Umeå University's logo

umu.sePublications
Change search
Refine search result
1 - 21 of 21
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abdulkader, Ammar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Förseningar i byggprojektering och hur de kan förebyggas2023Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Idag är förseningar inom byggbranschen vanliga och orsakar problem och konsekvenser i byggprojekt. När ett projekt blir försenat uppstår extra kostnader för projektägaren, entreprenören eller båda parter. Med andra ord innebär förseningar ekonomiska förluster och skapar en stressig arbetsmiljö för alla inblandade aktörer och projektmedlemmar. I detta examensarbete identifieras betydande risker som kan orsaka förseningar i projekteringsfasen av byggprocessen, samt presenteras lösningar för att förebygga dem.

    Byggprocessen består av fyra faser: förstudie, projektering, produktion och överlämning. Projekteringsfasen är ett av de viktigaste stegen i byggprocessen och har stor betydelse för att förebygga förseningar. I denna fas utformas och ritas byggnader, och bygghandlingar tas fram med konstruktionsritningar, tekniska lösningar och beskrivningar upprättas för att styra hela byggprocessen.

    Detta arbete fokuserar på förseningar i själva projekteringsfasen och dess påverkan på hela projektet, samt hur de kan förebyggas. Arbetet består av en teoretisk och en praktisk del. Syftet med arbetet är att undersöka orsakerna till förseningar inom projekteringsfasen och att hantera dem på bästa sätt genom att utveckla riskhanteringen. Orsakerna kan vara ofullständig information, förändringar i projektspecifikationer och tekniska problem. Teorin bygger på litteratur om projektering i byggprocessen för att ge en bred kunskapsbas om projektering innan den praktiska delen genomförs. Den praktiska delen baseras på intervjuer med erfarna projektledare inom projektering som har varit involverade i olika försenade projekteringsprocesser. Resultatet presenterar projektledarens svar angående orsakerna till förseningarna i de två projekten. I diskussionen jämförs och analyseras resultaten med teorin, vilket visar att sjukdomar och bristande kommunikation, tillsammans med andra risker, kan vara orsaker till förseningar i projekteringsfasen. Förbättringsförslag inkluderar att skapa en trygg och hälsosam arbetsmiljö som en viktig faktor för projektets framgång, genom att anlita ytterligare konsulter från andra företag vid arbetsbelastning och erbjuda avkopplande aktiviteter som exempelvis spa-besök när det behövs. Andra förslag innefattar att lägga extra tid på riskanalys för att identifiera potentiella problem samt att etablera en kommunikationsmetod för grupper, såsom en grupp på Messenger eller en annan applikation, där all information om projektet regelbundet delas.

    Download full text (pdf)
    fulltext
  • 2.
    Amin, Khabat
    et al.
    Swedish Transport Agency, Department of Roads and Railways, Sweden; Centre for Societal Risk Research, Karlstad University, Sweden.
    Skyving, Marie
    Swedish Transport Agency, Department of Roads and Railways, Sweden.
    Bonander, Carl
    School of Public Health & Community Medicine, University of Gothenburg, Gothenburg, Sweden.
    Krafft, Maria
    Umeå University. Swedish Transport Administration, Sweden.
    Nilson, Finn
    Department of Political, Historical, Religious and Cultural Studies, Karlstad University, Sweden.
    Fall- and collision-related injuries among pedestrians in road traffic environment – A Swedish national register-based study2022In: Journal of Safety Research, ISSN 0022-4375, E-ISSN 1879-1247, Vol. 81, p. 153-165Article in journal (Refereed)
    Abstract [en]

    Objective: To investigate the burden of pedestrian injuries, including pedestrian fall injuries (PFI), compared to other transport-related injuries in Sweden and document their characteristics in terms of demographics, causes, type of injuries, and severity level with a focus on long-term consequences.

    Methods: Data were retrieved from the national Swedish Traffic Accident Data Acquisition register. A total of 361,531 fatalities and injuries were reported by emergency hospitals during 2010–2019, of which 127,804 were pedestrians (35%). We assessed the magnitude of PFIs and conducted comparative analyses to assess differences compared to other types of road users regarding sex, age, severity level, injury circumstances, hospital care, causes of accidents, and type of injuries.

