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  • 1.
    Friberg, Ingemar
    Luleå University of Technology, Department of Arts, Communication and Education, Education, Language, and Teaching.
    The Art of Accepting: Ageing-as-art in Max Frisch’s Der Mensch erscheint im Holozän and Lars Gustafsson’s A Tiler’s Afternoon 2018In: European Journal of Scandinavian Studies, ISSN 2191-9399, E-ISSN 2191-9402, Vol. 48, no 1Article in journal (Refereed)
  • 2.
    Mahmood, Yasser Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Garmabaki, Amir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ahmadi, Alireza
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Verma, Ajit Kumar
    Western Norway University of Applied Sciences.
    Reliability model for frequency converter in electrified railway2018In: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 94, 385-392 p.Article in journal (Refereed)
    Abstract [en]

    Reliability analysis of frequency converters based on failures and outages reports constitute an important basis for asset performance and management. Two- and four-state reliability models that recognize the operating characteristics of base load units and peaking units are presented and compared in this study. In this study, a four-state model is modified to a three-state model by combining the ‘needed’ and ‘not-needed’ forced-out states. Moreover, the transitions in the three-state model for power frequency converter have been designed according to real operational data. An outage-reporting database modelled considering IEEE STD 762 is presented and compared with the existing failure-reporting database of the case considered here. Furthermore, a method to extract information missing in the failure-reporting database by electrical readings is proposed to meet the requirements of the outage-reporting database. The study found that the results of indexes based on the IEEE four-state model are not reasonable for the frequency converter given their differences with the gas-turbine results under operational conditions. The forced outage rates and availability factors of twelve actual traction frequency converters of Swedish railways network are presented to validate the modified model.

  • 3.
    Sanda, Mohammed-Aminu
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Cudjoe, Elikplim
    University of Ghana Business School, Accra, .
    Identification of Factors Predictive of Nurses’ Time Pressure, Workload and Job Satisfaction in Ghanaian Public Hospitals2018In: Advances in Human Factors, Business Management and Leadership: Proceedings of the AHFE 2017 International Conferences on Human Factors in Management and Leadership, and Business Management and Society, July 17−21, 2017, The Westin Bonaventure Hotel, Los Angeles, California, USA / [ed] Jussi Ilari Kantola, Tibor Barath, Salman Nazir, Cham, 2018, 65-76 p.Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to identify the factors that constitute time pressure, mental stress and job satisfaction among Ghanaian nurses working in public hospitals. Factor analysis of the collated data showed that not all the standardized factors of time pressure, mental stress and job satisfaction could be used to predict nurses’ work in the Ghanaian public hospital work environment. Based on correlation analysis, it was found that by ameliorating the time pressure associated with the nursing work, nurses will experience improved relationship with both superiors and among themselves. It is concluded that by eliminating the time pressure, moderating the task pace and eliminating the emotional strain and mental stress associated with the nursing work, the mental stress associated with the nursing work will also be reduced. By implication, this understanding can be used in designing, convulsive and friendly nursing work environments in Ghanaian public hospitals.

  • 4.
    Mozgovoy, Sergej
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Hardell, Jens
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Deng, Liang
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Oldenburg, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological Behavior of Tool Steel under Press Hardening Conditions Using Simulative Tests2018In: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 140, no 1, 011606Article in journal (Refereed)
    Abstract [en]

    Press hardening is employed in the automotive industry to produce advanced high-strength steel components for safety and structural applications. This hot forming process depends on friction as it controls the deformation of the sheet. However, friction is also associated with wear of the forming tools. Tool wear is a critical issue when it comes to the dimensional accuracy of the produced components and it reduces the service life of the tool. It is therefore desirable to enhance the durability of the tools by studying the influence of high contact pressures, cyclic thermal loading, and repetitive mechanical loading on tool wear. This is difficult to achieve in conventional tribological testing devices. Therefore, the tribological behavior of tool-workpiece material pairs at elevated temperatures was studied in a newly developed experimental setup simulating the conditions prevalent during interaction of the hot sheet with the tool surface. Uncoated 22MnB5 steel and aluminum-silicon (Al-Si)-coated 22MnB5 steel were tested at 750 °C and 920 °C, respectively. It was found that higher loads led to lower and more stable friction coefficients independent of sliding velocity or surface material. The influence of sliding velocity on the coefficient of friction was only marginal. In the case of Al-Si-coated 22MnB5, the friction coefficient was generally higher and unstable due to transfer of Al-Si coating material to the tool. Adhesion was the main wear mechanism in the case of uncoated 22MnB5

  • 5.
    Pocorni, Jetro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Powell, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Frostevarg, Jan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Kaplan, Alexander F. H.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Dynamic laser piercing of thick section metals2018In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 100, 82-89 p.Article in journal (Refereed)
    Abstract [en]

    Before a contour can be laser cut the laser first needs to pierce the material. The time taken to achieve piercing should be minimised to optimise productivity. One important aspect of laser piercing is the reliability of the process because industrial laser cutting machines are programmed for the minimum reliable pierce time. In this work piercing experiments were carried out in 15 mm thick stainless steel sheets comparing a stationary laser and a laser which moves along a circular trajectory with varying processing speeds. Results show that circular piercing can decrease the pierce duration by almost half compared to stationary piercing. High speed imaging (HSI) was employed during the piercing process to understand melt behaviour inside the pierce hole. HSI videos show that circular rotation of the laser beam forces melt to eject in opposite direction of the beam movement, while in stationary piercing the melt ejects less efficiently in random directions out of the hole.

  • 6.
    Yan, Baili
    et al.
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University, Nanjing .
    Zeng, Changfeng
    College of Mechanic and Power Engineering, Nanjing Tech University.
    Yu, Liang
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Wang, Chongqing
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing.
    Zhang, Lixiong
    State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing.
    Preparation of hollow zeolite NaA/chitosan composite microspheres via in situ hydrolysis-gelation-hydrothermal synthesis of TEOS2018In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 257, 262-271 p.Article in journal (Refereed)
    Abstract [en]

    In situ hydrolysis-gelation-hydrothermal (HGH) synthesis of tetraethylorthosilicate (TEOS) technique was developed to prepare hollow zeolite NaA/chitosan composite microspheres. The chitosan solution coated calcium alginate microspheres served as template to generate hollow structure, which were pre-modified by oleic acid and coated by TEOS. Furthermore, the calcium alginate microspheres were prepared by a simple homemade double T-junction mixer. During the hydrothermal process, the TEOS hydrolyzed and provided silica source for the zeolite NaA shell, meanwhile the inner calcium alginate microsphere core dissolved by the alkaline synthesis mixture and left the hollow structure. The obtained products were characterized by XRD, FT-IR, SEM, TG et al. techniques. The preparation method for calcium alginate microspheres template was simple and the preparation process had no NaA crystal seeds been involved. The hollow size could be adjusted by controlling the synthesis parameters of calcium alginate/chitosan microspheres. In addition, the functional magnetic γ-Fe2O3 nanoparticles could be introduced into the cavity during synthesis of calcium alginate/chitosan microspheres and guest magnetic γ-Fe2O3 nanoparticles had no effect on the properties of host zeolite NaA. The obtained functional magnetic hollow NaA/chitosan microspheres had decent adsorption performance for Cu2+ ions and were easy to recycle.

  • 7.
    Bagheri, Azam
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gu, Irene Y.H.
    Chalmers University of Technology.
    Improved characterization of multi-stage voltage dips based on the space phasor model2018In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 154, 319-328 p.Article in journal (Refereed)
    Abstract [en]

    This paper proposes a method for characterizing voltage dips based on the space phasor model of the three phase-to-neutral voltages, instead of the individual voltages. This has several advantages. Using a K-means clustering algorithm, a multi-stage dip is separated into its individual event segments directly instead of first detecting the transition segments. The logistic regression algorithm fits the best single-segment characteristics to every individual segment, instead of extreme values being used for this, as in earlier methods. The method is validated by applying it to synthetic and measured dips. It can be generalized for application to both single- and multi-stage dips.

