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  • 1.
    Abbo, Mari
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Elevers perspektiv på motiverande matematikundervisning i grundskolans tidigare år2020Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    I denna studie har jag undersökt vilka lärandeaktiviteter som bidrar till en ökad motivation för elevers inlärning. För att göra detta har jag använt mig av en kvalitativ forskningsmetod. Studiens datamaterial utgjordes av enkäter och intervjuer med elever i årskurs 3 i grundskolan. Resultatet av studien visar att det är huvudsakligen två faktorer som motiverar eleverna i deras matematiklärande. Läraren beskrevs som den största påverkande faktorn genom att eleverna jämförde olika lärare med varandra. Eleverna framhöll även hur en varierad matematikundervisning bidrog till att göra undervisningen lustfylld. Det gemensamma för denna studie samt tidigare studier inom området är att en varierad och lustfylld undervisning bidrar till motiverade elever.

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  • 2.
    Abgaryan, Garnik V.
    et al.
    Department of Applied Mathematics and Artificial Intelligence, Institute of Computational Mathematics and Information Technology, Kazan Federal University, Kremlevskaya Street 35, Kazan 420008, Russia.
    Shestopalov, Yury
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics. Russian Technological University MIREA, Moscow 119454, Russia.
    TE-Polarized Electromagnetic Wave Diffraction by a Circular Slotted Cylinder2023In: Mathematics, E-ISSN 2227-7390, Vol. 11, no 9, article id 1991Article in journal (Refereed)
    Abstract [en]

    The problem of diffraction of a TE-polarized electromagnetic wave by a circular slotted cylinder is investigated. The boundary value problem in question for the Helmholtz equation is reduced to an infinite system of linear algebraic equations of the second kind (SLAE-II) using integral summation identities (ISI). A detailed study of the matrix operator of the problem is performed and its Fredholm property in the weighted Hilbert space of infinite sequences is proven. The convergence of the truncation method constructed in the paper for the numerical solution of SLAE-II is justified and the results of computations are presented and discussed, specifically considering the determination of resonance modes.

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  • 3.
    Abraham, Yoseph
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Development of Advanced X-ray Micro-Tomography Helical Scan andTomographic Data Processing2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Micro-computed tomography (Micro-CT) is an imaging technique that allows for high-resolution,three-dimensional (3D) internal visualization of small objects in a non-destructive manner. However,a significant limitation arises when attempting to image elongated samples at higher resolutions andmagnifications due to the inherently small field of view (FOV). This thesis project introduces anapproach aimed at overcoming this limitation by combining helical scanning with the utilization ofthe open-source Astra Toolbox. The toolbox provides flexible scanning geometry parametrizationand facilitates tomographic reconstruction using the Feldkamp-Davis-Kress (FDK) algorithm.Helical data scanning represents a departure from traditional data acquisitions. Instead ofcapturing data at a fixed height, helical scanning acquires data by rotating and translating theimaged sample. This acquisition process extends the effective FOV, enabling the reconstruction oflarger samples. To illustrate this approach, a micro-CT helical scan was performed on a pencil asan elongated sample and compared with a conventional circular scan.While Micro-CT is a powerful imaging tool, it faces challenges when imaging weakly attenuating materials with hard X-rays. X-ray radiation possesses both amplitude and phase components,but conventional CT can only capture intensity information. This limitation often leads to poorcontrast in images of weakly absorbing samples. To address this issue, the project also designedpost-processing software to enhance CT image quality through phase retrieval. Phase informationprovides better contrast for small structures of weakly absorbing materials compared to intensityalone. The Paganin phase-retrieval algorithm is employed to retrieve this phase information, resulting in improved contrast-to-noise ratio (CNR) in tomographic reconstructions and subsequentsegmentation. As a result, the generated images exhibit sharper delineations and offer a morecomprehensive representation of the sample’s internal structure, especially after 3-D rendering.In summary, in this thesis, I designed the micro-CT procedure both from acquisition with anadvanced helical scanning technique and from a post-processing point of view through designingsoftware with a phase retrieval algorithm. The project has improved the conventional microCT intwo aspects, namely the field of view and the phase contrast. 

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  • 4.
    Adamsson, Maria
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Undersökande arbetssätt: inom naturvetenskap och teknik i årskurs 4-62020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att söka kunskap om hur lärare och elever arbetar med undersökande arbetssätt, inom ämnena naturvetenskap och teknik i årskurs 4-6. I studien deltog en lärare och elever i årskurs 5 på en kommunal grundskola i Mellansverige. Kvalitativa metoder används i undersökningen samt i analysen och materialet har samlats in genom klassrumsobservationer. Resultatet av studien visar att eleverna, i alla fall till viss del, arbetar med undersökande arbetssätt men att de skulle gynnas av att träna mer på de olika momenten för att sedan själva kunna genomföra egna undersökningar. Kopplingen till det naturvetenskapliga området behöver också göras tydligare, det är lätt att få uppfattningen att det enbart är undersökningar som ingår i arbetssättet. Att tydliggöra de olika delarna i undersökande arbetssätt skulle kunna göra det lättare för lärare att undervisa i ämnet och ge eleverna mer likvärdiga kunskaper i naturvetenskap och teknik, oavsett lärare och skola.

     

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  • 5.
    Agrell, Jenny
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    ”Det de gör med händerna, det minns de”: En intervjustudie om laborativt material i årskurs 1–32023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna studie är att förstå lärares resonemang om användningav laborativt material inom aritmetik i årskurs 1–3. Arbetet syftar även till att undersöka hur lärare resonerar kring vad som har betydelse för deras aritmetikundervisning med avseende pålaborativt material. För att uppnå syftet har semistrukturerade intervjuer med sju lärare genomförts. De data som samlats in har analyserats med hjälp av en tematisk analys och tolkats med den sociokulturella teorin som teoretiskt ramverk. Studiens resultat visar att lärarna använder laborativa material i olika syften där att underlätta för att eleverna ska gå från konkret till abstrakt förståelse är mest framträdande. Det som har högst betydelse i lärarnas aritmetikundervisning med laborativa material visar sig vara influenser från andra lärare och från internet. Slutsatserna som kan dras är att lärare kan ha svårt att veta hur de ska gå vidare från det laborativa materialet med elever som har svårt för aritmetik. Lärarna önskar även mer utbildning i hur de kan använda laborativa material med sina elever.

