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  • 251.
    Axner, Emil
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Att utvändigt värmeisolera köldbryggor i utkragade balkonggolv: En fallstudie om energianvändning, kostnader och påverkan av byggnadens yttre gestaltning2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In order for Sweden to reach its goals for a sustainable future, the government continues to increase demands on improving energy efficiency of buildings. A first step should be to improve the buildings ability to keep its heat. This means that the thermal insulation of the envelope should be improved and effect of thermal bridges in various constructions be minimized. A recurrent problem when renovating already existing buildings is the requirement of preservation and how that affects the possibilities on how to renovate. All buildings constitute a storytelling that illustrates how society has developed over time. Building characteristics and expressions must be preserved even if it leads to higher renovation costs. This thesis aims to study the energy use caused by thermal bridges in balcony slabs and how the energy use is affected by insulating the balcony slabs. It also investigates how the overall building appearance is affect by this figuration. And last, the study aims to explore however the investment in material is defensible when comparing it with the cost for energy in a life cycle perspective. The result shows that the thermal bridges caused by the balcony slabs increase the energy use by almost 4000 kWh per year and building and by adding insulation to the slabs, the energy usage decline by almost 75 %. In view of the buildings appearance, the additional insulation has a minimal affect. When comparing the investment cost in a life cycle perspective with the saving of energy, results shows that the costs in material is too high and at the same time the price for energy is too low for obtaining any profit for the given time period.

  • 252.
    Azad, A. K. M.
    et al.
    Northern Illinois University, United States.
    Cowan, N. J.Johns Hopkins University, United States.Tokhi, M. O.Univeristy of Sheffield, United Kingdom.Virk, Gurvinder SinghUniversity of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.Eastman, R. D.Loyola University, United States.
    Adaptive Mobile Robotics: Proceedings Of The 15th International Conference On Climbing And Walking Robots And The Support Technologies For Mobile Machines, Baltimore, USA, 23–26 July 20122012Conference proceedings (editor) (Refereed)
    Abstract [en]

    This book provides state-of-the-art scientific and engineering research findings and developments in the area of mobile robotics and associated support technologies. The book contains peer reviewed articles presented at the CLAWAR 2012 conference. Robots are no longer confined to industrial manufacturing environments. A great deal of interest is invested in the use of robots outside the factory environment. The CLAWAR conference series, established as a high profile international event, acts as a platform for dissemination of research and development findings and supports such a trend to address the current interest in mobile robotics to meet the needs of mankind in various sectors of the society. These include personal care, public health, services in the domestic, public and industrial environments. The editors of the book have extensive research experience and publications in the area of robotics in general and in mobile robotics specifically, and their experience is reflected in editing the contents of the book.

  • 253.
    Azadehnia, Arefeh
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science.
    What benefits will 5G be for small and mid-sized companies?2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

  • 254.
    Azagury, Luna
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Små barns matematik: 2 åringars begreppsförståelse2010Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 255.
    Backenhamn Ohlsson, Margareta
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Fysik genom musik: en introduktion av fysikaliska fenomen i förskolans vardag med stöd av ett arbetsmaterial och en lärarhandledning2013Independent thesis Basic level (professional degree), 210 HE creditsStudent thesis
  • 256.
    Backlund, Andreas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Konstruktion av ett automatiserat hybrid värmesystem2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport presenterar hur en konstruktionsuppgift av ett automatiserat hybrid värmesystem har genomförts. Två värmekällor skulle inkluderas i systemet, primärkällan var en fastbränslepanna på 30 kW. Och som sekundärvärmekälla ett solfångarsystem med totalt tio solfångarmoduler. Värmesystemet skulle värma en bostad, en maskinverkstad samt ett maskingarage. Temperaturregleringen skulle styras med hjälp av automatik. För att inhämta data på de befintliga byggnader som var berörda av projektet gjordes fysiska mätresultat på plats, studier av ritningar, litteratur, internet källor samt samråd med den externa handledaren.Detta gav i slutändan ett system som är uppdelat i två olika delsystem. Ett system med en fastbränslepanna, och ett system med solfångarmoduler. Den uppvärmda median lagras i fyra ackumulatortankar, varje enskild ackumulatortank har olika volym och väljes med hjälp av automatik. Automatiken sköts av en så kallad PLC, som står för Programmable Logic Controller (Eng.). Denna PLC styr hela systemets elektriska utrustning, vilket innefattar pumpar, reglerventiler, avstängningsventiler och temperatur inhämtning från sensorer. Som presentations metod av resultatet valdes att använda ritningar som kan hittas som större bilagor i denna rapport. Samtliga formler som har använts för att dimensionera systemet återfinns under teori avsnittet, med kortfattade kommentarer. Vissa moment har fler än en lösning, vilket ställer krav på att även klara av att göra analyser av olika lösningar samtidigt ta i beaktande den externa handledarens önskemål.

  • 257.
    Backlund, Sandra
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering. Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem.
    Efficient improvement of energy efficiency in small and medium-sized Swedish firms2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This is a dissertation about efficient implementation of energy efficiency measures in small and medium-sized Swedish firms. The aim is to investigate the potential for economically efficient implementation of energy efficiency improvement measures in small and medium-sized firms. The thesis contains five papers that analyse different aspects that have been put forth in policy documents and academic debate as  methods to improve energy efficiency in non-energy intensive sectors.

    By reading policy documents, interviewing representatives of small and medium- sized firms and energy auditors as well as analysing data from the Swedish energy audit program, different aspects of energy management practices, energy services and energy audits are considered. The thesis is the product of an interdisciplinary context but economic theory is at the foundation of the analysis and has helped formulate questions and hypotheses that have been tested and explored with the data.

    The results show that while the potential for improving energy efficiency in the small and medium- sized sector in Sweden is large there are challenges to realizing it in each individual firm. There is potential for improving energy efficiency in the sector and not just for investments in new technology but also for adjusting existing machinery and changing behaviour, but costs for investigating the potential and implementing the measures are large relative to the improvement potential in each company. Energy management practices in this sector are lacking and energy services will only be demanded if reduction in production cost is estimated larger than transaction costs of the service. The Swedish energy audit program has led to the implementation of energy efficiency improvements in the participating firms but compared to other policy instruments it has been a less cost-efficient way to improve energy efficiency in Sweden.

  • 258.
    Backlund, Sofia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Avsättningsalternativ för avloppsslam utifrån effektiviserad slambehandlingsmetod i Avesta kommun: med fokus på hygienisering och miljömässig nytta2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sewage sludge contains nutrients, which should be returned to nature to create a so-called nutrient circulation. By optimizing sanitisation of sewage sludge with effective treatment methods, sewage sludge can be more appropriately disposed from a better economic- and environmental perspective. The aim of this work was to investigate and judge the efficiency of existing sludge treatment is possible to achieve a sufficent sanitation. Based on the streamlined sludge treatment method investigate the disposal options that is best suited for sewage sludge in Avesta town. A literature review was conducted to increase the knowledge and understanding of sewage sludge, its treatment and disposal. The case study is formed with qualitative method and information which has been collected from the scientific articles, authorities, reports, theses and personal contact as a complement to obtain a good understanding. Upgrading of mesophilic digestion of sludge at 37 ° C to thermophilic digestion at 55 ° C - 65 ° C means increased temperature; this requires more energy and hence increases energy costs. Components of the mesophilic digestion process need to be upgraded or replaced and therefore additional costs should also be considered. The advantages of the thermophilic digestion include short residence time, smaller digester and sludge becomes sufficiently disinfected. A future scenario is developed based on more efficient sludge treatment where two disposal options are most appropriate for the sewage sludge in Avesta town. Returning digestate to productive land is one of those suggested alternatives that allows phosphorus to be recovered and recycled. If not thermophilic digestion as streamlining is not effective enough for sufficient sludge sanitation, other complementary processes have to be introduced, for instance, composting drum or pasteurization. A full cost comparison between the existing sludge treatment and more efficient sludge treatment method is, however, almost impossible to be performed when all costs depend on the choice of components, factors and so on. This case study contributes with first-hand information that can provide greater opportunities for Avesta Vatten och Avfall AB to select the most appropriate options for sewage sludge disposal in Avesta town in the future.

  • 259.
    Backman, Mathilda
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electrical Engineering, Mathematics and Science, Mathematics.
    Se mig!: En studie om matematiskt särskilt begåvade elever2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

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

  • 260.
    Baena Juan, Cristian
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Comparison of the performance of silicon and thin film solar cells at the laboratory of the University of Gävle2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The huge environmental awareness emerging last years by reason of global warming and greenhouse effect, on one hand, and the need of finding other sources of energy production and conversion due to the declining of fossil resources and the increasing cost of this kind of energy resource, on the other hand, both have led position renewable energies as a powerful alternative on the energy production and conversion.

