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  • 1.
    Ali, Rony
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Värmeåtervinning - styrning för frånluftsvärmepump i flerbostadshus2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 2.
    Ali, ZAKI
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Självbalansering av MinSeg2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 3.
    Alizadeh, Mahmoud
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics. KTH, Teknisk informationsvetenskap.
    Characterisation, Modelling and Digital Pre-Distortion Techniques for RF Transmitters in Wireless Systems2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wireless systems have become an inevitable part of modern technologies serving humankind. The rapid growth towards large dimensional systems, e.g. 5th generation (5G) technologies, incurs needs for improving the performance of the systems and considering aspects to make them as far as possible environmentally friendly in terms of power efficiency, cost, and so on. One of the key parts of every wireless communication system is the radio frequency (RF) power amplifier (PA), which consumes the largest percentage of the total energy. Hence, accurate models of RF PAs can be used to optimize their design and to compensate for signal distortions. This thesis starts with two methods for frequency-domain characterisation to analyse the dynamic behaviour of PAs in 3rd-order non-linear systems. Firstly, two-tone signals superimposed on large-signals are used to analyse the frequency-domain symmetry properties of inter-modulation (IM) distortions and Volterra kernels in different dynamic regions of RF PAs in a single-input single-output (SISO) system. Secondly, three-tone signals are used to characterise the 3rd-order self- and cross-Volterra kernels of RF PAs in a 3 × 3 multiple-input multiple-output (MIMO) system. The main block structures of the models are determined by analysing the frequency-domain symmetry properties of the Volterra kernels in different three-dimensional (3D) frequency spaces. This approach significantly simplifies the structure of the 3rd-order non-linear MIMO model.

    The following parts of the thesis investigate techniques for behavioural modelling and linearising RF PAs. A piece-wise modelling technique is proposed to characterise the dynamic behaviour and to mitigate the impairments of non-linear RF PAs at different operating points (regions). A set of thresholds decompose the input signal into several sub-signals that drive the RF PAs at different operating points. At each operating point, the PAs are modelled by one sub-model, and hence, the complete model consists of several sub-models. The proposed technique reduces the model errors compared to conventional piece-wise modelling techniques.

    A block structure modelling technique is proposed for RF PAs in a MIMO system based on the results of the three-tone characterisation technique. The main structures of the 3rd- and higher-order systems are formulated based on the frequency dependence of each block. Hence, the model can describe more relevant interconnections between the inputs and outputs than conventional polynomial-type models.

    This thesis studies the behavioural modelling and compensation techniques in both the time and the frequency domains for RF PAs in a 3 × 3MIMO system. The 3D time-domain technique is an extension of conventional 2D generalised memory polynomial (GMP) techniques. To reduce the computational complexity, a frequency-domain technique is proposed that is efficient and feasible for systems with long memory effects. In this technique, the parameters of the model are estimated within narrow sub-bands. Each sub-band requires only a few parameters, and hence the size of the model for each sub-band is reduced.

  • 4.
    Alizadeh, Mahmoud
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics. KTH, Teknisk informationsvetenskap.
    Händel, Peter
    KTH, Teknisk informationsvetenskap.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Behavioral modeling and digital pre-distortion techniques for RF PAs in a 3 × 3 MIMO system2019In: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787Article in journal (Refereed)
    Abstract [en]

    Modern telecommunications are moving towards (massive) multi-input multi-output systems in 5th generation (5G) technology, increasing the dimensionality of the system dramatically. In this paper, the impairments of radio frequency (RF)power amplifiers (PAs) in a 3x3 MIMO system are compensated in both time and frequency domains. A three-dimensional(3D) time-domain memory polynomial-type model is proposed as an extension of conventional 2D models. Furthermore, a 3D frequency-domain technique is formulated based on the proposed time-domain model to reduce the dimensionality of the model, while preserving the performance in terms of model errors. In the 3D frequency-domain technique, the bandwidth of a system is split into several narrow sub-bands, and the parameters of the system are estimated for each subband. This approach requires less computational complexity, and also the procedure of the parameters estimation for each sub-band can be implemented independently. The device-under-test (DUT) consists of three RF PAs including input and output cross-talk channels. The proposed techniques are evaluated in both behavioural modelling and digital pre-distortion(DPD) perspectives. The results show that the proposed DPD technique can compensate the errors of non-linearity and memory effects by about 23.5 dB and 7 dB in terms of the normalized mean square error and adjacent channel leakage ratio, respectively.

  • 5.
    Andersson, Rabé
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Exploring Baxter Robot and Development of Python algorithms to Execute Holding, Lifting and Positioning Tasks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The greatest feature of using a Baxter robot among other industrial robots is the ability to train this robot conveniently. The training of the robot could be done within a few minutes and it does not need so much knowledge of programming. However, this type of training feature is limited in functionality and needs frequent updating of the software and the license from the manufactural company. As the manufacturer of Baxter Robot no longer exists due to a merger, the thesis has twofold aims, (1) Exploring different functional, installation, calibration, troubleshooting and hardware features of the Baxter robot and (2) demonstrate the functionality of Baxter to perform general tasks of holding, lifting and moving of test objects from one desired position to another position using custom-made programs in Python. Owing to this, details about different software and hardware aspects of Baxter robot is presented in this thesis. Additionally, systematic laboratory tutorials are also presented in appendices for students who want to learn and operate the robot from simple to complicated tasks. In order to keep the Baxter operational for students and researchers in future, when there is no more help available from its manufacturer, this thesis endeavour to cover all these aspects. Thus, the thesis presents a brief understanding of how to use the Baxter Robot in a simple and efficient way to perform a basic industrial task. The kinematics part will show the concepts of forward and inverse kinematics and the DH (the Denavit–Hartenberg) parameters that are important to understand the end-effector position according to the world frame that will give the knowledge of those who are interested in the kinematics part of Baxter robot. The work of the thesis will make it easier to understand how to program a Baxter robot by using Python language and using the simplest way to move the arm to certain positions. The ROS principles, kinematics and Python language programs will provide a good platform to understand the usability of Baxter robot. Furthermore, easy to use laboratory tutorials are devised and are presented in the appendices. These laboratory tutorials will improve the understanding of the readers and provide a step-by-step guide of operating Baxter robot according to the principles of Robotics. In addition to all these points above, the thesis shows useful functions that are built in ROS (Robot Operating System) that make it easier to program the robot in an untraditional way which is one of a contribution of this thesis itself. The usual way to program the robots, in general, is to study the robot kinematics and calculate the position of the end-effector or the tool according to some frame or the world coordinate frame. This calculation can be done by the forward kinematics or the inverse kinematics. The set of programming Baxter robot in this thesis is not the complex calculation of the forward or the inverse kinematics. The tf (transform)tool in ROS has made it easier to reach the joint angles and program Baxter robot using Python.