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  • 6.
    Ahlenius, Milla
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Hur mycket är klockan?: Lågstadieelevers kunskaper om att avläsa och mäta tid2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien är att skapa förståelse för lågstadieelevers kunskaper inom ämnesområdet mätning av tid. Studien baseras på ett skriftligt kvantitativt klocktest som 13 elever i årskurs 2 och 5 elever i årskurs 3 har genomfört, samt kvalitativa elevintervjuer som fyra elever i respektive årskurs har genomfört. Klocktesten har analyserats numeriskt och elevintervjuerna har analyserats tematiskt. Den teoretiska utgångspunkten är den sociokulturella teorin med inslag av lösningsstrategier. Studiens resultat indikerar att lågstadieelever har bättre kunskaper om den analoga klockan, jämfört med den digitala klockan. När eleverna har löst uppgifter om avläsning och mätning av tid har de främst använt strategin räkna uppåt. Slutsatsen som kan dras utifrån det är att lågstadieelever har kunskaper om klockan, men det finns kunskapsskillnader mellan de olika klocktyperna och mellan eleverna. Samtliga elever kunde redogöra för minst en lösningsstrategi som användes vid klockuppgifterna men strategierna fungerade olika bra. 

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  • 7.
    Ahlin, Eddie
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Implementation and standardization of vibration measurements in strip production processes2023Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Within the era of the fourth industrial revolution the steel production industry is faced with demands of lower environmental impact and more cost-effective production are some of the challenges faced. To achieve more sustainable and efficient manufacturing processes companies try to digitalize and automate their production to a greater extent. Creating more robust, energy-efficient and adaptable solutions to increase the competitiveness of their company.

    This master thesis is about reverse engineering an existing solution for vibration measurements used at Alleima Strip. The goal was to create a new in-house solution for vibration measurements according to local programming standards using an ABB AC500v2 CPU paired with a FM502-CMS module. Using vibration measurements as a health indicator Alleima Strip hopes to progress their way of working with maintenance towards being more condition based.

    The result is a solution for vibration measurements customized for Alleima Strip. The report contains suggestions for improvements of the developed solution as well as ideas for future work.

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  • 8.
    Ahlin, Eddie
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Presentation och lagring av data från vibrationsmätning utförd i ett kallvalsverk2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The fourth industrial revolution means that the steel manufacturing industry are faced with great challenges, where less environmental impact combined with high competition sets high expectations for the manufacturing method of steel. To achieve improvements in manufacturing and raise competitiveness, many manufacturers choose to digitalize their businesses to a greater extent. As a step in the digitalization process, Sandvik SMT Strip has chosen to extend one of their existing control systems with a CMS-module and sensors for vibration measurement.

    This bachelor thesis intends to present a proof of concept for presenting and storing data collected through vibration measurement in a cold rolling mill at Sandvik SMT Strip. The thesis work will be part of a pilot project at Sandvik SMT Strip. The goal of the pilot project is to achieve a well implemented vibration measurement solution to be able to use more predictive maintenance instead of the proactive and reactive maintenance used today. If an adaptation can be achieved where predictive maintenance is used to a larger extent the prospects are to save resources and time.

    The method for this thesis work has been experimental work in which the desired results have been governing. The result of this thesis work is a solution proposal for storing and presenting the data of vibration measurement in both time and frequency domain. Some parts of the solution proposal have been started with the goal to achieve a proof of concept.

    The conclusion presented in this thesis work is that an implementation for storing and presenting collected data with the desired soft- and hardware is possible, but more time is needed to obtain a proof of concept.

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  • 9.
    Ahmed, Rijon
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Evaluation, Design & Development of a Prototype 3-Link Mini Robot Manipulator2022Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    A 3-link robotic arm was designed, constructed, and tested as part of the thesis work. This prototype will assist students in applying their robotics and control system theory knowledge to real results. The kinematic equations are created to help with trajectory planning. Evaluation of different parameters was determined like (angles at which the servo motor operated, link length at which the servo can carry, spatial velocity, DH parameter, and Homogeneous transformation matrix). An Arduino-based closed-loop control system is built. Four Servo motors were used which are being controlled by Arduino UNO and Leonardo. The Arduino IDE is used to write proper codes. The main aim of the study was to apply the knowledge of robotics and control systems to develop a functional mini robot from scratch. Specifically, the thesis presents how to build a robotic arm that can move and lift objects. And, this task is done by using different controlling techniques where potentiometer, Bluetooth Module, and IR senor were used and compared which technique gives better results. The structural components had several issues. The project's linkages foundation and gripper are all 3-D printed pieces that are being designed using Autodesk Inventor Professional 2021 software. Although they did not cause any problems with strength, there were some difficulties with properly tightening the gears onto the shaft. To overcome these difficulties glue is being used so that all servo motors hold with the link properly. In a broad sense, the robot can position and orient the end-effector to pick and place the object accurately from a distance.

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  • 10.
    Ahmed, Sipan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Java integrering med PLC2020Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    Digitization has been given a greater role in the monitoring and control of a processing plant. This trend will grow globally to achieve a smarter production chain that generates ecenomic profits.

    The purpose of this thesis was to develop an existing process that respresents an automated drilling station. THis i scontrolled by integrating Java-netbeans software into the PLC hardware with a user interface that can read the data flow of PLC.The drilling station is controlled by PLC.

    This work describes the possible methods for achieving integration between Java-netbeans and PLC.

     The essential part of the work was literature study, programming of source code and programming of PLC. This work achieved all the objectives.