  • 8.
    D'Orazio, Christian Javier
    et al.
    School of Information Technology and Mathematical Sciences, University of South Australia, Australia.
    Rongxing, Lu
    Faculty of Computer Science, University of New Brunswick, Fredericton, NB, Canada.
    Choo, Kim Kwang Raymond
    School of Information Technology and Mathematical Sciences, University of South Australia, Australia.
    Vasilakos, Athanasios
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    A Markov adversary model to detect vulnerable iOS devices and vulnerabilities in iOS apps2017In: Applied Mathematics and Computation, ISSN 0096-3003, E-ISSN 1873-5649, Vol. 293, 523-544 p.Article in journal (Refereed)
    Abstract [en]

    With the increased convergence of technologies whereby a user can access, store and transmit data across different devices in real-time, risks will arise from factors such as lack of appropriate security measures in place and users not having requisite levels of security awareness and not fully understanding how security measures can be used to their advantage. In this paper, we adapt our previously published adversary model for digital rights management (DRM) apps and demonstrate how it can be used to detect vulnerable iOS devices and to analyse (non-DRM) apps for vulnerabilities that can potentially be exploited. Using our adversary model, we investigate several (jailbroken and non-jailbroken) iOS devices, Australian Government Medicare Expert Plus (MEP) app, Commonwealth Bank of Australia app, Western Union app, PayPal app, PocketCloud Remote Desktop app and Simple Transfer Pro app, and reveal previously unknown vulnerabilities. We then demonstrate how the identified vulnerabilities can be exploited to expose the user's sensitive data and personally identifiable information stored on or transmitted from the device. We conclude with several recommendations to enhance the security and privacy of user data stored on or transmitted from these devices.

  • 9.
    Alvarez Perez, Manuel Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Stochastic Planning of Smart Electricity Distribution Networks2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The penetration of intermittent Distributed Generation (DG) brought additional uncertainty to the system operation and planning. To cope with uncertainties the Distribution System Operator (DSO) could implement several strategies. These strategies range from the inclusion of smart technologies which will increment system’s flexibility and resiliency, to improvements in forecasting, modeling, and regulatory pledge that will facilitate the planning activity. Regardless of the nature of the solutions, they could be collected in a sort of toolbox. The planner will access the toolbox to conform cost effective plans, better able to deal with any uncertainty. The present work will address the problem of distribution system planning under uncertainties, considering smart solutions along with traditional reinforcements, in the short-term lead time up to 3 years ahead. The work will be focused on three aspects that are the cornerstones of this work:

     • A planning facilitating strategy: Distribution Capacity Contracts (DCCs).

     • A flexibility enabler technology: Energy Storage.

     • A binding methodology: Multistage Stochastic Programming. Stochastic dual dynamic programming (SDDP). 

    Under the present directive of the European Parliament concerning common rules for the internal market in electricity, distribution companies are not allowed to own DG but entitled to include it as a planning option to differ investment in traditional grid reinforcements. An evaluation of the regulatory context will lead this work to consider DCCs as a planning alternative available in the toolbox. The impact of this type of contract on the remuneration of the DG owner will be assessed in order to provide insight on its willingness to participate. The DCCs might aid the DSO to defer grid i ii investments during planning stages and to control the network flows during operation. 

    Given that storage solutions help to match in time production from intermittent sources with load consumption, they will play a major role in dealing with uncertainties. A generic storage model (GSM) based on a future cost piecewise approximation will be developed. This model inspired by hydro-reservoirs will help assessing the impact of storage in planning decisions. This model will be tested by implementing it in short-term hydro scheduling and unit commitment studies. 

    To trace a path towards the future of this research work, a discussion on the planning problem formulation, under consideration of the lead time, the expansion options, the smart strategies, and the regulatory framework will be presented. Special focus will be given to multistage stochastic programming methods and in particular to the SDDP approach.

  • 10.
    Grip, Niklas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Sabourova, Natalia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Tu, Yongming
    School of Civil Engineering, Southeast University, Nanjing.
    Sensitivity-based model updating for structural damage identification using total variation regularization2017In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 84, no A, 365-383 p.Article in journal (Refereed)
    Abstract [en]

    Sensitivity-based Finite Element Model Updating (FEMU) is one of the widely accepted techniques used for damage identification in structures. FEMU can be formulated as a numerical optimization problem and solved iteratively making automatic updating of the unknown model parameters by minimizing the difference between measured and analytical structural properties. However, in the presence of noise in the measurements, the updating results are usually prone to errors. This is mathematically described as instability of the damage identification as an inverse problem. One way to resolve this problem is by using regularization. In this paper, we compare a well established interpolation-based regularization method against methods based on the minimization of the total variation of the unknown model parameters. These are new regularization methods for structural damage identification. We investigate how using Huber and pseudo Huber functions in the definition of total variation affects important properties of the methods. For instance, for well-localized damages the results show a clear advantage of the total variation based regularization in terms of the identified location and severity of damage compared with the interpolation-based solution.For a practical test of the proposed method we use a reinforced concrete plate. Measurements and analysis were performed first on an undamaged plate, and then repeated after applying four different degrees of damage.

  • 11.
    Chibba, Aron
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Supply Chain Quality Management - Exploring performance of manufacturing organizations2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis addresses the issue of quality performance in supply chains in the manufacturers’context. Research shows that the management and performance of supply chains play a major rolein gaining competitive advantage, especially in times of decreasing international trade barriers andquickly evolving information technology. Some researchers claim that it is the supply chain itselfthat competes on a market and not merely the organisations with their specific strategies andgoals. Supply chain performance has been widely discussed in the research literature in recentyears. However, this research points out that supply chain quality management (SCQM) and itsimpact on firm performance (both inter-organisational and intra-organisational) have not beensufficiently understood. Further studies are needed to identify the direct and indirect impact ofSCQM practices on firm performance at multiple levels.A problem that many organisations face is the lack of resources and knowledge on how to managesupply chain quality performance (i.e., which performance to measure, how to controlperformance, and how to improve performance). Studies show that often even large companiesmeasure effectiveness using key performance indicators (KPI) and that these indicators often donot depict key characteristics critical to organisational performance or customer behaviour.Therefore, such indicators might be inadequate for fully capturing the performance of supplychains. As quality management standards evolve, managers need to adapt to changingrequirements. To fulfil the new version of ISO 9001, organisations are required to determinecriteria and apply methods to ensure effective operation and control of their processes (both intraorganisationaland inter-organisational performance). This includes monitoring and measuringperformance indicators. The quality performance of a supply chain is dependent on its ability toimprove and thereby enable organisations to stay competitive over time. Good measurements ofsupply chain quality performance must reflect this ability. To do so, organisations need to knowwhich measures and metrics to use and how to analyse performance of their supply chains.From the seven studies presented in this thesis we are able to draw a number of more generalconclusions that bear on the main research question: What improves quality performance of supplychains that include manufacturing? At the process level, it has been found that manufacturersshould focus on the quality and delivery performance of each process within the organisation. Atthe internal, integrated supply chain level, a manufacturing organisation should focus on quality(conformance), delivery performance (on-time delivery), and cost cutting in the internal supplychain. Collaboration using cross-functional teams seems most appropriate when working withproduct development. The use of a process-oriented mapping tool was found to facilitatedescription of information flows and physical material flows and also to identify disturbances thatcould be improved and rationalized to generate a better flow in the total supply chain. At both theupstream and downstream sides of the supply chain, one-sided measures that depict performanceover organisational boundaries were found to be the most common. At the downstream side of asupply chain, suppliers could be chosen based on cost, conformance, speed, and flexibility. At theupstream side, procedures that handle changing requirements and information about delays orincorrectness of materials were found to influence flow. The results from these seven studies arethe basis for the development of a supply chain quality improvement model. In the literature,supply chain performance is often discussed on a strategic level with measures for quality,flexibility and delivery. Managers also need metrics that can be followed up on at a detailed level(e.g., capacity load, breakdown rates, claims, cost of poor quality, and lead-times). To bridge thisgap, a Key Performance Indicators Matrix of supply chain quality performance indicators formanufacturers is proposed.

  • 12.
    Qarahasanlou, Ali Nouri
    et al.
    Faculty of Mining, Petroleum & Geophysics, Shahrood University of Technology, .
    Khalokakaie, Reza
    Faculty of Mining, Petroleum & Geophysics, Shahrood University of Technology, .
    Ataei, Mohammad
    Faculty of Mining, Petroleum & Geophysics, Shahrood University of Technology, .
    Ghodrati, Behzad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Operating Environment-Based Availability Importance Measures for Mining Equipment: (Case Study: Sungun Copper Mine)2017In: Journal of Failure Analysis and Prevention, ISSN 1547-7029, E-ISSN 1864-1245, Vol. 17, no 1, 56-67 p.Article in journal (Refereed)
    Abstract [en]

    When a system’s performance is inadequate, the concept of availability importance can be used to improve it. The availability of an item depends on the combined aspects of its reliability and maintainability. In a system consisting of many subsystems, the availability of some subsystems is more important to system performance than others. The availability measure determines the priority of availability across subsystems. Most researchers only consider operation time and ignore the influence of the operating environment; therefore, their estimations are not accurate enough. In contrast to previous research, we focus on the influence of the operating environment on the system/subsystem’s characteristics with a view to prioritizing them based on the importance of availability. The paper considers part of the mining fleet system of Sungun copper mine, including the wagon drill, loader, bulldozer, and dump truck subsystems. We identify an ordered list of possibilities for availability improvement and suggest changes or remedial actions for each item to either reduce its failure rate or reduce the time required to repair it.