  • 6.
    Asami-Johansson, Yukiko
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Conditions and constraints for transferring Japanese structured problem solving to Swedish mathematics classroom2019In: Article in journal (Refereed)
  • 7.
    Asami-Johansson, Yukiko
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Japanese Mathematics Teachers’ Professional Knowledge: International case studies based on praxeological analysis2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis describes and studies the Japanese mathematics teachers’ professional knowledge and its dissemination. This theme is investigated in several concrete situations: the knowledge of teaching practice of school mathematics taught in the teacher education, the relation between the educational goals described in the national curriculum and concrete teaching methods discussed among the Japanese lower secondary teachers in service. The thesis investigates also critical phenomena, which arise in an attempt to transfer the Japanese teaching practice in a different teaching context.

  • 8.
    Asami-Johansson, Yukiko
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics. University of Copenhagen, Copenhagen, Denmark.
    The Didactic Notion of “Mathematical Activity” in Japanese Teachers’ Professional Scholarship: A case study of an open lesson2019In: International Journal of Mathematical Education in Science and Technology, ISSN 0020-739X, E-ISSN 1464-5211Article in journal (Refereed)
  • 9.
    Asami-Johansson, Yukiko
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Attorps, Iris
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Japanese and Swedish Mathematics Teacher Educators’ Pedagogical Content Knowledge: An Institutional Perspective2019In: Educaçao Matemática Pesquissa, ISSN 1983-3156, Vol. 21, no 4, p. 157-170Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to investigate which kind of conditions and constraints affect Japanese and Swedish teacher educators’ pedagogical content knowledge (PCK). We analyse the praxeologies of the lessons in which the educators teach area determination. Our study shows that the Japanese teacher educators’ PCK are more explicitly shared by the community of the teacher educators compared to the Swedish counterpart. Also, the detailed Japanese curriculum and the structured problem solving approach promote to illustrate how to construct rich mathematical and didactical organisations for prospective teachers.

  • 10.
    Asami-Johansson, Yukiko
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Attorps, Iris
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Laine, Anu
    University of Helsinki, Helsinki, Finland.
    Comparing the practices of primary school mathematics teacher education Case studies from Japan, Finland and Sweden2017In: PROCEEDINGS OF THE TENTH CONGRESS OF THE EUROPEAN SOCIETY FOR RESEARCH IN MATHEMATICS EDUCATION (CERME10) / [ed] Dooley, T.; Gueudet, G., Dublin, 2017, p. 1602-1609Conference paper (Refereed)
    Abstract [en]

    In this study, we have observed three different teacher educators’ lessons, concerning area determination of polygons in primary school teacher training courses in Japan, Finland and Sweden. The aim of this paper is to investigate the main elements of the lessons and to compare the differences between the countries. We focus on how the teacher educators relate the didactic construction of the lessons for prospective teachers to the school mathematical and didactical organisations by applying Chevallard’s anthropological theory of the didactic (ATD). The analysis shows how the curricula and the different traditions of teaching practice in each country influence the mathematical and didactical construction of the lessons.

  • 11.
    Asami-Johansson, Yukiko
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics. Department of Science Education, University of Copenhagen, Copenhagen, Denmark.
    Attorps, Iris
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Winsløw, C.
    Department of Science Education, University of Copenhagen, Copenhagen, Denmark.
    Comparing mathematics education lessons for primary school teachers: case studies from Japan, Finland and Sweden2019In: International Journal of Mathematical Education in Science and Technology, ISSN 0020-739X, E-ISSN 1464-5211Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to investigate and compare lessons given in primary school teacher education in Japan, Finland and Sweden. We analyse one lesson from each country and compare them using a common framework. Chevallard’s anthropological theory of the didactic (ATD) is used to frame this analysis and in particular to model teacher educators' didactic organization of the lessons. The focus is on how the didactic organizations of the teacher educators relate to the mathematical and didactic organizations of primary school. Based on official documents and viewpoints of the teacher educators, we also discuss how the contents and descriptions of the national curricula, and the different traditions of the teaching practices in each country, influence the didactic organizations found in the lessons. 

  • 12.
    Azadehnia, Arefeh
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    What benefits will 5G be for small and mid-sized companies?2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The fifth generation of mobile communication (5G) is the latest generation of wireless technology and it is expected to have an immense opportunity for great different number of industries. This technology is going to meet current wireless technologies limitations and enable fully smart factories. Some large companies intend to developing their communication technologies to 5G, however, there are some surveys showing that small and mid-sized enterprises (SMEs) have paid less attentions to this technology and also they adopt the mindset of wait-and-see which increase the possibility of failing their business. The reason can be that SMEs mostly do not have IT specialists or researchers and due to the lack of financial resources for research in communication information technology (CIT) and automation. Consequently, enhancing their automation systems is going to be very costly and perhaps risky. The risk of this is that, many times due to using old technologies, their competitors will overcome them in the business. This research aims to study the benefit of the 5G for small and middle size manufacturing and to explore if 5G is an optimal solution for SMEs network communication. To provide that, five companies are selected and investigated in Gävleborg and Dalarna counties in Sweden. Then each company is interviewed individually and the evaluations are done by an observing survey and review of the literature. The investigation shows that wired systems are still providing the main communication network technologies in SMEs. Besides, current communication issues that SMEs are dealing with are usually due to using insufficient technologies. In other hands, current radio access is still based on the advanced LTE, whereas the 5G, which is promised to meet all a fully smart industrial requirements is known as 5G New radio (NR), is still on the progress and predicted to have expensive implementation.

    On the other hand, in future when 5G NR system will be widespread accessible everywhere, and also when we will have optimal and straightforward factory ecosystem transformation, broad 5G applications and simple IT-support the business, a fundamental change is going happen on the way of business scenery for all size of enterprises. As a consequence, if SMEs do not adapt themselves to the new technology and new business model, they will go out of the business.

  • 13.
    Backman, Mathilda
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Se mig!: En studie om matematiskt särskilt begåvade elever2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien är att utforska vilka uppfattningar lågstadielärare har av matematiskt särskilt begåvade elever, samt undersöka vilka arbetssätt lärare har för att motivera och stimulera de här eleverna i matematik. Studien har en metod med kvalitativ ansats med en fenomenografisk och fenomenologisk inriktning. Datainsamlingsmetoden för studien är intervjuer. Fyra lärare intervjuades och de är alla något så när överens om att matematiskt särskilt begåvade elever skiljer sig från andra elever, samt på vilket sätt de gör det. Lärarnas uppfattningar av matematiskt särskilt begåvade elever överensstämmer även med tidigare forskning gällande ämnesområdet. Samtliga lärares arbetssätt innehåller extra anpassningar för de här eleverna och största skillnaden som kunnat urskiljas mellan arbetssätten är huruvida de även innehåller särskilt stöd. Till viss del överensstämmer dessa uppfattningar även med tidigare forskning då det även där råder oenigheter om matematiskt särskilt begåvade elever ska differentieras eller inte.