    PV-systems have emerged at an exponential rate in recent year as the main candidate and a satisfactory possibility with respect to environmental and economic sustainability.

    Nowadays, the large volume on photovoltaic market is currently dominated by four types of solar cells, divided by the semiconductor material used to absorb light and convert the energy into electricity: (1) crystalline silicon (monocrystalline and polycrystalline), (2) amorphous silicon, (3) CIGS and (4) cadmium telluride; and among them, monocrystalline silicon and CIGS technologies are installed on the building 45 of the University of Gävle, at the south face of the laboratory.

    In this context and with the motivation to contribute knowledge on PV field, a comparison between single crystal solar technology and thin film CIGS technology has carried out through f ratio and performance ratio procedures in order to perform an assessment of the energy conversion of each one under field conditions.

    A logger monitors the power conversion from the PV modules since June 2014 while two pyranometers monitor global and diffuse solar radiation since March 2016. It must take into account that only clear sunny days have been considered during a period from 8:00 to 14:00 in order to avoid shadows effect on the PV systems.

    The results come to conclude that single crystal silicon modules present a better behavior with respect to energy conversion under no shadows effect conditions by two reason: (1) f ratio, relationship of PV conversion per kW (PV yield) between CIGS and single crystal silicon, is about 87.25% with some variations along a day due to ambient temperature, cell temperature and incidence angle; (2) PV module's performance ratio of monocrystalline silicon modules is higher than thin film CIGS ones during a sunny day about 87.56% and 76.38%, respectively; and they are consistent with usual performance ratio values between 80% and 90% since 2010 onwards.

    In light of the outcome and in order to confirm these conclusions, it intends to launch a project with the objective of evaluating the data collected and compare the performance of the module after a year of measurements outdoors by the PV module's performance ratio procedure.

    Along the same lines, the next step of the University of Gävle will be to launch a project with the objective of evaluating the potential to be self-sufficient.

  • 261.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Combination of seismic and an isostatic crustal thickness models using Butterworth filter in a spectral approach2012In: Journal of Asian Earth Sciences, ISSN 1367-9120, E-ISSN 1878-5786, Vol. 59, p. 240-248Article in journal (Refereed)
  • 262.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS. Division of Geodesy and Satellite Positioning, Royal Institute of Technology (KTH), Stockholm, Sweden .
    Deformation monitoring using different least squares adjustment methods: a simulated study2016In: KSCE Journal of Civil Engineering, ISSN 1226-7988, E-ISSN 1976-3808, Vol. 20, no 2, p. 855-862Article in journal (Refereed)
    Abstract [en]

    This study aims to investigate the ability of different least squares adjustment techniques for detecting deformation. A simulated geodetic netwo rk is used for this purpose. The observations are collected using the Total Station instrument in three epochs and different least squares adjustment methods are used to analyze the simulated network. The applied methods are adjustment-byelement, using variance-covariance components and Tikhonov regularization. For numerical computation, we utilized exist geodetic network around the simulated network and the deformation (changes in the simulated network) imposes to the object using a simulator in each epoch. The obtained results demonstrate that more accurate outcome for detection of small deformation is possible by estimating variance-covariance components. The difference of the estimated and the simulated deformations in the best scenario, i.e., applying variance-covariance components, is 0.2 and 0.1 mm in x and y directions. In comparison with adjustment by element and Tikhonov regularization methods the differences are 1.1 and 0.1 in x direction and 1.4 and 1.1 mm in y direction, respectively. In addition, it is also possible to model the deformation and therefore it can be seen that how the calculated displacement will affect the result of deformation modelling. It has been demonstrated that determining reasonable variance-covariance components is very important to estimate realistic deformation model and monitoring the geodetic networks. 

  • 263.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Global earth isostatic model using smoothed Airy-Heiskanenand Vening Meinesz hypotheses2012In: Earth Science Informatics, ISSN 1865-0473, Vol. 5, no 2, p. 93-104Article in journal (Refereed)
  • 264.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Impact of compensating mass on the topographic mass: A study using isostatic and non-isostatic Earth crustal models2012In: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 47, no 1, p. 29-51Article in journal (Refereed)
  • 265.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS. KTH Royal Institute of Technology, Stockholm, Sweden.
    Bai, Yongliang
    School of Geosciences, China University of Petroleum (East China), Qingdao, China.
    Sjöberg, Lars
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Tenzer, Robert
    NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Plzeň, Czechia.
    Abrehdary, Majid
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Miranda, Silvia
    Departamento de Geofísica y Astronomía, FCEFN Universidad Nacional de San Juan, San Juan, Argentina.
    Sanchez, Juan M. Alcacer
    Departamento de Geofísica y Astronomía, FCEFN Universidad Nacional de San Juan, San Juan, Argentina.
    Effect of the lithospheric thermal state on the Moho interface: a case study in South America2017In: Journal of South American Earth Sciences, ISSN 0895-9811, E-ISSN 1873-0647, Vol. 76, p. 198-207Article in journal (Refereed)
    Abstract [en]

    Gravimetric methods applied for Moho recovery in areas with sparse and irregular distribution of seismic data often assume only a constant crustal density. Results of latest studies, however, indicate that corrections for crustal density heterogeneities could improve the gravimetric result, especially in regions with a complex geologic/tectonic structure. Moreover, the isostatic mass balance reflects also the density structure within the lithosphere. The gravimetric methods should therefore incorporate an additional correction for the lithospheric mantle as well as deeper mantle density heterogeneities. Following this principle, we solve the Vening Meinesz-Moritz (VMM) inverse problem of isostasy constrained by seismic data to determine the Moho depth of the South American tectonic plate including surrounding oceans, while taking into consideration the crustal and mantle density heterogeneities. Our numerical result confirms that contribution of sediments significantly modifies the estimation of the Moho geometry especially along the continental margins with large sediment deposits. To account for the mantle density heterogeneities we develop and apply a method in order to correct the Moho geometry for the contribution of the lithospheric thermal state (i.e., the lithospheric thermal-pressure correction). In addition, the misfit between the isostatic and seismic Moho models, attributed mainly to deep mantle density heterogeneities and other geophysical phenomena, is corrected for by applying the non-isostatic correction. The results reveal that the application of the lithospheric thermal-pressure correction improves the RMS fit of the VMM gravimetric Moho solution to the CRUST1.0 (improves ∼ 1.9 km) and GEMMA (∼1.1 km) models and the point-wise seismic data (∼0.7 km) in South America.

  • 266.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Eshagh, Mehdi
    Avd för naturvetenskap, lantmäteri- och maskinteknik, Institutionen för ingenjörsvetenskap, Högskolan i Väst.
    Combined Moho Estimators2014In: Geodynamics : Research International Bulletin, ISSN ISSN 2345-4997, Vol. 1, no 3, p. 1-11Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    In this study, we develop three estimators to optimally combine seismic and gravimetric models of Moho surface. The first estimator combines them by their special harmonic coefficients; the second one uses the spherical harmonic coefficients of the seismic model and use integral formula for the gravimetric one. The kernel of the integral terms of this estimator shows that a cap size of 20◦ is required for the integration, but since this integral is presented to combine the low frequencies of the gravimetric model, a low resolution model is enough for the integration. The third estimator uses the gravity anomaly and converts its low frequencies to those of the gravimetric Moho model, meanwhile combining them with those of seismic one. This integral requires an integration domain of 30◦ for the gravity anomalies but since the maximum degree of this kernel is limited to a specific degree, the use of its spectral form is recommended. The kernel of the integral involving the gravity anomalies, developed for recovering high frequencies of Moho, is written in a closed-from formula and its singularity is investigated. This kernel is well-behaving and decreases fast, meaning that it is suitable for recovering the high frequencies of Moho surface.

  • 267.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Eshagh, Mehdi
    Royal Institute of Technology (KTH), Stockholm, Sweden, and K.N.Toosi University of Technology, Tehran, Iran .
    Crustal thickness recovery using an isostatic model and GOCE data2012In: Earth Planets and Space, ISSN 1343-8832, E-ISSN 1880-5981, Vol. 64, no 11, p. 1053-1057Article in journal (Refereed)
    Abstract [en]

    One of the GOCE satellite mission goals is to study the Earth's interior structure including its crustal thickness. A gravimetric-isostatic Moho model, based on the Vening Meinesz-Moritz (VMM) theory and GOCE gradiometric data, is determined beneath Iran's continental shelf and surrounding seas. The terrestrial gravimetric data of Iran are also used in a nonlinear inversion for a recovering-Moho model applying the VMM model. The newly-computed Moho models are compared with the Moho data taken from CRUST2.0. The root-mean-square (RMS) of differences between the CRUST2.0 Moho model and the recovered model from GOCE and that from the terrestrial gravimetric data are 3.8 km and 4.6 km, respectively.