  • 13.
    Lidström Brock, Malin
    Luleå University of Technology, Department of Arts, Communication and Education, Education, Language, and Teaching.
    Writing Feminist Lives: The Biographical Battles over Betty Friedan, Germaine Greer, Gloria Steinem, and Simone de Beauvoir2017Book (Refereed)
    Abstract [en]

    This book draws attention to the controversy that surrounds Betty Friedan, Germaine Greer, Gloria Steinem, and Simone de Beauvoir’s lives and the important role that their life stories have played in their feminist writing. Directly and indirectly, the four women have contributed to battles over feminism’s meaning through autobiographically informed political writing. Inevitably, therefore, their biographers are also participants in these battles, yet not always on the same side as their subjects. Writing Feminist Lives introduces a further fold of nuance into considerations of biography and feminism by showing that the biographers of the four women have made methodological choices that reflect their loyalty to, or their scepticism towards, competing ideological definitions of the exemplary feminist life. 

  • 14.
    Khoshkhoo, Mohammad
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Dopson, Mark
    Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sandström, Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    New insights into the influence of redox potential on chalcopyrite leaching behaviour2017In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 100, 9-16 p.Article in journal (Refereed)
    Abstract [en]

    Chalcopyrite (CuFeS2) is the most economically important and most refractory copper mineral when treated in conventional sulphate media leaching systems. In this study, the effect of solution redox potential on leaching of a pure and a pyritic chalcopyrite concentrate was investigated using concentrates with fresh and aged surfaces. In experiments using concentrates with fresh surfaces, the response to redox potential depended on the presence of pyrite: fresh pyritic concentrate leached more effectively at low redox potential (in agreement with reductive leaching mechanisms), while the leaching efficiencies from fresh pure concentrate were similar at high and low redox potentials. The data suggested that the reductive leaching mechanism does not necessarily result in higher and faster recoveries in the absence of the galvanic interaction induced by the presence of pyrite. It was also found that exposure of chalcopyrite to atmospheric oxidation prior to leaching (ageing) had an effect on leaching behaviour in response to redox potential: copper recoveries in leaching of aged concentrates were higher at high redox potentials. This behaviour was attributed to the presence of iron–oxyhydroxides on the surface of aged concentrates. Based on the data from this investigation and previous surface studies, it is proposed that iron–oxyhydroxides play an important role in triggering the hindered dissolution of chalcopyrite.

  • 15.
    Hjulman, Tore Andersson
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Ett med naturen: En studie av hur naturen omförhandlades i mellankrigstidens konflikter mellan naturskydd och samiska rättigheter2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Tore Andersson Hjulman: One with Nature: An Inquiry into the Renegotiation of Nature in the Conflicts between Nature Preservation and Sámi Rights during the Interwar Period.[Ett med naturen: En studie av hur naturen omförhandlades i mellankrigstidens konflikter mellan naturskydd och samiska rättigheter.] PhD dissertation in Swedish, Luleå University of Technology, Sweden 2017.

    In 1909 the Swedish national parks law was adopted with the assumption that theSámi people living in the areas to be preserved were, in principle, one with nature. Therefore the perception of their land as pristine was consolidated and they could be excepted from park regulations. About thirty years later the national park administration stated that the aim to keep the national park nature untouched would fail without a restriction of Sámi rights within the parks. The aim of this thesis is to investigate how the distinction of nature from culture was renegotiated during the conflicts that preceded and followed this new stance. Tracing the impulses that fostered the reactions of the state administration back to their original contexts, complex interactions of differing interests are revealed. These contexts are examined in three case studies. The first case centers on nomad school superintendent Erik Bergström and his warning of the effects on the national parks from reindeer herders activities. The intersection of nature preservation and Sámi politics sheds light on their common outset in the use of the nature-culture dichotomy in approaching the Sámi. This contributes to explain the resistance by which the interest of change was met by those invested in the prevailing state policy towards the Sámi.The second case concerns a conflict of Sámi land use in the Abisko national park by the early 1930s. Several factors that possibly induced state officials to react on Sámi fishing and hunting in the national park are illuminated. These include different understanding of nature preservation, the moral ecology among the Sámi and antagonism between Sámi reindeer herders and inhabitants in the railway towns.The third case involves concerns raised in the process of establishing a new national park in the Muttos/Muddus area. A shift in focus from mountainous to forest landscapes among nature preservationists resulted in the inclusion of new stakeholders and fields of knowledge about land use and its effects. This seems to have spurred problematizing of both the ideal of pristine nature and of Sámi land use. A conflict was triggered by the in-migration of two reindeer herding families.In conclusion, it will be argued that it was a series of quite contextually different conflicts that interacted to undermine the institutionalized demarcation of nature. This simultaneously challenged Sámi rights in the national parks and took place in ideological opposition to the foundation of segregationist Sámi policy.

  • 16.
    Popescu, Cosmin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    CFRP Strengthening of Cut-Out Openings in Concrete Walls – Analysis and Laboratory Tests2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Redesigning buildings to improve their space efficiency and allow changes in use is often essential during their service lives to comply with shifts in living standards and functional demands.This may require the introduction of new openings in elements such as beams, walls, and slabs,which inevitably reduces their structural performance and hence requires repair or strengthening.However, there are uncertainties regarding both the effects of openings and the best remedial optionsfor them. Traditionally, two methods have been used to strengthen reinforced concrete (RC) walls with openings, these being either to create a frame around the opening using RC/steel membersor to increase the cross-sectional thickness. Currently, intervention in existing buildings must be minimal in order to minimise inconvenience caused by limiting the use of the structure during repairs. One option is to use externally-bonded fibre-reinforced polymers (FRPs).

    In this study, the author reports on an experimental investigation of the effectiveness of carbonFRP (CFRP)–based strengthening for restoring the axial capacity of a solid reinforced concretewall after cutting openings. Nine half-scale specimens, designed to represent typical wall panels in residential buildings with and without door-type openings, were tested to failure. The walls were tested in two-way action and subjected to axial loading with low eccentricity (defined as one sixth of the wall’s thickness) along the weak axis to represent imperfections due to thickness variation and misalignment of the panels during the construction process. An extensive instrumentation scheme was used to monitor the specimen’s behaviour during the loading cycles. In addition to classical approaches for measuring strains and displacements, optical 3D measurements were also acquired using the digital image correlation (DIC) technique. These provided better overviews of the failure mechanism by recording the crack pattern development and deformation of the walls throughout the loading history.

    Reducing the cross-sectional area by cutting out openings i.e. 25% (hereafter referred to as small opening) and 50% (hereafter referred to as large opening) led to 36% and 50% reductions in peak loads, respectively. In both situations the failure was brittle due to crushing of concrete with spalling and reinforcement buckling. The CFRP strengthening increased the axial capacity of walls with small and large openings by 34 – 50% and 13 – 27%, respectively. This partially restored theircapacities to 85 – 95% and 57 – 63% of their precutting capacity (i.e. solid wall), respectively. A procedure based on a rigid-plastic approach for evaluating the ultimate load of walls with cut-out openings that have been strengthened with FRPs was also proposed in this study. Predictions made using the proposed method agree closely with experimental results.