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  • 11.
    Akash, Md Abdur Rahman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Prediction of industrial machine failure by analysing anomalies2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The sudden downtime and unplanned maintenance not only drastically increase the maintenance cost but also decreases the production capacity for the manufacturer industries. This is because the machines on these industries fail suddenly and totally stop the production as the machine should be fixed by maintenance before it can run again. To deal with it, several maintenance techniques have been adopted. But as soon as an automated maintenance technique comes in named predictive maintenance, the future machine failure can be predicted. To perform this prediction, a synthetic dataset is used that is taken from 100 industrial machines. From this dataset, the simulated sensor data, error, and failure history have used to calculate the probability of error and failure during the time period of an anomaly. This probability is calculated by the basic probability equation. In addition, the sum of the calculated probability of error and failure, give the intuition about the most relevant sensor data for a machine. This relevant sensor data is then used as response for the prediction with gaussian process regression algorithm. This prediction of response is shown for machine number 85 which is the most important from all 100 machines as this machine is very sensitive to any of the 4 sensor anomalies. Then, the sum of probability can be coherent with the anomaly on the predicted response which is the most relevant sensor data. This defines that the machine is in high risk of experiencing machine failure and thus the machine should be fixed by adopting maintenance. In contrast, the opposite is also true for low probability of error and failure for an anomaly on the predicted response. To evaluate the performance of the algorithm, four statistical metrics are used among which three matric is to estimate the errors and the other one is the correlation coefficient between the actual and predicted data. 

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  • 12.
    Alanko, Tobias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Detektering och identifiering av sur mjölk och ruttet kött i ett kylskåp med hjälp av en elektronisk näsa.2020Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    To find devices mimicking the human nose have under some time been an area of interest for researchers. These devices can potentially be a useful tool to achieve UN: s global goals for sustainable development, Agenda 2030.

    This project is an experimental quantitative study with the aim to investigate the possibility to create a stand-alone measuring system for detecting and identifying spoiled milk and rotten meat in a fridge.

    A wireless measuring system with an array of gas sensors was developed together with interface for remote control. Measurements was made from known measuring objects for two weeks. Thereafter measurements of unknown measuring objects were also done for two weeks.

    The result of the study showed that the developed measuring system can be remotely controlled to detect and identify spoiled milk and rotten meat without external software. The measuring system has an accuracy of 89% when it comes to classify unknown measurement objects.

    This study shows that the measuring system can detect and identify spoiled milk and rotten meat via remote control.

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  • 13.
    Alekseev, Gennady
    et al.
    Institute of Applied Mathematics FEB RAS, Vladivostok, Russia; School of Natural Sciences, Far Eastern Federal University, Vladivostok, Russia .
    Tereshko, Dmitri
    Institute of Applied Mathematics FEB RAS, Vladivostok, Russia.
    Shestopalov, Yury
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Optimization approach for axisymmetric electric field cloaking and shielding2021In: Inverse Problems in Science and Engineering, ISSN 1741-5977, E-ISSN 1741-5985, Vol. 29, no 1, p. 40-55Article in journal (Refereed)
    Abstract [en]

    In this paper we study inverse problems of electric conductivity that arise in the design of spherical shielding or cloaking shells and other functional devices used to control static electric fields. The shells are considered consisting of a finite number of layers filled with homogeneous isotropic or anisotropic medium. The inverse problems under study are reduced to control problems with the layers electric conductivities taken as controls. A different choice of minimized functionals allows us to solve a wide range of design problems using one approach. A numerical algorithm to solve these problems is based on particle swarm optimization. Various results of numerical experiments are discussed in order to find the most effective designs. The findings obtained in this study describe a broad set of specific easy-to-manufacture structures that have the highest cloaking or shielding performance in the class of layered shells.

  • 14.
    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
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  • 15.
    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
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  • 16.
    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.

  • 17.
    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 1759-0787, Vol. 11, no 10, p. 989-999Article 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.

  • 18.
    Alsanius, Beatrix
    et al.
    VKM; SLU.
    Magnusson, Christer
    VKM; NIBIO.
    Nicolaisen, Mogens
    VKM; Aarhus University.
    Wright, Sandra A. I.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology. VKM.
    Wendell, Micael
    VKM.
    Krokene, Paal
    VKM; NINBIO.
    Stenberg, Johan
    VKM; SLU.
    Thomsen, Iben M
    VKM; University of Copenhagen.
    Rafoss, Trond
    VKM; University of Agder.
    Assessment of treatment methods and validation criteria for composting and biogas facilities in relation to plant health risks and the risk of spreading alien organisms: Scientific Opinion of the Panel on Plant Health of the Norwegian Scientific Committee for Food and Environment2021Report (Other academic)
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  • 19.
    Altberg, Lena
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Utveckling och utvärdering av en lektionsplanering gällande densitet i naturorienterande ämnen för årskurs 2-3.2021Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
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  • 20.
    An, Siwen
    et al.
    Mittuniversitet.
    Reza, Salim
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Norlin, Börje
    Mittuniversitet.
    Fröjdh, Christer
    Mittuniversitet.
    Thungström, Göran
    Mittuniversitet.
    Signal-to-noise ratio optimization in X-ray fluorescence spectrometry for chromium contamination analysis2021In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 230, article id 122236Article in journal (Refereed)
    Abstract [en]

    In most cases, direct X-ray fluorescence (XRF) analysis of solutions entails technical difficulties due to a high X-ray scattering background resulting in a spectrum with a poor signal-to-noise ratio (SNR). Key factors that determine the sensitivity of the method are the energy resolution of the detector and the amount of scattered radiation in the energy range of interest. Limiting the width of the primary spectrum by the use of secondary targets, or filters, can greatly improve the sensitivity for specific portions of the spectrum. This paper demonstrates a potential method for SNR optimization in direct XRF analysis of chromium (Cr) contamination. The suggested method requires minimal sample preparation and achieves higher sensitivity compared to existing direct XRF analysis. Two states of samples, fly ash and leachate from municipal solid waste incineration, were investigated. The effects of filter material, its absorption edge and filter thickness were analyzed using the combination of Monte Carlo N-Particle (MCNP) code and energy-dispersive XRF spectrometry. The applied filter removes primary photons with energies interfering with fluorescence photons from the element of interest, thus results in lower background scattering in the spectrum. The SNR of Cr peak increases with filter thickness and reaches a saturation value when further increased thickness only increases the measurement time. Measurements and simulations show that a Cu filter with a thickness between 100 μm and 140 μm is optimal for detecting Cr by taking into account both the SNR and the exposure time. With direct XRF analysis for solutions, the limit of quantitation (LOQ) of the achieved system was 0.32 mg/L for Cr, which is well below the allowed standard limitation for landfills in Sweden. This work shows that XRF can gain enough sensitivity for direct monitoring to certify that the Cr content in leachate is below environmental limits.