  • 268.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Eshagh, Mehdi
    Islamic Azad Univ, Dept Surveying.
    Recovery of Moho’s undulations based on the Vening Meinesz–Moritz theory from satellite gravity gradiometry data: A simulation study2012In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 49, no 6, p. 1097-1111Article in journal (Refereed)
  • 269.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Sjöberg, Lars E.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    A synthetic Earth gravity model based on a topographic-isostatic model2012In: Studia Geophysica et Geodaetica, ISSN 0039-3169, E-ISSN 1573-1626, Vol. 56, no 4, p. 935-955Article in journal (Refereed)
    Abstract [en]

    The Earth's gravity field is related to the topographic potential in medium and higher degrees, which is isostatically compensated. Hence, the topographic-isostatic (TI) data are indispensable for extending an available Earth Gravitational Model (EGM) to higher degrees. Here we use TI harmonic coefficients to construct a Synthetic Earth Gravitational Model (SEGM) to extend the EGMs to higher degrees. To achieve a high-quality SEGM, a global geopotential model (EGM96) is used to describe the low degrees, whereas the medium and high degrees are obtained from the TI or topographic potential. This study differes from others in that it uses a new gravimetric-isostatic model for determining the TI potential. We test different alternatives based on TI or only topographic data to determine the SEGM. Although the topography is isostatically compensated only to about degree 40-60, our study shows that using a compensation model improves the SEGM in comparison with using only topographic data for higher degree harmonics. This is because the TI data better adjust the applied Butterworth filter, which bridges the known EGM and the new high-degree potential field than the topographic data alone.

  • 270.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sjöberg, Lars E.
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Improving gravimetric–isostatic models of crustal depth by correcting for non-isostatic effects and using CRUST2.02013In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 117, p. 29-39Article, review/survey (Refereed)
    Abstract [en]

    The principle of isostasy is important in different fields of geosciences. Using an isostatic hypothesis for estimating the crustal thickness suffers from the more or less incomplete isostatic model and that the observed gravity anomaly is not only generated by the topographic/isostatic signal but also by non-isostatic effects (NIEs). In most applications of isostatic models the NIEs are disregarded. In this paper, we study how some isostatic models related with Vening Meinez's isostatic hypothesis can be improved by considering the NIE. The isostatic gravity anomaly needs a correction for the NIEs, which varies from as much as 494 mGal to − 308 mGal. The result shows that by adding this correction the global crustal thickness estimate improves about 50% with respect to the global model CRUST2.0, i.e. the root mean square differences of the crustal thickness of the best Vening Meinesz type and CRUST2.0 models are 6.9 and 3.2 km before and after improvement, respectively. As a result, a new global model of crustal thickness using Vening Meinesz and CRUST2.0 models is generated. A comparison with an independent African crustal depth model shows an improvement of the new model by 6.8 km vs. CRUST2.0 (i.e. rms differences of 3.0 and 9.8 km, respectively). A comparison between oceanic lithosphere age and the NIEs is discussed in this study, too. One application of this study can be to improve crustal depth in areas where CRUST2.0 data are sparse and bad and to densify the resolution vs. the CRUST2.0 model. Other applications can be used to infer the viscosity of the mantle from the NIEs signal to study various locations around the Earth for understanding complete, over- and under-compensations of the topography.

  • 271.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sjöberg, Lars E
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Modelling the density contrast and depth of the Moho discontinuity by seismic and gravimetric–isostatic methods with an application to Africa2012In: Journal of African Earth Sciences, ISSN 0899-5362, Vol. 68, p. 111-120Article in journal (Refereed)
    Abstract [en]

    The crustal thickness (Moho depth) is of interest in several geosciences applications, such as geography, geophysics and geodesy. Usually the crustal depth and density variations are estimated by seismic survey data. As such data collection is very time-consuming and expensive an attractive option could be to use a gravimetric/isostatic model. In this case, realistic estimates for the crustal density and Moho density contrast (MDC) are important. In this study, we first use the seismic crustal thickness of CRUST2.0 model as a known parameter in combination with gravimetric data in estimating the crust–mantle density contrast by the isostatic model of Vening Meinesz–Moritz. We present different models to estimate the MDC and its impact on the modelling of the gravimetric–isostatic Moho depth. The theory is applied to estimate the Moho depth of the African continental crust by using different models for the MDC: (a) constant value (0.6 g/cm3), (b) Pratt–Hayford’s model, (c) CRUST2.0 as input to three gravimetric/isostatic models based on Vening Meinesz–Moritz theory. The isostatic models agree by 5.8–7.1 km in the rms with the regional seismic model at a resolution of 2 x2, and the smallest rms difference at a resolution of 1x1is of

    7.2 km. For comparison, the rms differences of CRUST2.0 and the regional seismic model are 8.8 and 9.1 km at the resolutions of 2 deg (interpolated) and 1 deg respectively. The result suggests that the gravimetric/isostatic Moho model can be used in densification of the CRUST2.0 Moho geometry, and to improve it in areas with poor data.

  • 272.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sjöberg, Lars E.
    KTH Royal Institute of Technology, Division of Geodesy and Geoinformatics.
    Non-isostatic effects on crustal thickness: A study using CRUST2.0 in Fennoscandia2012In: Physics of the Earth and Planetary Interiors, ISSN 0031-9201, E-ISSN 1872-7395, Vol. 200, p. 37-44Article in journal (Refereed)
  • 273.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS. KTH.
    Sjöberg, Lars E.
    KTH.
    Tenzer, Robert
    Wuhan University, China.
    Abrehdary, Majid
    KTH.
    A new Fennoscandian crustal thickness model based on CRUST1.0 and a gravimetric-isostatic approach2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 145, p. 132-145Article, review/survey (Refereed)
    Abstract [en]

    In this paper a new gravimetric-isostatic crustal thickness model (VMM14_FEN) is estimated for Fennoscandia. The main motivation is to investigate the relations between geological and geophysical properties, the Moho depth and crust-mantle density contrast at the crust-mantle discontinuity. For this purpose the Bouguer gravity disturbance data is corrected in two main ways namely for the gravitational contributions of mass density variation due to the different layers of the Earth's crust such as ice and sediments, as well as for the gravitational contribution from deeper masses below the crust. This second correction (for non-isostatic effects) is necessary because in general the crust is not in complete isostatic equilibrium and the observed gravity data are not only generated by the topographic/isostatic masses but also from those in the deep Earth interior. The correction for non-isostatic effects is mainly attributed to unmodeled mantle and core boundary density heterogeneities. These corrections are determined using the recent seismic crustal thickness model CRUST1.0. We compare our modeling results with previous studies in the area and test the fitness. The comparison with the external Moho model EuCRUST-07 shows a 3.3. km RMS agreement for the Moho depth in Fennoscandia. We also illustrate how the above corrections improve the Moho depth estimation. Finally, the signatures of geological structures and isostatic equilibrium are studied using VMM14_FEN, showing how main geological unit structures attribute in isostatic balance by affecting the Moho geometry. The main geological features are also discussed in the context of the complete and incomplete isostatic equilibrium. 

  • 274.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Tenzer, Robert
    Institute of Geodesy and Geophysics, School of Geodesy and Geomatics, Wuhan University, Wuhan, China .
    Comparative analysis of Vening-Meinesz Moritz isostatic models using the constant and variable crust-mantle density contrast – a case study of Zealandia2013In: Journal of Earth System Science, ISSN 0973-774X, Vol. 122, no 2, p. 339-348Article in journal (Refereed)
    Abstract [en]

    We compare three different numerical schemes of treating the Moho density contrast in gravimetric inverse problems for finding the Moho depths. The results are validated using the global crustal model CRUST2.0, which is determined based purely on seismic data. Firstly, the gravimetric recovery of the Moho depths is realized by solving Moritz’s generalization of the Vening-Meinesz inverse problem of isostasy while the constant Moho density contrast is adopted. The Pratt-Hayford isostatic model is then facilitated to estimate the variable Moho density contrast. This variable Moho density contrast is subsequently used to determine the Moho depths. Finally, the combined least-squares approach is applied to estimate jointly the Moho depths and density contract based on a priori error model. The EGM2008 global gravity model and the DTM2006.0 global topographic/bathymetric model are used to generate the isostatic gravity anomalies. The comparison of numerical results reveals that the optimal isostatic inverse scheme should take into consideration both the variable depth and density of compensation. This is achieved by applying the combined least-squares approach for a simultaneous estimation of both Moho parameters. We demonstrate that the result obtained using this method has the best agreement with the CRUST2.0 Moho depths. The numerical experiments are conducted at the regional study area of New Zealand’s continental shelf.