  • 17.
    Grzenda, Maciej
    et al.
    Faculty of Mathematics and Information Science, Warsaw University of Technology,, Research and Development Center.
    Furtak, Janusz
    Military University of Technology, Warszawa.
    Legierski, Jarosław
    Faculty of Mathematics and Information Science, Warsaw University of Technology, Warszawa.
    Awad, Ali Ismail
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Network Architectures, Security, and Applications: An Introduction2017In: Advances in Network Systems: Architectures, Security, and Applications / [ed] Maciej Grzenda, Ali Ismail Awad, Janusz Furtak, Jarosław Legierski, Berlin: Springer Berlin/Heidelberg, 2017, 1-10 p.Chapter in book (Refereed)
    Abstract [en]

    Owing to the ever growing communication systems, modern networks currently encompass a wide range of solutions and technologies, including wireless and wired networks and provide basis for network systems from multiple partly overlapping domains such as the Internet of Things (IoT), cloud services, and network applications. This appears in numerous active research areas with particular attention paid to the architecture and security of network systems. In parallel, novel applications are developed, in some cases strongly linked to rapidly developing network-based data acquisition and processing frameworks. This chapter presents a general introduction to the topics of network architectures, security, and applications in addition to short descriptions of the chapters included in this volume

  • 18.
    Trivedi, Chirag
    et al.
    Waterpower Laboratory, Norwegian University of Science and Technology.
    Cervantes, Michel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Fluid-structure interactions in Francis turbines: A perspective review2017In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 68, no 1, 87-101 p.Article in journal (Refereed)
    Abstract [en]

    Competitive electricity prices and reduced profit margins have forced hydraulic turbines to operate under critical conditions. The demand for extended operating ranges and the high efficiency of the turbine runners have forced manufacturers to produce lightweight runners. A turbine runner sometimes experiences resonance when a forced (flow-induced) excitation frequency approaches the runner’s natural frequency, resulting in failure. The cost of structural failure after commissioning is prohibitive. To attain a reliable and safe runner design, understanding of the structural response to flow-induced excitations is important. High amplitude pressure pulsations cause fatigue loading of the blades, which develop cracks over time. The amplitudes are dependent on the flow conditions, type of turbine and stator/rotor vane combinations. The structural response is dependent on the material properties, flow-induced damping and natural frequencies. Moreover, in a hydraulic turbine, changes in flow velocity from less than 1 m s−1 to over 40 m s−1 create challenges in predicting the response.

    The main objective of this article is to review the studies conducted on fluid-structure interactions within hydraulic turbines. Several aspects are reviewed, such as flow-induced excitation, added mass effect, hydrodynamic damping, and blade flutter. Both experimental and numerical studies are discussed in this article. This review also discusses the consequences of an increased number of transient cycles, such as load variation, start-stop and total load rejection, on the turbines and the fatigue loading. Finally, an attempt is made to highlight the important requirements for prospective fluid-structure analysis to fill current gaps in the literature.

  • 19.
    Zairov, Rustem
    et al.
    A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences.
    Mustafina, Asyia
    A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences.
    Shamsutdinova, Nataliya
    A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences.
    Nizameev, Irek
    A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences.
    Moreira, Beatriz
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Sudakova, Svetlana
    A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences.
    Podyachev, Sergey
    A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences.
    Fattakhova, Alfia
    Kazan (Volga region) Federal university.
    Safina, Gulnara
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Lundström, Ingemar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gubaidullin, Aidar
    A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    High performance magneto-fluorescent nanoparticles assembled from terbium and gadolinium 1,3-diketones2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 40486Article in journal (Refereed)
    Abstract [en]

    Polyelectrolyte-coated nanoparticles consisting of terbium and gadolinium complexes with calix[4]arene tetra-diketone ligand were first synthesized. The antenna effect of the ligand on Tb(III) green luminescence and the presence of water molecules in the coordination sphere of Gd(III) bring strong luminescent and magnetic performance to the core-shell nanoparticles. The size and the core-shell morphology of the colloids were studied using transmission electron microscopy and dynamic light scattering. The correlation between photophysical and magnetic properties of the nanoparticles and their core composition was highlighted. The core composition was optimized for the longitudinal relaxivity to be greater than that of the commercial magnetic resonance imaging (MRI) contrast agents together with high level of Tb(III)-centered luminescence. The tuning of both magnetic and luminescent output of nanoparticles is obtained via the simple variation of lanthanide chelates concentrations in the initial synthetic solution. The exposure of the pheochromocytoma 12 (PC 12) tumor cells and periphery human blood lymphocytes to nanoparticles results in negligible effect on cell viability, decreased platelet aggregation and bright coloring, indicating the nanoparticles as promising candidates for dual magneto-fluorescent bioimaging

  • 20.
    Alfieri, Luisa
    et al.
    Department of Engineering, University of Naples Parthenope, Centro Direzionale of Naples.
    Bracale, Antonio
    Department of Engineering, University of Naples Parthenope, Centro Direzionale of Naples.
    Carpinelli, Guido
    Department of Electrical Engineering and Information Technology, University of Naples Federico II.
    Larsson, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    A Wavelet-Modified ESPRIT Hybrid Method for Assessment of Spectral Components from 0 to 150 kHz2017In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 1, 97Article in journal (Refereed)
    Abstract [en]

    Waveform distortions are an important issue in distribution systems. In particular, the assessment of very wide spectra, that include also components in the 2-150 kHz range, has recently become an issue of great interest. This is due to the increasing presence of high-spectral emission devices like end-user devices and distributed generation systems. This study proposed a new sliding-window wavelet-modified estimation of signal parameters by rotational invariance technique (ESPRIT) method, particularly suitable for the spectral analysis of waveforms that have very wide spectra. The method is very accurate and requires reduced computational effort. It can be applied successfully to detect spectral components in the range of 0-150 kHz introduced both by distributed power plants, such as wind and photovoltaic generation systems, and by end-user equipment connected to grids through static converters, such as fluorescent lamps.

  • 21.
    Näslund, Rebecka
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    “The World at Your Fingertips if You Know the Computer”: Agency, Information and Communication Technologies and Disability2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the relationships between agency, Information and Communication Technologies (ICT) and people with disability (in various ages). The aim has been to create an understanding by describing and analysing, and as such, to develop knowledge of how people with disabilities experience agency, ICT, and disability in their everyday lives. The frame of reference is inspired by disability studies, feminist studies and science and technologies studies (STS). The empirical material was collected in, Norrbotten (Sweden’s northernmost region) and Muscat (the capital area of the Sultanate of Oman) by an autobiographical account, audio-visual material, drawings, interviews, observations, and reading of textual documents. The thesis consists of six papers. The main findings outline that agency, ICT, disability, and gender are part of intra-actions between material entities (such as bodies, technologies, etc.) and practices. The thesis also explores that disability in Sweden and Oman are understood in a variety of ways. Additionally, it presents that the combination of the notions of interference with situated knowledges can contribute with alternative methodological insights about the interference of disability, gender, ICT, the participants’ and researchers’ experiences and understandings to make accountable knowledge claims. Moreover, the thesis presents that material entities (bodies and technologies) and practices are part of different modes of ordering disability which bear effects on the lives of people with disabilities. It additionally disentangles that materialities such as the Internet intra-act with other material entities (for instance, bodies) and practices which enact various forms of agency which bear effects on the everyday lives of people with disability and their ways to participate. Finally, the thesis outlines some implications that an intra-acting understanding of the use of Internet can contribute with in research which focuses on disability, participation, and agency.

  • 22.
    Edvardsson, David
    et al.
    The Medical Faculty, Department of Nursing, Umeå University, .
    Sjögren, Karin
    The Medical Faculty, Department of Nursing, Umeå University, .
    Lood, Qarin
    The Medical Faculty, Department of Nursing, Umeå University, .
    Bergland, Ådel
    Department of Nursing Science, Faculty of Medicine, Institute of Health and Society, University of Oslo .
    Kirkevold, Marit
    Department of Nursing Science, Faculty of Medicine, Institute of Health and Society, University of Oslo.
    Sandman, Per-Olof
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    A person-centred and thriving-promoting intervention in nursing homes: study protocol for the U-Age nursing home multi-centre, non-equivalent controlled group before-after trial2017In: BMC Geriatrics, ISSN 1471-2318, E-ISSN 1471-2318, Vol. 17, 22Article in journal (Refereed)
    Abstract [en]

    Background

    The literature suggests that person-centred care can contribute to quality of life and wellbeing of nursing home residents, relatives and staff. However, there is sparse research evidence on how person-centred care can be operationalised and implemented in practice, and the extent to which it may promote wellbeing and satisfaction. Therefore, the U-Age nursing home study was initiated to deepen the understanding of how to integrate person-centred care into daily practice and to explore the effects and meanings of this.

