Change search
Refine search result
59606162636465 3051 - 3100 of 3243
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.
  • 3051.
    Walton, K.
    et al.
    School of Mathematics, University of Bath.
    Digby, Peter
    Luleå tekniska universitet.
    Wave propagation through elastically-anisotropic fluid-saturated porous rocks1989In: Journal of applied mechanics, ISSN 0021-8936, E-ISSN 1528-9036, Vol. 56, no 4, p. 744-750Article in journal (Refereed)
    Abstract [en]

    An elastically-anisotropic sedimentary rock is modeled by a simple cubic packing of identical, contacting spherical particles. The connected pore space is filled with an inviscid, compressible fluid. A set of averaged equations is derived to relate the constitutive and dynamic coupling coefficients, and hence also the effective wave speeds in any given direction explicitly to the microstructural properties of the rock considered. Simple, explicit results are obtained when the propagation of either a purely longitudinal or a purely transverse wave is considered.

  • 3052.
    Wandt, Karina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Karim, Ramin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Context adapted prognostics and diagnostics2012In: The Ninth International Conference on Condition Monitoring and Machinery Failure Prevention Technologies, 2012, Vol. 1, p. 541-550Conference paper (Refereed)
    Abstract [en]

    Context adaptation is an important aspect of prognostics and diagnostics as it facilitates the ability to provide relevant information to the consumers of that information. For example, eTechnologies facilitate the communication of data between systems and they assist stakeholders in different parts of an enterprise to make decisions based on the same data. However, decisions may differ, depending on individual stakeholders and specific prognostic and diagnostic processes and techniques, e.g. data fusion or data mining. The correct use of eTechnologies can improve the maintenance of an item or system, thus extending its remaining useful life. The challenge is learning how to make good use of eTechnology and ensure that the right information is provided to the right information consumer, e.g. stakeholders within various processes of an enterprise.Technical solutions in industry are often complex; they are created in heterogeneous environments and the information generated must adapt to different user contexts. Hence, context adaptation can be considered a key requirement for systems operating in heterogeneous environments. This paper considers context to be a template that describes a set of generalised characteristics of a real-world situation; the information in the template differs depending on the situation but the type of information is the same. It defines context adaption as the process of gathering information about the context template, such as structure and information type, evaluating this information and changing the observable behaviour to fit the current context

  • 3053.
    Wandt, Karina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Tretten, Phillip
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Karim, Ramin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Usability aspects of eMaintenance solutions2012In: Proceedings of the 2nd International Workshop & Congress on eMaintenance: Dec 12-14 Luleå, Sweden : eMaintenace: trends in technologies and methodologies, challenges, possibilities and applications / [ed] Ramin Karim; Aditya Parida; Uday Kumar, Luleå: Luleå tekniska universitet, 2012, p. 77-84Conference paper (Refereed)
  • 3054.
    Wang, Q Z
    et al.
    Department of Civil Engineering and Applied Mechanics, Sichuan University.
    Jia, X M
    Department of Civil Engineering and Applied Mechanics, Sichuan University.
    Kou, S Q
    Luleå tekniska universitet.
    Zhang, Z X
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    More accurate stress intensity factor derived by finite element analysis for the ISRM suggested rock fracture toughness specimen-CCNBD2003In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 40, no 2, p. 233-241Article in journal (Other academic)
  • 3055.
    Wang, Q Z
    et al.
    Department of Civil Engineering and Applied Mechanics, Sichuan University.
    Jia, X M
    Department of Civil Engineering and Applied Mechanics, Sichuan University.
    Kou, S Q
    Luleå tekniska universitet.
    Zhang, Z X
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    The flattened Brazilian disc specimen used for testing elastic modulus, tensile strength and fracture toughness of brittle rocks: analytical and numerical results2004In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 41, no 2, p. 245-253Article in journal (Refereed)
    Abstract [en]

    The flattened Brazilian disc specimen is proposed for determination of the elastic modulus E, tensile strength sigma (sub t) and opening mode fracture toughness K (sub IC) for brittle rocks in just one test. This paper is concerned with the theoretical analysis as well as analytical and numerical results for the formulas. According to the results of stress analysis and Griffith's strength criteria, in order to guarantee crack initiation at the centre of the specimen, which is considered to be crucial for the test validity, the loading angle corresponding to the flat end width must be greater than a critical value (2alpha > or =20 degrees ). The analysis shows that, based on the recorded complete load-displacement curve of the specimen (the curve should include the "fluctuation" section after the maximum load), E can be determined by the slope of the section before the maximum load, sigma (sub t) by the maximum load, and K (sub IC) by the local minimum load immediately subsequent to the maximum load. The relevant formulas for the calculation of E, sigma (sub t) , K (sub IC) are obtained, and the key coefficients in these formulas are calibrated by finite-element analysis. In addition, some approximate closed-form formulas based on elasticity are provided, and their accuracy is shown to be adequate by comparison with the finite-element results.

  • 3056.
    Wang, Weidi
    et al.
    Tongji Univ, Peoples R China.
    Tang, Ou
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, Faculty of Science & Engineering.
    Huo, Jiazhen
    Tongji Univ, Peoples R China.
    Dynamic capacity allocation for airlines with multi-channel distribution2018In: Journal of Air Transport Management, ISSN 0969-6997, E-ISSN 1873-2089, Vol. 69, p. 173-181Article in journal (Refereed)
    Abstract [en]

    Due to fierce competition in markets, recently, many airlines have faced the challenge of reducing channel distribution costs. However, channel distribution decisions are often made separately from inventory allocation decisions in practice. Thus, in this study, we propose a dynamic programming model to derive the optimal policy and investigate customer-shift behaviours in a problem setting with the above two issues combined. The numerical experiment results illustrate that introducing the channel distribution into the airline revenue system significantly improves the revenues and efficiently reduces the channel distribution costs. The improvement comes mainly from a better match between channels and fare classes and a subsequent risk reduction of revenue losses.

  • 3057.
    Wang, Xiaohui
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Achieve a balance between publicness and commercialisation: Space for public street life in South Luogu Lane Block, Beijing, China2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    China is now seeking for more sustainable and healthy urban development and pays much attention to better quality of urban life in the process of new-type urbanization. Beijing, as the capital and economic centre in China, plays a leading role in practices for vital and diverse urban life in the existing urban space, especially Hutong redevelopment. A lot of problems and challenges emerge in this process, such as over commercialization of public space, gentrification, and exclusion of original inhabitants. Based on a combination of western public life study and Chinese practises, this thesis tries to figure out the problems and spatial role of Hutong in the process of regenerating thriving public street life in South Luogu Lane Block in Beijing. To find proper solutions for these problems, the thesis looks into Gehl’s public life theory, Hillier’s space syntax and practices from Project for Public Spaces. With the placemaking strategy, the thesis aims to find a way to achieve a balance between publicness and commercialization in Hutong redevelopment and create good public street space for commercial activities and everyday life in South Luogu Lane Block.