  • 14.
    Bai, S.
    et al.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Christensen, S.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Islam, M.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Rafique, Sajid
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Masud, Nauman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Mattsson, Per
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    O’Sullivan, L.
    University of Limerick, Limerick, Ireland.
    Power, V.
    University of Limerick, Limerick, Ireland.
    Development and testing of full-body exoskeleton AXO-SUIT for physical assistance of the elderly2019In: Wearable Robotics: Challenges and Trends: Proceedings of the 4th International Symposium on Wearable Robotics, WeRob2018, October 16-20, 2018, Pisa, Italy / [ed] Maria Chiara Carrozza, Silvestro Micera, José L. Pons, Cham: Springer, 2019, Vol. 22, p. 180-184Conference paper (Refereed)
    Abstract [en]

    This paper presents the design and preliminary testing of a full-body assistive exoskeleton AXO-SUIT for older adults. AXO-SUIT is a system of modular exoskeletons consisting of lower-body and upper-body modules, and their combination as full body as well to provide flexible physical assistance as needed. The full-body exoskeleton comprises 27 degrees of freedom, of which 17 are passive and 10 active, which is able to assist people in walking, standing, carrying and handling tasks. In the paper, design of the AXO-SUIT is described. End-user testing results are presented to show the effectiveness of the exoskeleton in providing flexible physical assistance.

  • 15.
    Bautista Gonzalez, Oscar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Integration of a Wireless Sensor Network and IoT in the HiG university2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The number of Internet of Things applications for Wireless Sensor Networks is increasing every year due to the emerging of new brands such as Big Data and Industry 4.0. With the rise of new technologies related to these fields, new opportunities have become possible with a reasonable cost, but the requirements of WSNs still being the same, where energy efficiency, robustness, scalability and others must be accomplished. The commercial hardware developed by companies can be configured through different programs to be compatible among them, taking into account multiple variables, protocols, mechanisms and options provided by new solutions. Therefore, the configuration of different devices and choosing the optimum configuration can become quite challenging due to the number of paths. In this thesis, the configuration of commercial devices provided is carried out to be able to apply this hardware in different Internet of Things applications for Wireless Sensor Networks. Transceivers, sensors of temperature, relative humidity and CO2, a gateway, and different development kits are provided on this work, where the selection of the software to set these devices is made. Repeaters are configured to be compatible with the sensors and perform under the TDMA protocol and the request-response pattern, which synchronize the communication on the network, and under the flooding mechanism, which allows to route packets through the nodes due to the short range of RF low power technologies. The connection between the WSN and the Internet is made through the GW, which is also connected to the WSN, under the TCP/IP protocol, which is configured to provide Message Queue Telemetry Transport and SecureSHell services to access the GW remotely through the Internet and send requests to the WSN automatically. Node-Red is the programming tool installed upon the GW to implement data processing, storage and visualization, via the JavaScript programming language, where the user can deploy the data, which is stored in a CSV file, to make an analysis and visualize the data and the status of the network through a live data dashboard. Finally, an experiment is carried out over the HiG university where sensors are placed to measure different halls of the university and integrate an Internet of Things application for a Wireless Sensor Network. Due to the followed process, we have been able to measure data of temperature, relative humidity and CO2 concentration levels, creating a WSN, where this data has been saved in a connected USB to the gateway. Having a performance of 90% of messages received by the GW, and we have also been able to connect the GW to the Internet, creating a system that can be accessed remotely via the MQTT broker and providing different services such as data visualization. 

  • 16.
    Berg, Björn
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Sun, Tao
    Johansson, Maj-Britt
    Sanborn, Paul
    Ni, Xiangying
    Lönn, Mikael
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Magnesium dynamics in decomposing foliar litter - a synthesis2019In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259Article in journal (Refereed)
  • 17.
    Berglund, Jessica
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Vill du spela bingo med mig?: En studie med laborativt material för att utveckla elevers kunskaper om positionssystemet2019Independent thesis Advanced level (degree of Master (Two Years)), 240 HE creditsStudent thesis
    Abstract [sv]

    Studiens syfte är att med hjälp av en learning study med förtest och eftertest undersöka elevers förkunskaper om positionssystemet samt om elever genom laborativt material kan fördjupa sina kunskaper om positionssystemet. Studiens teoretiska utgångspunkt är hämtad från variationsteorin. Att arbeta med ett laborativt material möjliggör för eleverna att utveckla en utökad förståelse för positionssystemet med basen 10. En av slutsatserna från denna studie är att ett variationsteoretiskt perspektiv på undervisningen underlättar lärandet.

  • 18.
    Bergman, Karl-Olof
    et al.
    Linköping University.
    Burman, Joseph
    Swedish University of Agricultural Sciences; anterbury Christ Church UniversityCanterburyUK.
    Jonason, Dennis
    Linköping University.
    Larsson, Mattias C.
    Swedish University of Agricultural Sciences.
    Ryrholm, Nils
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Westerberg, Lars
    Linköping University.
    Milberg, Per
    Linköping University.
    Clear-cuts are temporary habitats, not matrix, for endangered grassland burnet moths (Zygaena spp.)2019In: Journal of Insect Conservation, ISSN 1366-638X, E-ISSN 1572-9753Article in journal (Refereed)
    Abstract [en]

    Burnet moths (Zygaena spp.) are day-flying Lepidoptera considered indicative of species-rich grasslands. In the present study, our aim was to clarify whether clear-cuts are habitat, supporting habitat or matrix for three species of Zygaena. We did so by sampling these species with sex pheromones on 48 clear-cuts, varying in amount of host and nectar plants, in southern Sweden. To compare the efficiency of such sampling, we also conducted transect walks on these clearcuts. Overall, host-plants on clear-cuts best explained the abundance of Zygaena spp. recorded, better than nectar-plants or connectivity with nearby grasslands. These results indicate that clear-cuts with an abundance of host plants are used as a fully functional habitat, and not a supporting habitat in the sense of only providing nectar. There is no support in these results for considering clear-cuts as an inert matrix. With about half the work-effort, pheromone traps recorded 100 times more Zygaena spp. as transect walks. The poor correspondence between observations during transects walks and pheromone trap catches suggest Zygaena spp. being difficult to monitor by transect walks. In contrast to grasslands, clear-cuts are short-term in nature requiring repeated recolonization, indicating the importance of permanent grasslands. However, clear-cuts are important temporary insect habitats due to their great acreage, and suitable management can increase the time they remain a habitat.

  • 19.
    Bergroth, Simon
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Implementering av MPPT-enhet med återkoppling: avsedd för solceller2019Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
  • 20. Birkedal, Sven
    et al.
    Ryrholm, Nils
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Hultengren, Svante
    Fritz, Örjan
    Dagfjärilar en fältguide2019Book (Other academic)
    Abstract [sv]

    I denna nya fältguide till svenska dagfjärilar beskrivs drygt 180 arter, underarter, former och tillfälliga besökare. Boken är rikt illustrerad och fjärilarna åtföljs av fotografier på hane, hona och undersida jämte grafiska bilder över utbredningar och flygtider. Boken är den tredje i Naturcentrums serie om växter och djur i Sverige. Tidigare har "Lavar - en fältguide" och "Mossor en fältguide" utgivits.