    Methods

    The study aims to evaluate effects and meanings of a person-centred and thriving-promoting intervention in nursing homes through a multi-centre, non-equivalent controlled group before-after trial design. Three nursing homes across three international sites have been allocated to a person-centred and thriving-promoting intervention group, and three nursing homes have been allocated to an inert control group. Staff at intervention sites will participate in a 12-month interactive educational programme that operationalises thriving-promoting and person-centred care three dimensions: 1) Doing a little extra, 2) Developing a caring environment, and 3) Assessing and meeting highly prioritised psychosocial needs. A pedagogical framework will guide the intervention. The primary study endpoints are; residents’ thriving, relatives’ satisfaction with care and staff job satisfaction. Secondary endpoints are; resident, relative and staff experiences of the caring environment, relatives’ experience of visiting their relative and the nursing home, as well as staff stress of conscience and perceived person-centredness of care. Data on study endpoints will be collected pre-intervention, post-intervention, and at a six-month follow up. Interviews will be conducted with relatives and staff to explore experiences and meanings of the intervention.

    Discussion

    The study is expected to provide evidence that can inform further research, policy and practice development on if and how person-centred care may improve wellbeing, thriving and satisfaction for people who reside in, visit or work in nursing homes. The combination of quantitative and qualitative data will illuminate the operationalisation, effects and meaning of person-centred and thriving-promoting care.

  • 23.
    Zainy, Maher T.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Bauer, Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ask, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The Tectonic and Structural Classifications of the Western Part of the Zagros Fold and Thrust Belt, North Iraq, Review and Discussion2017In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 7, no 2, 71-89 p.Article in journal (Refereed)
    Abstract [en]

    The Zagros fold and thrust belt represents a tectonically significant area, and one of the richest areas in oil and gas reservoirs in the world. The Zagros fold and thrust belt is the deformational product of the Cretaceous-present day convergence of the Arabian and Iranian (Eurasian) plates (subduction and collision). The belt extends more than 2000 km from southern Turkey through the north and northeastern Iraq to the Strait of Hormuz in southwestern Iran. The Zagros fold and thrust belt is divided into two parts which are; Western part within Iraqi region and Eastern part within Iranian region. The western part of the Zagros fold and thrust belt has been traditionally subdivided into several structural zones that are generally striking parallel to the plate boundary. This is characterized by exposure of Late Ordovician to Pliocene - Pliestocene formations with different types of Quaternary Sediments. This research will concentrate on Western part of Zagros fold and thrust belt and the styles of structural classifications, which will aid to clarify and better understand the tectonic and structural history and evolution of the region. We have considered the last version of structural classification as the most relevant one to the reality, especially within outer platform (Unstable shelf). Where it divides the region into four structural zones, which are: Low Folded zone, High Folded Zone, Imbricate Zone, and Zagros Suture Zone and these zones were further divided to several subzones. This classification is based on the structural style and intensity of deformation, stratigraphy, mechanicalstratigraphy and tectono-stratigraphy of the deformed sequences, Age of deformation, surface physiography and morphology. The data used in the classification is more reliable, up to date and relevant.

  • 24.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Moderna Fysiken på 15 Minuter2017Book (Other (popular science, discussion, etc.))
  • 25.
    Bucur, Diana Maria
    et al.
    University POLITEHNICA of Bucharest.
    Cervantes, Michel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Dunca, Georgiana
    University POLITEHNICA of Bucharest.
    Maximum pressure evaluation during expulsion of entrapped air from pressurized pipelines2017In: Journal of Applied Fluid Mechanics, ISSN 1735-3572, E-ISSN 1735-3645, Vol. 10, no 1, 11-20 p.Article in journal (Refereed)
    Abstract [en]

    Pressurized pipeline systems may have a wide operating regime. This paper presents the experimental analysis of the transient flow in a horizontal pipe containing an air pocket, which allows the ventilation of the air after the pressurization of the hydraulic system, through an orifice placed at the downstream end. The measurements are made on a laboratory set-up, for different supply pressures and various geometries of water column length, air pocket and expulsion orifice diameter. Dimensional analysis is carried out in order to determine a relation between the parameters influencing the maximum pressure value. A two equations model is obtained and a criterion is established for their use. The equations are validated with experimental data from the present laboratory set-up and with other data available in the literature. The results presented as nondimensional quantities variations show a good agreement with the previous experimental and analytical researches.

  • 26.
    Abdullah, Twana
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Groundwater Vulnerability Using DRASTIC model Applied to Halabja Saidsadiq Basin, IRAQ: 2017Licentiate thesis, comprehensive summary (Other academic)
  • 27.
    Stenström, Christer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Nyckeltal för driftsäkerhet inom järnvägstransport2017Report (Other academic)
    Abstract [sv]

    Driftsäkra järnvägar och tåg är avgörande för konkurrenskraftig och ökande andel järnvägstranport. För uppföljning av driftsäkerhet använder infrastrukturförvaltare (Trafikverket), tågoperatörer och entreprenörer olika indikatorer, så som merförsening och antal funktionsfel. Indikatorerna mäter olika aspekter och kan illustreras mer eller mindre intuitivt och tilltalande. Metod för definiering och införsel av indikatorer skiljer sig mellan organisationer. En enkel och vanlig metod är diskussion och beslut inom en sammanträdande grupp. En mer objektiv metod är att följa uppsatta riktlinjer för definiering och utvärdering av indikatorer. Dock är det få allmängiltiga metoder tillgängliga för att definiera indikatorer. Utifrån behov inom järnvägstransport och avsaknaden av metoder för definiering och utvärdering av indikatorer, avses i denna studie en sådan allmänt tillämplig metod presenteras och appliceras inom järnvägstransport. Applicering innebär att i detalj dokumentera två indikatorer som kan användas som branschgemensamma nyckeltal inom järnvägstransport.

    Två indikatorer definierades och utvärderade i denna studie avseende möjlighet att tillämpa dessa som branschgemensamma indikatorer inom järnvägstransport. Val av indikatorer utgick från litteraturstudie av i Sverige gällande standarder avseende driftsäkerhet. Definiering och utvärdering av valda indikatorer utgick från mall av Neely (2002) bestående av 46 frågor.

    De definierade och utvärderade indikatorerna är tillgänglighet och feleffektmatris. Definiering och utvärdering av de två indikatorerna, med utgång från givna 46 frågor, tog i denna rapport fyra arbetsdagar (16 timmar/nyckeltal). Detta ger en fingervisning på arbetsinsatsen som krävs för en organisation som vill införa föreslagen metod för att definiera indikatorer. Förutsatt att data och ett underhållssystem finns tillgängligt, består kostnaderna vid implementering och drift i stora drag av: definiering och utvärdering; implementering av kod i underhållssystem; förbättringsarbete av indikatorer och kod; samt drift av kod i underhållssystem. Det kan därmed vara relevant att utföra en kostnad-nytta-analys avseende indikatorerna. En stor kostnad i sammanhanget är insamling av data. Dock ska denna kostnad eventuellt inte tillskrivas till indikatorerna, eftersom det troligtvis inte är acceptabelt att inte samla in data avseende antal fel, återställelsetider och merförseningar.

    Tre överväganden berörande indikatorn tillgänglighet som bör tas i beaktning är: möjlighet att bryta ner indikatorn för att komma närmare orsakerna till indikatorvärden; tidsrymd för beräkning; samt användande av median, medelvärde och registrerade återställningstider vid beräkning. Valen som görs vid en mjukvaruimplementering kan uppdateras efterhand med erfarenhet från tillämpning.

    En egenskap hos feleffektmatrisen, så som den är tillämpad i denna studie, är att den påverkas av tidtabeller och gångtidstillägg. Tillgänglighet påverkas inte av tidtabeller och gångtidstillägg, men kan istället inte fånga upp skillnaden mellan få långa fel och många korta fel, så som feleffektmatrisen gör. I detta avseende kompletterar tillgänglighet och feleffektmatris varandra.

  • 28.
    Wright, E.
    et al.
    Department of Physics and I3N, University of Aveiro, Campus Santiago.
    Coutinho, J.
    Department of Physics and I3N, University of Aveiro, Campus Santiago.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Torres, V.J.B.
    Department of Physics and I3N, University of Aveiro, Campus Santiago.
    A first-principles model of copper-boron interactions in Si: for the light-induced degradation of solar Si2017In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 29, no 6, 065701Article in journal (Refereed)
    Abstract [en]

    The recent discovery that Cu contamination of Si combined with light exposure has a significant detrimental impact on carrier life-time has drawn much concern within the solar-Si community. The effect, known as the copper-related light-induced degradation (Cu-LID) of Si solar cells, has been connected to the release of Cu interstitials within the bulk (2016 Sol. Energy Mater. Sol. Cells 147 115-26). In this paper, we describe a comprehensive analysis of the formation/dissociation process of the CuB pair in Si by means of first-principles modelling, as well as the interaction of CuB defects with photo-excited minority carriers. We confirm that the long-range interaction between the Cu-i(+) cation and the B-s(-) anion has a Coulomb-like behaviour, in line with the trapping-limited diffusivity of Cu observed by transient ion drift measurements. On the other hand, the short-range interaction between the d-electrons of Cu and the excess of negative charge on B-s(-) produces a repulsive effect, thereby decreasing the binding energy of the pair when compared to the ideal point-charge Coulomb model. We also find that metastable CuB pairs produce acceptor states just below the conduction band minimum, which arise from the Cu level emptied by the B acceptor. Based on these results, we argue that photo-generated minority carriers trapped by the metastable pairs can switch off the Coulomb interaction that holds the pairs together, enhancing the release of Cu interstitials, and acting as a catalyst for Cu-LID.