  • 3058.
    Wangel, Josefin
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Environmental Strategies. School of Computer Science and Communication (CSC), Centres, KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC.
    Exploring social structures and agency in backcasting studies for sustainable development2011In: Technological forecasting & social change, ISSN 0040-1625, E-ISSN 1873-5509, Vol. 78, no 5, p. 872-882Article in journal (Refereed)
    Abstract [en]

    This paper examines how social structures and agency have been included in backcasting studies for sustainable development. For this purpose an analytical framework was developed, based on what objects of change (whats), measures (hows) and change agents (whos) are included in the scenario, and to which extent these are approached in an explorative way. Through reviewing a number of backcasting studies it was found that these typically are built upon and elaborated with a predominant focus on the questions of what and how physical/technical aspects could change. Social objects of change and explicit representation or analysis of the question of who could change is rarely included in the analysis. This unbalance brings a number of implications. Firstly, not including social structures and agency obstructs developing socio-technically consistent and comprehensive scenarios. Secondly, through not addressing the questions of how to change and change by whom in an explicit and explorative way, social structures and agency become represented only implicitly and/or are maintained according to the status quo.

  • 3059.
    Warsame, Abukar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Building and Real Estate Economics.
    Song, Han-Suck
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Building and Real Estate Economics.
    Lind, Hans
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Building and Real Estate Economics.
    Quality of road construction projects in sweden between 1990 and 20102014In: Australasian Journal of Construction Economics and Building, ISSN 1835-6354, Vol. 14, no 1, p. 78-87Article in journal (Refereed)
    Abstract [en]

    It has been reported that productivity developments in construction are slow compared to other sectors. Measuring productivity is however not easy and it might have been underestimated due to deficiencies in the index that is used when the value added in current prices is converted into value added at constant prices. A central problem when deflating nominal prices is that the deflation should only take away price changes for identical products and not price changes related to quality changes and improvements necessitated by new environmental conditions and legislation as well as demand for higher safety. The aim of this project is to help fill this gap by looking at the quality changes over time in road construction. A combination of comparative studies and interviews with practitioners from public and private sectors that are involved in road construction projects were conducted. It was found that there had been both direct quality changes in the roads, primarily to improve safety on the roads and for noise protection, and indirect quality changes related to building in more difficult circumstances because of giving higher weight to other social objectives, especially environmental objectives. As these quality increases are not taken into account when productivity is measured, productivity improvements could be underestimated by around 1% per year.

  • 3060.
    Wathugala, Deepa N.
    et al.
    Department of Mining and Geological Engineering, University of Arizona, Tucson.
    Kulatilake, Pinnaduwa H.S.W.
    Department of Mining and Geological Engineering, University of Arizona, Tucson.
    Wathugala, Gamage W
    Center for Computing and Information Technology, University of Arizona, Tucson.
    Stephansson, Ove
    Luleå tekniska universitet.
    A general procedure to correct sampling bias on joint orientation using a vector approach1990In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 10, no 1, p. 1-31Article in journal (Refereed)
    Abstract [en]

    Observed relative frequencies of joints should be corrected for sampling bias before inferring statistical distributions for orientations. The procedure available for sampling bias correction when finite size joints intersect finite size sampling domains is directly applicable only for vertical sampling planes [1-3]. Thus, a general procedure applicable for sampling domains of any orientation is developed in the present study. The corrected frequency of a joint is obtained by assigning a weight to each joint through a weighting function which is inversely propotional to the probability of intersection between the joint and the sampling plane. This probability of intersection is determined from a hypothesis indicating "the probability of intersection is proportional to the volume in which the center of the sampling domain should lie in order to intersect the joint". A vector approach to find this volume is described herein, followed by applications of this method to study the influence of the sampling bias correction on orientation frequency and to find statistical distributions for orientation data

  • 3061.
    Wei, Lide
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Study on migration and pollution in shallow groundwater near a slag field2015In: Journal of Residuals Science & Technology, ISSN 1544-8053, Vol. 12, no 4, p. 191-197Article in journal (Refereed)
    Abstract [en]

    This paper investigates contaminant migration in groundwater near tail slag through large-scale three-dimensional numerical simulation, comparison of numerical simulation results and test results and prediction on the status and scope of groundwater pollution, to provide a scientific theory basis for management of the tailings. It supposes that a 2D simulation model should be used for inverse analysis to get key saturated permeability coefficients for large-scale, three-dimensional numerical simulation. The key parameters of the materials used in dispersion calculations should be identified based on unsaturated material dispersion test results and empirical values in geotechnical engineering. The comparison results show that the numerical simulation results basically agree well with the test results, so that numerical simulation can be used as the basis of groundwater environmental evaluation. As time goes on, the arsenic concentration in the slag field migrates outward slowly, but the concentration in the groundwater does not exceed 0.00001 kg/m3

  • 3062.
    Weihed, Pär
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gehör, Seppo
    University of Oulu.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Vikstedt, Helen
    University of Oulu.
    Ylineimi, Leen
    University of Oulu.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nordic Mining School (NMS) for advanced extractive technology and natural resources managment: a joint Luleå University of Technology and Oulu University initiative2009In: Conference in minerals engineering: Luleå, 3-4 februari 2009 / [ed] Johanna Alatalo, Luleå: Luleå tekniska universitet, 2009Conference paper (Other academic)
  • 3063.
    Weihed, Pär
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Luleå tekniska universitet.
    Greberg, Jenny
    Luleå tekniska universitet, Geoteknologi.
    Björkman, Bo
    Luleå tekniska universitet, Mineralteknik och metallurgi.
    Abrahamsson, Lena
    Luleå tekniska universitet, Arbetsvetenskap.
    Andersson, Eira
    Luleå tekniska universitet, Arbetsvetenskap.
    Fältholm, Ylva
    Luleå tekniska universitet, Arbetsvetenskap.
    Bäckblom, Göran
    LKAB, Sverige.
    Project: Strategic Research and Innovation Agenda for the Swedish Mining and Metal Producing Industry2014Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Developing the Strategic Research and Innovation Agenda for the Swedish Mining and Metal Producing Industry, for the years 2013-2030.

  • 3064.
    Weihed, Pär
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Greberg, Jenny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Abrahamsson, Lena
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Andersson, Eira
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Fältholm, Ylva
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Bäckblom, Göran
    LKAB, Sverige.
    Project: Strategic Research and Innovation Agenda for the Swedish Mining and Metal Producing Industry2014Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Developing the Strategic Research and Innovation Agenda for the Swedish Mining and Metal Producing Industry, for the years 2013-2030.

  • 3065.
    Weijl, Terje
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kvalitetssäkring av modellfiler2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Creating 3D-models is a common feature for the constructor in the planning phase. However, this has proved to be problematic as the models do not meet the right quality. Lacking quality in 3D-models can lead to bad consequences and it is therefore important to perform a quality control on the model. Tyréns in Umeå has seen a need to have a process of controlling 3D-models to ensure that they have the right quality.

    The purpose of this study has been to analyze whether there are any methods for quality control of 3D-models that Tyréns can make use of today. The goal of the work has been to present a working method that Tyréns can use in the future to quality assure 3D-models.

    The work has been completed by studying literature from the university library and city library in Umeå. The law about construction and Boverket website have also helped to carry out the work of the report. To get a picture of how problems can look like in a 3D-model, a couple of reference objects have been used. The information about the reference objects are collected from interviews, investigations and magazines.