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  • 21.
    Anbessa, Gedion Biredaw
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Implementation of Spectrum Analysis Functionality for IQ-Signal.2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The spectrum analyzer is a standard tool used to measure signals in the frequency domain. Traditional spectrum analyzers are based on sweeping a local oscillator and using this to mix signals down to an intermediate frequency (IF) and, subsequently filter them with a filter of settable characteristics, called the Resolution Bandwidth (RBW). This is still the preferred method when the requirement on dynamic range of the signals being measured is large. However, this approach has the drawbacks of being relatively slow, not adaptive and flexible for some specific need and certain special measurement functionalities cannot be done due to the sweeping. Due to this, Ericsson production test development would like to perform software-based spectrum analysis on sampled In-phase and Quadrature (IQ) signals.

    In this thesis, the introduction of IQ-signals and synthetic spectrum analysis (SSA) are presented. The statistical properties of root mean-square (RMS) and sample detectors for standard spectrum analyzer are investigated. The effect of swept time on statistical properties of the RMS and sample detectors were investigated and the results are presented in this work. The results of swept time effect for sample detector show the change in the variance of the statistical properties when continuous wave (CW) and two-tone test signals were used, however, for bandlimited Gaussian test signal, the variance of the statistical properties is not changed. For RMS detector, the swept time using two-tone and Gaussian test signals show the change in the variance of the statistical properties. Whereas, for CW test signal the statistical properties result in shift from higher power distribution level to lower power distribution level with increase in sweep-time.

    The emulation of spectrum analysis functionalities (RBW, envelope detector and 0detectors) for IQ-signal has been implemented in MATLAB. The verification of the implemented functionalities has been done by investigating the statistical properties of RMS and sample detectors for SSA for various test signals. These were found to agree with standard spectrum analyzer results.

    Moreover, the comparison of spectral traces and statistical properties between implemented functionality and standard spectrum analyzer have done. The results are showing agreement with industrial standard spectrum analyzer results.

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  • 22.
    Andersson, Amanda
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science. Amanda Andersson.
    Kemiundervisningsstrategier utifrån två perspektiv – sociokulturellt- och pragmatiskt perspektiv.2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med arbetet är att genomföra en undersökning som ska kartlägga vilken undervisningsstrategi utav det sociokulturella- och det pragmatiska perspektivet som lämpar sig för och gynnar elevernas kunskapsprogression bäst vid kemiundervisning. Undersökningen utfördes genom att eleverna fick delta vid ett antal undersökningslektioner. Deltagarna fick även göra ett för- och eftertest som utgjorde underlaget för elevernas kunskapsprogressioner. För att fastställa vilken undervisningsstrategi eleverna föredrog, fick de även delta vid en enkätundersökning. Undersökningens resultat är att det är svårt att finna den utav dessa strategier som lämpar sig bäst för alla kemiundervisnings-områden. Undersökningen visade att elevernas kunskapsprogressioner efter utförandet av de olika strategierna ofta berodde på elevernas förkunskaper i ämnet. Eleverna bedömde att undervisning utifrån det pragmatiska perspektivet var mer motiverande för dem, än det sociokulturella perspektivet.

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    Kemiundervisningsstrategier utifrån två perspektiv – sociokulturellt- och pragmatiskt perspektiv
  • 23.
    Andersson, Jenny
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Undervisningsstrategier i biologi - ett f-3 lärarperspektiv2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Undersökningens syfte var att undersöka vilka undervisningsstrategier behöriga lärare tillämpar i sin biologiundervisning och varför, med det övergripande syftet att diskutera och reflektera kring arbetssätt och metoder som kan skapa en varierad undervisning i biologi. Semistrukturerade intervjuer gjordes med sex behöriga f-3 lärare samt observationer vid två lärares lektioner. Arbetssätten och metoderna som lärarna tillämpar i sin biologiundervisning resulterade i fyra huvudkategorier: Praktiskt arbete, teoretiskt arbete, digitala verktyg och samarbete. Undersökningen visade att flest praktiska arbetssätt och metoder tillämpades av lärarna i biologiundervisning och det även var flest argument för praktiskt arbete. Flest gemensamma argument för praktiskt arbete är att eleverna får nyttja fler sinnen. Genom att lärarna använde och gav många argument för olika arbetssätt och metoder är slutsatsen att lärarna i denna kommun i stor utsträckning varierar sina arbetssätt och metoder i biologiundervisningen.

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  • 24.
    Andersson, Rabé
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    The Robustness and Energy Evaluation of a Linear Quadratic Regulator for a Rehabilitation Hip Exoskeleton2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The implications of gait disorder, muscle weakness, and spinal cord injuries for work and age-related mobility degradation have increased the need for rehabilitation exoskeletons. Specifically, the hip rehabilitation exoskeletons due to a high percentage of the mechanical power is generated by this join during the gait cycle. Additionally, the prolonged hospitalisation after hip replacement and acetabular surgeries that affect human mobility, the social-economic impacts and the quality of life. For these reasons, a hip rehabilitation exoskeleton was our focus in this research, as it will contribute being a sustainable solution to take over the burden of physiotherapy and let patients perform their rehabilitation at home or outdoors. 

    This thesis details an approach of creating a hip rehabilitation exoskeleton, starting with modelling, simulating, and controlling the rehabilitation hip joint in a based-simulation environment. The mathematical model and the reason for using a series elastic actuator in the hip joint to execute the movement in a sagittal plane are more detailed. Because trajectory tracking is commonly used for controlling rehabilitation exoskeletons to ensure safe and reliable motion tracking methods; therefore, two desired torque signals were tested and analysed with the optimal linear quadratic regulator (LQR). The experiments were performed using two torque signals of a healthy hip joint—representing the sit-to-stand (STS) and the walking activity for their importance in lower limb movements. However, the mathematical model used as a basis of the optimal control strategy is usually influenced by multiple sources of uncertainties. Therefore, four case studies of various optimal control strategies were tested for a twofold reason: to choose the most optimal control strategy, and to test the energy consumption of these cases during the STS and walking movements, because the long-term goal is to produce a lightweight and reliable rehabilitation hip exoskeleton.

    The research showed compelling evidence that tuning the control strategy will not influence the robustness of an optimal controller only, but affect the energy consumption during the STS and walking activity, which needs to be considered in exoskeleton control design regarding its applications.

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  • 25.
    Andersson, Rabé
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    The Energy Consumption and Robust Case Torque Control of a Rehabilitation Hip Exoskeleton2022In: Applied Sciences, E-ISSN 2076-3417, Vol. 12, no 21, article id 11104Article in journal (Refereed)
    Abstract [en]

    Gait disorders, muscle weakness, spinal cord injuries (SCIs) and other work-related disorders have increased the need for rehabilitation exoskeletons—specifically, for the hip because a huge percentage of mechanical power comes from the hip joint. However, realising a lightweight rehabilitation hip exoskeleton for mobility and at-home use with reliable control is challenging. The devices developed are restricted by a joint actuator and energy source design and tend to have various uncertainties. Thus, this study tested the robustness of four optimal controller cases in a simulation-based environment. We sought to determine whether the most robust optimal controller consumed less energy and demonstrated better performance in tracking the desired signal. The robustness of the optimal cases was tested with the hip torque signals of healthy subjects. The number of sit-to-stand (STS) instances and the walking distance at various speeds were calculated. The results showed that the most robust case controller was more energy efficient for STS, but not for walking activity. Furthermore, this study provides compelling evidence that various optimal controllers have different degrees of robustness and effects on energy consumption.

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  • 26.
    Andersson, Rabé
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    The MATLAB Simulation and the Linear Quadratic Regulator Torque Control of a Series Elastic Actuator for a Rehabilitation Hip Exoskeleton2022Conference paper (Refereed)
    Abstract [en]

    Almost the half of mechanical energy of a human gait cycle is generated by a hip joint. Therefore, this paper discusses a rehabilitation hip exoskeleton, starting with the modeling, simulation and ending with controlling its hip joints. A MATLAB based simulation environment with the use of Simscape Multibody toolbox was utilized to design and control the robotic hip exoskeleton. More details of adding a series elastic actuators (SEA) to the hip joints with the mathematical model are presented. However, the linearised mathematical model of the entire exoskeleton was found in simulation software which establish the basic need of controlling hip joints. The trajectory tracking is commonly used of controlling rehabilitation exoskeleton and to ensure a safe and reliable motion tracking methods, two desired torque signals were tested and analysed with the optimal linear quadratic regulator (LQR). The experiments with two torque signals–representing the sit-to-stand (STS) and the walking activity, demonstrated good performance of the motion gait tracking based on torque signals of a healthy person, which is carried out in the simulation environment. Furthermore, some studies in a human robot interaction are also mentioned in this paper.

  • 27.
    Andersson, Rabé
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    The Technical Challenges in Orthotic Exoskeleton Robots with Future Directions: a Review Paper2023Conference paper (Refereed)
    Abstract [en]

    The robotic wearable exoskeletons have been developed due to various advantages offered by these devices. These advantages are manifested by integrating the human and a robot into one system under the user's control, which motivated researchers to develop different exoskeletons through years. However, several advances in exoskeleton; still, dealing with the various technical challenges in designing these impressive devices is inevitably. This paper aims to introduce informative resources and quick guidance of various technical challenges as such information is critical for exoskeleton development. The constructive discussion is intended to encourage researchers, innovators and academia to be aware of these challenges. Finally, the contemporary research gaps with various challenges have been highlighted, which remain to be solved as well as some future directions in this field that will have far-reaching effects on developing exoskeletons.

  • 28.
    Andersson, Rabé
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Björsell, Niclas
    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.
    Robots are a promising investment to fight pandemics2021In: 2021 8th International Conference on Signal Processing and Integrated Networks (SPIN), IEEE , 2021, p. 458-463Conference paper (Refereed)
    Abstract [en]

    Coronavirus caused pandemics as many viruses did through human history. The current pandemic causes overwhelmed healthcare system, locked down cities, and massive fatality among humans. Thus, different robots have been used since the COVID outbreak worldwide to reduce spreading infectious diseases and support frontline healthcare workers. This paper sets out the different robots implemented for hospital, non-hospital use, and possible use that can be deployed amidst the pandemic. A literature survey of versatile robots during COVID-19 is introduced. Roboticists contributed with wheeled and drone robots with various applications to assist medical care systems and society during the ongoing crisis. Pandemics are common throughout human history and difficult to avoid or prevent; thus, we intend to encourage societies, academia, engineers and innovators to invest more in robots that cannot catch the virus and consequently introduce beneficial solutions to fight such pandemic in the future.

  • 29.
    Andrews, Paul
    et al.
    Stockholms universitet.
    Palm Kaplan, Kristina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    PISA, TIMSS and Swedish students' knowledge of linear equations: A 'telling' case of a system fixing something that may not be broken2020In: Annales Universitates Paedagogicae Cracoviensis. Studia ad Didacticam Mathematicae Pertinentia, ISSN 2080-9751, Vol. 12, p. 5-29Article in journal (Refereed)
    Abstract [en]

    In this paper, we construct a 'telling' case to highlight a problematic inconsistency between the results of international large-scale assessments (ILSAs) and other studies of Swedish students' knowledge of linear equations. In this context, a 'telling' case, based on the scrutiny of appropriately chosen cases, is presented as a social science counter-example to the prevailing view that ILSAs' assessments are not only valid but should underpin systemic reform. Our 'telling' case comparison of the different forms of study shows that Swedish students, in contrast with the summative assertions of the different ILSAs, have a secure and relational understanding of linear equations that persists into adulthood. We conclude with a cautionary message for the curriculum authorities. 

  • 30.
    Argume, A.
    et al.
    Universidad Privada de Tacna, Peru.
    Coaguila, R.
    Universidad Católica de Santa María, Peru.
    Yanyachi, P. R.
    Universidad Nacional San Agustin de Arequipa, Peru.
    Chilo, José
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    NOAA Image Data Acquisition to Determine Soil Moisture in Arequipa - Perú2021In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 68, no 8, p. 1933-1936Article in journal (Refereed)
    Abstract [en]

    In recent years, irrigations have been built on dry areas in Majes-Arequipa. Over time, the irrigations water forms moist areas in lower areas, which can have positive or negative consequences. Therefore, it is important to know in advance where the water from the new irrigation will appear. The limited availability of real-time satellite image data is still a hindrance to some applications. Data from environmental satellites NOAA (National Oceanic and Atmospheric Administration) are available fee and license free. In order to receive data, users must obtain necessary equipment. In this work we present a satellite data acquisition system with an RTL SDR receiver, two 137-138 Mhz designed antennas, Orbitron, SDRSharp, WXTolmag and MatLab software. We have designed two antennas, a Turnstile Crossed dipole antenna with Balun and a quadrifilar helicoidal antenna. The antennas parameter measurements show very good correspondence with those obtained by simulation. The RTL SDR RTL2832U receiver, combined with our antennas and software, forms the system for recording, decoding, editing and displaying Automatic Picture Transmission (APT) signals. The results show that the satellite image receptions are sufficiently clear and descriptive for further analysis.

  • 31.
    Argume, Abel
    et al.
    Universidad Privada de Tacna, Peru.
    Coaguila, Ronald
    Universidad Nacional de San Agustin, Arequipa, Peru.
    Yanyachi, Pablo
    Universidad Nacional de San Agustin, Arequipa, Peru.
    Chilo, José
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Design of Turnstile, Quadrifilar Helical and V-Dipole Antennas to Obtain NOAA Images2020In: 2020 IEEE Congreso Bienal de Argentina (ARGENCON), IEEE , 2020Conference paper (Refereed)
    Abstract [en]

    Satellite image processing of an ecosystem allows us to understand it and know, prevent, and investigate the events that take place in the environment. For this we need cheap and simple image reception systems, which include antennas, receivers and hardware/software for signal processing. In this work a turnstile antenna, a quadrifilar helical antenna and a V-dipole antenna were designed, constructed and used to obtain automatic NOAA image transmission signal and convert to a NOAA satellite image.

  • 32.
    Arningsmark, Felicia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Naturen förundrar: En intervjustudie kring användandet av utomhuspedagogik och dess möjligheter i naturorienterande ämnen och teknik2023Independent thesis Advanced level (professional degree), 240 HE creditsStudent thesis
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  • 33.
    Arturson, Marina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Att räkna potatisar, arean på en gitarr och matematiska tygkunskaper – eller?: En studie om ämnesintegrerat arbetssätt inom matematikundervisningen2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Som blivande lärare behöver man kunskap inom olika undervisningsmetoder, insyn i lärarkollegors erfarenheter och med forskning som grund. Syftet med den här undersökningen har varit två huvudsakliga frågeställningar; i vilken utsträckning används ämnesintegrerat arbetssätt inom matematikundervisningen och vilken är den allmänna synen och erfarenheterna bland matematiklärarna i de utvalda skolorna. Resultatet av enkätundersökningen och intervjun har analyserats för att se på vilket sätt det hänger ihop med resultatet av tidigare forskning. Sammanfattningsvis har resultatet visat att flera matematiklärare använder sig av ämnesintegrerat arbetssätt i sin matematikundervisning. Den allmänna synen på arbetssättet är överlag positivt och att det har flera fördelar. Ett ämnesintegrerat arbetssätt anses motiverande för eleverna och bidrar till ökad förståelse inte minst för de med särskilda svårigheter. Den största nackdelen med undervisningsmetoden tycks vara tidsaspekten. Det administrativa arbetet är en stor utmaning för läraren och det saknas tid för planering.

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  • 34.
    Arvidsson, Anton
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Projekt Hälsa - En Lärarhandledning2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Biologiundervisningen syftar i stora delar på att ge eleverna en förståelse samt kunskaper kring naturen och människan. Med människan som utgångspunkt syftar detta arbete till att skapa en produkt i form av en lärarhandledning i ämnet biologi, idrott och hälsa samt hemoch konsumentkunskap där ämnet hälsa står i fokus. Lärarhandledningen avser att motivera lärare att arbeta ämnesövergripande samt att ge elever verktyg att ta egna beslut gällande deras egen hälsa. Med hjälp av Skolverkets läroplaner och forskning om hälsa har lärarhandledningen utformats med hälsa som grund. Den blivande produkten har under arbetes gång utvärderas utifrån intervjuer med pedagoger. Slutsatsen av arbetet visar att lärarhandledningen går att använda, samt att den är flexibel vilket också medför ett mervärde till lärare som undervisar i ämnena biologi, idrott och hälsa samt hem- och konsumentkunskap. 

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  • 35.
    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 classroom2021In: Recherche en Didactique des Mathématiques, ISSN 2728-2422, Vol. 41, no 3, p. 347-391Article in journal (Refereed)
    Abstract [en]

    This case study investigates to what extent a specific theory and a practice of mathematics teaching − the Japanese structured problem solving, as formulated by K. Souma can be transferred and applied in a new context (Sweden). The analysis is based on tools from the anthropological theory of the didactic. It turns out that the Swedish teacher can manage the didactic techniques, which are supported by a didactic theory shared within the community of Swedish teachers. However, there are common didactic techniques within the Japanese structured problem solving approach for which this is not the case, and which were indeed difficult to manage for the Swedish teacher. Among these were techniques related to bansho (blackboard organisation); letting the students formulate a kadai (derived task) of the lesson; and kikan-shido (monitoring students’ work to plan a subsequent whole-class discussion). Further, the paper provides an ecological analysis on the underlying conditions and constraints that brought about this phenomenon − a discrepancy concerning the didactic praxeologies of teachers. In Japan, teachers focus on the students’ personal development in the processes of the reflective and collective way of learning, while the Swedish teacher focuses more on individual student’s achievement of the knowledge.