    Ett kort inledande avsnitt beskriver bokens tillkomst, hur den är uppbyggd, terminologi, litteratur samt lite om fjärilsskådning. Därefter följer bokens huvuddel som utgörs av artbeskrivningarna och ca 1.000 illustrationer ledsagar läsaren. Boken, som omfattar 200 sidor, är framtagen av Sven Birkedal, naturälskare och fotograf från Åhus. Fjärilsforskaren Nils Ryrholm har stått för kompletterade texter och beskrivningar, vetenskaplig granskning, utbredningskartor, flygtider, m. m.

  • 21.
    Björk, Petter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Hur stor är sannolikheten?: En studie om traditionellt och laborativt lärande inom sannolikhetsläran2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att förklara, analysera och jämföra traditionell och laborativ undervisning inom matematikens sannolikhetslära genom learning study. Studien syftar även till att synliggöra elevernas upplevelser från de olika undervisningsmetoderna. Under en veckas matematiklektioner är klassens elever indelas i en kontroll- och testgrupp. Med hjälp av för- och eftertest, traditionell och laborativ undervisning inom sannolikhetslära, enkäter och anteckningar jämförs elevernas resultat och skillnader i elevernas uppfattningar. Learning study påvisar en ökning av elevernas kunskaper beträffande sannolikhetslära i grupperna. Eleverna i testgruppen framlägger även positiva åsikter beträffande de laborativa undervisningstillfällena.

  • 22.
    Blank, Jonathan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Motivation till matematik: En kvalitativ studie om hur elever i årskurs 4–6 kan motiveras i matematikundervisningen ur ett lärarperspektiv2019Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att undersöka hur lärare arbetar med att motivera elever i årskurs 4–6 i matematik. För att undersöka detta genomfördes klassrumsobservationer och semistrukturerade intervjuer med tre verksamma lärare i årskurs 4–6. Studiens resultat visar att en hög motivation hos eleverna skapas av tydliga strukturer i klassrummet, att läraren synliggör målen för eleverna, att läraren varierar sina arbetssätt och undervisningsformer samt att eleven tar ansvar för sitt eget lärande. 

  • 23.
    Bui, Tuyet T. A.
    et al.
    Laboratory of Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium.
    Wright, Sandra A. I.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Falk, Anders B.
    Valthornsvagen, Uppsala, Sweden.
    Vanwalleghem, Tanja
    Department of Mycology, Proefcentrum Fruitteelt vzw, Sint-Truiden, Belgium.
    Van Hemelrijck, Wendy
    Department of Mycology, Proefcentrum Fruitteelt vzw, Sint-Truiden, Belgium.
    Hertog, Maarten L.A.T.M.
    Division of MeBioS, Department of Biosystems, Faculty of Bioscience Engineer-ing, KU Leuven, Leuven, Belgium.
    Keulemans, Johan
    Laboratory of Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium.
    Davey, Mark W.
    Laboratory of Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium.
    Botrytis cinerea differentially induces postharvest antioxidant responses in 'Braeburn' and 'Golden Delicious' apple fruit2019In: Journal of the Science of Food and Agriculture, ISSN 0022-5142, E-ISSN 1097-0010, Vol. 99, no 13, p. 5662-5670Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The fruit of two apple cultivars - 'Braeburn', which is susceptible to inoculation with Botrytis cinerea, and the less susceptible cv. 'Golden Delicious' - were investigated with respect to their response to inoculation with B. cinerea. Successful infection by B. cinerea leads to an oxidative burst and perturbation of plant redox homeostasis. To investigate the interaction between apple fruit and B. cinerea, antioxidant metabolism in fruit samples from sun-exposed and shaded sides of different tissue types was measured over time.

    RESULTS: The sun-exposed tissue of 'Braeburn' had higher initial levels of total vitamin C in the peel and phenolic compounds in the flesh than 'Golden Delicious', despite its greater susceptibility to gray mold. A substantial antioxidant response was recorded in diseased 'Braeburn' fruit 14 days after inoculation, which involved an elevated superoxide dismutase activity and ascorbate peroxidase activity, a progressive oxidation of total vitamin C, and a decrease in peroxidase activity and phenolic content. Disease development was slower on the sun-exposed sides than on the shaded sides.

    CONCLUSION: The two cultivars appeared to utilize different strategies to defend themselves against B. cinerea. 'Golden Delicious' almost entirely escaped infection. Preharvest exposure of apple fruit to high light / temperature stress appears to prepare them to better resist subsequent postharvest attack and disease. 

  • 24.
    Burman, Elin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Är det inne med utomhuspedagogik?: En enkätundersökning om lärares inställningar till utomhuspedagogik2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med arbetet var att undersöka lärares inställningar till utomhuspedagogik. Genom att belysa möjligheter och redogöra för hinder för utomhuspedagogisk verksamhet kan arbetet inspirera och motivera lärare och lärarstudenter till att använda sig av utomhuspedagogik, samt skapa diskussion. Den datainsamlingsmetod som använts i detta arbete är en webbaserad enkätundersökning som distribuerats via mejl till skolor i Stockholm. Resultatet visar att samtliga lärare som svarade ser möjligheter med utomhuspedagogik där ökad förståelse, möjligheten att upptäcka och uppleva naturen samt hälsofrämjande aspekter är de mest framträdande. Resultatet visar att det största hindret är bristen på personal. Resultatet visar även att lärare på skolor i innerstaden, upplever närmiljön som ett större hinder än lärare på skolor utanför innerstaden. Min undersökning visar på flera möjligheter med utomhuspedagogisk verksamhet.

  • 25.
    Cappello, Barbara
    et al.
    Politecnico di Torino, Torino, Italy.
    Shestopalov, Yury
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Matekovits, Ladislau
    Politecnico di Torino, Torino, Italy.
    Analysis of the surface impedance of a sinusoidally modulated metasurface2019In: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), IEEE, 2019, p. 0075-0077Conference paper (Refereed)
    Abstract [en]

    Metasurfaces have been extensively exploited in recent years for mantle cloaking applications. In this type of problems it is of fundamental importance to determine the connection between the metasurface geometrical parameters and the realised value of surface impedance, in order to properly design the metasurface. In this paper the surface impedance of a non homogeneous metasurface, based on a sinusoidally modulated metallic pattern is analysed.

  • 26.
    Carlqvist, Rebecca
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Inspirerad teknikundervisning i grundskolans årskurs 1–3: Granskning, utvärdering och undersökning av ett inspirationsmaterial till teknikundervisning i grundskolan2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med det här arbetet har varit att undersöka teknikundervisningen i olika skolor samt att undersöka ett inspirationsmaterial som heter: ”200 timmar teknik”. Det har valts att använda båda kvantitativa och kvalitativa metoder i och med en enkät, semistrukturerade intervjuer samt materialtest med efterföljande diskussion. Resultatet har visat på att teknikundervisningen skiljer sig till viss del i olika skolor och genomförs inte i en annan. Skilda åsikter presenteras utifrån behovet, för verksamma lärare i årskurs 1–3, av inspirationsmaterialet samt och framtida möjligheter. Resultatet genererar en slutsats att teknik som begrepp är svårtolkat, men det behöver inte nödvändigtvis påverka hur en lärare förhåller sig till teknikundervisningen. Trots skilda åsikter verkar ändå ett material som ”200 timmar teknik” vara nödvändigt för verksamma lärare med behörighet i årskurs 1–3.