    Results: Pedestrians were the second largest group of traffic-related deaths in Sweden after car occupants and accounted for just over a quarter of all fatal accidents in the road traffic environment. Of the total number of pedestrian fatalities, three out of four have been in collision accidents and the others in fall-related accidents. In terms of injuries, pedestrians were the largest group among all road users, regardless of the type of accident. PFIs accounted for a third of all injuries in the road traffic environment and nearly half of all injuries resulting in permanent medical impairment (i.e., 2.2 times more long-term consequences among PFIs compared to injured car occupants). Females (particularly middle-aged and older) and older adults were overrepresented, and most PFIs occurred on urban and municipal roads. The causes were often related to maintenance (e.g., slippery surfaces such as ice, snow, leaves or gravel together with uneven pavements and roads are the cause three out of four of PFIs). Among collision injuries, the representation was almost equal for sex and age.

    Conclusions: Injuries and fatalities among pedestrians are a considerable issue in the road traffic environment in Sweden. Contrary to other traffic groups, the incidence has not decreased over time, meaning that this issue must be met with specific measures and address the specific risk factors they are associated with.

    Practical Application: Including fall accidents in the definition of traffic accidents increases the chances of getting better information about the accidents and taking preventive measures.

    Download full text (pdf)
    fulltext
  • 3.
    Björklund, Johannes
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Projektering av träbroar: En undersökning av förbättringsåtgärder för anpassning av Tekla Structures mot träbroprojektering2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this project has been to study which requirements apply on wooden bridges from a design perspective, observing both external requirements and internal requirements from the company Martinsons. Based on these requirements measures would be proposed to adapt Martinsons Tekla-template model for the design of timber bridges. The theoretical part of the project has, as a starting point been conducted by studies of the Transport Administration's requirements on wooden bridges. Discussions with designers working with wooden bridges have also been conducted to get an understanding of their experiences and opinions. Furthermore, a number of previously constructed wooden bridges have been studied in order to find areas in need of improvement. With this background, it then examined which measures were feasible in Tekla. Several measures that would aim to improve the drawing quality and comply with the applicable requirements was produced and declared in the project. Measures aimed to streamline the modeling and drawing creation was also proposed. The measures proposed should enhance Martinsons Tekla-template model in a significant way, but shall in no way be considered as a definitive solution in the quest to meet the requirements concerning the design of wooden bridges. The projekct made it clear that it is not reasonable, or even feasible, to adjust the template model to meet all requirements, some adjustments must be done in each project. It also became clear that it would be good to open a dialogue with the Swedish Transport Administration to make sure what their requirements are so that Martinsons can comply with them in an effective way.

    Download full text (pdf)
    Projektering av träbroar
  • 4.
    Brändström, Tobias
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Människors rörelse i Umeå centrum: Apbergets position analyserad med en agent-baserad simuleringmodell2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Simuleringsmodeller kan användas för att bättre förstå och förutspå

    människors rörelse i olika gatumiljöer. Olika typer av modeller är bra på

    olika saker, med vissa kan man på makronivå simulera hundratusentals

    personer samtidigt för att få en överblick och med vissa kan man gå ner

    på mikronivå och följa enskilda individers rörelse. Problemet med dessa

    modeller är att de inte tar hänsyn till det faktum att merparten av människor

    i en folkmassa inte är ensamma, ca 70 procent av personerna har

    kompisar, kollegor eller anhöriga som de vill hålla sig nära. Den här rapporten

    tar hänsyn till dessa grupper av människor, det tas även hänsyn

    till stillastående personer runt omkring i den simulerade miljön. I denna

    rapport belyses fördelarna och möjligheterna som nns med att använda

    simulering som hjälpmedel vid planering av olika byggnadsprojekt. Syftet

    med projektet är att skapa en simuleringsplattform och med denna simulera

    människors rörelser i Umeå centrum. Umeå centrum har genomgått

    ombyggnationer under det senaste året och genom att jämföra simulering

    av både den ursprungliga layouten och den nybyggda så erhölls följande

    resultat. I den nybyggda layouten så var  ödet av människor bättre, enligt

    simuleringen så tjänade personerna som rörde sig i centrum i snitt

    en sekund på grund av den minskade trängseln. Det nns kommersiell

    mjukvara för att simulera människors rörelse men i och med skapandet av

    denna rapport visas att motsvarande resultat kan fås med relativt enkla

    medel. Med denna simuleringsplattform kan man dessutom lätt rita upp

    de miljöer man vill simulera samt inkludera några fenomen som inte nns

    med i de kommersiella varianterna. I detta projekt så har fokus legat på

    resultatet och inte på att få simuleringen att gå så snabbt som möjligt, så

    det nns utrymme för an hel del förändringar för att snabba upp simuleringsprocessen.