  • 29.
    Pérez-Ràfols, Francesc
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    van Riet, Egbert J.
    Shell Global Solutions International BV, Innovation, Research and Development.
    Almqvist, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    On the flow through plastically deformed surfaces under unloading: A spectral approach2017In: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983Article in journal (Refereed)
    Abstract [en]

    This study considers flow through the gap left between two surfaces during unloading, in other words, when an applied load is gradually reduced after loading to a state where plastic deformation occurs. In particular, the permeability of the gap is studied. It was found that a substantial reduction of the applied load is required before the permeability starts to increase significantly. The explanation for this phenomenon is given by the combination of components with different wavelengths present in the surface. Components with long wavelengths deform elastically and those with shorter wavelengths may also deform plastically. We found that plastic deformation acts to keep the permeability nearly constant at the beginning of the unloading and elastic spring-back is responsible for the rapid increase at lower loads. This principle constitutes a basis for the strategy that was developed in order to predict the load at which the rapid increase of permeability starts.

  • 30.
    Schnabel, Stephan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Golling, Stefan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Marklund, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    The influence of contact time and event frequency on acoustic emission signals2017In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305XArticle in journal (Refereed)
    Abstract [en]

    Studies of acoustic emissions (AE) of rotating machine elements is often performed under a constant speed. There are few investigations on speed and contact time dependency of acoustic emission signals, even though some investigations have reported difficulties at elevated rotational speeds. Simplified experiments are, therefore, presented in this article to increase the understanding of the time dependency of acoustic emission signals. Hertzian impacts and tensile tests are used to study contact time, the time duration of an event and offset time, the time between events and accordingly the event frequency. The results of these model experiments indicate an indirect quadratic proportionality of acoustic emission amplitudes and contact time (umax∝1/(tc2)">u max ∝1/(t 2 c ) umax∝1/(tc2) ), as well as a proportional relationship between the root mean square and event frequency (RMS∝fevent∝1/toffset">RMS∝f event ∝1/t offset  RMS∝fevent∝1/toffset ). The relationship between contact time and the root mean square of acoustic emission signals is strongly dependent on the damping of the system

  • 31.
    Cervantes, Michel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Trivedi, Chirag
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Dahlhaug, Ole Gunnar
    Department of Energy and Process Engineering, Water Power Laboratory, Norwegian University of Science and Technology, Trondheim, Norwegian University of Science and Technology (NTNU), Trondheim.
    Nielsen, Torbjørn Kristian
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Francis-99 Workshop 2: transient operation of Francis turbines2017In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 782, 11001Article in journal (Other academic)
  • 32.
    Samuelsson, Björn
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Arbetsskador i byggverksamhet 2015: Privat och offentlig verksamhet : bygg- och anläggning, byggnadsplåtslageri, elinstallation, ventilation, VVS, måleri, Glasmästeri, maskinentreprenad2017Report (Other academic)
  • 33.
    Johansson, Charlotta
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Lindelöw, David
    Sweco.
    Rosander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Förstudie: Effekter av att satsa på transportslaget gång2017Report (Other academic)
  • 34.
    Kokkola, Lydia
    et al.
    Luleå University of Technology, Department of Arts, Communication and Education, Education, Language, and Teaching.
    Valovirta, Elina
    The University of Turku.
    The Disgust that Fascinates: Sibling Incest as a Bad Romance2017In: Sexuality & Culture, ISSN 1095-5143, E-ISSN 1936-4822, Vol. 21, no 1, 121-141 p.Article in journal (Refereed)
    Abstract [en]

    This article compares the discourse of sibling incest evident in a corpus offiction with the discourse found in clinical, sociological and criminal literature.Whereas the former prima rily regards the coupling as a bad romance, the latterpresents the idea that it is unequivocally harmful. This discrepancy between the twodiscourses surrounding sexual relationships between brothers and sisters speaks toliterary fiction’s need for thwarted romances for the purposes of the literary market.A more detailed look into three novels from the corpus, Tabitha Suzuma’s For-bidden (2010), Donna Tartt’s The Secret History (1992) and Pauline Melville’s TheVentriloquist’s Tale (1997) shows how this logic of sibling incest as a bad romanceworks in practice.

  • 35.
    Häggström, Jens
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Bridge over Åby River: Evaluation of full scale testing2017Report (Other academic)
  • 36.
    Näslund, Rebecka
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Al Said, Shariffa Khalid Qais
    Ministry of Education, Sultanate of Oman.
    Modes of ordering disability: students living with visual disabilities in the Sultanate of Oman2017In: Scandinavian Journal of Disability Research, ISSN 1501-7419, E-ISSN 1745-3011, Vol. 19, no 2, 79-90 p.Article in journal (Refereed)
    Abstract [en]

    This article examines how a group of students with visual disabilities speak about becoming disabled and living with disability in relation to: material entities, practices, and their own expectations regarding the future in the Sultanate of Oman. It draws upon individual interviews among six adults with visual disabilities. The article outlines, from a material semiotics approach, how various forms of modes of ordering enact disability. An interdisciplinary approach, informed by disability studies and science and technology studies, is implemented to interpret: How do students with visual disabilities express the relationships between material entities (such as bodies and technologies) and practices? In what ways are these relationships enacting different modes of ordering disability? What kind of modes of ordering disability are the participants experiencing in their lives? How have they responded to the modes of ordering that they have encountered?

  • 37.
    Byström, Alexandra
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Compartment Fire Temperature Calculations and Measurements2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is devoted to heat transfer and fire dynamics in enclosures. It consists of a main part which summarizes and discusses the theory of heat transfer, conservation of energy, fire dynamics and specific fire scenarios that have been studied. In the second part of this thesis, the reader will find an Appendix containing seven scientific publications in this field.

    In particular, one- and two-zone compartment fire models have been studied. A new way of calculating fire temperatures of pre- and post-flashover compartment fires is presented. Three levels of solution techniques are presented including closed form analytical expressions, spread-sheet calculations and solutions involving general finite element temperature calculations. Validations with experiments have shown good accuracy of the calculation models and that the thermal properties of the surrounding structures have a great impact on the fire temperature development. In addition, the importance of the choice of measurement techniques in fire engineering has been studied. Based on the conclusions from these studies, the best techniques have been used in further experimental studies of different fire scenarios.

  • 38.
    Bollen, Math
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Yang, Kai
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Interharmonic currents from a Type-IV wind energy conversion system2017In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 143, 357-364 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents, for the first time, the verification of the classic model for the origin of interharmonic emission from a frequency converter, for a Type-IV wind turbine by using long-term measurements. Interharmonic variations in magnitude and in frequency are due to the difference between the generator-side and grid-side frequency of the full-power converter. The model verification consists of three parts: correlation between frequencies; relation between magnitude of interharmonics and active-power production, and relation between magnitudes of different interharmonics. The measurements are in agreement with the model predictions. The paper also introduces a novel graphical correlation method to extract information on interharmonics from long-term measurement series.

  • 39.
    Hertting, Krister
    et al.
    Högskolan i Halmstad.
    Karlefors, Inger
    Luleå University of Technology, Department of Arts, Communication and Education, Education, Language, and Teaching.
    Nyanländas integration kan vitalisera föreningslivet2017Other (Other (popular science, discussion, etc.))
  • 40.
    Pesämaa, Ossi
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Personnel- and action control in gazelle companies in Sweden2017In: Journal of Management Control, ISSN 2191-4761, E-ISSN 2191-477X, Vol. 28, no 1, 107-132 p.Article in journal (Refereed)
    Abstract [en]

    Behavioral accounting theory questions the role of accounting and how accounting constructs can support other organizational activities. This paper examines whether personnel and action controls and the perception of current growth mediate meaningful support of innovative ideas (i.e., innovativeness) on future growth. While some literature has supported innovativeness as a spontaneous process, this paper examines whether innovative ideas are supported by formal behavioral controls on current and future growth. The paper further develops and finds support for the notion that future growth builds on the relative confidence of current growth. This paper uses exploratory factor analysis (EFA) for construct validation and further tests mediation using structural equation modeling and the bootstrapping technique of indirect effects. The model testing is based on a survey conducted in Sweden with key informants from high-growth (i.e., gazelle) companies. A total of 150 usable responses were returned.  The results may stimulate further research as they show that the predefined hypothesis has different direct and indirect roles in the building of future growth.

