, Mats
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Roller ski rolling resistance and its effects on elite athletes’ performance2009In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 11, no 3, p. 143-157Article in journal (Refereed)
    Abstract [en]

    Modern ski-treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical fitness in a laboratory environment whilst performing classical and freestyle (skating) techniques on roller skis. For elite athletes, the differences in performance between test occasions are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance in order to allow the correct comparison between the results of different test occasions. In this study, the roller skis’ rolling resistance was measured on the ski-treadmill’s surface using a roller ski rolling resistance measurement system specially produced for this purpose. The study investigated the influence of significant changes in rolling resistance on physiological variables. The results showed that during submaximal exercise, power, oxygen uptake, heart rate and blood lactate were significantly changed by different rolling resistances, while there were no significant or only small changes to cycle rate, cycle length and ratings of perceived exertion. Incremental maximal tests showed that time to exhaustion was significantly changed by different rolling resistances and this occurred without significant changes in maximal power, maximal oxygen uptake, maximal heart rate and blood lactate, and that the influence on ratings of perceived exertion were insignificant or small.

     

  • 246.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Ainegren, Mats
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Rolling resistance for treadmill roller skiing2008In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 11, no 1, p. 23-29Article in journal (Refereed)
    Abstract [en]

    Modern treadmills allow cross-country skiers, biathletes and ski-orienteers to test their physical performance under laboratory conditions using classical and freestyle techniques on roller skis. The differences in performance between tests are quite small for elite athletes, and it is therefore of great importance to control the rolling resistance of the roller skis. Otherwise different physiological tests cannot be accurately compared.

    This study shows that during a warm-up period of  30 minutes the coefficient of rolling resistance (µR) decreases to about 60-65% and 70-75% of its initial value for freestyle and classical roller skis respectively.

    Simultaneous measurements of temperature and µR shows that stabilized rolling resistance corresponds to a certain running temperature for a given normal force on the roller ski.

    Tests were also performed on the influence on µR of normal force, velocity and inclination. Normal forces produced significant influence on µR , while different velocities and inclinations of the treadmill only resulted in small changes in µR.

  • 247.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Ainegren, Mats
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Laaksonen, Marko
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Work economy of amateur and elite cross-country skiers during treadmill roller skiing2009In: 4th Asia Pacific Congress on Sports Technology, APCST2009, 2009Conference paper (Refereed)
    Abstract [en]

    This study focused on the work economy of cross-country skiers during treadmill roller skiing in the perspectives; skill, age and gender. The study was investigating the external power output from elevating the transported mass against gravity and overcoming the roller skis rolling resistance, and the internal power from measured oxygen uptake and energy consumption. The roller skis rolling resistance was measured with a fixture on the ski-treadmill and the results showed a significant correlation between normal force and rolling resistance. The results also showed that it was only the amateur skiers who significantly differed in work economy among the five studied groups.

  • 248.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Laaksonen, Marko S.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    The influence of grip on oxygen consumption and leg forces when using classical style roller skis2014In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, no 2, p. 301-310Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate the influence of classical style roller skis' grip (static friction coefficients, μ S) on cross-country skiers' oxygen consumption and leg forces during treadmill roller skiing, when using the diagonal stride and kick double poling techniques. The study used ratcheted wheel roller skis from the open market and a uniquely designed roller ski with an adjustable camber and grip function. The results showed significantly (P≤0.05) higher oxygen consumption (∼14%), heart rate (∼7%), and lower propulsive forces from the legs during submaximal exercise and a shorter time to exhaustion (∼30%) in incremental maximal tests when using roller skis with a μ S similar to on-snow skiing, while there was no difference between tests when using different pairs of roller skis with a similar, higher μ S. Thus, we concluded that oxygen consumption (skiing economy), propulsive leg forces, and performance time are highly changed for the worse when using roller skis with a lower μ S, such as for on-snow skiing with grip-waxed cross-country skis, in comparison to ratcheted wheel roller skis with several times higher μ S.

  • 249.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    A portable roller ski rolling resistance measurement system2013In: The Impact of Technology on Sport V: Procedia Engineering / [ed] Subic A, Fuss FK, Clifton P, Chan KM., Elsevier, 2013, p. 79-83Conference paper (Refereed)
    Abstract [en]

    Roller skis are used by cross-country skiers, biathletes and ski-orienteers for their snow-free training and in roller ski competitions. Additionally, much of the current sports research into the physiology and biomechanics of crosscountry skiing is conducted indoors on treadmills using roller skis. For elite athletes, the differences in performance are quite small, thus emphasising the importance of knowing the roller skis' rolling resistance coefficient, especially in connection to research and roller ski competitions. The purpose of this study was to develop a roller ski rolling resistance measurement system (P-RRMS) that is portable and therefore useful in different contexts and locations. The P-RRMS was designed as a small treadmill, equipped with roller ski stabilizing lateral supports and a screwed bar for applying different vertical loads on the roller ski. The design uses only one force sensor, with possible measurements of three directions of force and torque around three axes. The weight of the P-RRMS is 100 kg and it is equipped with wheels to facilitate transportation.

  • 250.
    Ainegren, Mats
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Carlsson, Peter
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Tinnsten, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    An experimental study to compare the grip of classical style roller skis with on-snow skiing2013In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 16, no 2, p. 115-122Article in journal (Refereed)
    Abstract [en]

    Cross-country skiers use roller skis for their snow-free training with the aim of imitating skiing on snow. Also, exercise laboratories evaluate the biomechanics and physiology of cross-country skiing using roller skis on a treadmill. The roller skis on the market that are constructed for use in the classical style are equipped with a front and a back wheel, one of which has a ratchet to enable it to grip the surface when diagonal striding and kick double poling (static friction). The aim of this study was to investigate static friction coefficients (μS) of ratcheted wheel roller skis, and compare the results to the μS reported from skiing on snow with grip-waxed cross-country skis. Also, a new type of roller ski with a camber and adjustable grip function was evaluated. The results showed that ratcheted wheel roller skis, on a treadmill rubber mat and on dry and wet asphalt surfaces, reached μS values that were five to eight times greater than the values reported from on-snow skiing with grip-waxed cross-country skis. For the roller skis with a camber and adjustable grip function, the μs could be varied from no grip at all up to the level of the tested ratcheted wheel roller skis.

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