    The result of this study shows that there are no general working methods for analyzing 3D-models. On the other hand, there are quality assurance methods in the manufacturing industry that could be used to control the models as well. The problem with these methods is that they are adapted to an industrial environment. This means that they are not developed to detect errors that may occur during the planning phase. Therefore, the quality control methods used in the manufacturing industry are required to be corrected and adjusted so that they can be used to control 3D-models. However, what can be used from industry methods is that the quality control should be planned at an early stage and then carry out the controls. The method developed in this report is a work method that includes planning, control and follow-up, which makes the workflow time consuming. However, the conclusion of the work is that the most important thing about quality control of 3D-models is that it is planned and then performed.

  • 3066.
    Wendel, Jesper
    Karlstad University, Faculty of Social and Life Sciences.
    Digital fotogrammetri som metod för uppdatering av kartdatabas: en jämförelse av tre programvaror2012Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
  • 3067.
    Wendel, Karolina
    Blekinge Institute of Technology, Faculty of Engineering, Department of Spatial Planning.
    Planeringen och platsmaktsordningen2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Denna uppsats syftar till att undersöka hur maktrelationer mellan stad och land samverkar med maktrelationer mellan kvinnor och män samt vad det möjligen kan få för konsekvenser för den fysiska planeringen. Uppsatsens huvudsakliga syfte är att söka förståelse för hur tjänstepersoner som arbetar med fysisk planering kopplat till glesbygd i norra Sveriges inland förhåller sig till dessa maktrelationer. För att göra detta görs en fallstudie av Åsele kommun i Västerbottens län.

    Uppsatsen utgår ifrån att det finns ett urbant tolkningsföreträde som medför att det urbana uppvärderas gentemot det rurala. Genom detta perspektiv studeras Åsele kommun och intervjuer görs med tjänstepersoner och konsulter som på olika sätt är knutna till den fysiska planering som bedrivs i kommunen. Den analytiska tolkningsramen utgörs av fyra dikotoma begrepp: 1) stad/land, 2) kvinna/man, 3) investering/stöd samt 4) utveckling/problem. Det material som analyseras är Åsele kommuns översiktsplan samt transkriberat material från ovan nämnda intervjuer.

    I uppsatsen framkommer det att den planering som bedrivs i glesbygd till stor del präglas av ett utifrånperspektiv. Då utifrånperspektivet är lokaliserat i städer och staden är priviligierad i förhållande till glesbygd kan detta få konsekvenser för det förhållningssätt som finns gentemot den planering som bedrivs i glesbygd.

    Det framkommer att det finns en kedja av parallella maktordningar som ger dubbla utslag, mot såväl förmågan att planera i glesbygd som involveringen av genus och jämställdhet i planeringen. I detta är könsmaktsordningen något som har begreppsliggjorts. I uppsatsens diskussion och slutsats myntar jag begreppet platsmaktsordning som jag menar kan begreppsliggöra maktrelationer mellan stad och land. Ett begreppsliggörande kan ge planerare ett verktyg att arbeta med dessa frågor. Jag hävdar att ett erkännande av att det existerar en platsmaktsordning genererar möjligheter till nya och utmanande perspektiv på planering i glesbygd.

  • 3068.
    Wendel, Karolina
    Blekinge Institute of Technology, Faculty of Engineering, Department of Spatial Planning.
    Planeringen och platsmaktsordningen2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 3069.
    Wennström, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Estimations of Delay Costs caused by Roadworks2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When roadworks are performed, one of the impacts is delays in the traffic. Partly because of reduced speed limits past the work zones but mainly because of the facility's limited quality of service. This could result in significant delays for the road users with lost work and spare time as a consequence. The lost time in congestions could have been used more efficiently. It is therefore of interest to estimate these delays for different types of roadworks to calculate its macro economical impact. The estimations may be a factor in different types of planning, for example in roadwork planning, in work zone scheduling or in life cycle assessments.

    The estimations can be conducted using different methods, such as analytical, queuing theory or macrosimulation. However, to include the details of specific work zones an analysis method of higher detail is required. First to include varying geometric details, secondly due to the higher level of detail in the representation of the traffic. Therefore may microsimulation be a suitable analysis method. The purpose of this master thesis was to investigate microsimulations suitability for work zone analysis, by using the software AIMSUN.

    AIMSUN were different work zone types modeled, first of highways. Later was a 2-lane road modeled for which the traffic control was a fixed signal, then controlled by a simpler extension developed in C++ that simulated a flagger control.

    Using a developed helper program, the work zone models could be simulated for a large set of daily flow levels and heavy vehicle ratios. Together with corresponding results for normal conditions, it was possible to calculate the delays. The results were relationships between the total delays, for various heavy vehicle ratios.

    A concern with the results was deviations of the delays for different daily flows and heavy vehicle ratios. Even if the deviations will not have any greater impact on the total cost, they may be unwanted in decision models. Processing of the result may therefore be necessary.

    This master thesis has showed that microsimulation may be a suitable method to analyze work zone impacts. Using the high level of detail, work zones special character can be captured. Possible future work is to improve the reliability of results by performing validations of results with real work zone data to compare speeds, headways and queue lengths. Additional work may include to consider the diversion delays.

  • 3070.
    Werner, Nicklas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Industrial Engineering & Management.
    Den svenska äldrevården: Behov, konkurrens, kvalitet och valfrihet ur ett fastighetsperspektiv2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis an explorative study was undertaken with the aim to study how a number of private care providers, as well as politicians and officials from councils in and around the Stockholm and Uppsala counties, think about the future of the Swedish elderly care from a property perspective, i.e. homes for the elderly. The analysis shows that there is a demand for capacity in 6 out of 16 municipalities, and that the property is an important part of this capacity, and the fulfillment of it. This was mainly due to the cost of capital, but also because of several other factors such as lack of land, a wish to guide the design, ideology, and in many cases a wish to use the property as an instrument of domination to control private health care providers.

    Also, the property was show to be connected to economic competition, to freedom of choice, and to quality. The problems related to the property in the market for elderly care still remains to be solved. The writer of this thesis suggests that, among other things, patients should be treated as customers to a larger extent and problems that counter competition must be solved.

    Lastly, the writer has analyzed the situation in the Swedish market for elderly care from a value creation perspective. It is suggested that value can be created in both the network and within the company, even if the companies are competing, and thus ought to compete and not cooperate.

  • 3071.
    Werner, Nicklas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Construction Engineering.
    Sju äldreboenden i Enköping kommun: En granskning av nyckeltal, riktvärden och internhyressystemet.2010Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis the principles that govern the internal rent for a group of retirement homes in Enköping municipality is examined. Also the operation and maintenance cost levels are compared to other municipal-owned homes for the elderly in the rest of Sweden. Facility managers in Enköping municipality today consider the internal rent to be on a too low level. Therefore they cannot maintain the houses to the extent they consider necessary. 

    A comparison of the maintenance costs, media consumption, management expenses and several other expenses against the statistics from all of Sweden makes it possible to form an opinion on the current level. 

    The internal rent has been examined in two ways. First, by examining how well the municipality administration follows its own directives and policy documents and, secondly, by comparing the governing document with the available literature. 

    Key comparison shows that Enköping historically have had low amounts of both planned and unplanned maintenance expenses. A change has occurred in recent years and maintenance costs have increased significantly when large maintenance needs have arisen. Their written policy on internal rent has basically not been updated since it was written in 1990. This thesis culminates in a recommendation to both the municipal administration and facility management. They must begin to monitor key indicators and measure effectiveness. Municipal leaders need to update and establish guidelines for internal rent. If the amount of maintenance is raised to an acceptable level the rent also needs to be raised to avoid a deficit. 