  • 41.
    Beka, Thomas I.
    et al.
    Faculty of Science and Technology, UiT-The Arctic University of Norway.
    Senger, Kim
    Department of Arctic Geology, The University Centre in Svalbard.
    Autio, Uula A
    Oulu Mining School, Geophysics, University of Oulu.
    Smirnov, Maxim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Birkelund, Yngve
    Faculty of Science and Technology, UiT-The Arctic University of Norway.
    Integrated electromagnetic data investigation of a Mesozoic CO2 storage target reservoir-cap-rock succession, Svalbard2017In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 136, 417-430 p.Article in journal (Refereed)
    Abstract [en]

    Recently acquired time-domain electromagnetic (TEM) and magnetotelluric (MT) data sets are utilized in the first electromagnetic (EM) characterization of a geological CO2 storage target site in Adventdalen, Arctic Norway. Combining the two EM data sets enabled to resolve the electrical resistivity structure of the target site better than either of the methods alone. 2D inverting the MT data in the audio period interval (0.003–1 s) with supporting input derived from the TEM data (0.01–10 ms) provided a geologically meaningful resistivity model that included information not previously evident from existing seismic and borehole data. The ca. 1.8 × 1 km 2D resistivity model displays a laterally constrained highly conductive anomaly (ca. 10 Ω m) at about 400–500 m depth, where reflectors of a parallel seismic section are concealed and core samples indicate a highly fractured décollement zone formed during Paleogene compression. The base of the permafrost is imaged at ca. 200 m depth. Synthetic inversion tests, however, suggest that this may be exaggerated by tens of meters, due to a thin conductive layer present approximately between 10 and 25 m depth. The resistivity model does not give indication for a fluid pathway we can connect to leakage, in line with water injection and leak-off tests in the reservoir and cap-rock, both of which indicate a sealing shale-dominated cap-rock separating an over-pressured compartment above the sealing shale from a severely under-pressured reservoir interval. The results we present indicate the advantage of integrating EM exploration techniques in a CO2 reservoir-cap-rock study to obtain a more complete picture.

  • 42.
    Andersson, Camilla
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Bezabih, Mintewab
    Environment and Climate Research center at the Ethiopian Development Research Institute, Addis Ababa.
    Mannberg, Andrea
    School of Business and Economics, UiT the Arctic University of Norway.
    The Ethiopian Commodity Exchange and spatial price dispersion2017In: Food Policy, ISSN 0306-9192, E-ISSN 1873-5657, Vol. 66, 1-11 p.Article in journal (Refereed)
    Abstract [en]

    In this article, we study the impact of an institutional intervention on market efficiency in Ethiopia. More specifically, we analyze to what extent the Ethiopian Commodity Exchange (ECX) in combination with regional warehouses have contributed to a reduction in price spreads between regional markets. Our hypothesis is that warehouses connected to the ECX reduce the dispersion between export prices and local retail prices in different coffee growing areas, as well as the dispersion between export prices and local retail prices in different coffee growing areas. By doing so, the ECX has the potential to improve the market efficiency. To identify the causal effect, we combine retail price data with information on the gradual rollout of warehouses connected to the ECX from 2007 to 2012. Our results suggest that, when two markets both have access to an operating warehouse, the average price spread is 0.86–1.78 ETB lower than it is for markets where at least one part lacks warehouse access. This is a substantial reduction considering that the average price spread over the full period is 3.33 ETB. The main results are robust to various econometric specifications, and our analysis thus suggests that local warehouses connected to the ECX have indeed improved market efficiency

  • 43.
    Yu, Liang
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ye, Pengcheng
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ultra-thin MFI membranes for olefin/nitrogen separation2017In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 524, 428-435 p.Article in journal (Refereed)
    Abstract [en]

    The recovery of light hydrocarbons such as propylene and ethylene from vent streams in polymer plants is desirable since it opens up for more efficient conversion of the monomers with high economic value. Consequently, polymer membrane vapour-gas separation systems have been used for this purpose for decades [1,2]. However, an alternative is zeolite membranes. In this work, ultra-thin MFI zeolite membranes (0.5 µm) were used to separate propylene or ethylene from binary 20/80 olefin/nitrogen mixtures at different temperatures. The membranes were olefin selective with high permeance at all investigated temperatures. At room temperature, the permeance of propylene was 22×10-7 mol m-2 s-1 Pa-1 and the separation factor was 43, which corresponds to a separation selectivity of around 80. For a mixture of 20 mol.% ethylene in nitrogen, the maximum separation factor was 6 (corresponds to a separation selectivity of 8.4) at 277 K with an ethylene permeance of 57×10-7 mol m-2 s-1 Pa-1. The membrane selectivity was governed by more extensive adsorption of olefin, especially propylene, as compared to nitrogen. Comparing with ethylene, propylene has higher heat of adsorption, which probably caused the higher propylene/nitrogen selectivity compared to ethylene/nitrogen selectivity. The permeance and the selectivity for propylene were much higher than for commercial polymeric membranes. For ethylene, the permeance was much higher, and the selectivity was comparable to commercial polymeric membranes. Modelling showed that the pressure drop over the support limited the flux through the membranes especially at higher temperatures and in particular for the ethylene/nitrogen system with high flux. Further, modelling indicated that the result obtained at high temperatures, where the flux was high, was also affected by concentration polarization. However, for the propylene/nitrogen system at the optimum separation temperature, the pressure drop over the support and the concentration polarisation were small. The results show that ultra-thin MFI zeolite membranes are promising candidates for light olefins/nitrogen separation in polymer plants.

  • 44.
    Søberg, Laila
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Do salt and low temperature impair metal treatment in stormwater bioretention cells with or without a submerged zone?2017In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 579, 1588-1599 p.Article in journal (Refereed)
    Abstract [en]

    Although seasonal temperature changes and (road) salt in winter and/or coastal stormwater runoff might interfere with the metal treatment performance of stormwater bioretention cells, no previous study has evaluated the effect of these factors and their interactions under controlled conditions. In this 18 week long study 24 well established pilot-scale bioretention columns were employed to evaluate the individual and combined effect(s) of low/high temperature, salt and presence of a submerged zone with an embedded carbon source on metal removal using a three factor, two-level full factorial experimental design. In most instances, the three factors significantly influenced the metal outflow concentrations and thus the treatment performance; the effect of temperature depended on the metal in question, salt had an overall negative effect and the submerged zone with carbon source had an overall positive effect. Despite these statistically significant effects, the discharge water quality was generally markedly improved. However, leaching of dissolved Cu and Pb did occur, mainly from bioretention cells dosed with salt-containing stormwater. The highest concentrations of metals were captured in the top layer of the filter material and were not significantly affected by the three factors studied. Overall, the results confirmed that bioretention provides a functioning stormwater treatment option in areas experiencing winter conditions (road salt, low temperatures) or coastal regions (salt-laden stormwater). However, validation of these results in the field is recommended, especially focusing on dissolved metal removal, which may be critically affected under certain conditions.

  • 45.
    Magnusson, Simon
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Bedömning av omgivningspåverkan från olika fyllmaterial i konstgräsplaner: Fallstudie av dräneringsvatten2017Report (Other academic)
    Abstract [sv]

    För studier av miljöprestanda för konstgräsplaner har fokus främst legat på miljöaspekter kring innehåll av ämnen i konstgräsmaterial. Det är främst miljöaspekter kring fyllmaterialens kemiska innehåll och potentiell utlakning till vatten som har studerats. Denna studie syftade till att analysera kvalitén på vatten som rinner från konstgräsplaner med olika fyllmaterial (granulat). Målet var att jämföra och bedöma omgivningspåverkan från konstgräsplanens fyllmaterial utifrån utlakade ämnen till dräneringsvatten. Metoden bestod av kemisk analys av dräneringsvatten som uppsamlats med lysimetrar,  med avseende på primärt metaller och organiska ämnen samt kvantifiering av vattenflöden och den potentiella mängden partiklar från fyllmaterial som transporteras genom konstgräsplanen och överbyggnaden till dräneringen. Efter ett års provtagning och analys av vatten från konstgräsplaner med SBR  respektive EPDM fyllmaterial var slutsatserna bl.a. följande:

    • Utlakade ämnen från fyllmaterialen som dränerat genom överbyggnaden och som kan transporteras vidare till grundvatten eller till dagvatten bedöms ha liten omgivningspåverkan.