  • 275.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Tenzer, Robert
    The Key Laboratory of Geospace Environment and Geodesy, School of Geodesy and Geomatics, Wuhan University, Wuhan, China.
    Comparative study of the uniform and variable Moho density contrast in the Vening Meinesz-Moritz’s isostatic scheme for the gravimetric Moho recovery2016In: International Association of Geodesy Symposia: 3rd International Gravity Field Service, IGFS 2014; Shanghai; China; 30 June 2014 through 6 July 2014 / [ed] Jin, S.G., Springer Berlin/Heidelberg, 2016, Vol. 144, p. 199-207Conference paper (Refereed)
    Abstract [en]

    In gravimetric methods for a determination of the Moho geometry, the constant value of the Moho density contract is often adopted. Results of gravimetric and seismic studies, however, showed that the Moho density contrast varies significantly. The assumption of a uniform density contrast thus might yield large errors in the estimated Moho depths. In this study we investigate these errors by comparing the Moho depths determined globally for the uniform and variable models of the Moho density contrast. These two gravimetric results are obtained based on solving the Vening Meinesz-Moritz’s inverse problem of isostasy. The uniform model of the Moho density contrast is defined individually for the continental and oceanic lithosphere to better reproduce the reality. The global data of the lower crust and upper mantle retrieved from the CRUST1.0 seismic crustal model are used to define the variable Moho density contrast. This seismic model is also used to validate both gravimetric solutions. Results of our numerical experiment reveals that the consideration of the variable Moho density contrast improves the agreement between the gravimetric and seismic Moho models; the RMS of differences is 5.4 km (for the uniform density contrast) and 4.7 km (for the variable density contrast).

  • 276.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. KTH, Geodesy & Geoinformatics, Stockholm, Sweden.
    Tenzer, Robert
    School of Geodesy and Geomatics, Wuhan University, Wuhan, China.
    Geoid-to-Quasigeoid Separation Computed Using the GRACE/GOCE Global Geopotential Model GOCO02S: A Case Study of Himalayas and Tibet2013In: Terrestrial, Atmospheric and Oceanic Science, ISSN 1017-0839, E-ISSN 2223-8964, Vol. 24, no 1, p. 59-68Article in journal (Refereed)
    Abstract [en]

    The geoid-to-quasigeoid correction has been traditionally computed approximately as a function of the planar Bouguer gravity anomaly and the topographic height. Recent numerical studies based on newly developed theoretical models, however, indicate that the computation of this correction using the approximate formula yields large errors especially in mountainous regions with computation points at high elevations. In this study we investigate these approximation errors at the study area which comprises Himalayas and Tibet where this correction reaches global maxima. Since the GPS-leveling and terrestrial gravity datasets in this part of the world are not (freely) available, global gravitational models (GGMs) are used to compute this correction utilizing the expressions for a spherical harmonic analysis of the gravity field. The computation of this correction can be done using the GGM coefficients taken from the Earth Gravitational Model 2008 (EGM08) complete to degree 2160 of spherical harmonics. The recent studies based on a regional accuracy assessment of GGMs have shown that the combined GRACE/GOCE solutions provide a substantial improvement of the Earth’s gravity field at medium wavelengths of spherical harmonics compared to EGM08. We address this aspect in numerical analysis by comparing the gravity field quantities computed using the satellite-only combined GRACE/GOCE model GOCO02S against the EGM08 results. The numerical results reveal that errors in the geoid-to-quasigeoid correction computed using the approximate formula can reach as much as ~1.5 m. We also demonstrate that the expected improvement of the GOCO02S gravity field quantities at medium wavelengths (within the frequency band approximately between 100 and 250) compared to EGM08 is as much as ±60 mGal and ±0.2 m in terms of gravity anomalies and geoid/quasigeoid heights respectively.

  • 277.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS. Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Tenzer, Robert
    School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan, China .
    Sjöberg, Lars E.
    Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Abrehdary, Majid
    Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    On the residual isostatic topography effect in the gravimetric Moho determination2015In: Journal of Geodynamics, ISSN 0264-3707, E-ISSN 1879-1670, Vol. 83, p. 28-36Article in journal (Refereed)
    Abstract [en]

    In classical isostatic models, a uniform crustal density is typically assumed, while disregarding the crustal density heterogeneities. This assumption, however, yields large errors in the Moho geometry determined from gravity data, because the actual topography is not fully isostatically compensated. Moreover, the sub-crustal density structures and additional geodynamic processes contribute to the overall isostatic balance. In this study we investigate the effects of unmodelled density structures and geodynamic processes on the gravity anomaly and the Moho geometry. For this purpose, we define the residual isostatic topography as the difference between actual topography and isostatic topography, which is computed based on utilizing the Vening Meinesz-Moritz isostatic theory. We show that the isostatic gravity bias due to disagreement between the actual and isostatically compensated topography varies between -382 and 596 mGal. This gravity bias corresponds to the Moho correction term of -16 to 25 km. Numerical results reveal that the application of this Moho correction to the gravimetrically determined Moho depths significantly improves the RMS fit of our result with some published global seismic and gravimetric Moho models. We also demonstrate that the isostatic equilibrium at long-to-medium wavelengths (up to degree of about 40) is mainly controlled by a variable Moho depth, while the topographic mass balance at a higher-frequency spectrum is mainly attained by a variable crustal density.

  • 278.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Tenzer, Robert
    Wuhan University, China.
    Sjöberg, Lars
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Novak, Pavel
    University of West Bohemia, Plzen, Czech Republic.
    Improved global crustal thickness modeling based on the VMM isostatic model and non-isostatic gravity correction2013In: Journal of Geodynamics, ISSN 0264-3707, E-ISSN 1879-1670, Vol. 66, p. 25-37Article in journal (Refereed)
    Abstract [en]

    In classical isostatic models for a gravimetric recovery of the Moho parameters (i.e., Moho depths and density contrast) the isostatic gravity anomalies are usually defined based on the assumption that the topographic mass surplus and the ocean mass deficiency are compensated within the Earth’s crust. As acquired in this study, this assumption yields large disagreements between isostatic and seismic Moho models. To assess the effects not accounted for in classical isostatic models, we conduct a number of numerical experiments using available global gravity and crustal structure models. First, we compute the gravitational contributions of mass density contrasts due to ice and sediments, and subsequently evaluate respective changes in the Moho geometry. Residual differences between the gravimetric and seismic Moho models are then used to predict a remaining non-isostatic gravity signal, which is mainly attributed to unmodeled density structures and other geophysical phenomena. We utilize three recently developed computational schemes in our numerical studies. The apparatus of spherical harmonic analysis and synthesis is applied in forward modeling of the isostatic gravity disturbances. The Moho depths are estimated globally on a 1 arc-deg equiangular grid by solving the Vening-Meinesz Moritz inverse problem of isostasy. The same estimation model is applied to evaluate the differences between the isostatic and seismic models. We demonstrate that the application of the ice and sediment density contrasts stripping gravity corrections is essential for a more accurate determination of the Moho geometry. We also show that the application of the additional non-isostatic correction further improves the agreement between the Moho models derived based on gravity and seismic data. Our conclusions are based on comparing the gravimetric results with the CRUST2.0 global crustal model compiled using results of seismic surveys.

  • 279.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. KTH.
    Tenzer, Robert
    Royal Institute of Technology (KTH), Stockholm, Sweden .
    Sjöberg, L.E.
    Wuhan University, Wuhan, China .
    Moho depth uncertainties in the Vening-Meinesz Moritz inverse problem of isostasy2014In: Studia Geophysica et Geodaetica, ISSN 0039-3169, E-ISSN 1573-1626, Vol. 58, no 2, p. 227-248Article in journal (Refereed)
    Abstract [en]

    We formulate an error propagation model based on solving the Vening Meinesz-Moritz (VMM) inverse problem of isostasy. The system ofobservation equations in the VMM model defines the relation between theisostatic gravity data and the Moho depth  by means of a second-order Fredholm integralequation of the first kind. The corresponding error model (derived in aspectral domain) functionally relates the Moho depth errors with the commissionerrors of used gravity and topographic/bathymetric models. The error model alsoincorporates the non-isostatic bias which describesthe disagreement, mainly of systematic nature, between the isostatic andseismic models. The error analysis is conducted at the study area of theTibetan Plateau and Himalayas with the world largest crustal thickness. TheMoho depth uncertainties due to errors of the currently available globalgravity and topographic models are estimated to be typically up to 1-2 km,provided that the GOCE gravity gradient observables improved themedium-wavelength gravity spectra. The errors due to disregarding sedimentarybasins can locally exceed ~2 km. The largest errors (which cause a systematic bias betweenisostatic and seismic models) are attributed to unmodeled mantleheterogeneities (including thecore-mantle boundary) and other geophysical processes. These errors aremostly less than 2 km under significant orogens (Himalayas, Ural), but canreach up to ~10 km under the oceanic crust.