  • 3072.
    Werneskog, Caroline
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Ideskog, Jenny
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    ENERGIEFFEKTIVISERING AV ICKE ISOLERADE TEGELBYGGNADER MED KULTURHISTORISKT VÄRDE2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Purpose: The building stock in Sweden consists mainly of buildings built before 1977, when the building standard regarding energy balance was introduced. These buildings usually have low energy efficiency. The Swedish Parliament has set up goals that focus on decreasing the energy use in residential and commercial buildings with 50 % by the year 2050, compared with the level in 1990. This study aims to investigate how the energy efficiency of existing non-insulated brick buildings can be improved while taking into consideration historical preservation. These buildings, which make up our cultural heritage, have a large potential for reduction of energy use, environmental impact and heating costs. Therefore, they are an important part of achieving the environmental goals.

    Method: The main method of this study was a case study in which collection of documents and interviews took place. The case study has been performed on a non-insulated brick building at Södra Munksjön, Jönköping. Information about the building was gathered through the document collection. Based on this information, a specific energy use has been calculated using an energy calculation program. Energy efficiency measures have been put into the program to understand which specific energy use that can be achieved. In the interviews, people active in the field determined if these measures can be implemented without distorting the cultural-historical value of the building.

    Findings: The study shows how extensive the renovation and restoration of a noninsulated brick building has to be to meet the requirements of specific energy use according to Boverkets byggregler 21. The existing building has a specific energy use of 430 kWh/m2 and year. After adding insulation, renovation of windows and doors, replacement of ventilation and heating system this is equal to 79 kWh/m2 and year. Boverkets byggregler 21 has a requirement for new constructions of 80 kWh/m2 and year for premises in climatic zone III. Additionally, this study shows that these measures can be executed without distorting cultural-historical values of the building.

    Implications: The study indicates a great potential of energy-savings in non-insulated brick buildings and that it can be done without distorting the cultural-historical values. The energy consumption for residential and commercial buildings can then be considerably reduced which creates an opportunity to fulfil environmental goals. Boverket is recommended to review which requirements of specific energy use that should be set up at reconstruction of cultural-historical buildings. Fundamentally, it is the same requirements that are applied at reconstructions as at new constructions. However, several exemptions allow an adaption of the requirement levels to ensure the cultural-historical value. The study indicates that these exemptions are not required.

    Limitations: Since all buildings are unique, the result in this study cannot directly be generalised to other buildings. Instead, this study can be used as reference material indicating which measures that have a significant impact on the energy use. Interpreting the interviews, it is possible to determine whether the planned measures can be executed without distorting the cultural-historical value of the building.

    Keywords: Cultural-historical valuable buildings, distortion, energy efficiency, noninsulated brick buildings, specific energy use.

  • 3073.
    Wessely, Alexandra
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Markägares och arrendators rättsliga styrka vid tvist om jordbruksarrende2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 3074.
    Westberg, Jon
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Janzon, Åsa
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Baslinjelängdens och sessionstidens betydelse för lägesosäkerheten vid statisk GNSS-mätning2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    HMK Geodesy, GPS was published in 1996 and is still the regulations that currently apply to static measurement with GNSS. The study is conducted to provide recommendations for new HMK Control networks for static GNSS surveying.

     

    The purpose of the study was to investigate how the baseline and session length influence the position uncertainty when measuring short baselines. A second purpose was to investigate whether there will be any difference in the position uncertainty when using different frequencies: L1, L1 + L2 or L3. The study investigates baseline lengths 0,7–100 km and session lengths 20 min–6 h. The study was designed to mimic measurements during practical conditions and investigate the position uncertainties that can be expected to be achieved by users.

     

    Two sub-studies were conducted in two different geographical areas. In the Gävle area self-produced data was used combined with data from a SWEPOS station for calculating the spread in the position for short baselines. In the Gothenburg area the data was obtained from observations of known SWEPOS reference stations. An error vector was calculated between the station's estimated position of the study and a given position calculated by SWEPOS.

     

    In the Gävle area the differences in standard uncertainty between different session lengths for the coordinates were less than 3 mm and 7 mm in plane and height. For baselines up to 5 km the spread in height in half of the cases was lower than in plane for the frequencies L1, L1+L2 and L3. During longer sessions the results for the different frequencies are equal. In the Gothenburg area the height differences increased when associated/combined/correlated with baseline length. The three-dimensional deviations of the base lines were 1–71 mm.

     

    The position uncertainty in plane is not affected significantly by increased baseline length. Location Uncertainty in height becomes larger when baseline length increases. Unlike previous studies our study showed no clear improvement in position uncertainty when session length increases.

  • 3075.
    Westberg Wilde, Marie
    et al.
    ÅF Industry, Stockholm, Sweden .
    Johansson, Fred
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Probability-based guidelines for design and assessment of concrete dams2013In: Safety, Reliability, Risk and Life-Cycle Performance of Structures and Infrastructures - Proceedings of the 11th International Conference on Structural Safety and Reliability, ICOSSAR 2013 / [ed] George Deodatis, Brude R. Ellingwood, Dan M. Frangopol, London: Taylor & Francis Group, 2013, p. 5187-5194Conference paper (Refereed)
    Abstract [en]

    Dams are designed and assessed based on a factor of safety methodology. Several drawbacks of this approach exist; for example varying failure probability for structures where the factor of safety is the same. Dam owners in Sweden recently decided to bring forth a probability-based guideline. This paper describes the intended process, where the first step is to put together a probabilistic model code for concrete dams based on JCSS Probabilistic model code (2001). A summary of the level of knowledge for relevant limit states, safety index and load and resistance parameters, as well as the expected difficulties involved in the process are also discussed.

  • 3076.
    Westerlund, Anton
    Mälardalen University, School of Business, Society and Engineering.
    Verifiering av beräknad energiprestanda: En jämförelse mellan simulerad och uppmätt energianvändning för byggnaden Drottningparken2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 3077.
    Westerlund, Vanja
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    På spåret. Vart är vi på väg?: En studie av Tvärbanans förlängningar i Stockholm2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Forskning pekar på att spårvägar kan generera positiva effekter till stadsmiljöer och bidra till attraktiva städer om spårvägarna byggs integrerade i gaturummet, vilket det ofta görs i andra städer än Stockholm. I Stockholm är spårvägarna däremot vanligtvis helt separerade från övrig trafik och mer järnvägslika i sin utformning än i andra länder. Syftet med denna studie är därför att undersöka vilka faktorer som har haft inverkan på de anläggningsprinciper som valts vid utbyggnaderna Solna- samt Kistagrenen av Tvärbanan i Stockholm.

    Studien utreder detta genom intervjuer med personer med kunskap om spårväg, representanter från intresseorganisationer, en politiker och tjänstemän som varit involverade i planering av Tvärbanan samt litteraturstudier och sammanställning av olycksstatistik.

    I analysen framträder att det finns ett flertal faktorer som kan ha inverkat på hur Tvärbanans förlängningar har utformats samt att planering av spårväg är en komplex verksamhet vilket innebär att det inte finns en entydig lösning på vilken anläggningsprincip som ska användas vid planering och byggande av spårväg.

    Efter genomförd studie är slutsatsen att det finns flera faktorer som har haft inverkan vid beslut om anläggningsprincip vid Tvärbanans förlängningar, vilka är planeringsideal, politiska incitament, prioritering av spårvägens egenskaper, planerarnas tidigare erfarenhet av spårväg, kontexten, inspiration från andra länder samt intresseorganisationer. Hur dessa faktorer har inverkat i valet av anläggningsprincip beror i sin tur på vilka aspekter som framhävts samt utelämnats av inblandade aktörer i planeringsprocessen.

    Arbetet pekar på att det sker en förändring i hur spårvägar planeras att utformas som följer den renässans som spårvägen haft internationellt, vilket kan resultera i mer integrerade spårvägar i framtiden om politiker och andra aktörer med makt prioriterar stadsmässiga aspekter vid utveckling av nya spårvägar.

  • 3078.
    Westin, Tomas
    Luleå tekniska universitet.
    Försök med dynamisk neddrivning av klen spont i lilt1978Report (Other academic)
  • 3079.
    Westin, Tomas
    Luleå tekniska universitet.
    Mekaniserad bergbultning: inventering av teknik och tillämpningar1979Report (Other academic)
  • 3080.
    Westling, Anna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Projektering av Coop i Piteå hos a och d arkitektkontor: med fokus på framtagande av uppställningsritningar och ritningsförteckningar2018Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
  • 3081.
    Westlund, Hans
    Jönköping University, Jönköping International Business School, JIBS, Economics, Finance and Statistics. KTH, Department of Urban Planning and Environment.
    Urban futures in planning, policy and regional science: Are we entering a post-urban world?2014In: Built Environment, ISSN 0263-7960, Vol. 40, no 4, p. 447-457Article in journal (Refereed)
  • 3082.
    Westlund, Hans
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies. Jönköping International Business School, Sweden.
    Li, Y.
    From urban-rural to global dependencies2014In: International Journal of Global Environmental Issues, ISSN 1466-6650, E-ISSN 1741-5136, Vol. 13, no 2-4, p. 141-149Article in journal (Refereed)
    Abstract [en]

    Against the background of global urban knowledge economy, this paper discusses some of the challenges that sustainable urban life is facing in the global knowledge economy of the 21st century. The paper makes an overview of the fundamental change in urban-rural relations, urban and rural demographics, the concepts of place surplus and place attractiveness, agglomeration and the new economic geography, global threats to long-term urban sustainability and finally the needs of policy visions and strategies for sustainable urban life across the world.

  • 3083.
    Westlund, Hans
    et al.
    Jönköping University, Jönköping International Business School, JIBS, Economics, Finance and Statistics. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    Li, Yuheng
    College of Resources Science and Technology, Beijing Normal University.
    From urban-rural to global dependencies2014In: International Journal of Global Environmental Issues, ISSN 1466-6650, E-ISSN 1741-5136, Vol. 13, no 2-4, p. 141-149Article in journal (Refereed)
    Abstract [en]

    Against the background of global urban knowledge economy, this paper discusses some of the challenges that sustainable urban life is facing in the global knowledge economy of the 21st century. The paper makes an overview of the fundamental change in urban-rural relations, urban and rural demographics, the concepts of place surplus and place attractiveness, agglomeration and the new economic geography, global threats to long-term urban sustainability and finally the needs of policy visions and strategies for sustainable urban life across the world.

  • 3084.
    Weston, Miles
    et al.
    TWI Technology Centre Wales.
    Liaptsis, Dimos
    TWI Technology Centre Wales.
    Wright, B.
    TWI Technology Centre Wales.
    Knight-Gregson, Ben
    TWI Technology Centre Wales.
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Reliable sub-surface ultrasonic inspection of cast manganese steel crossings2014In: 6th IET Conference on Railway Condition Monitoring (RCM 2014), 2014, article id Issue CP631Conference paper (Refereed)
    Abstract [en]

    This paper presents lab trials from an ultrasonic technique capable of reliable sub-surface inspection of cast high manganese steel railway crossings. Volumetric inspection of the component is achieved using a combination of low frequency ultrasound and an advanced ultrasonic technique known as Synthetic Aperture Focussing Technique (SAFT) which uses spatial averaging to reduce back-scattered noise from grain boundaries. The application of the ultrasonic SAFT technique is discussed, and results from empirical studies are presented before finally offering concluding remarks on the future of the technology

  • 3085.
    Wicksell, Martin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Vädrets påverkan på olika aktiviteter i urbana parker2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the urban landscape, parks are places with beneficial assets for the city. When people have access to parks in the city several effects get an impact on them, such as improved physical health and reduced stress levels. In Sweden, parks have the largest use during the summer months because of the cold climate during the other periods of the year. This study provides information on how people can increase their use of parks for a longer period of the year. The focus of the study is to evaluate how activities carried out in parks can extend in the spring. The object was to find out how users who performed different activities perceived different weather conditions. The study also finds out how different attributes in the park would make it better for the activities. To divide the activities a comparison between the activities that were tied to a site and the activities that were not tied to a place was made. The goal was to find a design that would suit the respective activity during the months of March, April and May. A survey taking into account user opinions regarding their current use, weather conditions and desired changes for the park was included. Another method was observations over people’s activities and at what location in the park users perform them. The methods resulted in a distinction in terms of weather conditions between the different activities. The study states that during the months of March, April and May, activities are affected by weather conditions in the park. Users want different attributes in the park to be able to perform the activity more this time of year. Activities that are tied to a place showed a greater difference between the different views than those that were not tied. Future planning should include attributes of site-based activities that meet user needs.

  • 3086.
    Widström, Torun
    et al.
    The Royal Institute of Technology, Stockholm, Sweden.
    Mattsson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Building science - installation technology.
    Whole building simulation and damage risk assessment in historical buildings2011In: Energy Management in Cultural Heritage / [ed] Vlasta Zanki, UNDP Croatia , 2011Conference paper (Refereed)
    Abstract [en]

    When simulating historical buildings, available tools tend to be intended for simulations of either of two kinds: whole building simulations of energy-/moisture performance, from which we can determine general conditions that may give an indication of potential damage risks, though unspecific, or detailed simulations that look into what takes place at specific points/materials, which provides us with knowledge about the specifics but without much context. Both are efficient scientific methods, but when dealing with reality we need both perspectives simultaneously. This paper describes multi-criteria simulations that take this into account, using a new tool integrating display of specific moisture-connected risk-factors into whole building simulations, providing a coherent basis for decision-making when retro-fitting, and compares the results to case-study measurements.

  • 3087. Wijaya, Andi
    et al.
    Kumar, Rupesh
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Implementing lean principle into mining industry issues and challenges2009Conference paper (Refereed)
    Abstract [en]

    The lean production concept has its origin in automotive industry and is widely used in manufacturing sectors. What makes its applicability in mining difficult is the dynamic nature of mining operations bringing high degree of uncertainty in various unit operations. To reduce the wastage of efforts, one needs to remove uncertainty and predict the process behaviour as correct as possible. Furthermore, to achieve lean approach in mining, the entire mining chain needs to be considered starting from Mine exploration, mine planning, drilling operation, blasting, loading and transportation, ore dressing processes, reclamation, etc. To be lean in mining is not only dependent on mine production systems consisting of equipments and machines but it also depends on quality and reliability of information flow in real time generating action plans. Also, the reliability and maintenance preparedness have major influence on the degree of waste being generated in the process. For example if ore body is not correctly delineated/characterised or drilling operations not performed correctly, wrong charging process and wrong loading process- all may lead to wastage of resources. In fact Lean production has its origin (leans on) in JIT, TQM and TPM. The common denominator of all these philosophies is the human in the process. To improve any process one needs to measure the current status so that any change in current status can be recorded. The paper presents issues and challenges associated with implementation of Lean Principles in Mining industries.

  • 3088.
    Wijaya, Andi
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    The effect of the operator, the mine room and their interaction on the measured vibration level of a scaling machine2012In: International Journal of Systems Assurance Engineering and Management, ISSN 0975-6809, E-ISSN 0976-4348, Vol. 3, no 2, p. 145-152Article in journal (Refereed)
    Abstract [en]

    The objective of the present study is to find out the effect of the operator, the mine room and their interaction on the vibration measured on a scaling machine. Vibration measurements were conducted for three different mine rooms and three different drivers. The vector sum value of the root-mean-square acceleration, the vector sum value of the acceleration dose and the kurtosis sum were utilized to quantify the measured vibration. The unbalanced two-way ANOVA and the Kramer-Tukey test were utilized for the statistical analysis. The results show that the operating styles of the drivers in performing scaling activity and their interaction with the mine rooms have no significant effect on the vector sum value of the acceleration, the vector sum value of the acceleration dose and the kurtosis sum value. The mine rooms have a significant effect on the kurtosis sum value and the vector sum value of the acceleration dose, but not on the vector sum value of the acceleration

  • 3089.
    Wijaya, Andi
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Downtime analysis of a scaling machine2012In: International Journal of Mining, Reclamation and Environment, ISSN 1748-0930, E-ISSN 1748-0949, Vol. 26, no 3, p. 244-260Article in journal (Refereed)
    Abstract [en]

    Scaling machines are identified as one of the major contributors to unplanned downtime. In general, to gain a better understanding of downtime, an analysis of the downtime should be performed. Downtime analysis usually involves a group consisting of many people with various backgrounds. The use of a visualisation method can act as a bridge that eliminates the knowledge gap within the group. The present study has two purposes: firstly to develop a method for visualisation of downtime and secondly to analyse the downtime of a scaling machine utilising the proposed visualisation method. The proposed method provides a visualisation of the downtime estimation and the precision and the uncertainty of the estimation at a given confidence level, as well as the factors influencing the failure. An analysis of the failures of the critical components of the scaling machine has also been conducted and suggestions for improvement have been proposed.

  • 3090. Wijaya, Andi
    et al.
    Lundberg, Jan
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Graphical method for visualization of machine's downtime: case study of scaling machine2010In: Proceedings of the 1st international workshop and congress on eMaintenance, Luleå tekniska universitet, 2010, p. 99-106Conference paper (Refereed)
    Abstract [en]

    Visualization is the foundation for human to understand as human think and create in a graphic world. By nature, maintenance activity is a multi discipline approach, where maintenance engineer should be able to convey their idea to people with various backgrounds. In this situation, visualization is a powerful mode; it can act as a bridge to eliminate the knowledge gap within the group. Knight (2001) developed Jack-knife diagram for visualizing total downtime and factors influencing the failure (failure frequency and mean downtime) in a point estimation. As failure data is a probabilistic in nature, it is important to look not only point estimation but also interval estimation, so the precision and uncertainty of estimation can be identified. This paper proposes a way of visualizing total downtime and factors influencing the failure (failure frequency and mean downtime) in interval estimation. Case study from scaling machines is used for illustration.

  • 3091.
    Wijaya, Andi
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, Uday
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Robust-optimum multi-attribute age-based replacement policy2012In: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 18, no 3, p. 325-343Article in journal (Refereed)
    Abstract [en]

    Purpose - A common model in the age-based replacement policy is based on the cost attribute and assumes that the model parameters are known. In practice, the model parameters are estimated from limited historical data, which brings uncertainty into the model. Moreover, minimizing the cost is not the only goal of the maintenance activity. From the decision maker's point of view, the multi-attributes and the uncertainty of the age-based replacement policy are two important aspects to take into consideration in the decision-making process. The purpose of this paper is to propose an approach for a robust-optimum multi-attribute age-based replacement policy. Design/methodology/approach - The proposed approach is based on a combination of the multiattribute age-based replacement policy and robust design problem philosophy. A case study is provided for illustrating the application of the proposed method. Findings - It is found that the proposed approach can determine the interval time for preventive replacement that provides a robust and optimum solution for a multi-attribute age-based replacement policy. Practical implications - The proposed approach can be used by the decision maker in determining a robust-optimum interval time for preventive replacement of multi-attribute age-based replacement, a time interval which is not only optimum, but also robust. Originality/value - This paper presents an approach that simultaneously considers the multi-attributes and the uncertainty in the age-based replacement policy which is, to date, not available

  • 3092.
    Wijaya, Andi Rahadiyan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Methods for availability improvements of a scaling machine system2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Scaling is the process of cleaning loose material from the roof, face and wall of the mine room in underground mining. The purpose of scaling is to make the mine room safe for the next operation. Due to the nature of the task, scaling has been identified as an operation with a high number of accident occurrences. The use of a scaling machine to replace hand scaling has successfully reduced the number of scaling-related accidents. However, due to the combination of a hostile environment (such as falling rock, dust, high humidity, etc.), the operation context (e.g. significant vibrations), and reliability and maintainability issues, the scaling machine is identified as one of the major contributors to unplanned downtime.The purpose of this research is to develop methods that can be used for identifying the availability related problems and improving the availability of the scaling machine system in a cost effective way. To achieve the purpose of this research, literature studies, case studies, and simulations study have been conducted. Empirical data have been collected from field measurements, document studies, interviews, and observations. For data analysis, theories and methodologies within reliability, availability and maintainability (RAM), ergonomics and optimization have been combined with the best practices from the related industry. A first result of this study is the development of a method for visualization of the downtime that provides a visualization of the downtime estimation and the precision and the uncertainty of the estimation at a given confidence level, as well as factors influencing the failure. Second result is the identification of components that significantly contribute to the downtime and the reason for that downtime (reliability and/or maintainability problem). Based on the failures analysis, suggestion for the improvement of the critical component is also proposed. Third result is the identification and analyzing of performance shaping factors (PSFs) that can affect to the reliability of scaling machine system. Fourth result is a proposed methodology that can help the design team to select which components of a system are needed to be improved and to which level the improvement should be done to optimize the availability of system in a cost effective way. Finally, the fifth result is a proposed method for a robust-optimum multi-attribute age-based replacement policy. The proposed approach can be used to determine the interval time for preventive replacement that provides a robust and optimum solution for a multi-attribute age-based replacement policy. These results are related to specific industrial challenges, and are expected to enhance the capability for improving the availability of the scaling machine system in a cost effective way. The results have been verified through interaction with experienced practitioners from both the manufacture and the user (i.e. mining company) of the scaling machine.

  • 3093.
    Wijesinghe, Jeff
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Zetterquist, Anton
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Fastighetstaxeringssystem: En jämförelse mellan det svenska och nederländska systemet2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Swedish Mapping, Cadastral and Land Registration Authority, Lantmäteriet, is interested to see how other developed countries organizes and carry out their real estate property taxation. The study aims to improve the Swedish property tax system by providing Lantmäteriet with a comparative picture of the Dutch counterpart.