    Download full text (pdf)
    Människors rörelse i Umeå centrum: Apbergets position analyserad med en agent-baserad simuleringmodell
  • 5.
    Coric, Vedad
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Mapping of Dependent Structural Responses on a Prestressed Concrete Bridge using Machine Learning Regression Analysis and Historical Data: A Comparison of Different Non-linear Regression Approaches2023Student paper first term, 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Prestressed concrete bridges are susceptible to deterioration over time which might significantly affect their capacity and overall performance. In previous decades, infrastructure owners have found that continuous monitoring of these assets is a valuable tool for their management as it facilitates the decision-making process regarding the intervention strategies required. However, as data acquisition and measurement technologies have advanced tremendously in recent years, the amount of information that can be retrieved daily is not easy to manage and analyse. This study presents an evaluation of the effectiveness between different machine learning methods regarding prediction and interpretation of structural responses as well as the feasibility of mapping an independent variable, aspects such as metric performance, learning curves and residual plots was analysed. A comparison was made on the machine learning algorithms performing regression analysis where each model scored over 98% in the R-square metric. This study utilised data collected from a prestressed concrete bridge located in Autio, northern Sweden, that has been continuously monitored for more than three years.

    Download full text (pdf)
    fulltext
  • 6.
    Davoli, Lorenzo
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Redström, Johan
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Materializing infrastructures for participatory hacking2014In: DIS '14 Proceedings of the 2014 conference on Designing interactive systemsPages, Association for Computing Machinery (ACM), 2014, p. 121-130Conference paper (Refereed)
    Abstract [en]

    This paper presents a design exploration of opportunities for opening up industrial infrastructures in order to make them supportive of more sustainable and locally adaptive configurations. Taking logistic services in a rural area as a case study, we describe a set of interventions in tracing and expressing their underlying functionalities to make them available as design material. The insights gained inspired the speculative design of a concept for a distributed and community-owned delivery network performed by drones. The case illustrates the potential that can be made available when opening up infrastructures for participative design interventions.

  • 7.
    Davoli, Lorenzo
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Wiltse, Heather
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Redström, Johan
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Trojans & Drones: Materializing possibilities for transforming industrial infrastructures2015In: Proceedings of the 2nd Biennial Research Through Design Conference, Cambridge, UK, 2015Conference paper (Refereed)
    Abstract [en]

    Emerging post-industrial societal needs require the evolution of existing networks of industrial infrastructures toward more distributed and citizen-centered configurations. This opens up new questions regarding what design processes and practices are necessary to effect change within these systems that are often deliberately not accessible and open for design interventions. We here present a set of design explorations in tracing and materializing infrastructures in order to make them available for design and participation, taking logistic services in a remote rural

    area of northern Sweden as a case study and field site. A design concept consisting of a drone and drone postbox were used to speculate about the possibility of a community-owned delivery network operated by drones

    in synergy with existing infrastructures. We used these artifacts in staging participatory processes of imagination and experimentation in order to explore possible future configurations. The project provides an example of a possible framework for initiating and curating the transformation

    of industrial systems towards more open and locally adaptive forms and functions.

    In particular, it illustrates the rich potential and opportunities for design when it comes to ways of knowing and designing with the infra- structural—that which is usually hidden beneath the surface. 

  • 8.
    Eriksson, Martin
    Umeå University, Faculty of Social Sciences, Unit of Economic History.
    To the mutual benefit of the member states. Nordic transnational road cooperation, 1956–19662022In: Journal of Transport History, ISSN 0022-5266, E-ISSN 1759-3999, Vol. 43, no 3, p. 440-460Article in journal (Refereed)
    Abstract [en]

    This article deals with the Nordic Council as a cooperation organ for building transnational roads outside of the E-road network during the period 1956–1966. The Nordic experience of planning and interconnecting transnational roads is related to the United Nations Economic Commission for Europe (ECE) and the development of the E-road network. It is noted that whereas the E-road network built on an ambition within the ECE to create mutual understanding and fraternity between the European nations, the Nordic Council viewed roads as instruments to deal with shared economic and social problems. Another difference is that while the member states of the ECE interacted with societal groups and expert organisations during the interconnection of the E-road network, such actors did not participate directly with the Nordic Council. The inter-Nordic stream of technical expertise was primarily channelled through the national road administrations which cooperated to interconnect the trans-Nordic network.