  • 27.
    Carpio, A. J.
    et al.
    University of Cordoba, Spain; IREC (UCLM-CSIC-JCCM)Instituto de Investigación en Recursos CinegéticosCiudad RealSpain.
    De Miguel, R. J.
    University of Cordoba, Spain.
    Oteros, J.
    Center of Allergy and Environment (ZAUM), Member of the German Center for Lung Research (DZL)Technische Universität München/Helmholtz CenterMunichGerman.
    Hillström, Lars
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Tortosa, F. S.
    University of Cordoba, Spain.
    Angling as a source of non-native freshwater fish: a European review2019In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 21, no 11, p. 3233-3248Article in journal (Refereed)
    Abstract [en]

    In a context of the growing concern about the impact of biological invasions, our objective is to review the role of those non-native species that have primarily been introduced for angling purposes in at least one European country. We are particularly interested in: (1) the relative role of sport fish species in the context of non-native species introductions; (2) assessing the relative importance of different fish taxa; (3) identifying similarity patterns in the composition of the angling fish species introduced throughout the continent, and (4) assessing the underlying factors that drive their diversity in Europe. According to our results, 23.6% of the freshwater fish introduced into Europe during the last century were released primarily for angling purposes. The species composition differed among countries, with a higher diversity of introduced angling species in larger countries and in those with a greater GDP per capita, along with a lower latitude. This review stresses that angling was a significant pathway for the introduction of invasive fish species into Europe in the last century. Furthermore, some of the introduced angling species had severe environmental impacts on many European regions. However, introductions of non-native angling species are still occurring. Therefore, existing EU regulations need better enforcement as well as to increase public awareness regarding invasive fish. This will help to preserve biodiversity and improve the sustainability of current angling schemes in increasingly managed European freshwater ecosystems. However, non-native fish could make angling sustainable, although not for biodiversity generally.

  • 28.
    Christensen, Simon
    et al.
    Aalborg University, Aalborg, Denmark.
    Bai, Shaoping
    Aalborg University, Aalborg, Denmark.
    Rafique, Sajid
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Isaksson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    O'Sullivan, Leonard
    University of Limrick, Limerick, Ireland.
    Power, Valerie
    University of Limrick, Limerick, Ireland.
    Virk, Gurvinder Singh
    Innovative Technology and Science Limited, Cambridge, United Kingdom.
    AXO-SUIT: A Modular Full-Body Exoskeleton for Physical Assistance2019In: Mechanism Design for Robotics: Proceedings of the 4th IFToMM Symposium on Mechanism Design for Robotics / [ed] Alessandro Gasparetto and Marco Ceccarelli, Cham: Springer Netherlands, 2019, Vol. 66, p. 443-450Chapter in book (Refereed)
    Abstract [en]

    This paper presents the design of a modular full-body assistive exoskeleton (FB-AXO) for older adults which was developed with funding under the AAL funded AXO-SUIT project. Processes used to formulate a prioritized set of functional and design requirements via close-end-user involvement are outlined and used in realizing the exoskeleton. Design of the resulting mechanics and electronics details for the lower and upper-body subsystems (LB-AXO and (UB-AXO)) are described. Innovative designs of shoulder and spine mechanisms are presented. TheFB-AXO system comprises 27 degrees of freedom, of which 17 are passive and 10 active. The exoskeleton assists full-body motions such as walking, standing, bending, as well as performing lifting and carrying tasks to assist older users performing tasks of daily living.

  • 29.
    Dahlqvist, Rebecka
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Kan lika gärna skriva siffrorna upp och ner, det står väl samma sak ändå?: En studie om hur lärarna upptäcker och hjälper elever med matematiksvårigheter2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att ta reda på hur lärarna upptäcker och hjälper elever med matematiksvårigheter. För att kunna besvara undersökningens frågeställningar har kvalitativa intervjuer gjorts med olika lärare. Resultatet analyserades med hjälp av kognitivismen och konstruktivismens som mitt analysverktyg. Undersökningen visar på att lärarna var eniga om vilka tydliga tecken som var specifikt för matematiksvårigheter, eleverna tappar koncentrationen och räknar oftast på fingrarna istället för huvudräkning. En del lärare var positiva till digitala verktyg i undervisningen medan andra föreslog hellre praktiskt material till eleverna med svårigheter. Det som kan tänkas ligga till grund för matematiksvårigheter är motivationen och nivån på undervisningen.

  • 30.
    Danarp, Pernilla
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Att lära biologi: Lärares och elevers uppfattning om motivationsfaktorer2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien var att synliggöra hur lärare arbetar för att försöka motivera elever i ämnet biologi samt undersöka i vilken grad eleverna uppfattar lärares olika motivationfaktorer som viktiga för deras egen motivation. Studien har genomförts via lärarintervjuer samt via elevenkäter. Intervjuresultatet visade att lärare i årskurs två och tre i sina försök att motivera elever lyfte motivationsfaktorer utifrån delaktighet, skapa intresse, läraregenskaper, arbetsmetoder, undervisningsrum, föräldraengagemang, bekräftelse, relationer och föräldraattityd. Lärarnas motivationsarbete motsvarade till stor del elevernas egna motivationsfaktorer. Det som minst svarade mot elevernas motivationsfaktorer var bekräftelse från andra. Enkätsvaren lyfter fram betydelsen av goda relationer och bra samarbete samt betydelsen av att eleven får hjälp av läraren och förstår undervisningsmaterialet. I resultatet framkommer att både lärare och elever i högre grad betonar motivatorer som är kopplade till inre motivation än till motivatorer kopplade till yttre motivation.

     

  • 31. De Marco, Anna
    et al.
    Berg, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Zarrelli, A.
    Virzo De Santo, Amalia
    Changes in soil C and N pools across a chronosequence on volcanic parent material following afforestation with Pinus pinea and Pinus nigra Arn.2019In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259Article in journal (Refereed)
  • 32.
    Dong, Lili
    et al.
    Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
    Sun, Tao
    Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
    Berg, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology. Department of Forest Sciences, University of Helsinki, Helsinki, Finland.
    Zhang, Lili
    National Engineering Laboratory for Soil Nutrient Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
    Zhang, Quanquan
    School of International Education, Beijing University of Chemical Technology, Beijing, China.
    Wang, Zhengwen
    Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
    Effects of different forms of N deposition on leaf litter decomposition and extracellular enzyme activities in a temperate grassland2019In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 134, p. 78-80Article in journal (Refereed)
    Abstract [en]

    Despite the importance of decomposition for biogeochemical cycles, it is still not clear how this process is affected by different forms of nitrogen (N). Equal amounts of N with different ratios of inorganic N: organic N (0 : 0, 10 : 0, 7 : 3, 5 : 5, 3 : 7, and 0 : 10) were added to the soil in a steppe. We studied the response of litter decomposition to different forms of N enrichment. The treatment with 30% organic N resulted in the fastest decomposition, which was higher than with inorganic N or organic N addition alone. Our results highlight the need for studies of N deposition on carbon cycles that consider different components in N deposition.