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  • 36.
    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.

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  • 37.
    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 lesson2021In: REDIMAT - Journal of Research in Mathematics Education, E-ISSN 2014-3621, Vol. 10, no 1, p. 88-112Article in journal (Refereed)
    Abstract [en]

    This paper investigates how Japanese mathematics teachers produce and share didactic knowledge together. It is a case study of a post-lesson reflection meeting so-called open lesson. The crucial idea of this study is the dialectic between the specific and generic level of foci of the participants’ reflections about the observed teaching practice; namely, about applied teacher’s specific didactic technique for achieving a specific mathematical goal, and more general pedagogical issues such as realisation of the objectives of mathematics education. This dialectic is mediated by the meso-level notion of mathematical activity, described in the guidelines for Japanese national curriculum. The application of the scale of levels of didactic co-determination, provided by the anthropological theory of the didactic into the analysis shows in what way the dialectic interplay between the teachers’ comments with focus of the specific and generic levels influences the development and establishment of the Japanese teachers’ shared professional scholarship.  

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  • 38.
    Asami-Johansson, Yukiko
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Attorps, Iiris
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics. Univ Gavle, Gavle, Sweden..
    Applying the structured problem solving in teacher education in Japan - A case study2015In: PROCEEDINGS OF THE NINTH CONFERENCE OF THE EUROPEAN SOCIETY FOR RESEARCH IN MATHEMATICS EDUCATION (CERME9) / [ed] Krainer, K; Vondrova, N, CHARLES UNIV, FAC EDUC , 2015, p. 2741-2747Conference paper (Refereed)
    Abstract [en]

    In this paper, we examine the implementation of a Japanese teacher educators' lesson, where he applies and, at the same time, inform the students about "structured problem solving". We describe a specific lesson titled "Quantity and Measurement" for elementary school teacher students and we show how the educator make the students aware of the didactic transposition of the material and how he makes the students experience and learn about applying "structured problem solving" in practice. We also show how the Japanese curriculum influences the scale of the mathematical praxeology to be learned and how the students are given opportunities to develop their insight into the PCK during their education in mathematics.

  • 39.
    Asami-Johansson, Yukiko
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Attorps, Iiris
    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.

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  • 40.
    Asami-Johansson, Yukiko
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Attorps, Iiris
    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.

  • 41.
    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, Iiris
    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 Sweden2020In: International Journal of Mathematical Education in Science and Technology, ISSN 0020-739X, E-ISSN 1464-5211, Vol. 51, no 5, p. 688-712Article 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. 

  • 42.
    Asplund, Jennie
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Naturen som resurs inom matematikundervisning: En kvalitativ studie om hur lärare F-3 uppfattar utomhusmatematik2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Studiens syfte var att ta reda på hur utomhusmatematik används av lärare i årskurs F-3. Sju intervjuer har genomförts med F-3 lärare för att ta reda på hur de uppfattar naturen som resurs i matematikundervisning samt vilka fördelar och nackdelar de anser finns med utomhusmatematik. Kvalitativa intervjuer har transkriberats och tematiskt analyserats och därframgick det att; utomhusmatematik är ett verklighetsnära och undersökande arbetssätt som hjälper elever att förstå matematik. Utomhusmatematik ökar möjligheten till ett diskussionsrikt arbete i matematik vilket är av betydelse för att det ökar elevernas tilltro till sin matematiska förmåga. Det framgick även i studien att utomhusmatematik är ett önskvärt arbetssätt men attlite resurser, för stora grupper och närheten till skog är faktorer som gör att det inte används i den utsträckning som lärarna i denna studie skulle vilja.

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  • 43.
    Astley, Pamela
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    Fysisk aktivitets påverkan avseende skolprestationer2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Examensarbetet fokuserar på fysisk aktivitets påverkan avseende elevers skolprestationer inom momentet Kropp och Hälsa, biologi för årskurs 1-3. Examensarbetet utgår ifrån huruvida fysisk aktivitet kan stimulera kognitiva funktioner. Examensarbetet belyser faktorer i samhället som påverkar elevers lärande och behöver tas i beaktande för att lyfta elevers skolprestationer. Examensarbetets huvudsakliga syfte är att undersöka huruvida ett pedagogiskt upplägg innehållande fysisk aktivitet påverkar elevers skolprestationer. Syftet med framtagandet av det pedagogiska upplägget var att bidra med ett arbetsmaterial som undervisande pedagoger kan använda i undervisning för att förbättra elevers skolprestationer. Studien är ett försök till att sammanföra pedagogik med neurovetenskaplig forskning i undervisningsdesign. Studien utgörs av en kvantitativ forskningsansats där urvalsgrupperna har bestått av en kontroll- och en experimentgrupp. Studiens resultat har visat ett signifikant resultat för fysisk aktivitets positiva påverkan avseende skolprestationer. Resultatet visar att det pedagogiska upplägget lämpar sig väl för att användas i undervisningsdesign i syfte att förbättra elevers skolprestationer.