    Download full text (pdf)
    fulltext
  • 9.
    Forsberg, Rebecca
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Holgersson, Annelie
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Bodén, Ida
    Passengers' Perceptions of Railway Safety2017In: International Journal of Transportation, ISSN 2287-7940, Vol. 5, no 2, p. 47-54Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to identify the passengers' perceptions of railway safety, with emphasis on the internal safety and potential safety improvements. Train passengers (n=243) in Sweden were surveyed and data were analyzed with descriptive and bi-variate statistics. Results showed that only 40% judged the internal train safety as safe. Closed luggage racks and more space for luggage were the most acceptable changes. Both regarding internal safety and acceptable safety changes there were significant differences between high-and low-frequency travelers, with more seasoned travelers less worried about safety and less excepting of additional safety features and costs. The conclusion was that high-frequency and low-frequency travelers differ in their perceptions of safety and that acceptability of safety features followed the perceived effects on comfort.

  • 10.
    Hammar, Evelina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Flygare, Wilda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    ÅTERBRUK AV TRÄBROAR: En undersökning om att flytta en träbro efter dess tekniska livslängd2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

     This report investigates the potential of reusing a timber bridge beyond its original technical lifespan and explores the possibility of altering its geometry. Central to this inquiry are the questions about which obstacles exists in ensuring the quality if a wooden bridge after its technical lifespan to reuse it, and how much can the geometry of the bridge change. The study includes a literature review covering various aspects such as reuse practices, timber bridge construction, and regulatory frameworks governing bridges. To complement the literature review, unstructured interviews with experts in the field of timber, engineering and bridge construction are conducted. These conversations aim to bridge the gap between theoretical knowledge and practical insights. The discussions are structured to allow the expert to share their experiences and expertise. Selected questions then delve deeper into specific areas of their knowledge, facilitating engaging discussions and follow-up inquiries. The search for relevant literature primarily uses online sources as Google and DiVA-portal, with a focus on topics such as reuse practices, timber bridge construction methods, and the regulations set forth by agencies like the Swedish Transport Administration.

    Calculations are carried out using programs like MathCad and Frame analysis, with results presented through Excel spreadsheets to provide visual clarity. The analysis focuses on a specific type of timber bridge, a prestressed glulam deck bridge, where the total length is adjusted to varying degrees and the span is modified accordingly. The findings suggest that with adequate maintenance, timber bridges can indeed be reused beyond their original lifespan. It’s also important that scheduled inspections are carried out and documentation is also of value to simplify the reuse process. The calculations demonstrate that even with modifications to the length and span, timber bridges can be successfully reused. Challenges arise from the stringent regulations of the Swedish Transport Administration, which may prevent the integration of repurposing practices. To enable reuse of timber bridges some changes to the existing regulations needs to be done, provided safety and structural integrity are not compromised.

    Download full text (pdf)
    fulltext
  • 11.
    Khodadad, Davood
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Advancing road safety assessment with digital holography: a study on skid resistance of asphalt pavements2023In: Proceedings of SPIE - The International Society for Optical Engineering / [ed] Thilo Erbertseder; Nektarios Chrysoulakis; Ying Zhang, SPIE - The International Society for Optics and Photonics, 2023, article id 1273507Conference paper (Refereed)
    Abstract [en]

    Enhancing road safety through improved skid resistance is a critical endeavor in preventing accidents and promoting secure driving conditions. This study delves into the investigation of skid resistance in asphalt pavements using digital holography, focusing on macro and microtexture attributes. By employing off-axis digital holography, the paper presents a novel method to accurately measure surface profiles and assess friction properties. The experimental setup leverages single-shot dual-wavelength holography, providing precise 3D topographic information. The study demonstrates how the obtained phase information aids in deriving surface profiles and subsequently determining friction coefficients. The approach overcomes limitations of conventional methods, offering micron-level accuracy for surface roughness measurements. Through experimental results, the versatility of adjusting measurement accuracy and range based on requirements is showcased. The paper concludes by highlighting the interplay between surface features and friction characteristics, paving the way for improved road safety assessment.

  • 12.
    Lee, Sang Hoon
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Holme, Petter
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Geometric properties of graph layouts optimized for greedy navigation2012In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 86, no 6, p. 067103-Article in journal (Refereed)
    Abstract [en]

    The graph layouts used for complex network studies have been mainly developed to improve visualization. If we interpret the layouts in metric spaces such as Euclidean ones, however, the embedded spatial information can be a valuable cue for various purposes. In this work, we focus on encoding useful navigational information to geometric coordinates of vertices of spatial graphs, which is a reverse problem of harnessing geometric information for better navigation. In other words, the coordinates of the vertices are a map of the topology, not the other way around. We use a recently developed user-centric navigation protocol to explore spatial layouts of complex networks that are optimal for navigation. These layouts are generated with a simple simulated annealing optimization technique. We compare these layouts to others targeted at better visualization and discuss the spatial statistical properties of the optimized layouts for better navigability and its implication.