    Sweden has a system based on a national authority that has the mandate to carry out real estate valuation for the entire country. The assessed value is decided every sixth year, with a simplified assessment during the third year of the six year period. In the Netherlands, they have a decentralized organization of real estate assessment. The municipalities perform the entire process. They have a central authority, Waarderingskamer, which controls and ensures that the quality of the assessed value have a good and consistent level. The assessed value is decided every year. This study will only handle residential properties.

    The methods that are used are; a comparative method where the comparison between existing descriptions of each country's real estate property tax system is performed. This will answer one the first questions asked in the in the issue section. The other method that is used is interviews, it will be with qualitative grounds and will answer the second and third question of the issue section.

    In Sweden, there are two assessment models that is used, one for one-to-two family houses and one for residential apartments. As for The Netherlands, there is one model for all residential properties, although the municipalities are allowed to have different models for their assessments. It can differ from two municipalities in what characteristic that is used; however, there are some mandatory characteristics that they must apply to the model for it to be approved.

    In Sweden, the assessed value is available to the public, while in the Netherlands, only the owner of the property that can see the assessed value. Sweden has an advantage with this in its system, since transparency is likely an important part of a property tax system and helps to improve confidence. However, The Netherlands will soon go public with their assessed values.

  • 3094.
    Wijk, Olle
    et al.
    Systecon, Stockholm, Sweden.
    Andersson, Patric
    Systecon, Stockholm, Sweden.
    Block, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Saab Support and Services, Logistics Analysis and Fleet Monitoring, Lifecycle Logistics Division.
    Righard, Thord
    Systecon, Stockholm, Sweden.
    Phase-out maintenance optimization for an aircraft fleet2017In: International Journal of Production Economics, ISSN 0925-5273, E-ISSN 1873-7579, Vol. 188, p. 105-115Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel approach for cost-effective optimization of stop-maintenance strategies for a set of repairable items (rotables). The optimization method has two steps. First, the novel concept of matrix simulations is introduced to locate the solution space of the optimization problem in question. Second, a genetic algorithm is applied to find the minimum cost solution. The combination of matrix simulations and genetic algorithm is shown to constitute a powerful method for solving the optimization problem in a fast manner. To demonstrate the efficacy of the proposed method, it is compared with a crude search, and a steepest descent algorithm. Our proposed method is faster than the crude search and also locates the optimum more often than the steepest descent search. The method is illustrated by applying it to a phase-out scenario of an aircraft fleet, where the optimal stop-maintenance strategy is determined for a set of rotables.

  • 3095.
    Wikstén, Johan
    et al.
    Luleå tekniska universitet.
    Johansson, Marcus
    Luleå tekniska universitet.
    Viklund, Jan
    Luleå Flygteknik.
    Parida, Aditya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Automation of turbine engine trend analysis2006In: Condition Monitoring and Diagnostic Engineering Management: COMADEM 2006 ; proceedings of the 19th international congress, Luleå, Sweden, 12 - 15 June 2006 / [ed] Uday Kumar, Luleå: Luleå tekniska universitet, 2006, p. 67-74Conference paper (Refereed)
    Abstract [en]

    Collecting engine performance data and analyzing the data for condition monitoring of the aircraft health status has been a challenging and most sought after task for the airline operators. If the health status of the engine is in a good level, then the time before overhaul (TBO) can be lengthened. The present excel system is old and aged and takes lot of time to record the data and analyze. There was a need for simpler and more accurate way to analyze and manage the data. As part of the project course study, the authors have tried to develop a system for plotting engine data, which are collected during the flight. The data were limited to torque, exhaust temperature, compressor and turbine speed, and fuel flow only for Pratt and Whitney engine PT6A-41.

  • 3096.
    Wilstrand, Karin
    Blekinge Institute of Technology, Faculty of Engineering, Department of Spatial Planning.
    Medborgardeltagande innan samråd?: En studie om medborgardeltagande i översiktsplaneprocessen med fokus på dialogskedet2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 3097.
    Wimmer, Matthias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Towards understanding breakage and flow in sublevel caving (SLC): Development of new measurement techniques and results from full-scale tests2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Blast function, fragmentation and gravity flow are core elements for sublevel caving (SLC). For the ore recovery to be as high and the waste rock dilution as low as possible all three elements have to work as planned. In the past some boundary conditions were changed: The scale and layout of SLC changed tremendously and production advanced to greater depths. As a consequence, blast performance and material flow are believed to have changed. The difficulties in simulating SLC relate to the physical scale as well as the broad range of time-scales involved, which results in a large number of unknowns and uncertainties. The present thesis contributes with the development of new measuring techniques, full-scale tests and analysis of results in all the above three core elements. Based upon that a better understanding of breakage and flow is obtained and this supports future process improvements.A remotely operated 3D photogrammetry system was designed and used to study the blast results from SLC rings in opening and hang-up situations. Various blasting situations were observed and this allowed a deeper study of the i) geometry of blasted cavity, ii) over- and underbreak and its effect on subsequently blasted rings, iii) interaction effects between adjacent holes/rings, iv) mapping of geological structures and its influence on the blast result and v) drilling accuracy based on identified boreholes. An attempt to identify malfunctions and categorize breakage problems was made. Some of the identified problems for initiation were unexpected and require a closer examination to increase blasting efficiency and to mitigate nitrate leakages. Potential improvements for blasting initial openings and scaling-up of rings are presented.Confined drift wall blasting tests in which the blasted burden was instrumented with various sensors to study movement and breakage were carried out. The main focus was the development of measuring equipment that could be scaled-up to full-scale SLC blasting and installed behind the rings. Results from an unconfined and confined blast situation are presented. A new measurement system to measure burden movement was developed, which combined the initial movement recorded by an accelerometer designed to minimize zero-shift with the later slower movement recorded by a photoelectric sensor (“fibre-optic zebra gauge”). In addition, time domain reflectometry (TDR) proved to be a reliable method for the verification of burden breakage (over- and underbreak).Fragmentation characteristics for blasted ore loaded from a specific ring were studied by sieving. For comparison lab-scale data from crushing, grinding and blasting, and also historical full-scale data from the mine, were analyzed. This data confirms that the material follows the NBC criteria (NBC = “natural breakage characteristics”) in the fines region (0 – 10 mm). However, a relative flattening of the sieving curves due to “selective” breakage in the mid-range (25 - 75 mm) and increased amount of fines was observed. The main conclusion is that magnetite behaves like normal hard rock from a fragmentation point of view despite this flattening deviation from Swebrec distribution behaviour as this is likely to be caused by the internal flow mechanisms in the SLC process.Gravity flow and the effects from confined blasting in hang-up situations were studied with the 3D imaging system and allowed the extension of conceptual models for breakage and flow. Evidence is given that gravity flow was disturbed and occurred in shallow, crescent-shaped flow zones. The front part of the burden was fractured, but immobilized. For the subsequent blast this meant that swell and compaction was limited to that zone with only marginal dilation and disaggregation of the burden at the sides. The operating figures for the blasted rings with observed flow zones indicated a disturbance-free extraction. Inflow of caving debris might occur either from above or in front when the loader penetrates into the flow zone of the previous ring. As a result of flow disruption in this narrow channel a temporary hang-up might evolve and the flow scheme be altered so that material is then loaded from previous blasts. With continued extraction, the cavity enlarges and finally becomes unstable, collapses and both previously “frozen ore” and waste rock enters the draw point.At the end a pivotal question remains: Are the recent observations of disturbed flow an inherent part of blasting SLC rings? This raises also the follow up question: Can we expect an undisturbed gravity flow if all borehole charges and rings detonate and break as planned? With continued investigations an answer seems to be obtainable in the near future. It is also recommended that the methods developed in this thesis be used in instrumented confined blasting tests in full-scale rings and be combined with gravity flow measurements.

