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  • 51.
    Akander, Jan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Morberg, Åsa
    University of Gävle, Faculty of Education and Business Studies, Department of Educational sciences, Educational science.
    Sustainability of world heritage: who inherits the ownership of decorated farmhouses of Hälsingland?2017In: A Good Life for All: Essays on sustainability celebrating 60 years of making life better / [ed] Fagerström, Arne and Cunningham, Gary M., Mjölby: Atremi AB , 2017, 1, p. 139-161Chapter in book (Other academic)
    Abstract [en]

    This chapter discusses sustainability of Sweden’s most recent World Heritage (WH) site, the Decorated Farmhouses of Hälsingland. A general overview presents what WH is, why it is special and why it should be preserved for future generations. The views of WH farm owners on managing a WH site and how they feel about the task have been assessed. WH must be preserved for future generations and it is necessary for the farms to interact sustainably with their local communities. Most WH farms are privately owned and have been within the same family for centuries. Will this continue in the future or are there problems with succession?

  • 52.
    Al Amin, A.
    et al.
    Department of EEE, Uttara University, Dhaka, Bangladesh.
    Islam, M.
    Department of EEE, Uttara University, Dhaka, Bangladesh.
    Masud, M. A.
    Department of EEE, Uttara University, Dhaka, Bangladesh.
    Khan, N. H.
    Department of EEE, Uttara University, Dhaka, Bangladesh.
    Zavala, J. W. A.
    Characterization Engineer, Radio Semiconductor Corporation, Netherlands.
    Minhaz-Ul-Islam, Mohammed
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Design and performance analysis of 3.4 ghz rectangular microstrip patch antenna for wireless communication systems2017In: International Journal on Communications Antenna and Propagation, ISSN 2039-5086, E-ISSN 2039-5094, Vol. 7, no 1, p. 80-86Article in journal (Refereed)
    Abstract [en]

    Wireless communication provides low-cost, high-speed and flexible communication in present days. Hence antenna plays a vital role in the wireless communication sector. The main concern of this paper is therefore to design a 3.4 GHz rectangular Microstrip patch antenna. Moreover, the feed probe based rectangular patch antenna will be designed. The performance of the designed rectangular patch antenna will be evaluated by analysing the major parameters of the simulation results. Hence the radiation pattern, gain, impedance matching and reflection coefficient or return loss calculation will be executed by the HFSS software to evaluate the performance of the antenna. 

  • 53.
    Al hamdany, Yarub
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Simulering och energieffektivisering för en kontorsbyggnad iForsmark2018Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    The society changes rapidly and is heavily dependent on energy. The Energy usage in buildings account for about 40% of total Sweden's energy usage, where energy is used by buildings for electricity, cooling and heating. Therefore, energy is an important issue in today's society from an energy use approach to stop the global warming. In this work, a survey was carried out by an office building in Forsmark Kraftgrupp AB to find out about energy use and create a basis for energy-saving measures. The IDA ICE 4.7.1 program was used to simulate the building's energy use by creating a base model of the building. After that, the base model has been compared with different energy efficiency measures to check where the biggest and least energy saving potentials occur. The result shows that the total energy use in the office building is 198 125 kWh / year. The simulations show that energy efficiency measures could reduce energy use in the building by 81 962 kWh / year, which corresponds to 41.4% of the total energy use. Time control of ventilation systems gives the largest energy savings of 51, 2 kWh / m2, year.

  • 54.
    Alayón Glazunov, Andrés
    et al.
    Division of Electromagnetic Engineering, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Prasad, Sathyaveer
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. Signal Processing Lab, KTH Royal Institute of Technology, Stockholm, Sweden.
    Händel, Peter
    ACCESS Linnaeus Centre; Signal Processing Lab, KTH Royal Institute of Technology, Stockholm, Sweden.
    Experimental Characterization of the Propagation Channel along aVery Large Virtual Array in a Reverberation Chamber2014In: Progress in Electromagnetics Research B, ISSN 1937-6472, E-ISSN 1937-6472, Vol. 59, p. 205-217Article in journal (Refereed)
    Abstract [en]

    We show that the combined use of radio frequency absorbers and directive antennas can produce significant changes of the radio propagation channel properties along the positions of a virtual array inside a reverberation chamber. A multidimensional characterization of the channel was performed at 40 antenna positions with spacing of 0:233λ at 1 GHz. The average power, the Ricean K-factor, the coherence bandwidth, the r.m.s. delay spread, the mean delay, the beamforming power angle spectrum and array antenna correlation have been studied for different arrangements in the reverberation chamber. The analysis shows that the joint average over time and frequency channel behavior is, as expected, rather homogeneous along the very large array. However, individual realizations of the channel present a pronounced selective behavior in space, time and frequency with parameters varying along the positions of the virtual array suggesting that a heterogeneous behavior of the radio channels can be emulated in reverberation chambers. An important application of the presented study comprises testing of antenna array designs and algorithms in multipath environments. Further development may lead to Over The Air testing of Multiple Input Multiple Output antenna systems of various sizes, i.e., from small to very large arrays.

  • 55.
    Albertsson, Hanna
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Läs- och skrivsvårigheter och matematiksvårigheter: En sambandsstudie gällande några specialpedagogers uppfattningar2010Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien är att utröna hur några verksamma specialpedagoger upplever ett eventuellt samband mellan läs- och skrivsvårigheter och matematiksvårigheter med fokus på hur detta eventuella samband kan yttra sig samt hur det går att underlätta i matematikämnet för elever med denna typ av problematik. För att finna ett resultat har kvalitativa intervjuer genomförts med fyra pedagoger som alla verkar inom det specialpedagogiska fältet. Resultatet visar att pedagogerna är splittrade i sina uppfattningar gällande omfattningen av samband men att alla pedagoger upplever ett visst mått av samband, vilket de anser kan ta sitt uttryck i matematikämnet främst i form av problem med problemlösning. Vidare är pedagogerna överens om att det går att underlätta för dessa elever med hjälp av konkreta/laborativa material, kompensatoriskt arbete samt genom att möta individen där denne befinner sig.

  • 56.
    Albertzeth, Gustav
    et al.
    Department of Industrial Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia.
    Pujawan, I. Nyoman
    Department of Industrial Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia.
    Hilletofth, Per
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management. University of Gävle, Center for Logistics and Innovative Production. Department of Industrial Engineering and Management, School of Engineering, Jönköping University, Jönköping, Sweden.
    Tjahjono, Benny
    Centre for Business in Society, Coventry University, Coventry, United Kingdom.
    Mitigating transportation disruptions in a supply chain: a cost-effective strategy2019In: International Journal of Logistics, ISSN 1367-5567, E-ISSN 1469-848XArticle in journal (Refereed)
    Abstract [en]

    Transportation disruptions can be damaging to a supply chain because goods may not arrive on time and this jeopardises the service level to the customers. While supply chain disruptions have gained significant attention from scholars, little has been done to explore these disruptions in the context of transportation. The study described in this paper aims to address disruptions occurring in the transportation of goods from a plant to a distribution centre. We modelled this real case to obtain insights on the effectiveness of different strategies to mitigate transportation disruptions. We evaluated four mitigation strategies and compared the outcomes in terms of service level and total costs: (1) the risk acceptance strategy, (2) the redundant stock strategy, (3) the flexible route strategy, and (4) the redundant-flexibility strategy. The results suggest that the best strategy differs depending on the budget that managers are willing to deploy to improve the service level. The simulation experiments and the use of the Incremental Cost Effectiveness Ratio (ICER) would be instrumental in helping decision makers in selecting the best disruption mitigation strategies where the best option would likely be different under varying circumstances. 