  • 13. Li, Jing
    et al.
    Yang, Song
    Muhammad, Yaseen
    Sahibzada, Maria
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Zhu, Zhaorong
    Liu, Tao
    Liao, Shengyu
    Fabrication and application of polyurea formaldehyde-bioasphalt microcapsules as a secondary modifier for the preparation of high self-healing rate SBS modified asphalt2020In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 246, article id UNSP 118452Article in journal (Refereed)
    Abstract [en]

    In this study, microcapsules were prepared from polyurea formaldehyde (as microcapsules wall) and bio-asphalt (as microcapsules core) and were in turn applied to prepare microcapsule-styrene-butadiene styrene (microcapsule/SBS) modified asphalt. When the asphalt wall was broken, the bio-asphalt (core) drifted out and was well blended with the SBS modified asphalt to repair the damaged gap, thereby improving the self-healing ability of the pristine SBS modified asphalt. Ductility test showed that the healing rate of microcapsule/SBS modified asphalt was much greater than that of pure SBS modified asphalt. Dynamic shear rheometer and multi-stress creep recovery tests revealed that microcapsule/SBS modified asphalt exhibited better viscoelasticity, high temperature stability (by thermogravimetric analysis) and rutting resistance than pure SBS modified asphalt attributed to the even dispersion of microcapsules in SBS as confirmed by fluorescent microscopy. Compared with the pure SBS modified asphalt, the storage modulus and loss modulus of 0.4% microcapsule/SBS modified asphalt increased by 24.8% and 17.7% at 46 degrees C, respectively. Scanning electron microscopy and transmission electron microscopy analyses revealed spherical morphology of the microcapsules with wrinkled depressions on the surface, while the wall of microcapsule coated the core. This study can be envisioned of great promise for the preparation of alternative types of modified asphalt for practical applications in construction and highway industries.

  • 14.
    Lindahl, Julia
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Framtidssäkra beräkningar för Umeå Energis elnät genom framtagande av datamodeller2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Examensarbetet utfördes i samarbete med Umeå Energi, som i sitt dagliga arbete med elnätet använder mjukvaran Digpro. Programmet har under en tid matas med värden för kablar och ledningar hämtade från andra energibolag och kabeltillverkare. I framtiden kommer användningen av solceller och elbilar att öka vilket kommer att ställa högre krav på elnätet. Felaktiga beräkningsmodeller kan skapa varmgång i kabel som förkortar livslängden och i extrema fall även kan skapa avbrott. Syftet med projektet var att undersöka vilken data som vore önskvärd att använda för att säkra korrekta beräkningar för ett framtidssäkert elnät. Målet var att ta fram en standardiserad modell för kablar, presentera förslag på val av parametrar samt att analysera och jämföra den gamla och nya beräkningsmodellens påverkan på nätet.

    Efter en litteraturstudie sammanställdes kabeldata från svensk standard. I dpPower (Digpro) byggdes ett mindre simulerat nät som skulle vara representativt för Umeå Energis elnät. Detta genom att använda de 20 kablar med längst geografisk längd i det befintliga 0,4 kV, respektive 10 kV nätet. Två nätberäkningar utfördes för det nya nätet, en med de gamla kabelvärdena och en med de som hämtats i svensk standard. Resultatet för märkström, korttidsström och maximal säkring för de totalt 40 utvalda kablarna och resultatet för kortslutningsström (Ik3) och kortslutning fas-nolla (Ij) för skena i nätstation, skena i kabelskåp och anslutningspunkt jämfördes mellan beräkningarna. Slutligen fördes även en diskussion kring möjliga korrektionsfaktorer.

    Mycket av resultaten tyder på att nätet idag överbelastas. Resultaten visade att för de flesta kablar som undersökts i detta projekt har en för hög märkström angetts i Digpro, både för 0,4 kV-kablar och 10 kV-kablar. För lågspänningskablarna innebar värdena hämtade från svensk standard en minskning på 31% jämfört med de värden som fanns i Digpro sedan tidigare. För mellanspänningskablarna var motsvarande minskning 13% respektive 3%, beroende på om man räknar med en kabeltemperatur på 65°C eller 90°C. Ett annat resultat som tyder på att nätet överbelastas var att för över hälften av kablarna som undersöktes i projektet verkar säkringarna vara överdimensionerade, vilket kan leda till överhettning.