  • 3098. Wimmer, Matthias
    et al.
    Moser, Peter
    University of Leoben.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Experimental investigation of blastability2008In: MassMin 2008: Proceedings of the 5th International Conference and Exhibition on Mass Mining, Lulea, Sweden 9-11 June 2008 / [ed] Håkan Schunnesson; Erling Nordlund, Luleå: Luleå tekniska universitet, 2008, p. 645-655Conference paper (Refereed)
    Abstract [en]

    An experimental investigation of blastability has been performed in small- and full-scale by continuous critical burden tests: A single inclined borehole is drilled into the rock face thus eventually exceeding a technically feasible burden. A useful definition of the “critical” burden Bcrit can be made by the study of the shape of the breakage area and it is defined by the maximum burden with complete breakage from the hole to the surface and by the shape factor SF that approaches a minimum at the same time. It has been shown that Bcrit is primarily a function of the specific charge and the prevailing rock conditions. Concerning the optimization of drilling and blasting patterns, an “optimum” burden Bopt can be found by systematic analysis. At this burden the specific charge shows a minimum and this has a positive influence on the size distribution of blasted rock, i.e. less fines. The full-scale experiments have shown that at smaller burdens the energy is sufficient for considerable breakage sideways whereas with increasing burden the shape of breakage becomes generally narrower, depending on the actual orientation of the strata. Bopt can be found at the section where the maximum area is obtained under the condition that Bcrit is still not exceeded and over-break ≥ 0 as well as 0 ≤ SF ≤ 1 at the same time. The study of experimentally derived breakage areas at Bopt can be useful in quantifying interactions between adjacent holes and thus be used in the design of spacing. Within operational possibilities the influence of the local rock conditions on the shape of the breakage area should additionally be considered in designing a blast. Considering the technically feasible drilling precision a drill and blast pattern optimized by using the described approach should lead to technical as well as economic benefits.

  • 3099.
    Wimmer, Matthias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordqvist, Anders A.
    Mining Technology R and D, LKAB Kiruna Mine.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nyberg, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Furtney, Jason
    Itasca Consulting Group.
    Burden movement in confined drift wall blasting tests studied at the LKAB Kiruna SLC mine2012In: Rock Fragmentation by Blasting, FRAGBLAST 10: Proceedings of the 10th International Symposium on Rock Fragmentation by Blasting / [ed] Pradeep K. Singh; Amalendu Sinha, Boca Raton, Fla.: CRC Press/Balkema , 2012, p. 373-383Conference paper (Refereed)
    Abstract [en]

    Blasting in SLC (sublevel caving) takes place in a semi-confined situation. Blasted material swells while the caved material compacts, and also, to a lesser extent, fills parts of the void volume of the production drift. Several analytical and empirical models have been developed in the past. However, understanding of the interaction of semi-confined blasting conditions, SLC blast design and rock mass characteristics on rock breaking performance is rudimentary. Instrumentation of the blasted burden with various sensors and study of the dynamics of burden movement against confinement is therefore important. Such measurements are very scarce and thus different systems have been tested both in laboratory and in the field. Main focus was thereby the development of measuring equipment that could be scaled up to full-scale SLC blasting and installed behind the rings. In the field tests, blastholes were drilled in a pillar, parallel to a cross cut drift in the LKAB Kiruna SLC mine. The burden constraint was achieved either by filling the drift of 7.0 x 5.2 m (width x height) with rock masses or reinforcing the drift wall. The tests were instrumented with different redundant sensors, which were installed in holes drilled from a parallel cross cut. The most promising one was a concept, which combines the initial movement recorded by an accelerometer designed to minimize zero-shift with the final displacement recorded by a fibre photoelectric sensor (‘fibre-optic zebra gauge’). For the filled drift wall blasting test the maximum velocity varied between 16 - 32 m/s with a compaction in the range of 4 - 5 %. A gap was verified to exist between the intact pillar and the blasted material. By comparison, the velocity for the unconfined situation yielded a considerably increased velocity (42 - 47 m/s). In addition, ‘Blo-Up’, a component within the Hybrid Stress Blast Model (HSBM), was used to model the blasting results. The ob-jective was to show that reasonable predictions of fragmentation and burden movement under confined conditions can be made. An unconfined reference experiment was used to calibrate Blo-Up and forward predictions of the confined case were made. In both cases, Blo-Up accurately reproduced the burden velocity and displacement observed in the experiments. The suggested measurement concept could be used for further measurements of confined burden movement in filled drift wall blasting tests and under controlled situations. As mentioned the final objective is instrumentation of the burden in SLC production rings.

  • 3100.
    Wimmer, Matthias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordqvist, Anders A.
    Mining Technology R and D, LKAB Kiruna Mine.
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Selldén, Håkan
    Mining Technology R and D, LKAB Kiruna Mine.
    Lenz, Gunther
    3G Software & Measurement.
    3D mapping of sublevel caving (SLC) blast rings and ore flow disturbances in the LKAB Kiruna mine2012In: MassMin 2012: Proceedings of the 6th International Conference and Exhibition on Mass Mining, Sudbury, Canada June 2012, Sudbury, Canada: Canadian Institute of Mining, Metallurgy and Petroeum , 2012Conference paper (Refereed)
    Abstract [en]

    Sublevel caving (SLC) is a highly productive mining method with the major disadvantages of irrepressible ore loss and dilution. The confined blasting situation of SLC rings is commonly regarded to have a significant impact upon the material flow characteristics and hence on the overall performance. The initial conditions for the ore flow after blasting are unknown, as both the blasted geometry and the fragmentation itself are normally hidden. However, when opening a new drawpoint and in hang-up situations an inspection of the actual conditions is feasible. For this purpose, a remotely operated 3D photogrammetry system was custom built and used to reconstruct the ring front and/or cavity as a geo-referenced mesh model with colour information. Various blasting situations have been observed and this allowed a deeper study of the i) broken geometry and height, ii) over- and underbreak and their effects on subsequently blasted rings, iii) interaction effects between adjacent holes/rings, iv) drilling accuracy based on identified boreholes and v) mapping of geological structures and their influence on the blast result. The capabilities of the 3D image acquisition system to evaluate the blasting results are demonstrated with an example, in which a series of blasts were surveyed. Monitoring under hang-up situations, has then revealed the actual effects from confined blasting and gravity flow related issues. The 3D photogrammetry system is now increasingly being used to study hang-ups. By revealing and quantifying hitherto inaccessible information, the system has proven to be a valuable tool in increasing the understanding of both SLC breakage and flow.

59606162636465 3051 - 3100 of 3243
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