  • 33.
    Ehl, Stefan
    et al.
    Biogeography, Trier University, Trier, Germany; Senckenberg German Entomological Institute, Müncheberg, Germany.
    Holzhauer, Stephanie I. J.
    Senckenberg German Entomological Institute, Müncheberg, Germany; Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany.
    Ryrholm, Nils
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Schmitt, Thomas
    Senckenberg German Entomological Institute, Müncheberg, Germany; Entomology, Department of Zoology, Institute of Biology, Faculty of Natural Sciences I, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
    Phenology, mobility and behaviour of the arcto-alpine species Boloria napaea in its arctic habitat2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, no 1, article id 3912Article in journal (Refereed)
    Abstract [en]

    Arctic and alpine environments present extreme, but different, challenges to survival. We therefore studied the ecological adaptation of the arctic-alpine fritillary Boloria napaea in northern Sweden and compared these results with the eastern Alps. Using mark-release-recapture, we analysed phenology, mobility, activity patterns, change in wing condition and nectar sources. The phenology showed no protandry, but a longer flight period of the females. Wing conditions revealed a linear decay being quicker in males than females. The mean flight distances were higher for males than females (143 vs 92 m). In general, males were more flight active, while females invested more time in feeding and resting. The shortness of the flight period in the Arctic is apparently a particular adaptation to these harsh conditions, not even allowing protandry, and constraining all individuals to hatch during a short period. These conditions also forced the individuals to concentrate on flight and alimentation. In general, Arctic and Alpine populations of B. napaea show few differences, but the species seems to be even better adapted to the northern environments. Thus, the short temporal separation of these populations seems not to have been sufficient for a divergent adaptation in the southern mountains.

  • 34.
    Enterfeldt, Caroline
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Specialundervisning i matematik2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 35.
    Eriksson, Johan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Studie av arkitektur för visuellt övervakningssystem vid fjärrstyrt underhåll av järnvägar2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 36.
    Fried, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Relevansen i dagens matematikinnehåll för gymnasieskolans yrkesprogram enligt Skolverkets läroplan Lgy-112019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med examensarbetet är att ta reda på hur relevant matematiken är för eleverna på yrkesprogrammen. Detta med anledning av att den här kategorin elever har högst andel elever med låg motivation och med låga meritvärden från grundskolan. Hur kan undervisningen bedrivas för bästa resultat och förståelse så den går att applicera på det kommande yrket men samtidigt också vara allmänbildande. Matematiken som yrkeseleverna lär sig idag ska vara både allmänbildande och yrkesrelaterad. Den allmänbildande matematiken är lika för alla yrkeselever medan den karaktärsrelaterade matematiken varierar. Med anledning av detta så är de nationella proven konstruerade på så sätt att de tar upp enbart den allmänna kunskapen i matematik. Därför finns också funderingar om varför yrkeselever behöver göra de nationella proven. För att försöka få svar på frågorna har intervjuer genomförts med ämneslärare, yrkeslärare på båda programmen och elever från vartdera programmet. Även elev som gått i skolan men är yrkesverksam nu har intervjuats.  Även Studier har gjorts mot tidigare forskning inom områden som berör yrkeselevernas matematikundervisning, deras svårigheter med matematik och hur de kan bli motiverade. Resultaten från intervjuerna jämfördes sedan mot den litteratur som studerats. Valet av yrkesinriktningar föll på Bygg- och anläggningsprogrammet samt Barn- och fritidsprogrammet då det är inom dessa inriktningar jag varit i kontakt med tidigare. Resultatet visar att matematiken är relevant då det är ämneslärarens uppgift att förhålla sig till den matematik som är nödvändig men att kursböckerna är allom rådande i de flesta fall. Matematikundervisningen ger bäst resultat för yrkesrelaterade kunskaper om matematikläraren samarbetar med yrkeslärarna vilket både intervjuerna och forskning visar. De nationella proven ansågs av de flesta som något bra då syftet med de nationella proven är att mäta den allmänna matematikkunskapen hos eleverna.

  • 37.
    Gautam, Mukesh Kumar
    et al.
    Division of Earth and Environmental Sciences, Korea Basic Science Institute, Ochang, Chungbuk, Republic of Korea; Biology Department, Medgar Evers College, City University of New York, New York, NY, USA.
    Lee, Kwang-Sik
    Division of Earth and Environmental Sciences, Korea Basic Science Institute, Ochang, Chungbuk, Republic of Korea.
    Berg, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology. Department of Forest Sciences, University of Helsinki, Helsinki, Finland.
    Song, Byeong-Yeol
    Division of Earth and Environmental Sciences, Korea Basic Science Institute, Ochang, Chungbuk, Republic of Korea; Chemical Analysis Division, National Forensic Service, Wonju, Republic of Korea.
    Yeon, Jeh-Yeong
    Division of Earth and Environmental Sciences, Korea Basic Science Institute, Ochang, Chungbuk, Republic of Korea.
    Trends of major, minor and rare earth elements in decomposing litter in a cool temperate ecosystem, South Korea2019In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 222, p. 214-226Article in journal (Refereed)
    Abstract [en]

    The decomposition dynamics of 34 different elements in four different litter types (foliar and woody litter) from Pinus densiflora (Korean red pine) and Castanea crenata (Korean chestnut) was investigated in a cool temperate ecosystem using the litterbag method. Two contrasting trends were observed in the dynamics of elements with accumulated mass loss of litter and carbon. Leaf litter of Korean chestnut, which was richer in elements, showed a general decrease in concentrations of elements with accumulated mass loss of litter and carbon on a dry mass basis during decomposition in the field. Other litter types, with initially lower concentrations of elements, exhibited an increase in concentration on a dry mass basis during field incubation. Highest relative increase in the concentration was noticed for the minor elements, and for the woody litters. Concentrations of major and minor elements increased by factors ranging from 1.07 for antimony (Sb) to 853.7 for vanadium (V). Rare earth elements (REE) concentrations increased by factors ranging from 1.04 for scandium (Sc) to 83.5 for thorium (Th). Our results suggest that litter type plays an important role for nutrient dynamics. Results from principal component analysis for major, minor, and rare earth elements showed grouping of elements and high correlation among them (P < 0.05), which suggests a common source. At both sites, element concentrations were high in the soil, especially for REE. This suggests that increase in element concentrations during field incubation probably was due to transfer of elements from soil to the overlying decomposing litter.

  • 38. Gautam, Mukesh
    et al.
    Lee, K-S.
    Berg, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Song, B.Y.
    Spatial distribution of elements in the soil, vegetation and litter in a cool temperate ecosystem, South Korea2019In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298Article in journal (Refereed)
  • 39.
    Ge, Jielin
    et al.
    Chinese Acad Sci, Inst Bot, State Key Lab Vegetat & Environm Change, 20 Nanxincun, Beijing 100093, Peoples R China..
    Berg, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology. Univ Helsinki, Dept Forest Sci, Helsinki, Finland..
    Xie, Zongqiang
    Chinese Acad Sci, Inst Bot, State Key Lab Vegetat & Environm Change, 20 Nanxincun, Beijing 100093, Peoples R China.;Univ Chinese Acad Sci, Beijing 100049, Peoples R China..
    Climatic seasonality is linked to the occurrence of the mixed evergreen and deciduous broad-leaved forests in China2019In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, no 9, article id e02862Article in journal (Refereed)
    Abstract [en]

    Evergreen and deciduous broad-leaved tree species can coexist across the globe and constitute different broad-leaved forests along large-scale geographical and climatic gradients. A better understanding of climatic influence on the distribution of mixed evergreen and deciduous broad-leaved forest is of fundamental importance when assessing this mixed forest's resilience and predicting potential dynamics of broad-leaved forests under future climate change. Here, we quantified the horizontal distribution of this mixed forest in mountains in relation to climate seasonality by compiling vegetation information from the earlier records and our own field sampling on major subtropical mountains of China. We found that the probability of occurrence of this forest in subtropical mountains was positively associated with the latitude but not the longitude. The occurrence probability of this forest was observed at high-temperature but not precipitation seasonality mountains. Temperature seasonality was five times more important than precipitation seasonality in explaining the total variation of occurrence of this mixed forest. For its distribution, our results shed light on that temperature seasonality was generally a more powerful predictor than precipitation seasonality for montane mixed forest distribution. Collectively, this study clearly underscores the important role of temperature seasonality, a previously not quantified climatic variable, in the occurrence of this mixed forest along geographical gradients and hence yields useful insight into our understanding of climate-vegetation relationships and climate change vulnerability assessment in a changing climate.

  • 40.
    Gustafsson, Kajsa
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Rörelse för lärande: Vilka är lärares kunskaper om och deras förhållningssätt till fysisk aktivitet för ökad inlärning?2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Denna studies syfte var att undersöka lärare och lärarstudenters kunskaper och uppfattningar om fysisk aktivitet för ökad inlärning. Vilka möjligheter som skolor ges till fysisk aktivitet var också ett av studiens syfte. Studien har en kvalitativ forskningsansats genom att enkäter med slutna frågor har använts tillsammans med uppföljande semistrukturerade intervjuer som metod för att besvara studiens forskningsfrågor. Arton lärare har genomfört enkät via skolbesök och sex av dem har deltagit i uppföljande intervjuer. Dessutom har 246 respondenter besvarat enkäten via länk i sociala medier. Resultatet visar på att lärare och lärarstudenter har uppfattningen om att fysisk aktivitet är en viktig faktor för inlärning. Resultatet visar även att den fysiska aktiviteten har positiva bieffekter inte bara på hjärnans funktioner utan även på elevernas sociala utveckling. Respondenterna i studien är eniga om att fysisk aktivitet påverkar elevers inlärning vilket borde motivera ännu fler till att använda och utforska metoden.

  • 41.
    Gustrin, Malin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Utomhuspedagogik: Hur kan man implementera regelbunden utomhuspedagogik i Grundskolan åk 1-3?2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 42.
    Hadin, Joacim
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    IT i matematikklassrummet: en resurs eller ett problem?: En undersökning av elevers och matematiklärares upplevelser av och inställningar till tillämpningar av IT i matematikklassrummet2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Under de senaste åren så har IT blivit ett allt mer normaliserat inslag i den svenska skolan. Även om digitaliseringen av skolan har pågått under en längre tid, så har majoriteten av den digitala utvecklingen skett under de senaste fem åren.  Även om den digitala utvecklingen har bidragit till en ökad mängd läranderesurser för lärare, så har denna rapida utveckling också medfört till att många lärare har bristande kunskaper gällande hur IT bör hanteras. En relativt betydelsefull fråga är således hur IT har påverkat den svenska gymnasieskolan. Baserat på den data som samlades in i Skolverkets (2016) studie, så kunde man konstatera att matematik är det ämne där IT används i lägst utsträckning i det svenska gymnasieklassrummet. Till följd av detta, så är utbudet av forskning kring IT:s påverkan på matematikundervisning nästintill obefintligt. Det finns därför ett samhälleligt behov av att undersöka hur IT påverkat matematikämnet. Syftet med detta arbete är följaktligen att undersöka hur IT har påverkat matematikundervisningen i den svenska skolan. För att kunna undersöka detta så har perspektiv och synpunkter från både elever och matematiklärare i den svenska gymnasieskolan samlats in och analyserats, med hjälp av blandade undersökningsmetoder. En av de slutsatser som framkommit ur studien är att många elever upplever att IT borde användas i en högre utsträckning inom matematikämnet. En annan slutsats som kan dras är att många lärare saknar kunskap och erfarenhet av att använda IT i matematikklassrummet, vilket vidare är en av de bidragande anledningarna till att många lärare väljer att inte använda IT matematikklassrummet.

  • 43.
    Haider, Usama
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Smart Maintenance using System Identification2019Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project discusses the use of System Identification for Smart Maintenance. System Identification is the process of finding a mathematical model of a system using empirical data. The mathematical model can then be used to detect and predict the maintenance needs, which is considered as Smart Maintenance. Smart maintenance strategies have gained pretty much importance recently, since it contributes to economically sustainable production. This project uses the LAVA-framework, proposed in [1] for non-linear system identification, which has the capability of explaining the dynamics of the system very well, and at the same time follows the principle of parsimony. A nominal model is first identified using data from a system that operates under normal operating conditions, then the identified nominal model is used to detect when the system starts to deviate from normal behavior, and these deviations indicate the deteriorations in the system. Furthermore, a new Multiple Model Method which is developed in [2] using the similar idea from LAVA, is applied on the large data set of a system that operates on separate batches and units, which identifies individual model for each batch and unit, which is then used to detect the deficient units or batches and changes in the system behavior. Finally, the proposed methods are applied to two different real world industrial cases; a Heat exchanger and a Wood Moulder Machine. In the first, the purpose is to detect the dirt in a Heat Exchanger, and in the second, the goal is to detect when the tool in a Wood Moulder Machine needs to be changed.

  • 44.
    Hernandez-Martinez, Paul
    et al.
    Swinburne University of Technology.
    Thomas, Stephanie
    Loughborough University.
    Viirman, Olov
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics. University of Agder.
    Rogovchenko, Yuriy
    University of Agder.
    "I'm still making dots for them": mathematics lecturers' views on their mathematical modelling practices2019In: International Journal of Mathematical Education in Science and Technology, ISSN 0020-739X, E-ISSN 1464-5211Article in journal (Refereed)
    Abstract [en]

    Using Cultural-Historical Activity Theory, we analyze lecturers’ views on the aims and teaching practices of mathematical modelling (MM) education in Norway and England. We aim to expose the tensions that exist within the activity of teaching MM at university, such as those between multiple, sometimes competing, aims for teaching MM, or between the lecturers’ professional identities and the structure of university degrees. Our conceptualization of these tensions might help lecturers consider how to overcome obstacles in their own contexts.

  • 45.
    Heyd-Metzuyanim, Einat
    et al.
    Technion, Israel Institute of Technology.
    Adler, Jill
    University of the Witwatersrand.
    Lavie, Irit
    Haifa University.
    Nachlieli, Talli
    Levinsky College.
    Tabach, Michal
    Tel Aviv University.
    Robertson, Sally-Ann
    Rhodes University.
    Graven, Mellony
    Rhodes University.
    Viirman, Olov
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Research Forum: Rituals and explorations in mathematical teaching and learning2019In: Proceedings: 43rd Annual Meeting of the International Group for the Psychology of Mathematics Education (Vol. 1) / [ed] Mellony Graven, Hamsa Venkat, Anthony A Essien and Pamela Vale, 2019, Vol. 1, p. 137-164Conference paper (Refereed)
  • 46.
    Hjalmarsson, Adam
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    ”Jordens resurser är inte oändliga, de tar slut och det gäller att vara rädd om våran jord”: - En kvalitativ intervjustudie gällande lärares användning av utomhuspedagogik angående hållbar utveckling2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien är att undersöka lärares uppfattningar av utomhuspedagogik med avseende på hållbar utveckling i urbana miljöer med inriktning på naturvetenskap och teknik under grundskolans tidiga år. Studiens utformning var av kvalitativ karaktär med intervjuer. Inter- vjuerna gjordes med semi-strukturerade intervjufrågor för att svara mot studiens syfte. Urvalet bestod av sex lärare som undervisar i grundskolans tidiga år från skolor i västra Sverige.

    Alla lärare förmedlar en positiv inställning till att bedriva utomhuspedagogik. De menar att de anser att det är viktigt att förmedla hållbar utveckling till eleverna eftersom det är de som är ”framtiden”. Majoriteten av lärarna i studien beskriver att de undervisar mindre utomhus nu än för tio år sedan. Dessutom, har flera av lärarna svårt att beskriva utomhusaktiviteter för att förmedla hållbar utveckling. Det finns flera olika anledningar till varför lärarna i studien inte undervisar utomhus gällande hållbar utveckling men även i andra ämnen. Anledningarna be- skrivs av lärarna som elevgrupper, stress, planering, tidsbrist och okunskap.

  • 47.
    Holmgren, Elin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Matematikinlärning med digitala verktyg för årskurserna F-3: - En studie som jämför svenska digitala verktyg med internationell forskning inom ämnet.2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 48.
    Händel, Peter
    et al.
    Department of Information Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Modeling Mixer and Power Amplifier Impairments2019In: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 29, no 7, p. 441-443, article id 8733818Article in journal (Refereed)
    Abstract [en]

    Combating the effects of mixer and power amplifier (PA) imperfections on transmitter performance is crucial for the design of wireless systems. PA compression and in-phase/quadrature imbalance are analyzed for a single-input-single-output transmitter model. The influence of the imperfection on the normalized mean squared error (NMSE) of the transmitter is studied using an analytical framework that relies on the classic Bussgang theory. The study concludes with a closed-form expression for the NMSE that provides insights into the behavior of the transmitter. © 2019 IEEE.

  • 49.
    Ivanchenko, Igor
    et al.
    O.Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine, Ukraine.
    Khruslov, Maksym
    O.Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine, Ukraine.
    Popenko, Nina
    O.Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine, Ukraine.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Combined L–S-bands antenna module2019In: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 13, no 5, p. 541-545Article in journal (Refereed)
    Abstract [en]

    A combined L-S-band antenna module consists of four rectangular patch antennas, two of which operate at the frequencies of the first harmonics (L-band), and two others at the frequencies of the second harmonics (S-band). The module is intended for use in super heterodyne signal reception circuits, for example in studying the various non-linear phenomena. The results of this study are presented in terms of improving the performance of each antenna and minimising their mutual influence. The resonance frequencies of the L-band antenna differ by 50MHz. All the antennas radiate close to the zenith and their beamwidths in two principal planes are virtually the same. At the resonance frequencies, the reflection coefficient is S-11<-30dB for the transmitting antenna, and S-11<-20dB for the receiving antenna. The minimum allowable distance between the antennas is determined, at which their mutual influence can be neglected (S-12<-50dB).

  • 50.
    Ivarsson, Lena Norback
    et al.
    Sodertorn Univ, Sch Nat Sci Technol & Environm Studies, Huddinge, Sweden..
    Andren, Thomas
    Sodertorn Univ, Sch Nat Sci Technol & Environm Studies, Huddinge, Sweden..
    Moros, Matthias
    Leibniz Inst Baltic Sea Res Warnemunde, Rostock, Germany..
    Andersen, Thorbjorn Joest
    Univ Copenhagen, Dept Geosci & Nat Resource Management, Copenhagen, Denmark..
    Lönn, Mikael
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology. Södertörn Univ.
    Andren, Elinor
    Sodertorn Univ, Sch Nat Sci Technol & Environm Studies, Huddinge, Sweden..
    Baltic Sea Coastal Eutrophication in a Thousand Year Perspective2019In: Frontiers in Environmental Science, ISSN 2296-665X, Vol. 7, article id 88Article in journal (Refereed)
    Abstract [en]

    Sediment cores from three sites along the east-coast of Sweden, north-western Baltic Proper, have been studied with respect to lithologies, geochemistry, and diatom assemblages to trace and date early human impact with emphasis on nutrient discharge. The three sites Braviken, Himmerfjarden, and Adfjarden, have been impacted to various degree during the last millennia by multiple stressors like excessive nutrient discharge and hazardous substances, leading to coastal hypoxia, eutrophication, and pollution. These stressors are mainly caused by drivers in the drainage area as increased human population, changed land use, and point sources as industries and a sewage treatment plant. Even though their detailed history differs, the results show similar general patterns for all three sites. We find no evidence in our data from the coastal zone supporting the hypothesis that the extensive areal distribution of hypoxia in the open Baltic Sea during the Medieval Climate Anomaly was caused by human impact. Timing of the onset of man-made eutrophication, as identified from delta N-15 and changes in diatom composition, differs between the three sites, reflecting the site specific geography and local environmental histories of these areas. The onset of eutrophication dates to similar to 1800 CE in Braviken and Himmerfjarden areas, and to similar to 1900 CE in the less urban area of Adfjarden. We conclude that the recorded environmental changes during the last centuries are unique in a thousand year perspective.

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