    Slutsatsen som dras i projektet är att Umeå Energi troligtvis överbelastar elnätet. Då det kommer att ställas högre krav på nätet i framtiden är det viktigt med en korrekt beräkningsmodell, och kabelvärden hämtade i svensk standard kan vara ett steg i rätt riktning. Korrektionsfaktorer har visat sig kunna medföra en mycket stor påverkan på belastningsförmågan, i vissa fall större påverkan än de standardiserade kabelvärdena. För mellanspänning kommer eventuell korrektionsfaktor troligtvis minska belastningsförmågan ytterligare. För lågspänning kan en sammanvägd korrektionsfaktor både över och under 1 vara möjlig, beroende på vilka förutsättningar man väljer att utgå från.

    Download full text (pdf)
    fulltext
  • 15.
    Mattsson, Anna
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Artesiskt vattentryck: Hur bygger man infrastruktur?2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is the result of my Bachelor of Science degree project in Building Technology at Umeå University.

    In 2009 Svevia began construction of a new road between the current route 363 and the E12, passing through the farmlands of Västerslätt. An artesian water pressure had been discovered previously, during the geotechnical investigation. When construction started Svevia realized that the high groundwater level caused more trouble than expected. The soil had very poor stability and after it ruptured a different method for the foundation of the road had to be devised, and it was decided to use timber piles.

    The object of this report has been to compare different foundation methods when building infrastructure over soil with artesian water pressures. I also try to explain what artesian groundwater pressure means as well as some basic concepts one can come upon in road construction. My final aim is to find out if any of the foundations I have studied is better than the others in these particular cases. The report is based primarily on literature studies but I have also used conversations/interviews with experts.

    When writing this report I have learned that construction on land with high artesian water pressure is generally avoided. If there are no other options then the first thing to do is to lower the water pressure. This can be done in different ways. One way is to use an excess load in order to force the water aside, another way is to put drainage in the soil. Often a combination of the two methods is used. A negative side effect of lowering the pressure in the soil can be uncontrolled settling of the soil surface, or even a mudflow. In both cases I have studied the best method has been to connect the layers of earth with piles or pillars.

    In the western parts of Sweden the poor buoyancy of the soil is generally due to the presence of quick clay. Even with low artesian water pressure you get soil that is very prone to slide if you combine it with quick clay.

    On Västerslätt the high level of the groundwater was the primary reason of the poor buoyancy of the soil. The fact that the foundation of the road was first laid down on frozen ground, that was kept free of snow in order to get the frost to go deeper into the soil, may explain why the settlings became so pronounced.

  • 16. Meng, Fei
    et al.
    Ma, Shuyi
    Muhammad, Yaseen
    Li, Jing
    Sahibzada, Maria
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Chi, Fengxia
    Analysis of Virgin Asphalt Brands via the Integrated Application of FTIR and Gel Permeation Chromatography2020In: Arabian journal for science and engineering, ISSN 2193-567X, Vol. 45, p. 7999-8009Article in journal (Refereed)
    Abstract [en]

    Counterfeit asphalts have often been deliberately adulterated to reduce costs, which has seriously impeded the development of road and highway construction. In this study, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and gel permeation chromatography (GPC) were applied in combination to explore a fast, accurate, low-cost and efficient method to better identify the brand and quality of asphalt. Results revealed that ATR-FTIR spectra of seven brands of asphalt were basically identical, while they differ in benzene ring substituent content and (-CH2-)n (n >= 4) content. The fingerprint intervals of virgin asphalt were 1770-1636 cm-1, 1060-985 cm-1 and 920-690 cm-1. The aging degree of the same brand of asphalt was identified by 1770-1636 cm-1 and 1060-985 cm-1, while 920-690 cm-1 range was used to identify the fingerprint interval of the original asphalt brand. GPC analysis revealed that the large molecular size (LMS) content of original Fu Lian and Shuang Long asphalt brands greatly differed which were not identified by FTIR. Owing to the thermal oxidation, the LMS content of the same brand of virgin asphalt increased by 4-6% after short-term aging. The present study based on the integrated operation of GPC-FTIR for the fast and accurate recognition and distinguishing between different brands of asphalts could be of potential practical applications.

  • 17.
    Rautio, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Anläggningsmodellering i AutoCAD Civil 3D2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    The purpose of this thesis is to give an overall picture of what BIM is and how the method of working can influence the building process positively. The report focuses on the road construction industry, primarily from a projector's perspective. A design example will also show how a model can be created by using software that supports workflows in BIM.