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  • 44.
    Attorps, Iiris
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Kellner, Eva
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Ett helhetsgrepp för likvärdig skola2021In: Nämnaren : tidskrift för matematikundervisning, ISSN 0348-2723, no 3, p. 35-39Article in journal (Other (popular science, discussion, etc.))
  • 45.
    Audusseau, Hélène
    et al.
    Dept of Zoology, Stockholm University; UK Centre for Ecology and Hydrology, Wallingford, UK..
    Ryrholm, Nils
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Biology.
    Stefanescu, Constanti
    Museu de Ciències Naturals de Granollers, Granollers, Barcelona, Spain.
    Tharel, Suzanne
    Dept of Zoology, Stockholm University.
    Jansson, Camilla
    Dept of Zoology, Stockholm University.
    Champeaux, Lucile
    Dept of Zoology, Stockholm University.
    Shaw, Mark R.
    National Museums of Scotland.
    Raper, Chris
    Angela Marmont Centre for UK Biodiversity, Natural History Museum, London, UK..
    Lewis, Owen T.
    Dept of Zoology, Univ. of Oxford, Oxford, UK. .
    Janz, Niklas
    Dept of Zoology, Stockholm University.
    Schmucki, Reto
    UK Centre for Ecology and Hydrology, Wallingford, UK..
    Rewiring of interactions in a changing environment: nettle-feeding butterflies and their parasitoids2021In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 130, no 4, p. 624-636Article in journal (Refereed)
    Abstract [en]

    Climate and land use change can alter the incidence and strength of biotic interactions, with important effects on the distribution, abundance and function of species. To assess the importance of these effects and their dynamics, studies quantifying how biotic interactions change in space and time are needed. We studied interactions between nettle-feeding butterflies and their shared natural enemies (parasitoids) locally and across 500 km latitudinal gradient in Sweden. We also examined the potential impact of the range-expansion of the butterfly Araschnia levana on resident butterflies via shared parasitoids, by studying how parasitism in resident butterflies covaries with the presence or absence of the newly-established species. We collected 6777 larvae of four nettle-feeding butterfly species (Aglais urticae, Aglais io, Ar. levana and Vanessa atalanta), over two years, at 19 sites distributed along the gradient. We documented the parasitoid complex for each butterfly species and measured their overlap, and analysed how parasitism rates were affected by butterfly species assemblage, variations in abundance, time, and the arrival of Ar. levana. Parasitoids caused high mortality, with substantial overlap in the complex of parasitoids associated with the four host butterflies. Levels of parasitism differed significantly among butterflies and were influenced by the local butterfly species assemblage. Our results also suggest that parasitism in resident butterflies is elevated at sites where Ar. levana has been established for a longer period. In our study system, variations in butterfly species assemblages were associated in a predictable way with substantial variations in rates of parasitism. This relationship is likely to affect the dynamics of the butterfly host species, and potentially cascade to the larger number of species with which they interact. These results highlight the importance of indirect interactions and their potential to reorganise ecological communities, especially in the context of shifts in species distributions in a warmer world.

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  • 46.
    Axelsson, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Analys och underhåll av komponenter i tuff kemisk miljö2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The thesis this report refers to has been carried out in one of Volvo Group truck operation’s(GTO) foundries in the engine factory in Skövde. Sandcasting is used to manufacture components for truck engines of cast iron. In the casting process, sandcores are manufactured according to the Epoxy-SO2-process. The sand cores are handled by robots in closed cells. The maintenance department experiences tha tcomponents on the robotic tools that move the cores have a short service life. One theory is that this is due to exposure to SO2. According to research, certain materials exposed to SO2 can corrode or become brittle. The corrosion process for metals can increase if SO2 react with water and oxygen to form sulfurous acid (H2SO3) or sulfuric acid (H2SO4). In order for thischemical process to begin, a relative humidity of at least 60% is required. Polymers such as plastic and rubber may swell, dissolve or become brittle upon exposed to SO2, H2SO3 or H2SO4. The final goal with this thesis is to define suitable components for the maintenance department that will be used in the renovation of the robotic tools. Before this can be done the tools need to be broken down to component level and be registered in a maintenance system. Furthermore, measurements of concentration of sulfur dioxide, humidity and temperature will be performed in the robotic cells. The results from the measurements are used as a basis for finding out if there are similar components that can withstand the environment better. When the tools are finally renovated, hopefully the unplanned stops will decrease. If the unplanned stops decrease, the maintenance costs associated with the robotic cells will also decrease. According to the measurements, the humidity was not high enough for the components in the robotic cells to risk corroding due to exposure to SO2. However, many pneumatic components are partly made of plastic that does not tolerate SO2. Many of these components are available as alternatives made of, for example, nickel-plated brass or stainless steel that can withstand the gas. The thesis has provided answers to the issues and led to concrete improvements. It has also created new ideas for continued improvement work.

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  • 47.
    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.

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  • 48.
    Azizi, Hadi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Electronics.
    Simulerad nivåreglering av vattenkraftverk2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Hydropower is an important part of the Swedish electricity supply and meets about 45% of the annual electricity needs in the country. Hydropower uses the height difference between inflow and outflow to power turbines and produces electricity. In Sweden, there are about 200 dams with a drop height greater than 15 m, and too high levels at any of these dams would lead to a dam break with extensive consequences. An important area in which a lot is invested today is dam safety, which is about avoiding uncontrolled flooding of the dam.

    Knowledge of drop height and water flow is necessary for hydropower to calculate the power produced and when dimensioning dams, waterways, and generators. Saturations on the inflow to a watercourse are very complicated and time-consuming, however, the outflow through the spillway can be calculated with mathematical correlations. Spillways refer to openings in the dam that are used to carry away water volumes. Thus, there are different types of spillways, and what influences the choices are aspects such as cost, weather conditions, etc. To avoid possible flooding of a dam, the spillways are often dimensioned with respect to the amount of water they should carry away. A requirement that is often made is that it must be able to carry away the highest water level (HHQ) of a watercourse. 

    The level in the water reservoir is measured with the help of sensors that are in different places by the dam and measured high levels lead to different alarm functions being triggered. The regulation of the water level then takes place by carrying away water in a controlled manner through the spillway.

    By simulating the regulation process of the water level in a virtual environment, different scenarios that can arise during reservoir management can be tested in an economical way and find suitable control strategies. Simulations are also one of the tools highlighted in industry 4.0, which can contribute to future solutions in automation projects. In the work, the various components of a hydropower plant are studied, and an intended method is presented for creating a virtual model of the level control process in Siemens SIMIT, controlling the model via a virtual PLC unit and visualizing the process on an HMI screen.

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  • 49.
    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.

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  • 50.
    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.

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