    • Halter av metaller i dräneringsvattnet från konstgräsplanerna var i jämförelse lägre än vad som förväntas påträffas i dagvatten från parkmiljöer med gångvägar och lågt trafikerade vägar.

    • Massflödet av mikropartiklar från fyllmaterial vertikalt till dräneringen bedöms vara litet. Det faktiska antalet partiklar och andra spridningsvägar har inte undersökts.

    • Analyser av vatten från stickprov direkt från dräneringsbrunn måste tolkas med försiktighet då det inte behöver representera halter för det totala vattenflödet över konstgräsplanen.

     

    Provtagning med analyser kommer fortsätta under 2017.

  • 46.
    Karim, Zoheb
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Afrin, Sadaf
    Department of Chemistry, Faculty of Sciences , Aligarh Muslim University .
    Hussain, Qayyum
    Department of Biochemistry, Faculty of Life Sciences , Aligarh Muslim University .
    Danish, Rehan
    Infinity Vacuum Technology , Geomdan Techpart Geomdangondan-Ro 26, Buk-Gu , Daegu .
    Necessity of enzymatic hydrolysis for production and functionalization of nanocelluloses2017In: Critical reviews in biotechnology, ISSN 0738-8551, E-ISSN 1549-7801, Vol. 37, no 3, 355-370 p.Article in journal (Refereed)
    Abstract [en]

    Nanocellulose (NC) from cellulosic biomass has recently gained attention owing to their biodegradable nature, low density, high mechanical properties, economic value and renewability. They still suffer, however, some drawbacks. The challenges are the exploration of raw materials, scaling, recovery of chemicals utilized for the production or functionalization and most important is toxic behavior that hinders them from implementing in medical/pharmaceutical field. This review emphasizes the structural behavior of cellulosic biomass and biological barriers for enzyme interactions, which are pertinent to understand the enzymatic hydrolysis of cellulose for the production of NCs. Additionally, the enzymatic catalysis for the modification of solid and NC is discussed. The utility of various classes of enzymes for introducing desired functional groups on the surface of NC has been further examined. Thereafter, a green mechanistic approach is applied for understanding at molecular level

  • 47.
    Martí Bigorra, Anna
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Customer Data in the Design Process with Focus on Customer Neds and Way of using the Product2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Owing to continuous advances in information technology, access to information via the Internet and the steady decline of cost related to data creation, big amounts of customer data now reside in many companies. This data is said to hold a large amount of valuable knowledge that could be used to design customer-focused products, a key factor for maintaining market-share. Information overload hinders the search for knowledge and, therefore, it is a challenge for companies to identify what is relevant to analyse. Different approaches based on data mining tools of web-based customer data have been shown to be useful for gaining customer insight. However, this information is not properly factored into the target setting process. Many improvements in modelling the relation between product performance and customer satisfaction during the target setting have been presented. However, these still rely on customer information obtained from traditional gathering techniques such as questionnaires, which do not provide enough valuable and deep customer information; therefore, designers are forced to make assumptions. While some studies highlight the potential of customer data as an aid to designing future product generations, they do not provide enough details on how such information should be processed to generate valuable information for the designers. 

    By taking advantage of the generated customer data, this work aims to increase the reliability of the design decisions on product specifications by reducing the existing gap between the customer and the designer world. To do so, customer information from different sources such as surveys and usage data have been combined to model customer satisfaction as a function of design requirements. In this process, customer needs are defined at a detailed level to be able to link customer satisfaction with a clear interface to the design requirements. By means of usage data, customer-product interaction in the customer environment is investigated, and differences between designer assumptions and customer picture are calculated towards the target fulfilment indicator. Results show that the work presented helps designers to set targets towards a higher customer focus, since customer needs and way of using the product become visible in the process. This allows the design team not only to identify differences among customers but also the possibility to detect changes in customer needs. The target fulfilment indicator acts as a feedback channel for continuous product improvement, allowing designers to validate their decisions. Since the voice of the customer drives the process, the presented approaches guide the design team towards the most relevant customer data, thus streamlining the design process in a situation where the amount of information rapidly increases. 

  • 48.
    Wahlberg, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Case study on electrical conductivity in wood poles2017Report (Other academic)
  • 49.
    Santelices, Gabriel
    et al.
    Department of Mining Engineering, Pontificia Universidad Católica de Chile, Santiago.
    Pascual, Rodrigo
    Pontificia Universidad Católica de Chile, Department of Mining Engineering, Pontificia Universidad Católica de Chile, Santiago.
    Lüer-Villagra, Armin
    Department of Engineering Sciences, Universidad Andres Bello, Santiago.
    Cawley, Alejandro Mac
    Department of Industrial Engineering, Pontificia Universidad Católica de Chile, Santiago.
    Galar, Diego
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Integrating mining loading and hauling equipment selection and replacement decisions using stochastic linear programming2017In: International Journal of Mining, Reclamation and Environment, ISSN 1748-0930, E-ISSN 1748-0949, Vol. 31, no 1, 52-65 p.Article in journal (Refereed)
    Abstract [en]

    Equipment selection is a key strategic decision in the design of a material handling system, because an improper one will lead to operational problems and unnecessary investment costs. It involves determining the number and combination of loaders and trucks which will move the material, fulfilling a specified production schedule. Previous works have addressed this problem with deterministic approaches, without considering the inter-dependent availability of trucks and loaders. In order to fill this gap, we developed a stochastic model that combines the selection and equipment replacement problems, subject to a stochastic production rate constraint. This is a new idea that will help decision-makers to decide faster and more reliable. The proposed model optimises the fleet by minimising the total life cycle costs. To solve it, we used a linearisation approach that reduces the computational effort. We tested our approach with a benchmark model, using a mining case study. Results indicate that the solutions ensure with a high probability a determined production target, producing good robust solutions compared to the deterministic counterpart.

  • 50.
    Du, Wei
    et al.
    Key Laboratory of Advanced Control and Optimization for Chemical Processes, Ministry of Education, East China University of Science and Technology, Shanghai.
    Leung, Sunney Yung Sun
    Institute of Textile and Clothing, The Hong Kong Polytechnic University, Hong Kong.
    Tang, Yang
    Key Laboratory of Advanced Control and Optimization for Chemical Processes, Ministry of Education, East China University of Science and Technology, Shanghai.
    Vasilakos, Athanasios
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Differential Evolution With Event-Triggered Impulsive Control2017In: IEEE Transactions on Cybernetics, ISSN 2168-2267, E-ISSN 2168-2275, Vol. 7, no 1, 244-257 p.Article in journal (Refereed)
    Abstract [en]

    Differential evolution (DE) is a simple but powerful evolutionary algorithm, which has been widely and successfully used in various areas. In this paper, an event-triggered impulsive (ETI) control scheme is introduced to improve the performance of DE. Impulsive control (IPC), the concept of which derives from control theory, aims at regulating the states of a network by instantly adjusting the states of a fraction of nodes at certain instants, and these instants are determined by event-triggered mechanism (ETM). By introducing IPC and ETM into DE, we hope to change the search performance of the population in a positive way after revising the positions of some individuals at certain moments. At the end of each generation, the IPC operation is triggered when the update rate of the population declines or equals to zero. In detail, inspired by the concepts of IPC, two types of impulses are presented within the framework of DE in this paper: 1) stabilizing impulses and 2) destabilizing impulses. Stabilizing impulses help the individuals with lower rankings instantly move to a desired state determined by the individuals with better fitness values. Destabilizing impulses randomly alter the positions of inferior individuals within the range of the current population. By means of intelligently modifying the positions of a part of individuals with these two kinds of impulses, both exploitation and exploration abilities of the whole population can be meliorated. In addition, the proposed ETI is flexible to be incorporated into several state-of-the-art DE variants. Experimental results over the IEEE Congress on Evolutionary Computation (CEC) 2014 benchmark functions exhibit that the developed scheme is simple yet effective, which significantly improves the performance of the considered DE algorithms. 

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