  • 280.
    Bahilo Rodríguez, Edgar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Power Plant Operation Optimisation: Unit commitment of gas turbines using Machine Learning and MILP programming2018Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 281.
    Bahilo Rodríguez, Edgar
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Swedish and Spanish electricity market: Comparison, improvements, price forecasting and a global future perspective2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report aims to make a comparison between the Swedish and Spanish electricity market, the design of new improvements that could achieve a better operation for both markets as well as the price forecasting for both spot markets. These enhancements are oriented to decrease electricity prices, energy use and the system CO2 emissions.

    Also, the main organizations of the market and their roles has been characterized, clarifying the functions of the Market Operator and the System Operator. In addition, the different markets, the trading products and the price formation have been explained and the picture of the market structure has been achieved with enough depth.

    Moreover, some of the most used methods in Time Series Analysis has been enumerated to understand which techniques are needed for forecast the electricity prices and the methodology used (Box-Jenkins Method) has been explained in detail. Later, all these methods have been implemented in an own code developed in Python 3.6 (TSAFTools .py) with the help of different statistics libraries mentioned during the method chapter.

    On the other hand, the description of the market situation has been carried out for both countries. Power installed capacity, electricity generation, average prices, main renewable technologies and policies to increase the renewable energy share has been analysed and corresponding described.

    Then, to estimate the market’s future spot electricity prices, ARIMA models have been selected to analyse the evolution of the day-ahead price using the TSAFTools.py. The final models show a proper performance in the two markets, especially in the Nordpool, achieving an RMSE: 37.68 and MAPE: 7.75 for the year in 2017 in Nordpool and a RMSE: 270.08 and MAPE: 20.24 in OMIE for 2017. Nordpool spot prices from 2015 to 2016 has been analysed too but obtaining a result not as good as the year 2017 with an RMSE: 49.01 and MAPE: 21.42.

    After this analysis, the strengths and weaknesses of both markets are presented and the main problems of the Spanish electricity system (power overcapacity, fuel dependency, non-cost-efficient renewable energies policies, lack of interconnexion capacity etc.) and the Swedish electricity system (dependency for nuclear power, uncertainty for solar electricity Generation) are presented.

    Finally, due to the quick development of the energy sector in the last years and the concern of the European Committee to reach a new design for the electricity market, different kinds of recommendations for the future have been considered.

  • 282.
    Bahonjic, Sabina
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Beslutsmodeller för val av insamlingssystem för matavfall till biogas- och biogödselproduktion: Avfallstaxan som styrmedel?2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    By 2018 at least 50 % of the Swedish food waste will be biologically treated. Stockholm Vatten are planning to quadruple the collection of food waste for biological treatment between 2015 and 2020. There are three different food waste collecting systems in Stockholm City; food waste bins, half open food disposer and sealed food disposer. The factor that affects the choice of collecting system are costs throughout the process, for example waste fees. Waste fees are seen as a powerful policy instrument to reduce unsorted waste, and should be designed to reduce overall waste, increase the sorting and reduce the environmental load. The purpose of the thesis is to design two decision models for collecting systems of food waste for biogas and digestate production. One model will be simple and be of support when deciding which system the kitchen should invest in, the other model will be designed to give an overview for each systems costs and processes from collection to production of biogas/digestate.

    The methodology was composed of a mixture of a qualitative and quantitative method, and a case study. The data collection was made by a literature study, mail contact, study tour and a map of the processes.

    The pre-treatment cost is 500kr/ton for food waste collected from bins, a cost that food waste does not accrue from disposers. The waste tariff is 57% lower for waste disposals, and they require 72% less transport when collected. The costs Stockholm Vatten have for transporting food waste is 75 % lower for waste disposals compared to food waste bins. If the waste tariff would reflect the costs more kitchens would choose waste disposals over food waste bins. Beside the differences in food waste bins and waste disposals, there are differences between types of waste disposals. Sealed food waste disposals require half of the transports compared to half open food waste disposals for the same biogas potential. When designing tariffs this should be taken in consideration. 

  • 283.
    Bahrami, Alireza
    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. Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran.
    Matinrad, Sina
    Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran.
    Response of steel beam-to-column bolted connections to blast loading2019In: International Journal of Recent Technology and Engineering, ISSN 2277-3878, Vol. 8, no 3, p. 3639-3648Article in journal (Refereed)
    Abstract [en]

    In this research, response of steel beam-to-column bolted connections to blast loading is investigated. Nonlinear analyses of the connections are performed using the finite element software ABAQUS. In order to demonstrate the accuracy of the finite element modelling, an experimental test of a steel beam-to-column bolted connection is modelled. Comparison of the obtained result from the modelling with that of the corresponding experimental test verifies the modelling. Then, a 5-storey steel building is designed using ETABS software from which a beam-to-column connection of the ground floor is selected for the nonlinear analysis in ABAQUS. Thereafter, the components of the selected connection are designed. Finally, the connection is nonlinearly analysed considering parameters as the distance from the blast centre (2.5 m, 5 m, and 10 m) and blast power (500 kg, 1000 kg, and 2000 kg TNT equivalent mass of explosive). Effects of these parameters on the response of the connection are evaluated. Failure modes of the connections are assessed, too.

  • 284.
    Bahrami, Alireza
    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.
    Yavari, Mojtaba
    Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran.
    Hysteretic assessment of steel-concrete composite shear walls2019In: International Journal of Recent Technology and Engineering, ISSN 2277-3878, Vol. 8, no 2, p. 5640-5645Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the hysteretic assessment of steel-concrete composite shear walls with reinforced concrete on one side of the steel plate. Finite element software ABAQUS is utilised to conduct this research. An experimental test on a composite shear wall is simulated to do the verification of the modelling. Then, modelling result is compared with the experimental test result which shows an insignificant difference between them and therefore uncovers the accuracy of the modelling. Thereafter, different parameters are considered to investigate their effects on the response of the walls. Thickness of reinforced concrete, steel plate thickness, and number of shear studs are studied as parameters. It is concluded that changing reinforced concrete thickness and number of shear studs do not considerably affect the ultimate load capacity, ductility, and energy dissipation of the walls. However, increasing the steel plate thickness enhances the ultimate load capacity, ductility, and energy dissipation. In addition, out-of-plane displacement of the walls is evaluated.

  • 285.
    Bai, S.
    et al.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Christensen, S.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Islam, M.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Rafique, Sajid
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Masud, Nauman
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Mattsson, Per
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    O’Sullivan, L.
    University of Limerick, Limerick, Ireland.
    Power, V.
    University of Limerick, Limerick, Ireland.
    Development and testing of full-body exoskeleton AXO-SUIT for physical assistance of the elderly2019In: Wearable Robotics: Challenges and Trends: Proceedings of the 4th International Symposium on Wearable Robotics, WeRob2018, October 16-20, 2018, Pisa, Italy / [ed] Maria Chiara Carrozza, Silvestro Micera, José L. Pons, Cham: Springer, 2019, Vol. 22, p. 180-184Conference paper (Refereed)
    Abstract [en]

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

  • 286.
    Balciunas, Dominykas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Thermoeconomic analysis of LNG physical exergy use for electricity production in small-scale satellite regasification stations2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Liquefied natural gas (LNG) cold utilization in small scale regasification stations is a novel topic in the industry, while such systems have been proven feasible in large scale LNG facilities. Cold recovery and utilization in LNG regasification facilities would increase the thermodynamic efficiency and reduce cold pollution. The aim of the study is to analyze the possibility to apply industry-proven thermodynamic cycles in small scale satellite regasification stations for electricity production, taking the characteristics of a real-world regasification station project in Druskininkai, Lithuania for which useful cold utilization is not currently planned.

    Direct Expansion (DE) and Rankine (ORC) Cycles are analyzed together with cascading using Aspen Hysys software to find the optimal solution considering thermal and exergy efficiency as well as the payback period.

    Thermoeconomically feasible retrofit solutions of approximately 13% thermal efficiency and approximately 17% exergy efficiency showing payback periods of 5 to 10 years and 3.3 to 6 thousand euro additional capital expenditure (CAPEX) per net kW of power production are found.

    Increase in complexity of thermodynamic cycles is directly proportional to both increased thermodynamic efficiencies and capital costs and the study proves that there is a limit at which increase in thermodynamic efficiency of a cycle by cascading becomes economically infeasible. Future work is suggested to improve the accuracy of the results by rigorous design to evaluate pressure drops as well as improvements in economic analysis by utilizing the discounted cash flow methodology. Sensitivity analysis of LNG physical and chemical conditions as well as ambient air could be performed whereas changes in working fluid and better engineering of the part related to intial heat exchange could improve thermodynamic efficiencies. Alternative solutions with a higher temperature heat source are also suggested.

  • 287.
    Ball, Linden J.
    et al.
    University of Central Lancashire, Preston, UK.
    Threadgold, Emma
    University of Central Lancashire, Preston, UK.
    Marsh, John E.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology. University of Central Lancashire, Preston, UK.
    Christensen, Bo T.
    Copenhagen Business School, Copenhagen, Denmark.
    The effects of stimulus complexity and conceptual fluency on aesthetic judgments of abstract art: Evidence for a default–interventionist account2018In: Metaphor and Symbol, ISSN 1092-6488, E-ISSN 1532-7868, Vol. 33, no 3, p. 235-252Article in journal (Refereed)
    Abstract [en]

    We report an experiment investigating how stimulus complexity and conceptual fluency (i.e., the ease of deriving meaning) influence aesthetic liking judgments for abstract artworks. We presented participants with paintings at two levels of complexity (high vs. low) and five levels of conceptual fluency (determined from a prior norming study) and requested separate ratings of beauty and creativity. Our predictions were derived from the PIA Model (Pleasure-Interest Model of Aesthetic Liking), which views aesthetic preferences as being formed by two, distinct fluency-based processes: an initial, automatic, stimulus-driven, default process and a subsequent, perceiver-driven deliberative process. A key trigger for deliberative processing is assumed to be disfluency at the default stage, as caused by factors such as visual complexity. We predicted that complexity and conceptual fluency would interact in determining aesthetic liking, with people preferring complex stimuli, but only when these are relatively easy to process conceptually. Our results supported this prediction for beauty judgments, although creativity judgments showed a curiously uniform profile. Nevertheless, the predictive capacity of the PIA Model in relation to beauty judgments attests to the explanatory strength of this default?interventionist theory of aesthetic liking. We conclude by noting important parallels between the PIA Model and the Revised Optimal Innovation Hypothesis, which likewise has broad reach in explaining how defaultness and non-defaultness affect pleasure across a range of linguistic and pictorial stimuli.

  • 288.
    Balogun, Kazeem Ayinde
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energy audit in Fridhemsskolan: A preschool in Gävle municipality2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is about the energy audit in Fridhemsskolan which is an educational facility. Fridhemsskolan is a preschool for children in Gävle municipality for children up to the age of six years and comprise of nine buildings in total. The project begins with an energy survey on the school facilities which ranges from checking the ventilation system, lightning system, number of occupants, equipment’s types and so on. The next step was to use a simulation program software called indoor climate and energy (IDA ICE) to create the base model for the building and input the data collected during the energy survey directly into the software and simulate it for a period of one year. After creating the base model, the total electricity use of the building was around 89 MWh/year while the district heating was 157 MWh/year.The energy conservation opportunities in Fridhemsskolan for the building was divide into two categories and these are referred to as non-retrofitting (no or minimal cost) and retrofitting (with cost) recommendations. The non-retrofitting involves reducing the indoor temperature and with this approach; the district heating consumption was reduced to 147.6 MWh/year which amount to 9.34 MWh/year in savings for the district heating while the electricity consumption was reduced to 86.4 MWh/year which amount to 2.6 MWh/year in savings for the electricity.Retrofitting (with cost) recommendations involves looking at the base model and see where some improvements can be carried out. In this research, the roof of the building has more energy losses and retrofitting with cost analysis was performed on that part of the building envelope.After retrofit, the district heating consumption was reduced to 142 MWh/year which is about 15 MWh/year in saving for the district heating while the electricity consumption was reduced to 26 MWh/year which also amount to 63 MWh/year saving in electricity consumption. The reason for this sharp decrease in the electrical consumption was because, the electrical radiators in the base model of the building was replaced with ideal heaters that uses district heating as the energy carrier and 170 mm of mineral wool was also added to the roof.Finally the research further looks at the thermal comfort and the indoor air quality of the occupants in the building by analysing the data on both thermal comfort and the indoor air quality to see if the value obtained are within the acceptable range. In most cases the value is within the acceptable range like in the case of carbon dioxide (CO₂) concentration in theiiioccupied zone, the value obtained after reducing the indoor temperature was less than 1000 parts-per-million (ppm) and that shows that the carbon dioxide (CO₂) concentration is within an acceptable level in the room. The thermal comfort of the occupants in the occupied zone was within the acceptable limit. However, lowering indoor temperature increases the PPD for both buildings. The percentage of the total occupant hours with thermal dissatisfaction increases to 13% from 14 % for Hus 9 and from 13% to 15% for Hus (4-8).

  • 289.
    Bandoophanit, Thianthip
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Ye, Lupeng
    University of Gävle, Faculty of Engineering and Sustainable Development.
    University of Gävle Environmental Performance After ISO 14001 CertificationReflected by Students’ Environmental Awareness2010Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Environmental problems are seen as the first priority that all countries try to find as a solution to be more sustainable. These issues arise due to the lack of our responsibility to the world. Researchers agree on that the starting point in changing our society to be green is to increase environmental awareness (Jiang et al., 1999). Several sectors accept this idea like UNESCO which focuses on education as a tool to promote sustainable development (UNESCO, 2002).

     

    Following UNESCO, our study investigates university students’ environmental awareness. The Authors hope that the outcome not only reflects university performance, but also helps to develop the environment in the future.  Hence, the authors selected the University of Gävle or HiG, as a case study because it is a best practice in Environmental Management System (EMS). Moreover, HiG received the ISO 14001 certificate and it has a continuous improvement program (Sammalisto, 2007, p.69). 

     

    The study was started by reviewing research literatures concerning Environmental Management System (EMS), Sustainable Development (SD), Education for Sustainable Development (ESD) and Environmental Awareness. The authors found that there are few studies talking about students’ awareness in universities after being awarded ISO 14001. Notice that the research was seen only from environmental perspective (Flint, 2004).

     

    To answer research questions, two surveys were adopted. The first part focused on teachers and officers (or staffs) who work on environmental issues. While, the second part focused on the students which were divided into Swedish and international.

     

    The research outcomes indicate that HiG has a good EMS performance supported by annual environmental audits, regular policy revision and the attempts to minimize non-conformities. Conversely, when the authors pointed at student awareness, it shows that students have insufficient environmental knowledge. Moreover, some students have lower environmental awareness and act in a less ecological friendly way. Nevertheless, a knowledge problem was also found among several university staffs. This is because of the lack of communication about environmental issues inside the staffs community and lack of environmental education for students.

     

    Whatever the university situation is, there are some groups of staff and students eager to develop themselves and their university. This point of strength could be the best driving force. It can push the university forward until the university reaches sustainable development and it brings the aware graduates into society.

  • 290.
    Baranov, Alexey
    et al.
    Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia; Institute of Earthquake Prediction Theory and Mathematical Geophysics, Russian Academy of Sciences, Moscow, Russia.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS. Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Tenzer, Robert
    Department of Land Surveying and Geo-Informatics, Hong Kong Polytechnic University, Hong Kong, China.
    Combined Gravimetric-Seismic Moho Model of Tibet2018In: Geosciences, ISSN 2076-3263, Vol. 8, no 12, article id UNSP 461Article in journal (Refereed)
    Abstract [en]

    Substantial progress has been achieved over the last four decades to better understand a deep structure in the Himalayas and Tibet. Nevertheless, the remoteness of this part of the world still considerably limits the use of seismic data. A possible way to overcome this practical restriction partially is to use products from the Earth’s satellite observation systems. Global topographic data are provided by the Shuttle Radar Topography Mission (SRTM). Global gravitational models have been derived from observables delivered by the gravity-dedicated satellite missions, such as the Gravity Recovery and Climate Experiment (GRACE) and the Gravity field and steady-state Ocean Circulation Explorer (GOCE). Optimally, the topographic and gravity data should be combined with available results from tomographic surveys to interpret the lithospheric structure, including also a Moho relief. In this study, we use seismic, gravity, and topographic data to estimate the Moho depth under orogenic structures of the Himalayas and Tibet. The combined Moho model is computed based on solving the Vening Meinesz-Moritz (VMM) inverse problem of isostasy, while incorporating seismic data to constrain the gravimetric solution. The result of the combined gravimetric-seismic data analysis exhibits an anticipated more detailed structure of the Moho geometry when compared to the solution obtained merely from seismic data. This is especially evident over regions with sparse seismic data coverage. The newly-determined combined Moho model of Tibet shows a typical contrast between a thick crustal structure of orogenic formations compared to a thinner crust of continental basins. The Moho depth under most of the Himalayas and the Tibetan Plateau is typically within 60-70 km. The maximum Moho deepening of similar to 76 km occurs to the south of the Bangong-Nujiang suture under the Lhasa terrane. Local maxima of the Moho depth to similar to 74 km are also found beneath Taksha at the Karakoram fault. This Moho pattern generally agrees with the findings from existing gravimetric and seismic studies, but some inconsistencies are also identified and discussed in this study.

  • 291.
    Baranov, Alexey
    et al.
    Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russian Federation; Institute of Earthquake Prediction Theory and Mathematical Geophysics, Russian Academy of Sciences, Moscow, Russian Federation.
    Tenzer, Robert
    Department of Land Surveying and Geo-Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS. Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Combined Gravimetric–Seismic Crustal Model for Antarctica2018In: Surveys in geophysics, ISSN 0169-3298, E-ISSN 1573-0956, Vol. 39, no 1, p. 23-56Article in journal (Refereed)
    Abstract [en]

    The latest seismic data and improved information about the subglacial bedrock relief are used in this study to estimate the sediment and crustal thickness under the Antarctic continent. Since large parts of Antarctica are not yet covered by seismic surveys, the gravity and crustal structure models are used to interpolate the Moho information where seismic data are missing. The gravity information is also extended offshore to detect the Moho under continental margins and neighboring oceanic crust. The processing strategy involves the solution to the Vening Meinesz-Moritz’s inverse problem of isostasy constrained on seismic data. A comparison of our new results with existing studies indicates a substantial improvement in the sediment and crustal models. The seismic data analysis shows significant sediment accumulations in Antarctica, with broad sedimentary basins. According to our result, the maximum sediment thickness in Antarctica is about 15 km under Filchner-Ronne Ice Shelf. The Moho relief closely resembles major geological and tectonic features. A rather thick continental crust of East Antarctic Craton is separated from a complex geological/tectonic structure of West Antarctica by the Transantarctic Mountains. The average Moho depth of 34.1 km under the Antarctic continent slightly differs from previous estimates. A maximum Moho deepening of 58.2 km under the Gamburtsev Subglacial Mountains in East Antarctica confirmed the presence of deep and compact orogenic roots. Another large Moho depth in East Antarctica is detected under Dronning Maud Land with two orogenic roots under Wohlthat Massif (48–50 km) and the Kottas Mountains (48–50 km) that are separated by a relatively thin crust along Jutulstraumen Rift. The Moho depth under central parts of the Transantarctic Mountains reaches 46 km. The maximum Moho deepening (34–38 km) in West Antarctica is under the Antarctic Peninsula. The Moho depth minima in East Antarctica are found under the Lambert Trench (24–28 km), while in West Antarctica the Moho depth minima are along the West Antarctic Rift System under the Bentley depression (20–22 km) and Ross Sea Ice Shelf (16–24 km). The gravimetric result confirmed a maximum extension of the Antarctic continental margins under the Ross Sea Embayment and the Weddell Sea Embayment with an extremely thin continental crust (10–20 km).

  • 292.
    Barath, Christian
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management.
    Amini, Nasrollah
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Management, Industrial Design and Mechanical Engineering, Industrial Management.
    Produktinformationens inverkan på returer inom e-handel: Fallstudie på tre företag inom modebranschen2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Med e-handelns snabba expansion har även returerna ökat, returvolymen inom e-handel kan vara så hög som 50% (Dissanayake och Singh, 2007). Returer kostar inte bara pengar utan påverkar även miljön i form av bl.a. ökade transporter. De vanligaste returorsakerna inom modebranschen är storlek och passform vilket kan härledas till bristande produktinformation som t.ex. undermåliga storleksguider. Tidigare forskning om produktinformation har oftast berört vikten av produktinformation vid konsumentköp samt vilka egenskaper i produktinformationen som är viktiga. (Chiu et al, 2014; Manvai och Venkataram, 2005; Markopoulos, Arin och Ungar, 2016) Syftet med denna fallstudie är att undersöka hur produktinformationen påverkar antalet produktreturer hos e-handelsföretag i modebranschen. Studiens frågeställningar berör hur fallföretagen arbetar med produktinformation och om det har påverkat returvolymen samt fallföretagens hållbarhetsarbete. Studien är baserad på en kvalitativ metod och med hjälp av semistrukturerade intervjuer med tre fallföretag besvaras studiens syfte och frågeställningar. Fallföretagen i denna studie arbetar med försäljning inom modebranschen, två av dessa är stora företag och har både fysiska butiker och e-handel. Det tredje fallföretaget är ett mindre företag som enbart har e-handel. Studien visar att fallföretagen får samma gynnsamma effekt av arbetet med produktinformation även om drivkraften bakom arbetet är olika. Studien visar även att produktinformationen kan ses som en kanal för att effektivt förmedla hållbarhetsarbete till kunderna. Studien bidrar med bredare kunskap om produktinformation samt att studien kan ligga till grund för vidare forskning om produktinformationens inverkan på returer. Studien styrker även vissa delar av tidigare forskning inom returer i modebranschen.

  • 293.
    Barattini, Paolo
    et al.
    kontor46, Torino, Italy.
    Virk, Gurvinder S.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Mirnig, Nicole
    University of Salzburg, Salzburg, Austria.
    Giannaccini, Maria Elena
    Bristol Robotics Laboratory, Bristol, United Kingdom.
    Tapus, Adriana
    Robotics and Computer Vision Lab ENSTA-ParisTech, Palaiseau, Paris, France.
    Bonsignorio, Fabio
    Universidad Carlos III de Madrid, Leganés, Madrid, Spain.
    Experimenting in HRI for priming real world set-ups, innovations and products2014In: HRI '14 Proceedings of the 2014 ACM/IEEE international conference on Human-robot interaction, New York: ACM Digital Library, 2014, p. 511-512Conference paper (Refereed)
    Abstract [en]

    Robotics is moving towards real world applications, beyond the well-structured environment of industrial robotics. In the world of assistant robots and medical robots, Human-Robot Interaction is essential. Also in emerging industrial scenarios there is a need of the human to be closely included in the loop. The companies are confronted with the lack of guidelines and of standards on how the higher features of HRI may be safely incorporated. Although the scientific research is burgeoning and worthy of praise, it is clear that its results are scattered and not capable of giving a clear input to be easily taken up by companies and standardization organizations like ISO and IEC. The workshop aims at the integration of empirical findings into complex real world robot systems by focusing on three typical sectors (industrial, service and medical) to develop systematic approaches to benchmark and evaluate experimental systems so that normative results can be realized rapidly. The present workshop focuses on bringing together scientists, representative of robotics companies and of standardization working groups to foster discussion in the definition of experimental scenarios and protocols in HRI, so to be able to prime real world set-ups and help realize the robotic products of the future.

  • 294.
    Barbe, Kurt
    et al.
    Vrije Universiteit Brussel, Brussels, Belgium.
    Olarte, Oscar
    Vrije Universiteit Brussel, Brussels, Belgium.
    Van Moer, Wendy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. Vrije Universiteit Brussel, Brussels, Belgium.
    Lauwers, Lieve
    Vrije Universiteit Brussel, Brussels, Belgium.
    Fractional models for modeling complex linear systems under poor frequency resolution measurements2013In: Digital signal processing (Print), ISSN 1051-2004, E-ISSN 1095-4333, Vol. 23, no 4, p. 1084-1093Article in journal (Refereed)
    Abstract [en]

    When modeling a linear system in a parametric way, one needs to deal with (i) model structure selection, (ii) model order selection as well as (iii) an accurate fit of the model. The most popular model structure for linear systems has a rational form which reveals crucial physical information and insight due to the accessibility of poles and zeros. In the model order selection step, one needs to specify the number of poles and zeros in the model. Automated model order selectors like Akaikeʼs Information Criterion (AIC) and the Minimum Description Length (MDL) are popular choices. A large model order in combination with poles and zeros lying closer to each other in frequency than the frequency resolution indicates that the modeled system exhibits some fractional behavior. Classical integer order techniques cannot handle this fractional behavior due to the fact that the poles and zeros are lying to close to each other to be resolvable and not enough data is available for the classical integer order identification procedure. In this paper, we study the use of fractional order poles and zeros and introduce a fully automated algorithm which (i) estimates a large integer order model, (ii) detects the fractional behavior, and (iii) identifies a fractional order system.