    BIM can be abbreviation for BuildingInformationModel, for this case it refers to the model or models and is a digital object-based representation of a building or facility. It can also be abbreviation for BuildingInformationModeling, it then refers to a way of working, i.e. process of creating and using one or several building information models in the construction or facility process.

    By using BIM there are many benefits, not only in the house construction but also in the road construction industry. The coordination would be considerably easier and of better quality. With the help of a coordination model it would for example possible to perform collisions checks to detect conflict between different technologies. In a complete model there is also material that the entrepreneur can use for e.g. machine control.

    The model is created in Autodesk Civil 3D with the add Naviate Road. I started by first establishing a terrain model over the existing ground. After that I designed an alignment, a profile and a normal section of the road, which together form a road corridor. The terrain model and the road corridor constitute a 3D model where different design options can be evaluated.

    The often missing demands for BIM from clients are a problem. Establishing BIM models can result in higher project costs and unfortunately some clients cannot see the benefits of these models.  If the client instead would invest more money in a well-established model, costs can be reduced in the production and the management which would lead to decreased in total cost. The knowledge to maintain the BIM model needs to be improved in the management stage. If the model is maintained and used properly, it is an excellent information base, not least as material for future changes.

    Download full text (pdf)
    fulltext
  • 18. Su, Zhibin
    et al.
    Muhammad, Yaseen
    Sahibzada, Maria
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Li, Jing
    Meng, Fei
    Wei, Yunhao
    Zhao, Zhenxia
    Zhang, Lei
    Preparation and properties of aminated graphene fiber incorporated modified asphalt2019In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 229, article id 116836Article in journal (Refereed)
    Abstract [en]

    The inert nature of polyacrylonitrile (PAN) fiber limits the development of fiber asphalt pavement, which can however be tackled by modifying PAN. In this paper, PAN was modified via self-polymerization of dopamine and covalent grafting of aminated graphene, which were in turn used to prepare three kinds of modified asphalt. Dynamic shear rheometer (DSR) tests showed that the aminated graphene modified fiber based asphalt had better viscoelasticity and resistance to permanent deformation than the pristine fiber added asphalt. 3% NH2-GNPs/D-PAN modified asphalt exhibited about 8% higher G* than 3% PAN modified asphalt at a fixed shear frequency. The aminated graphene modified asphalt exhibited enhanced hydrophobicity, adhesion work and water resistance (increased by 14%) than unmodified PAN fiber added asphalt as determined via contact angle measurement. Trabecular bending test and water-immersed Marshall stability test showed that NH2-GNPs/D-PAN incorporated modified asphalt mixture realized the best cracking resistance at low temperature and water damage resistance, which is consistent with the result of DSR and contact angle tests. FT-IR characterization confirmed the successful grafting of amino group onto graphene oxide and that graphite oxide was reduced to graphene. The fiber structure and successful grafting of aminated graphene onto the fiber surface in the PAN modified asphalt was further characterized and confirmed by SEM and AFM. 

  • 19.
    Säterdahl, Ida
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    De vanligaste tillbuden vid vägarbeten och hur de kan förebyggas2022Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Vägnätet spelar en viktig roll för ett fungerande samhälle, men samtidigt innebär trafiken en stor risk. Globalt var trafikolyckor den vanligaste orsaken till barn och ungas död i åldern 5 – 29 år under år 2016. Samma år dog 1,35 miljoner människor i trafiken världen över. Att halvera antalet dödsfall i trafiken till år 2020 är ett av delmålen i agenda 2030 samtidigt som andra mål handlar om en trygg och säker arbetsmiljö, koppla ihop samhällen och göra transportsystem tillgängliga för alla. Det ställer krav på utbyggnad och underhåll av transportsystemet samtidigt som säkerheten måste höjas.

    Trots att Sverige är ett av länderna med högst trafiksäkerhet i världen sker varje år flera trafikolyckor med dödlig utgång. År 2020 dog 204 personer i trafiken. Riksdagen tog år 1997 ett beslut om nollvisionen där målet var att ingen skulle dö eller skadas allvarligt i Sveriges transportsystem på sikt. Mellan åren 2003 - 2015 uppskattas att minst 3958 olyckor skett i anslutning till vägarbeten i Sverige. Bygg- och anläggningsbranschen var år 2020 den bransch där flest omkom. Svevia går i samma riktning som nollvisionen med sin vision om noll olyckor och branschens säkraste arbetsplats och säkraste trafikmiljö. För att nå målet krävs ett ständigt arbete för att förebygga risker och olyckor.