  • 57.
    Alcheikh, Ahmad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Advantages and Challenges of Hemp Biodiesel Production: A comparison of Hemp vs. Other Crops Commonly used for biodiesel production2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Reducing reliance on a fossil fuel is a major challenge to many advanced and developing economies. This is due to the fact that fossil fuel, a finite resource, is depleting at a rapid rate with increasing demand. Additionally, the burning of fossil fuel is responsible for the current climate change, as a result of produced greenhouse gas emissions. Lastly, developing alternative renewable fuels improves energy security and decreases vulnerability of fuel supply. This thesis work explores the advantages and challenges of hemp biodiesel production. The aim of this research is to present a comprehenive evaluation of these advantages and disadvantages in the way of large-scale production of biodiesel produced from hemp oil. The thesis work relies on relavent research paper in the field and reports from the industry. Industrial hemp, a variant of the Cannabis Sativa plant (Cannabis Sativa Linn), is an important industrial and nutritional crop. Hemp seed oil can be used to produce biodiesel though the process of transesterification. Oil from hemp seeds presents a viable feedstock option for biodiesel production. Hemp provides a competitively high yield compared to similar crops. Biodiesel from hemp seed oil exhibits superior fuel quality with the exception of the kinetic viscosity and oxidation stability parameters, which can be improved with the introduction of chemical additives. Hemp remains a “niche” crop in the food supply chain, which makes it prohibitively expensive a primary feedstock in biodiesel production. Legal and perception challenges remain a major challenge in the way of wide-scale hemp biodiesel production. 

  • 58.
    Alcoverro Colom, Pau
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    A new energy model for the Lakshadweep islands: Change from a diesel-based model to a hybrid model with renewable energy systems considering the ecological fragility of the islands2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 59.
    Alfaro Zavala, Juan Wilfredo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Improving Error Performance in Bandwidth-Limited Baseband Channels2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Channel coding has been largely used for the purpose of improving error performance on a communications system. Typical methods based on added redundancy allow for error detection and correction, this improvement however comes at a cost of bandwidth. This thesis focuses on channel coding for the bandwidth-limited channel where no bandwidth expansion is allowed.

    We first discuss the idea of coding for the bandwidth-limited channel as seen from the signal space point of view where the purpose of coding is to maximize the Euclidian distance between constellation points without increasing the total signal power and under the condition that no extra bits can be added. We then see the problem from another angle and identify the tradeoffs related to bandwidth and error performance.

    This thesis intends to find a simple way of achieving an improvement in error performance for the bandwidth-limited channel without the use of lattice codes or trellis-coded modulation.

    The proposed system is based on convolutional coding followed by multilevel transmission. It achieved a coding gain of 2 dB on Eb/No or equivalently, a coding gain of approximately 2.7 dB on SNRnorm without increase in bandwidth. This coding gain is better than that obtained by a more sophisticated lattice code Gosset E8 at the same error rate.

  • 60.
    Ali, Fadi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Urban classification by pixel and object-based approaches for very high resolution imagery2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Recently, there is a tremendous amount of high resolution imagery that wasn’t available years ago, mainly because of the advancement of the technology in capturing such images. Most of the very high resolution (VHR) imagery comes in three bands only the red, green and blue (RGB), whereas, the importance of using such imagery in remote sensing studies has been only considered lately, despite that, there are no enough studies examining the usefulness of these imagery in urban applications. This research proposes a method to investigate high resolution imagery to analyse an urban area using UAV imagery for land use and land cover classification. Remote sensing imagery comes in various characteristics and format from different sources, most commonly from satellite and airborne platforms. Recently, unmanned aerial vehicles (UAVs) have become a very good potential source to collect geographic data with new unique properties, most important asset is the VHR of spatiotemporal data structure. UAV systems are as a promising technology that will advance not only remote sensing but GIScience as well. UAVs imagery has been gaining popularity in the last decade for various remote sensing and GIS applications in general, and particularly in image analysis and classification. One of the concerns of UAV imagery is finding an optimal approach to classify UAV imagery which is usually hard to define, because many variables are involved in the process such as the properties of the image source and purpose of the classification. The main objective of this research is evaluating land use / land cover (LULC) classification for urban areas, whereas the data of the study area consists of VHR imagery of RGB bands collected by a basic, off-shelf and simple UAV. LULC classification was conducted by pixel and object-based approaches, where supervised algorithms were used for both approaches to classify the image. In pixel-based image analysis, three different algorithms were used to create a final classified map, where one algorithm was used in the object-based image analysis. The study also tested the effectiveness of object-based approach instead of pixel-based in order to minimize the difficulty in classifying mixed pixels in VHR imagery, while identifying all possible classes in the scene and maintain the high accuracy. Both approaches were applied to a UAV image with three spectral bands (red, green and blue), in addition to a DEM layer that was added later to the image as ancillary data. Previous studies of comparing pixel-based and object-based classification approaches claims that object-based had produced better results of classes for VHR imagery. Meanwhile several trade-offs are being made when selecting a classification approach that varies from different perspectives and factors such as time cost, trial and error, and subjectivity.

          Classification based on pixels was approached in this study through supervised learning algorithms, where the classification process included all necessary steps such as selecting representative training samples and creating a spectral signature file. The process in object-based classification included segmenting the UAV’s imagery and creating class rules by using feature extraction. In addition, the incorporation of hue, saturation and intensity (IHS) colour domain and Principle Component Analysis (PCA) layers were tested to evaluate the ability of such method to produce better results of classes for simple UAVs imagery. These UAVs are usually equipped with only RGB colour sensors, where combining more derived colour bands such as IHS has been proven useful in prior studies for object-based image analysis (OBIA) of UAV’s imagery, however, incorporating the IHS domain and PCA layers in this research did not provide much better classes. For the pixel-based classification approach, it was found that Maximum Likelihood algorithm performs better for VHR of UAV imagery than the other two algorithms, the Minimum Distance and Mahalanobis Distance. The difference in the overall accuracy for all algorithms in the pixel-based approach was obvious, where the values for Maximum Likelihood, Minimum Distance and Mahalanobis Distance were respectively as 86%, 80% and 76%. The Average Precision (AP) measure was calculated to compare between the pixel and object-based approaches, the result was higher in the object-based approach when applied for the buildings class, the AP measure for object-based classification was 0.9621 and 0.9152 for pixel-based classification. The results revealed that pixel-based classification is still effective and can be applicable for UAV imagery, however, the object-based classification that was done by the Nearest Neighbour algorithm has produced more appealing classes with higher accuracy. Also, it was concluded that OBIA has more power for extracting geographic information and easier integration within the GIS, whereas the result of this research is estimated to be applicable for classifying UAV’s imagery used for LULC applications.

  • 61.
    Ali, Rafef
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Matematik och estetiska lärprocesser: en studie om ämnesintegration av estetiska verktyg i matematikundervisning.2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med undersökningen var att observera hur lärarna arbetar med matematik i årskurserna F-3, med fokus på hur estetiska verktyg används i matematikundervisningen. Studien är baserad på klassobservationer i två årskurser i de tidigare skolåren F-3 samt elev- och lärarintervjuer och ämnade lyfta estetiska lärprocesser samt hur de spelar in på elevernas upplevelser vad gäller ämnesintegration i matematikundervisning. Resultaten visar att estetiska verktyg används mer med yngre elever och mindre ju äldre eleverna blir. Lärarna i denna studie påpekade att ett ämnesövergripande arbetssätt och att blanda in olika sinnen främjar elevernas inlärning. Majoriteten av de intervjuade lärarna betonade att det gäller att hitta en balans mellan olika metoder för att skapa en varierad undervisning. 

  • 62.
    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
  • 63.
    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
  • 64.
    Alieva, Jamila
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management. University of Gävle, Center for Logistics and Innovative Production.
    von Haartman, Robin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management. University of Gävle, Center for Logistics and Innovative Production.
    Digital collaboration within the supply chain: new booster for hidden lean potential2019Conference paper (Other academic)
    Abstract [en]

    This paper explores the hidden lean potential exposed by manufacturers’ usage of enterprise resource planning (ERP) systems. The potential can be classified into three types: unlocked lean potential in a connected ERP system, unlocked lean potential in an un-connected ERP system, and the lean potential for further unlocking in companies that do not use ERP systems when collaborating with suppliers/customers. Empirical data is obtained from two cases of manufacturing companies in Sweden and one ERP system company. The findings indicate that hidden lean potential can be unlocked through digital collaboration within the supply chain.

  • 65.
    Alikhani, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    A GIS-based crowdsourcing iPhone Application to Report Necessities, Civic Issues, and Public Events2011Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Civic issues in a society can be reported through a crowdsourcing web application. People can download the application on their smartphones and report the issues such as a pothole or broken streetlight. The report is submitted by taking a photo of the issue and additional information is entered. At first, the reports are submitted to a call center and after analyzing they will be transferred to organizations responsible for this type of events. In such a crowdsourcing project it is very vital to motivate people to participate in the project. The reports are supplied by users and without an acceptable number of users the application would be useless. In addition, having the exact location of a report is very helpful to facilitate the process of solving civic issues. Positioning with smartphones is not very accurate as they do not have strong and accurate GPSs. Therefore, there is a need to improve the accuracy of the positioning process and consequently accuracy of the spatial data. The aim of this thesis is to investigate how to employ GIS to help reporting civic issues and how to design an interesting client interface for such an application, in order to motivate user to download and use it. The goal is also to find out shortcomings and weaknesses of the positioning with smartphones and find a way to improve its accuracy.Some of successful similar applications’ structures and their interfaces were reviewed. In addition, a survey among existing users of crowdsourcing applications has been done in order to find out how to design the application to be interesting for users. Furthermore, some techniques and methods were chosen in order to improve the GPS accuracy especially in the places with a low GPS signal strength. These methods exploit WLAN and some of embedded features in a smartphone such as microphone, camera, accelerometer, gyroscope to improve the positioning accuracy. In the end, along reporting civic issues the user is able to report and get information about cheap and appropriate necessities and public events in different geographical areas through a map-based application. Furthermore, he or she is benefited by some location-based services such as online-food or taxi. The client application’s interface was designed for iPhone.This GIS-based mobile application would be an appropriate alternative for the old reporting methods like phone call or mail. Nevertheless, reporting civic issues itself, cannot be necessarily a strong motivation to attract the user to download and use the application. Therefore, desired feedbacks of the crowd need to be found out in order to encourage them to spend their time for the application. User needs to get motivated to use the application and considered additional parts can be very helpful to reach this aim.

  • 66.
    Alinazari, Shabnam
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Alvinder, Catrin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    I barn och ungas ögonhöjd: En checklista från barn till plan för detaljplanering2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Det demokratiska samhället med värderingar om allas lika rätt till inflytande har med Förenta Nationernas barnkonvention lyft frågan om barns rätt att påverka den fysiska planeringen (UNICEF, 2009). Plan- och bygglagen (PBL) gör ingen skillnad på barn eller vuxna vilket innebär att de ska ses som jämlika medborgare inom samhällsbyggnadsprocesser (SFS, 2010:900). Detta utgör den lagbestämda grunden till varför barn, precis som vuxna, ska ha samma rätt att påverka beslut som rör deras närmiljö. En barnchecklista kan tydliggöra att ett barnperspektiv tillämpas inom planeringsprocesser och frågorna utgår vanligen från vuxnas tolkningar av vad som bör innefattas (Boverket, 2000). Denna studie har uppmärksammat den brist på medverkan av barn och unga som ofta finns i planeringssammanhang och det finns därigenom utrymme för förbättringar. Studien har därför valt att fokusera på att få barnens röster hörda genom att undersöka vilka faktorer i miljön som är viktiga för dem. Detta har legat som grund till att utarbeta en ny checklista där deras värderingar varit grundläggande för frågornas utformande. För att uppnå detta anordnades workshops och enkätundersökningar med grupper av barn från lågstadiet upp till gymnasiet. Eftersom åldersspannen varierade mellan 9-18 år anpassades metoderna efter deras kognitiva förmåga.

    Resultatet från studien visade att barnen ansåg att det fanns flera faktorer i miljön som påverkar deras subjektiva upplevelse. Detta innefattade bland annat hur byggnader med dess utbredning och placering påverkar dem men även hur viktigt det är med bra gång- och cykelvägar för att främja för deras rörelsefrihet. Det betonades även hur bevarandevärden där exempelvis en enkel kulle för pulkaåkning eller en skogsdunge att busa i var viktigt att inte planera bort. Det slutgiltiga resultatet blev checklistan: Från barn till plan. Den är tänkt att fungera som ett arbetsverktyg med öppna frågor, vilket ger planeraren utrymme att belysa barnperspektivets tillämpning inom detaljplanering. Resultatet visade även på stor kunskap, intresse och medvetenhet hos barn och unga gällande den byggda miljön. De bör därför ses som självständiga kompetenta individer inom samhällsplanering med röster värda att höras.

  • 67.
    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.

  • 68.
    Alizadeh, Mahmoud
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. Royal Institute of Technology, Stockholm, Sweden.
    Amin, Shoaib
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. Royal Institute of Technology, Stockholm, Sweden.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Measurement and analysis of frequency-domain Volterra kernels of nonlinear dynamic 3x3 MIMO systems2017In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 66, no 7, p. 1893-1905Article in journal (Refereed)
    Abstract [en]

    Multiple-input multiple-output (MIMO) frequency-domain Volterra kernels of nonlinear order 3 are experimentally determined in bandwidth-limited frequency regions. How the effect of higher nonlinear orders can be reduced and how this affects the estimated errors are discussed. The magnitude and phase of the kernels areKramers-Kronig consistent. The self- and cross-kernels have different symmetries and the kernels are therefore determined and analyzed in different regions in the 3D frequency space. By analyzing the properties along certain paths in the 3D frequency space, the block structures for the respective kernels are determined. These block structures contain the significant blocks of the general block structures for third-order kernels. The device under test is a MIMO transmitter for radio frequency signals.

  • 69.
    Alizadeh, Mahmoud
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. KTH, Teknisk informationsvetenskap.
    Händel, Peter
    KTH, Teknisk informationsvetenskap.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Basis Function Decomposition Approach in Piece-Wise Modeling for RF Power Amplifiers2018In: 6th Telecommunications forum TELFOR 2018, Belgrade: Telecommunications society , 2018Conference paper (Refereed)
    Abstract [en]

    In this paper, a new approach is proposed to decompose the basis functions in a piece-wise modeling technique for nonlinear radio frequency (RF) power amplifiers. The proposed technique treats the discontinuity problem of the model output at the joint points between different operating points, whereas preserves the linear and nonlinear properties of the original model within each region. Experimental results show that the proposed technique outperforms the conventional piece-wise model in terms of model errors.

  • 70.
    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.

  • 71.
    Alizadeh, Mahmoud
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. Department of Signal Processing, ACCESS Linnaeus Center, The Royal Institute of Technology (KTH), Stockholm, Sweden.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    A two-tone test for characterizing nonlinear dynamic effects of radio frequency amplifiers in different amplitude regions2016In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 89, p. 273-279Article in journal (Refereed)
    Abstract [en]

    A new two-tone test method for radio frequency power amplifiers is presented. The test signal is a two-tone probing-signal superimposed on large-signals of different amplitude. The amplifier is, thus, excited in different amplitude regions. The amplitude and phase of the 3rd order intermodulation (IM) products are measured vs. frequency spacing and probing-signal amplitude in each region. The IM magnitude is a measure of the nonlinearity, while the frequency dependence and asymmetry are measures of the memory effects in the different regions. A Doherty and a class-AB amplifier were tested. For both amplifiers the IM magnitude increased by ∼15 dB from the lowest to the highest amplitude region. For the Doherty amplifier the behavior of the IM products vs. frequency spacing was similar in all regions, indicating similar memory effects. For the class-AB amplifier the IM vs. frequency spacing was significantly different in the different regions, which indicates different memory effects.

  • 72.
    Alizadeh, Mahmoud
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Händel, Peter
    Department of information science and engineering Royal Institute of Technology (KTH), Stockholm, Sweden.
    Characterization of Volterra Kernels for RF Power Amplifiers Using a Two-Tone Signal and a Large-Signal2018In: 2018 International Conference on Communications, COMM 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, Vol. 1, p. 351-356Conference paper (Refereed)
    Abstract [en]

    The 3rd-order Volterra kernels of a radio frequency (RF) power amplifier (PA) are characterized using a large-signal and a two-tone probing-signal. In this technique, the magnitude and phase asymmetries of the kernels of the PA excited by the probing-signal are analyzed in different amplitude regions of the large-signal. The device under test is a class-AB PA operating at 2.14 GHz. The maximum sweeping frequency space of the probing-signal is 20 MHz. The results indicate that the Volterra kernels of the PA show different behaviors (frequency dependency and asymmetry) in different regions.

  • 73.
    Alizadeh, Mahmoud
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. KTH.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Händel, Peter
    KTH.
    Isaksson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    A new Block-Structure Modeling Technique for RF Power Amplifiers in a 2x2 MIMO System2017In: 13th International Conference on Advanced Technologies, Systems and Services in Telecommunications (TELSIKS) / [ed] Milovanovic, B. D.; Doncov, N. S.; Stankovic, Z. Z.; Dimitrijevic, T. Z., IEEE , 2017, p. 224-227Conference paper (Refereed)
    Abstract [en]

    A new block-structure behavioral model is proposed for radio frequency power amplifiers in a 2x2 multiple-input multiple-output system including input cross-talk. The proposed model forms kernels of blocks of different nonlinear order that correspond to the significant frequency response of measured frequency domain Volterra kernels. The model can therefore well describe the input-output relationships of the nonlinear dynamic behavior of PAs. The proposed model outperforms conventional models in terms of model errors.

  • 74.
    Aljaberi, Saif
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Majeed, Aram
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science.
    Energisimulering i modulhus: Fallstudie för uppskattning av energiprestanda och därefter energieffektivisera enligt passivhusstandaren2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    The Building sector is today an important sector in our society, which means that more people move from the urban area to the big cities, which in turn increases building production. The building and service sector is the largest energy waste in Sweden and internationally, which is about 40% of Sweden's total energy use and 60% of that energy goes to heating. The EU Directive Energy Performance of Buildings Directive (EPBD), implemented the concept of near zero-energy houses, which comes into full force in 2020, which means that all newly-built buildings must be energy-efficient with better energy performance than todays buildings. This is in connection with the need of houses/buildings and rental costs continuing to increase. For this reason, Ljusbo Hyreshus AB has invented a solution that includes both climatesmart rental apartments and cheap rental costs, which has attracted more than 20 communes (kommuner in Sweden) to offer land for these apartments. The purpose of this thesis is to find out the energy performance of one of Ljusbo Hyreshus AB's prototype module houses. Furthermore, improvement proposals would be developed to make the module house more energy efficient. The prototype house consisted of a single-storey modularhouse that stay in Söderhamn, which has been chosen in this thesis for further investigations. The house had a total area of 45 m2 and consisted of 3 rooms and kitchen. In this case study, the energy performance has been developed using analysis methods in the form of hand calculations and the energy signature method. Subsequently, the result of the analysis would be validated and would form the basis for later identification of various energy efficiency measures that contributed to the reduction of energy performance in the house and thereby achieved the passive house standard. The result shows that the modularhouse does not fullfil BBR's requirements at present, because the house misses important components which is important for energy performance. For this reason, improvement proposals, specifically regarding the climate shell, on energy efficiency measures have been developed in this report. With the help of these energy efficiency measures, which mainly consist of additional insulation and energy-efficient windows and with an energy-efficient ventilation system with heat recovery (FTX) and an installed air-water heat pump, the passive house standard has been possible to achieve. Future measures, such as the installation of solar cells, have also been examined in the report. This is due to converting the building from a passive house to a plus energy house.

  • 75.
    Almberg, Stina
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Michel, Gabriella
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Analys av energianvändningen i kvarteren Carolina och Jenny: en fallstudie2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    An energy study has been performed on two blocks in an area called Gävle Strand. The buildings are owned by a tenant-owner’s association called brf Carolina and were built by the company Skanska 2008. The builder as well as brf Carolina are pussled by the fact that electricity use is higher than expected while heating is less. Skanska is also very interested in finding out how much heat recovery from stale exhaust air through a geo-thermal heat pump is contributing to the general heating requirement and energy balance in four out of the ten buildings located on the properties.

    To find possible answers to the higher electricity use a literature survey on user behaviour was conducted. Simulations were executed in the energy simulation program BV2 testing the efficiency of a mechanical ventilation system with fans dispatching the used stale air with heat recovery through the geo-thermal heat pump in comparison to a HRV-system. As BV2 can’t simulate heat pumps its impact was instead calculated manually and added to the result from BV2.

    The result show that there are significant differences in both water and electricity use between households. The mean value in brf Carolina is also higher for both water and electricity use than the typical pattern value most commonly used in energy simulations for new buildings. The simulations and calculations show that a HRV-system is practically equal to the system chosen for these buildings. The geo-thermal heat pump make a substantial contribution to the heating requirements but also increases the electricity use in comparison to the HRV-system.

    The buildings over all have a good energy performance. The chosen heat recovery system is working well. If the source for energy is also valued a HRV-system is still preferable since it requires less electricity.In regards to user behaviour the under floor heating installed in the bathrooms and operated by the occupants is very likely to have a substantial impact on the higher than average electricity use. There are however many other factors that could have an impact on energy use due to behaviour factors. This is also a factor when varations between households are viewed.

    Key words; energy, energy simulation, user behaviour

  • 76.
    Almingol, Oscar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Construction of a C-PV prototype2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The following Master Thesis will talk about a C-PV prototype using bifacial PV technology, based on the Solarus Collector. The Solarus Collector consists in two PV cells built on a metallic receiver, where there are some water channels flowing through it, allowing to cool down the PV cells, thus increasing their efficiency. The collector also presents a reflector to provide irradiance to the back part of the receiver, where the other PV cells are located. The new prototype will present bifacial PV cells but not a metallic receiver. This construction aims to reduce the price of the receiver, but will not have a system to cool down the solar cells. This Master Thesis will be developed in the Solarus facilities, in collaboration with the Solarus members.

    In order to grasp an idea of this prototype, two main procedures will be done. Regarding the bifacial technology, a bifacial PV module will be measured under different conditions, depending on which sides can be illuminated or shaded. On the other hand, a thermodynamic simulation will be carried out on different geometries of the reflector and receiver, in order to figure out the evolution of the temperatures on the new prototype. This simulation will be done with a finite element method, widely known in this applications.

    The results will show several problems concerning this prototype. Although the measurements of the bifacial PV module will result beneficial and informative, the problem with the temperature will tend to back down this prototype. The lack of some system to cool down the bifacial cells will imply that the receiver could reach unacceptable temperatures. This hypothesis will be drawn under some specific conditions, so they will not be completely devastating to the idea of using bifacial cells, but perhaps a different approach should be used in case it is desired to continue this work. 

  • 77.
    Almira, Memic
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management.
    Aida, Osmanovic
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management.
    Utformning av en ankomstkontroll: Möjligheter och utmaningar som en ankomstkontroll kan ge industriföretag2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Many companies strive to develop their arrival controls in an effective way as arrivals controls have proven to be significant for the companies. This is grounded in the fact that arrival controls improve the flow of production and minimize the risk for production errors since the controls enable an effective management of the company’s products and materials. Not establishing these controls consequently often leads to production default, stress and increased expenses. Nonetheless, many companies choose not to implement arrival controls because such implementations are accompanied by large costs. Furthermore, they require space, which smaller companies do not have.

    The purpose of this study is, through the analysis of previous literature and interaction with a local company, examine how efficient arrival controls can be structured. Additionally, this study aspires through, improvement proposals, to aid Munters AB in the construction of arrival controls.

    This is a qualitative case study conducted at Munters AB in Tobo. Empirical data was accumulated through semi-structured interviews, analytical observations and consistent visits to the company.

    Arrival controls are of significant importance for companies and the absence of such are undoubtly damaging for the company. This is evidential in the interviews, where both the quality director and the Lean coordinator were aware of the company’s shortcomings in this area. Further findings show that all workers in the production department experienced continuous defects in every day production and therefore hoped for an implementation of arrival controls. In conclusion the study found that Munters AB is in urgent need of arrival controls. However, in order for such an implementation to be as effective as possible, the company needs to utilize different methods, tools and system and crucial forward planning in production. 

  • 78.
    Almquist, Olivia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Testrutin för dricksvattenfilter för upp till 50 P.E.: ett förslag på tillvägagångssätt2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is, with the laws regarding drinking water filter up to 50 P.E. as the basis, to create a routine for how the tests should be for the filters in a test-bed facility. How will a common test routine be designed for better assessment of drinking water filters today?

     

    The thesis is based a literature study in the form of both websites and legislations. The information have been retrieved from the websides of relevant companies such as, the National Food Agency (NFA) and similar organizations working on drinking water issues. While the legislations have been taken from, for example, National Public Investigation and/or likewise. Several of the references that are used have backing from several other sources which should mean that the information is reliable. The legislation is the starting point for a functioning Sweden which should mean that it is reliable.

     

    It has also been conducted a survey through email, where approximately 50 companies in the drinking water filter industry were asked what they think about various statements. The questions were based on an already developed proposals for a test routine that the author developed earlier. This method was chosen because it is difficult to get a clear picture of what the market is interested in examining without asking them.

     

    Water in its raw form H2O does not taste or smells anything. It can, however, change when it is in contact with other materials. This is because water is highly soluble and thus dissolves other substances. Therefore it is important that materials used in drinking water treatment should be safe where the consumer might otherwise ingest unhealthy substances through drinking water. Building and Planning Agency together with the National Food Administration and the Swedish Chemicals Agency will design a platform where stakeholders can easily find information regarding approved materials in contact with drinking water.

     

    There are approximately 1.2 million households in Sweden (both permanenta- and leisure accommodations) who receive their drinking water from private well. It is therefore the well owner's responsibility to make sure that the drinking water has a good quality. There is no legislation on the control of its own drinking water. The recommendation suggest sampling every three years on the well if it only supplies a household but every year if there are more than one household that are supplied. Approximately 1/5 of all drinking water is estimated to be unfit.

     

    There are many different types of filters and methods which can make it confusing and difficult for people to choose the right one. Some of those types are ion exchange, activated carbon, reverse osmosis, sand filters, air filters, cartridge filters, UV light and scale filter. The filters have different characteristics and work in different ways. According to WHO guidelines for safe drinking water. Many substances are not regulated with any limits as long as the WHO does not consider that the concentration of that substance will be sufficient enough to affect people negatively. Examples of these are pH, iron chloride, manganese and potassium. Although EU has a list of safe drinking water which NFA base their limits on.

     

    The proposed test routine became somewhat shorter and less strict than the routine as it was based on. It is reported in Appendix 2 together with the questionnaire sent out to businesses to find out what they thought about the proposal on the test routine. Drinking water filters should be tested in 32 weeks during which a power failure will be simulated. It is even recommended that the capability of the filter should be tested at high flow and no flow for a certain number of hours during each week.

  • 79.
    Almstedt, Åsa
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Geospatial Sciences.
    Peterson, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Geospatial Sciences.
    Lägesosäkerhet vid nätverks-RTK-mätning med inbyggd lutningskompensator: en undersökning av Leica GS18 T2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A recently introduced GNSS instrument on the market is Leica GS18 T with tilt compensation, based on GNSS/Inertial Navigation Systems (INS) integration, with no need to centre the survey pole with the GNSS instrument over the target point being measured. Besides making surveying faster, the tilt compensation technique enables measuring of hidden points where the use of conventional GNSS measuring normally is not possible without more time-consuming methods. The instrument also has advanced GNSS signal tracking which makes surveying in challenging environments possible.

    In this study, the Leica GS18 T has on behalf of Lantmäteriet been tested through studying the measurement uncertainty in network RTK measurement with tilted survey pole in three different situations: with the survey pole tilted in various degrees in both favourable and challenging survey environments; with tilt towards north, east, south and west to test if the tilt direction would affect the result; and for surveying of building corners as a possible field of application. In the latter case, the result was compared with what can be achieved with the conventional hidden point method using intersection of distances. The analysis of the measurement uncertainty was based on calculations of standard uncertainty, RMS (Root Mean Square) and mean deviation.

    The measurement uncertainty from the first part of the test was on cm-level horizontally, both in favourable and challenging survey environments, and in height on mm-level in favourable survey environment and on cm-level in challenging survey environment. Further, the results indicate that the tilt direction affects measurement uncertainty. The reason for this is not clarified and needs further investigation. The measurements of building corners resulted in a mean deviation of approximately 12 mm when the survey pole was tilted 30°. The hidden point method using intersection of distances generally resulted in lower mean deviation, even though the difference is relatively small (4 mm at best). To summarize, Leica GS18 T seems to be well suited for measuring with tilt in detailed surveying, at least if the requirements of position uncertainty is on cm-level.

  • 80.
    Almström, Erica
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Att förstå evolution genom laboration2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Undersökningar visar att elever har svårt att ta till sig evolutionsteorin och i stället väljer att förklara evolutionen med icke vetenskapliga argument. Till exempel väljer de att förklara fjällharens vita vinterpäls med att en vit päls gör att den syns sämre. Det här är ett exempel på att eleverna gärna förklarar evolutionen som behovsstyrd. En laboration utformades för att illustrera hur variation och urval ger evolution i en plantpopulation. Laborationen går ut på att eleverna under en tid studerar en population med plantor som utsätts för torka. Plantorna har olika simulerade genotyper och kommer därför att reagera olika på torkstressen. Tanken med laborationen var att få elever att använda sig av mer vetenskapliga förklaringar till evolutionen istället för icke veteskapliga. Resultaten visar att eleverna ändrat uppfattning, men inte riktigt till en mer vetenskaplig förklaring utan de har gått från sin tidigare förklaringsmodell till att inte riktigt kunna förklara vad som händer vid evolution.

  • 81.
    Al-Mulla, Tiba
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Jämförelsestudier mellan olika typer av korslimmat träbjälklag:: Undersökning av konsekvenser vid ändring från betong- till korslimmat trä- bjälklag i ett flervåningshus2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Timber is one of the most common materials that had been use for a long time. The need for new buildings will affect the climate negatively, that is why it’s necessarily to find new ways to build quickly and sustainably. Cross-laminated timber (CLT) product came in the 1990- century. The material was developed to be used in high residential wood constructions buildings.

    The material considered to have good properties compared with other types of wood material, some of the studies showed the possibilities of building high residential with the CLT material. Such high rises buildings work best when CLT wood constructions combined with other materials, which called, Composite constructions.

    Case study preformed theoretically in Fullriggaren building in Alderholmen in Gävle city, the building have 14 floors and about 40 m high. With the purpose of trying to investigate the consequences that occur when the concrete floor slabs were replaces  with CLT wood floor slabs, taking into account the rules and standards for fire safety, acoustics, oscillations and vibrations. In order to achieve this and to determine the most suitable alternatives, the different types of CLT-wood floor slabs was compared.

    The building studied in its design and execution, and a simpler model created in Revit 2018. The challenge was that the building has a long span of maximum 10 m. The different types of CLT floor slabs which compared in the study was, CLT timber joist slaps, flat floor slab and CLT wood floor slabs in combination with steel hat beams and other beam steel types. Each type of floor slabs had its advantages and disadvantages, but the results and studies showed that timber and concrete composite floor slab combined with steel hat beams are the best possible options for the construction in Fullriggaren building, where the floor slab height is the shortest compared to other CLT wood floor types. With the chosen floor slab, the problem of vibration and oscillations will minimize. When using such a floor slab, the building height will increase, which means in this case, removing an entire floor from the building.

  • 82.
    Alonso Lozano, Alvaro
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Coal gasification in entrained flow gasifiers simulation & comparison2012Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 83.
    Al-Saour Rafie, Mais
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Farhad, Tafan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Tillgänglighet och användbarhet i nybyggnation: En fallstudie - Bostadslägenheter på Gävle Strand Etapp2 - Gavlegårdarna2014Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    Human beings are always considered to be the starting point for various construction projects; their needs and interests should always be the center of each successful design. At the same time, considerations should be given to activities and surrounding environment to ensure that buildings can be both accessible and usable.

    The accessibility and usability requirements for constructions were introduced in 1977 by the National Housing Board and have evolved since then. The requirements are still developing to achieve homes that are accessible and useable, especially for people with disabilities. They have also been tightened in particular concerning the design of new construction and alteration of buildings.

    Gavlegårdarna have, in 2012, built new residential apartments with high accessibility standards. The apartments in Gävle Strand, Stage 2 are located in an area next to the sea and offer new opportunities for a modern way of living. Considering the new residential area of Gävle Strand, this case study focuses on the accessibility standards concerning three categories of disabilities: limited mobility, limited vision and limited hearing. The case study examines three selected apartments with different living area. The purpose of the case study is to assess the accessibility and usability of the apartments. This is done through an inventory using a wheelchair, taking a walking tour while blindfolded and using a cane. Before the assessment of the apartments' requirements, an inventory list of respective apartments was prepared. The list is based on regulations, laws and recommendations from Building Regulations and Swedish Standard.

    The results of the case study categorize the apartments in two levels: normal- and high level accessibility. Spaces and details that are considered to have high accessibility have externally contrast markings including the entrances and stairways. Inside, the apartments are well planned for enhanced usability and there are spacious areas where a wheelchair can move without any difficulty.

    The conclusion shows that all apartments meet the requirements at normal level which is the minimum level of accessibility and usability. Despite the general assessment of the apartments’ well-planned design, the study finds flaws in the form of a cramped bathrooms and high thresholds to the balcony doors. Finally, in order to achieve high availability the case study presents improvements and measures that need to be changed to the presented deficiencies.

  • 84.
    Altabba, Abdulrahman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Karlsson, Lina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    A framework for implementing the VMI model in an MRO partnership2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Purpose - The purpose of this paper is to investigate the feasibility of implementing the Vendor Managed Inventory (VMI) model in an MRO (maintenance, repair, and operations) partnership, and highlight its potential economic, environmental, and organizational benefits, as well as limitations.

    Approach - First, a comprehensive literature review was conducted on fields relevant to VMI. Second, empirical data was gathered from a single exploratory case study with Momentum Industrial, and its customer Stora Enso. Semi-structured interviews were used to gather data from the case companies.

    Findings - Results suggest that VMI results in benefits for the supply chain in general, such as reduced administration and inventory costs, improved service levels, reduced information distortion, and improved relationship among partners. For the particular case of VMI in an MRO partnership, improved service levels can be obtained by a reduced risk of production downtime for the customer. Moreover, the implementation of VMI has potential environmental benefits, such as reduced paper use, and higher transportation fill rate. Limitations of implementing VMI include the difficulty in system integration, and information sharing. Trust could be a potential issue that limits information sharing amongst supply chain partners. Moreover, the difference in organizational cultures and policies of partners should be taken into consideration.

    Limitations - The study is limited to opinions from one MRO customer in the paper and packaging industry. Even though the questions asked to informants in Momentum and Stora Enso tackled benefits to MRO customers in general, a broader image could have been achieved by interviewing customers from different industries. Moreover, the case companies do not currently adopt VMI in their partnership, so the case study results are based on what they think would be the potential benefits and limitations of implementing VMI in an MRO partnership.

    Practical Implications - This paper can serve as a guideline for logistics managers who are considering VMI in an MRO partnership specifically, as it provides them with the benefits and limitations associated with VMI. More generally, any company considering VMI can also benefit from the theoretical framework presented.

  • 85.
    Alvarsson, Marcus
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Optimering av tippram: tillhörande lastväxlarvagn Parator LX10-202010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Norrborns Industri AB in Bollnäs manufactures truck trailers with the brand Parator. One of their trailers is Parator LX 10-20. The trailer is designed to transport hooklift containers with the option to tip loose goods such as gravel, asphalt and seed. The container is mounted on a frame which is placed on the chassis. To reduce weight a redesign of the trailer is needed. The purpose of this study was to develop a concept that makes the frame lighter and easier to manufacture while maintaining safety and rigidity. The thesis also discusses factors to consider when designing with high-strength steel.

     

    The optimization was based on existing 2D drawings of the frame. Analysis of the structure served as a basis for the optimization. First, a 3D model was created from the drawings. Then, the frame was analyzed with selected loads and boundary conditions. Initially simple models were used to develop concepts. From these, two concepts were selected and one of them was thoroughly analyzed.

     

    The optimization resulted in a concept design weight of 732 kg, which is 179 kg less compared to the current frame at 911 kg.

  • 86.
    Amarawardhana, Kumudu Nanditilaka
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Modeling of energy utilization of tourism industry to predict the future energy demand to showcase Sri Lanka - The ‘Miracle of Asia’2014Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Tourism industry in Sri Lanka shares a substantial amount of GDP (Gross Domestic Product) and predicts an immense expansion within a short time frame. Owing to its energy intensiveness and competitiveness, a scrutiny in the energy utilization and the related impact on the environment is crucial. Furthermore, trend towards ecotourism forces the requirement of foreseeing a green energy supply to meet the ever rising demand.   In this study, utilization of energy in the graded hotels in the country was modeled through LEAP (Long Range Energy Alternatives Planning System) software to predict the future energy demand. Monthly energy consumption data for three consecutive years for a sample of hotels covering classified and unclassified hotel establishments were used for modeling. Four scenarios were then analyzed based on the baseline scenario representing the country’s tourism industry profile of year 2010.  It is shown that the energy intensiveness of the tourism industry will be overwhelming unless the DSM (Demand Side Management) tools are properly amalgamated for mitigation. Further the results of the study revealed that the existing electricity generation plan does not accommodate fuel diversification and energy mix, and needs revisions to induct renewable sources for greening energy supply of the country. The study provides an insight in identifying socially acceptable policy scenarios in energy supply and use of the tourism industry.

  • 87.
    Amaya, Jorge
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Pedalkraft system: Stödsystem för elproduktion i småskalighet2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is aimed at people who are interested in using the new environmentally friendlymethods of electricity generation or people who already use small wind turbines and solarpanels with the need for an additional energy source in small cabins or remote locations whereaccess to electricity networks is impossible. Aims of this work is first to build a system forgenerating electricity using a bicycle. Second is determining the amount of electrical energy aperson can generate with the system. Finally answer if this system could be used as a supportsystem for electricity generation in small scale.

    The first objective is to design a system using power control where the power generatedsupplied the loads. The mechanical part will be constructed as part of the energy source, thenwill be designed a control for controlling the power via electronic components, electrical loadssupplied by the system, will be simulated. To know the generated power to the control circuitwill install a meter and a serial communication device for communicating with a computer.

    It carries out a research on other systems and products in the Swedish market, to answer whetherthis system can be a backup system for electricity generation in small scale.

    The construction of a pedaling power system is achieved using a twelve volt direct currentmotor with permanent magnet as an energy source. System has the ability to show in an LCDdisplay and transmit through the serial ports, the value of the generated power. System canguide the power to the loads by using a microcontroller. Power generated by the system showedthat it is significant to be considered as an additional energy source, stand-alone or integratedwith other systems.

  • 88.
    Ameen, Arman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Efficient Cooling with multiple impinging jets: Obtaining boundary condition and verification for a CFD model2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Saving energy and optimizing industrial processes are major priorities for companies around the world. In this study the cooling process (with air) of large rollers are examined. The result of these examinations are used to create a computational fluid dynamic model. These examination consists of geometry, volume flows, velocities, velocity profiles, temperature and pressure. A complication in the measurements occurred due to the nonsymmetrical installation of the nozzles in the cooling setup. The results highlights how this nonsymmetrical installation affects the cooling. Multiple methods were used to carry out this work, and some additional side project were implemented. The results in this thesis is not enough to create a CFD model and further work have to be carried out in the future.

  • 89.
    Ameen, Arman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energianalys och energieffektivisering av en förskola: Söderskolan (Slottets förskola) i Gävle, simulering utförd genom IDA ICE 4.612014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Bostad- och servicesektorn står för 38 % av Sveriges totala energianvändning. Av det här står bostäder och lokaler för 90 % av energianvändningen och nästan 60 % av det går till att värma upp byggnaderna och till varmvatten. Därför är det viktig att börja titta på den här sektorn och se om det finns möjlighet att spara på energianvändningen. I den här studien har en kartläggning gjorts av en gammal skolbyggnad för att kunna skapa ett underlag för energieffektiviseringsåtgärder. Genom att använda simuleringsprogrammet IDA ICE 4.61 har man skapat en basmodell av byggnaden som då används som simuleringsbas. Basmodellen har jämförts med fjärrvärmekostnader för att kunna verifieras. Därefter har man lagt in energieffektiviserar och tittat på vilka besparingar man har kommit fram till. Resultatet av den här studien visade att i den här byggnaden så är den mest effektiva åtgärden isolering av taket till vinden.

  • 90.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Reducing energy usage in multi-family housing2019In: 2019 9th International Conference on Future Environment and Energy 9–11 January 2019, Osaka, Japan, Institute of Physics Publishing (IOPP), 2019, Vol. 257, article id 012030Conference paper (Refereed)
    Abstract [en]

    The energy usage in residential sector have been around 22% of the total energy use in the world and increasing due to the population growth and higher living standards. The energy sources for this are made up primarily of non-renewable energy resources which generates a large amount of global greenhouse gases. A lot of countries have implemented various regulations and rules to reduce the energy usage in buildings and promoting the use of renewable energy technologies. This paper presents a parametric study of a typical multi-family building in its pre-design stage. The climate location used is Sweden (Gothenburg) and Japan (Osaka). The aim of the study is to compare various configurations and to examine how they affect the energy use. The most interesting configurations are the use of heat pump and solar cells. Other configurations that are examined are infiltration levels, pressure coefficients, wind impact, ventilation with heat recovery, ventilation scheduling, building orientation and finally changing U-values in the building material. Results of this study show that the energy saving, by utilizing a heat pump and solar panels, can reduce the total energy use by 34.9% for Gothenburg and 32% for Osaka. The results also show that the difference in total energy use between the two cities reduce substantially (3% difference) when utilizing a heat pump in combination with solar panels.

  • 91.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karimipanah, Taghi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental Investigation of Ventilation Performance of Different Air Distribution Systems in an Office Environment: Heating Mode2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 10, article id 1835Article in journal (Refereed)
    Abstract [en]

    A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.

  • 92.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Larsson, Ulf
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karimipanah, Taghi
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 7, article id 1354Article in journal (Refereed)
    Abstract [en]

    The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.

  • 93.
    Ameen, Arman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Choonya, Gasper
    Cehlin, Mathias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental Evaluation of the Ventilation Effectiveness of Corner Stratum Ventilation in an Office Environment2019In: Buildings, ISSN 2075-5309, E-ISSN 2075-5309, Vol. 9, no 7, article id 169Article in journal (Refereed)
    Abstract [en]

    An experimental study was conducted in a room resembling an office in a laboratory environment. The study involved investigating the ability of corner-placed stratum ventilation in order to evaluate the ventilation’s effectiveness and local thermal comfort. At fixed positions, the air temperature, air velocity, turbulence intensity, and tracer gas decay measurements were carried out. The results show that corner-placed stratum ventilation behaves very similar to a mixing ventilation system when considering air change effectiveness. The performance of the system was better at lower supply air flow rates for heat removal effectiveness. For the heating cases, the draught rates were all very low, with the maximum measured value of 12%. However, for the cooling cases, the maximum draught rate was 20% and occurred at ankle level in the middle of the room.

  • 94.
    Ameen, Havar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Sabra, Zakaria
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Moderna processutvecklingsverktyg för organisationer2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna C-uppsats ämnar att studera prioriteringar hos användare i ett system för processutveckling, med syftet att skapa underlag för en omarbetad implementation. I vissa organisationer handlar det om att öka utnyttjandegraden av investerade resurser, och en sådan plattform ger en bättre kontroll över vilka delar i ett system som påverkas av processförändringar. Underlaget för den konkreta implementation bestod till stor del av resultaten från en enkätstudie, där slutanvändare av ett existerande prototypsystem fick dela med sig av sina synpunkter. Resultatet från studien kombinerades också med relevanta vetenskapliga artiklar och litteraturstudier för att skapa underlag för modellen för den nya plattformen. En stor faktor som påvisades utifrån studien är behovet av tillgänglighet. Detta innefattar bl.a. tydligare relationer mellan entiteter, koncis presentation av data och snabbare informationsåtkomst. Modellen som skapats representerar ett system där fokus på ett dynamiskt och responsivt gränssnitt i kombination med tillgänglighet och logiska arbetsflöden utgör plattformen.

  • 95.
    Amin, A.
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. Teleconnect GmbH, Dresden, Germany; University of Applied Sciences Dresden, Dresden, Germany.
    Bluschke, A.
    Teleconnect GmbH, Dresden, Germany.
    Emery, S.
    Innodul AG, Zürich, Switzerland.
    Krüger, F.
    Teleconnect GmbH, Dresden, Germany; University of Applied Sciences Dresden, Dresden, Germany.
    Matthews, M.
    Teleconnect GmbH, Dresden, Germany.
    Rietzsch, P.
    Teleconnect GmbH, Dresden, Germany.
    Steglich, R.
    Contec Steuerungstechnik and Automation GmbH, Ebbs, Austria.
    Multi-carrier transmission over si-pof2011In: POF 2011: 20th International Conference on Plastic Optical Fibers - Conference Proceeding, 2011, p. 81-86Conference paper (Refereed)
    Abstract [en]

    Multi-carrier modulation (MCM) is today’s method of choice for communication systems. This is also true for SI-POF. The basics of MCM and special characteristics for the optical transmission using SI-POF are explained within this paper. Current approaches for MCM over SI-POF are described: Teleconnect’s G.hn based solution for home networking and Innodul’s DMT-based Gigabit solution.

  • 96.
    AMIN, AHMED
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Implementation and Investigation of VDSL2 Signal Modulation/Demodulation Functions for FDM Solution via POF Channel2011Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    For higher data rate and attractive price level internet service Very High Data rate Subscriber Line 2 (VDSL2) is a perfect option. VDSL2 is a great achievement in Digital Subscriber Line (DSL) technology. It has a good impact in modern triple play (Voice, Data and Video) Internet service but for modern world applications required more data rate than the VDSL2 system can provide but it should be inexpensive and easy to install. So the desired goal of this thesis work is to achieve higher bitrates for VDSL2 system, by transmitting multiple VDSL2 signal using Plastic Optical Fiber (POF) channel instead of copper channel. POF channel is a suitable solution for high data rate application. Moreover POF is very rugged and suitable for high data rate application because of optical based transmission and it’s also very easy to implement into the interior networking. Moreover POF doesn’t have any impact of Electro Magnetic Interference because of optical transmission. So several VDSL2 signals are amplitude modulated to allocate specific frequency band and combined together which can be called as frequency division multiplexing and POF is used as channel to carry the combined signal which provide much higher bit rate than single signal and efficiently utilize the bandwidth of the channel. Then at the receiver end the combined signals are split and amplitude demodulate at the respective receiver to recover the expected frequency band for the receiver.       

  • 97.
    Amin, Ahmed Angelus
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Morales, Federico
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Positionering och tid som faktorer i mobilanpassade enkäter: En kontextmedveten prototyp2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Det finns ett ökat problem med att färre personer väljer att delta i enkätundersökningar, både vad gäller webbenkäter och traditionella postenkäter. En möjlig lösning på problemet skulle kunna vara att ta tillvara på det faktum att det blir allt vanligare att personer väljer att använda sig av mobila enheter för att lösa vardagssysslor. Kanske kan man bättre använda sig av den tekniska utvecklingen och samhällsutvecklingen som allt mer går över till digitala lösningar och på så sätt bidra till ett ökat deltagande i enkäter. Denna uppsats har undersökt om det är möjligt att använda tekniken kontextmedvetenhet för att skapa mobilanpassade enkäter. Detta genom att tillverka en prototyp av en mobilapplikation som kan skicka frågor till smartphones beroende på dess position. Det är möjligt genom mobila enheters egna GPS-mottagare. Enligt den utvärdering som utförts finns det tecken på att användaren upplever det lättare att svara på frågor genom denna prototyp än deras tidigare upplevelser. Dessutom visar resultatet att funktionerna i vår kontextmedvetna prototyp fungerar så som önskat.

  • 98.
    Amin, Hadi
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Geospatial Sciences.
    Sjöberg, Lars
    Division of Geodesy and satellite positioning, KTH.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Geospatial Sciences.
    A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters2019In: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 93, no 10, p. 1943-1961Article in journal (Refereed)
    Abstract [en]

    The geoid, according to the classical Gauss–Listing definition, is, among infinite equipotential surfaces of the Earth’s gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2 s−2 and the semi-major and minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3 s−2.

  • 99.
    Amin, Shoaib
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. KTH Royal Institute of Technology, Stockholm, Sweden.
    Characterization and Linearization of Multi-band Multi-channel RF Power Amplifiers2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The World today is deeply transformed by the advancement in wireless technology. The envision of a smart society where interactions between physical and virtual dimensions of life are intertwined and where human interaction is mediated by machines, e.g., smart phones, demands increasingly more data traffic. This continual increase in data traffic requires re-designing of the wireless technologies for increased system capacity and flexibility. In this thesis, aspects related to behavioral modeling, characterization, and linearization of multi-channel/band power amplifiers (PAs) are discussed.

    When building a model of any system, it is advantageous to take into account the knowledge of the physics of the system and include into the model. This approach could help to improve the model performance. In this context, three novel behavioral models and DPD schemes for nonlinear MIMO transmitters are proposed.

    To model and compensate distortions in GaN based RF PAs in presence of long-term memory effects, novel models for SISO and concurrent dual-band PAs are proposed. These models are based on a fixed pole expansion technique and have infinite impulse response. They show substantial performance improvement. A behavioral model based on the physical knowledge of the concurrent dual-band PA is derived, and its performance is investigated both for behavioral modeling and compensation of nonlinear distortions.

    Two-tone characterization is a fingerprint method for the characterization of memory effects in dynamic nonlinear systems. In this context, two novel techniques are proposed. The first technique is a dual two-tone characterization technique to characterize the memory effects of self- and cross-modulation products in concurrent dual-band transmitter. The second technique is for the characterization and analysis of self- and cross-Volterra kernels of nonlinear 3x3 MIMO systems using three-tone signals.

  • 100.
    Amin, Shoaib
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Characterization and Linearization of Multi-channel RF Power Amplifiers2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The demands for high data rates and broadband wireless access requirethe development of wireless systems that can support wide and multi-bandsignals. To deploy these signals, new radio frequency (RF) front-ends are requiredwhich impose new challenges in terms of power consumption efficiencyand sources of distortion e.g., nonlinearity. These challenges are more pronouncedin power amplifiers (PAs) that degrade the overall performance ofthe RF transmitter.Since it is difficult to optimize the linearity and efficiency characteristicsof a PA simultaneously, a trade-off is needed. At high input power, a PAexhibits high efficiency at the expense of linearity. On the other hand, atlow input power, a PA is linear at the expense of the efficiency. To achievelinearity and efficiency at the same time, digital pre-distortion (DPD) is oftenused to compensate for the PA nonlinearity at high input power. In case ofmulti-channel PAs, input and output signals of different channels interactwith each other due to cross-talk. Therefore, these PAs exhibit differentnonlinear behavior than the single-input single-output (SISO) PAs. The DPDtechniques developed for SISO PAs do not result in adequate performancewhen used for multi-channel PAs. Hence, an accurate behavioral modeling isessential for the development of DPD for multi-channel RF PAs.In this thesis, we propose three novel behavioral models and DPD schemesfor nonlinear multiple-input multiple-output (MIMO) transmitters in presenceof cross-talk. A study of the source of cross-talk in MIMO transmittershave been investigated to derive simple and powerful modeling schemes.These models are extensions of a SISO generalized memory polynomial model.A comparative study with a previously published MIMO model is also presented.The effect of coherent and partially non-coherent signal generationon DPD performance is also highlighted. It is shown experimentally thatwith partially non-coherent signal generation, the performance of the DPDdegrades compared to coherent signal generation.In context of multi-channel RF transmitters, PA behavioral models andDPD schemes suffer from a large number of model parameters with the increasein nonlinear order and memory depth. This growth leads to highcomplexity model identification and implementation. We have designed aDPD scheme for MIMO PAs using a sparse estimation technique for reducingmodel complexity. This technique also increases the numerical stability whenlinear least square estimation model identification is used.A method to characterize the memory effects in a nonlinear concurrentdual-band PAs is also presented. Compared to the SISO PAs, concurrentdual-band PAs are not only affected by intermodulation distortions but alsoby cross-modulation distortions. The characterization of memory effects inconcurrent dual-band transmitter is performed by injecting a two-tone testsignal in each input channel of the transmitter. Asymmetric energy surfacesare introduced for the intermodulation and cross-modulation products, whichcan be used to identify the power and frequency regions where the memory effects are dominant.

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