  • 295.
    Barbé, Kurt
    et al.
    Vrije Universiteit Brussel, ELEC.
    Van Moer, Wendy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Lauwers, L
    Vrije Universiteit Brussel.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    A Simple Nonparametric Preprocessing Technique to Correct for Nonstationary Effects in Measured Data2012In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, no 8, p. 2085-2094Article in journal (Refereed)
    Abstract [en]

    The general approach for modeling systems assumes that the measured signals are (weakly) stationary, i.e., the power spectrum is time invariant. However, the stationarity assumption is violated when: 1) transient effects due to experimental conditions are dominant; 2) data are missing due to, for instance, sensor failure; or 3) the amplitude of the excitation signals smoothly varies over time due to, for instance, actuator problems. Although different methods exist to deal with each of these nonstationary effects specifically, no unified approach is available. In this paper, a new and general technique is presented to handle nonstationary effects, based on processing overlapping subrecords of the measured data. The proposed method is a simple preprocessing step where the user does not need to specify which nonstationary effect is present, nor the time interval where the nonstationary effect appears. The merits of the proposed approach are demonstrated on an operational wireless system suffering from interrupted link effects.

  • 296.
    Barbé, Kurt
    et al.
    Vrije Universiteit Brussel, ELEC.
    Van Moer, Wendy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Nagels, G
    Natl Ctr Multiple Sclerosis, Melsbroek, Belgium .
    Fractional-Order Time Series Models for Extracting the Haemodynamic Response From Functional Magnetic Resonance Imaging Data2012In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 59, no 8, p. 2264-2272Article in journal (Refereed)
    Abstract [en]

    The postprocessing of functional magnetic resonance imaging (fMRI) data to study the brain functions deals mainly with two objectives: signal detection and extraction of the haemodynamic response. Signal detection consists of exploring and detecting those areas of the brain that are triggered due to an external stimulus. Extraction of the haemodynamic response deals with describing and measuring the physiological process of activated regions in the brain due to stimulus. The haemodynamic response represents the change in oxygen levels since the brain functions require more glucose and oxygen upon stimulus that implies a change in blood flow. In the literature, different approaches to estimate and model the haemodynamic response have been proposed. These approaches can be discriminated in model structures that either provide a proper representation of the obtained measurements but provide no or a limited amount of physiological information, or provide physiological insight but lacks a proper fit to the data. In this paper, a novel model structure is studied for describing the haemodynamics in fMRI measurements: fractional models. We show that these models are flexible enough to describe the gathered data with the additional merit of providing physiological information.

  • 297.
    Barguilla Jiménez, Núria
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    The effect of a thin foil on the heat losses behind a radiator2013Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

     

    This thesis work is the study of the effect of an aluminium foil on the losses that produced by a radiator, situated under a window, through the wall behind it. The reason behind this topic is due to the energy problem and the different goals that governments have set up to try to reduce the use of energy. For example, more specifically a Swedish national goal is to decrease the energy use of the built stock with 50% by 2050.

     

    For this purpose, an experimental set-up was built in the University of Gävle, Sweden. The arrangement was composed by a radiator and a window facing a climate chamber. A total of twenty-one temperatures and two heat fluxes in the exterior wall were measured in the set-up. Ten different measurement scenarios with different radiator temperature, 40°C, 50°C and 60°C; two different distance between the radiator and the wall, 5 and 9 centimetres and with and without the aluminium foil, were performed.

     

    With the experimental results, a CFD model was validated. Two different models were done, first a 2D model and afterwards a 3D model. For the turbulence, the chosen model was standard k-ε model. There were 54 cases simulated with the 2D model and the 3D model was used just for validation. The cases had different variables such as radiator temperature, outdoor temperature and wall insulation. With these cases, analysis of the effectiveness of the presence of an aluminium foil behind the radiator is performed to evaluate if there is a significant reduction of the losses.

     

    The results showed with both methods that the aluminium foil reduces the losses of the wall behind the radiator. The savings varied depending on the boundary conditions of the case and it were obtained a maximum of 4% and a minimum of 1,3%.

  • 298.
    Barrefjord, Madelene
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Delin, Hanne-Marie
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Förrättningslantmätarens hantering av stiftelser utifrån Kammarkollegiets och tillsynsmyndigheternas prövningar2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Huvudsyftet med studien var att utreda och klargöra hur förrättningslantmätaren bör handla när en stiftelse blir sakägare i en lantmäteriförrättning och hur stiftelsen ska behandlas utifrån förrättningslantmätarens undersökningsplikt. Studien hade även två delsyften där det första skulle beskriva och analysera hur stiftelsers föreskrifter kan ändras, medan de andra skulle utreda hur tillsynsmyndigheternas registrering av stiftelser genomförs. Förrättningslantmätare är en yrkesroll inom lantmäterimyndigheten och har till uppgift att handlägga samt besluta i fastighetsbildnings-ärenden. Lantmäterimyndigheten är den myndighet som har till uppgift att ansvara för att en effektiv och rättssäker fastighetsindelning genomförs. En stiftelse är en typ av juridisk person som bildas av en eller flera personer för att verka för ett bestämt ändamål. Stiftelsen ska förvalta en ekonomisk förmögenhet som har avsatts för ett bestämt ändamål, där förvaltningen ska ske över en längre tid. Förmögenheten kan bestå av fast egendom i form av fastigheter.

    Metoder som använts för att besvara studiens syften och forskningsfrågor var en litteraturstudie, en intervjustudie och en fallstudie. Litteraturstudien granskade tidigare forskning inom ämnes-området, lagstiftningen och facklitteratur för att ge en vetenskaplig grund. Intervjustudien genom-fördes för att få en grundlig förståelse för hur tillsynsmyndigheternas och Kammarkollegiets prövningar går till vid ändring av stiftelsers föreskrifter. Fallstudien granskade och jämförde tillsynsmyndigheternas och Kammarkollegiets prövningar vid ändring av stiftelsers föreskrifter, men fallstudien jämförde även vilka dokument tillsynsmyndigheterna kräver in av en stiftelse när den ska registreras. Intervjuer gjordes i fallstudien med samtliga tillsynsmyndigheter för att samla information om hur deras prövningar går till när stiftelser ska registreras i stiftelseregistren.

    Resultatet av litteraturstudien bestod av beskrivningar av förrättningslantmätarens yrkesroll, fastighets-, ägande- och stiftelsebegreppet. Resultatet av intervjustudien visade att de intervjuade tillsynsmyndigheterna och Kammarkollegiet har olika grundliga prövningar vid ändring av stiftelsers föreskrifter. Detta visade även fallstudien samt att tillsynsmyndigheternas prövningar skiljer sig åt vid registrering av en stiftelse. Slutsatsen beskriver hur förrättningslantmätaren ska handla när en stiftelse blir sakägare i en lantmäteriförrättning och hur stiftelsen ska behandlas utifrån förrättningslantmätarens undersökningsplikt. Två mallar finns i slutsatsen som innehåller riktlinjer för hur en kontroll av stiftelsens föreskrifter kan göras för att vara säker på att fastighets-bildningen inte strider mot stiftelsens föreskrifter.

  • 299.
    Barreiro-Gen, Maria
    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. University of A Coruna, A Coruna, Spain.
    Discussing Approaches to Standard of Living2019In: Decent Work and Economic Growth: Encyclopedia of the UN Sustainable Development Goals / [ed] Walter Leal Filho, Anabela Marisa Azul, Luciana Brandli, Pinar Gökcin Özuyar, Tony Wall, Cham: Springer, 2019Chapter in book (Refereed)
  • 300.
    Barreiro-Gen, Maria
    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.
    Carpenter, Angela
    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. School of Earth and Environment, University of Leeds, Leeds, UK.
    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.
    Lozano, Rodrigo
    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. Organisational Sustainability Ltd., Cardiff, UK.
    Examining Relations Between Public Participationand Public Expenditure: Opinions from English and French Users on Environmental Issues in the English Channel2019In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 11, no 8, article id 2230Article in journal (Refereed)
    Abstract [en]

    Governments need to decide how to allocate their public expenditure, which is commonly misconstrued as simply targeting social issues. Most scientific literature highlights that the role of public spending is to enhance social welfare and fight poverty and inequality. Nonetheless, public expenditure also includes spending on environmental issues. This paper analyses relations between public participation, support for public expenditure, and pro-environmental behaviour (PEB) intentions in the English Channel region. An online public survey was developed to investigate public use of the English and French sides and the public's willingness to change their behaviour to better protect the Channel region. The survey was undertaken in the summer of 2014 and was answered by 2000 respondents. The Channel region public is willing to participate more in behaviour that involves direct changes or switches between buying/purchasing choices. In contrast, there is less willingness to engage in pro-environmental behaviour intentions that involve more active engagement activities. French respondents were slightly less inclined to change their consumer behaviour intentions, while women and older people were slightly more likely to do so. This research shows that pro-environmental behaviour could positively affect support for proposed public expenditure on environmental issues.

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