    Genom att studera Svevias inrapporterade tillbud kan risker upptäckas i tid vilket ger en möjlighet att hinna förebygga dessa innan en olycka sker. Syftet med detta examensarbete är att kunna bidra till en förbättrad arbetsmiljö inom drift av väg samt en ökad trafiksäkerhet förbi vägarbeten. Målet är att föreslå möjliga åtgärder som kan minska risken för de vanligaste tillbuden.

    De studerade tillbuden visar att i 44% av fallen var oaktsamma trafikanter eller brist på respekt för vägarbetet orsaken till tillbudet. För 12% var orsaken hög fart, för 11% var orsaken mänskliga faktorn och för 10% fel på fordon/utrustning. I resterande 23% kategoriserades orsaken som övrigt. Detta beror på en stor spridning av svaren och att en orsak endast förekom ett fåtal gånger. Exempel ur kategorin övrigt är renar på vägen.

    Med hjälp av de studerade tillbuden har åtgärder tagits fram som kan bidra till en möjlig minskning av tillbuden samt förebygga olyckor. En viktig åtgärd är att minska machokulturen inom bygg- och anläggningsbranschen som kan bidra negativt till säkerheten på arbetsplatser. Att höja allmänhetens respekt för vägarbeten är också viktigt.

    Download full text (pdf)
    fulltext
  • 20.
    Winter, Stephan
    et al.
    The University of Melbourne.
    Tomko, Martin
    The University of Melbourne.
    Vasardani, Maria
    RMIT.
    Richter, Kai-Florian
    Umeå University.
    Khoshelham, Kouroush
    The University of Melbourne.
    Kalantari, Mohsen
    The University of Melbourne.
    Infrastructure-Independent Indoor Localization and Navigation2019In: ACM Computing Surveys, ISSN 0360-0300, E-ISSN 1557-7341, Vol. 52, no 3, article id 61Article in journal (Refereed)
    Abstract [en]

    In the absence of any global positioning infrastructure for indoor environments, research on supporting human indoor localization and navigation trails decades behind research on outdoor localization and navigation. The major barrier to broader progress has been the dependency of indoor positioning on environment-specific infrastructure and resulting tailored technical solutions. Combined with the fragmentation and compartmentalization of indoor environments, this poses significant challenges to widespread adoption of indoor location-based services. This article puts aside all approaches of infrastructure-based support for human indoor localization and navigation and instead reviews technical concepts that are independent of sensors embedded in the environment. The reviewed concepts rely on a mobile computing platform with sensing capability and a human interaction interface (“smartphone”). This platform may or may not carry a stored map of the environment, but does not require in situ internet access. In this regard, the presented approaches are more challenging than any localization and navigation solutions specific to a particular, infrastructure-equipped indoor space, since they are not adapted to local context, and they may lack some of the accuracy achievable with those tailored solutions. However, only these approaches have the potential to be universally applicable.

    Download full text (pdf)
    fulltext
  • 21.
    Zäll, Emma
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Modelling Pedestrian-Induced Vertical Vibrations of Footbridges2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A pedestrian crowd walking on a footbridge causes the footbridge to vibrate. These vibrations become an issue of serviceability and can give rise to discomfort for the pedestrians, whereby they should, to as large extent as possible, be prevented. Currently, there is a lack of reliable models to describe a dynamic load on a footbridge, due to a walking crowd. Therefore, there is a need for such models.

    Lately, a great amount of research has been carried out on the subject pedestrian-induced vibrations of footbridges, though most of it with focus on lateral vibrations. Conversely, this project has been performed aiming to accurately model pedestrian-induced vertical vibrations of a general footbridge. For that purpose, starting from an existing model, a somewhat improved model, comprising three sub-model, has been developed. The sub-models are: one model of the pedestrian crowd walking along the footbridge, one model describing the load from the pedestrian footstep and one model describing the interaction between the pedestrians and the footbridge.

    In order to get statistically reliable results, numerous simulations of the pedestrian-induced vertical vibrations of a specific footbridge have been performed, using the developed model. Averaging the results over the simulations, we could conclude that the model gives an average error of 7 %, compared to experimental data. The measured quantity giving these results was the absolute maximum value of the acceleration at the midpoint of the footbridge. The achieved dynamical response of the footbridge is qualitatively satisfying, while the quantitative error is larger than we hoped for, whereby we conclude that further improvement of the model is needed before we are able to accurately model pedestrian-induced vertical vibrations of footbridges.

    Download full text (pdf)
    fulltext
1 - 21 of 21
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf