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  • 1.
    Wimo, Anders
    et al.
    Aging Research Centre, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet .
    Jönsson, Linus
    Aging Research Centre, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet.
    Fratiglioni, Laura
    Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet, Huddinge .
    Sandman, Per-Olof
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    Gustavsson, Anders
    Aging Research Centre, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet.
    Sköldunger, Anders
    Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet, Huddinge.
    Johansson, Lennarth
    Stockholm Gerontology Research Centre.
    Erratum to: The societal costs of dementia in Sweden 2012: relevance and methodological challenges in valuing informal care2019In: Alzheimer's Research & Therapy, ISSN 0065-6755, E-ISSN 1758-9193, Vol. 9, no 1, 12Article in journal (Refereed)
    Abstract [en]

    During production of the original article [1], the line referring to “Informal Care” was omitted from Table 3. It should have been mentioned between “Total social care sector” and “Indirect costs”.

  • 2.
    Cool, Julie
    et al.
    University of British Columbia.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Stephen, James D
    Queen’s University.
    Mabee, Warren E
    Queen’s University.
    Avramidis, Stavros
    University of British Columbia.
    Bull, Gary Q
    University of British Columbia.
    An Integrated Forest Products Cluster for Off-Grid Lumber Production Using Biomass CHP in Remote Indigenous Communities2017Conference paper (Refereed)
  • 3.
    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.

  • 4.
    Yolal, Medet
    et al.
    Anadolu Üniversitesi.
    Chi, Christina Geng-Qing
    Washinton State University.
    Pesämaa, Ossi
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Innovation and Design.
    Examine destination loyalty of first-time and repeat visitors at all-inclusive resorts2017In: International Journal of Contemporary Hospitality Management, ISSN 0959-6119, E-ISSN 1757-1049, ISSN 0959-6119, Vol. 29, no 7Article in journal (Refereed)
  • 5.
    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.

  • 6.
    Grzenda, Maciej (Editor)
    Faculty of Mathematics and Information Science, Warsaw University of Technology,, Research and Development Center.
    Awad, Ali Ismail (Editor)
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Furtak, Janusz (Editor)
    Military University of Technology, Warszawa.
    Legierski, Jarosław (Editor)
    Faculty of Mathematics and Information Science, Warsaw University of Technology, Warszawa.
    Advances in Network Systems: Architectures, Security, and Applications2017Book (Refereed)
  • 7.
    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.

  • 8.
    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.
    Deichsel, Eckard
    Bystronic Laser AG, Industriestrasse 21, CH-3362 Niederönz.
    Frostevarg, Jan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Fibre laser cutting stainless steel: Fluid dynamics and cut front morphology2017In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 87, 87-93 p.Article in journal (Refereed)
    Abstract [en]

    In this paper the morphology of the laser cut front generated by fibre lasers was investigated by observation of the ‘frozen’ cut front, additionally high speed imaging (HSI) was employed to study the fluid dynamics on the cut front while cutting. During laser cutting the morphology and flow properties of the melt film on the cut front affect cut quality parameters such as cut edge roughness and dross (residual melt attached to the bottom of the cut edge). HSI observation of melt flow down a laser cutting front using standard cutting parameters is experimentally problematic because the cut front is narrow and surrounded by the kerf walls. To compensate for this, artificial parameters are usually chosen to obtain wide cut fronts which are unrepresentative of the actual industrial process. This paper presents a new experimental cutting geometry which permits HSI of the laser cut front using standard, commercial parameters. These results suggest that the cut front produced when cutting medium section (10 mm thick) stainless steel with a fibre laser and a nitrogen assist gas is covered in humps which themselves are covered by a thin layer of liquid. HSI observation and theoretical analysis reveal that under these conditions the humps move down the cut front at an average speed of approximately 0.4 m/s while the covering liquid flows at an average speed of approximately 1.1 m/s, with an average melt depth at the bottom of the cut zone of approximately 0.17 mm.

  • 9.
    Samarjy, R.S.M.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. University of Mosul, College of Engineering, Department of Mechanical Engineering.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Transient interaction of a boiling melt with a pulsed Nd:YAG-laser2017In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 88, 28-36 p.Article in journal (Refereed)
    Abstract [en]

    The boiling front induced by a pulsed Nd:YAG-laser at very slow translation speed was studied. The purpose is to understand fundamental melt movement mechanisms. The melt was observed by high speed imaging, with and without illumination. When switching on the laser beam a hole is drilled through a bulk of melt. The hole expands and the boiling pressure gradually opens the melt bridge, instead developing an interaction front similar to cutting. These conditions remain in quasi-steady state during the pulse. The ablation pressure from boiling shears waves down the front and keeps the melt downwards in a stable position. When switching off, the waves smoothen and in absence of boiling the surface tension drags the melt back upwards, to semi-torus-like Catenoid shape. Evidence on the large melt pool and its shape was achieved by three-dimensional reconstruction from cross section macrographs. The basic findings how melt can move with and without ablation pressure can enable controlled melt dynamics for various laser processing techniques, like remote cutting, ablation, keyhole welding or drilling.

  • 10.
    Jafri, Yawer
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kirtania, Kawnish
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gebart, Rikard
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Granberg, Fredrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    A study of black liquor and pyrolysis oil co-gasification in pilot scale2017In: Biomass Conversion and Biorefinery, ISSN 2190-6815Article in journal (Refereed)
    Abstract [en]

    The effect of the blend ratio and reactor temperature on the gasification characteristics of pyrolysis oil (PO) and black liquor (BL) blends with up to 20 wt% PO was studied in a pilot-scale entrained-flow gasifier. In addition to unblended BL, three blends with PO/BL ratios of 10/90, 15/85, and 20/80 wt% were gasified at a constant load of 2.75 MWth. The 15/85 PO/BL blend was used to investigate the effect of temperature in the range 1000–1100 °C. The decrease in fuel inorganic content with increasing PO fraction resulted in more dilute green liquor (GL), and a greater portion of the feedstock carbon ended up in syngas as CO. As a consequence, the cold gas efficiency increased by about 5%-units. Carbon conversion was in the range 98.8–99.5% and did not vary systematically with either fuel composition or temperature. Although the measured reactor temperatures increased slightly with increasing PO fraction, both unblended BL and the 15% PO blend exhibited largely similar behavior in response to temperature variations. The results from this study show that blending BL with the more energy-rich PO can increase the cold gas efficiency and improve the process carbon distribution without adversely affecting either carbon conversion or the general process performance.

  • 11.
    Strandkvist, Ida
    et al.
    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.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Effect of FeO/MgO Ratio on Dissolution and Leaching of Magnesiowüstite2017In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Refereed)
    Abstract [en]

    If slag is to be used as construction material, the leaching of some elements, such as chromium must be limited. The leaching of slag depends on the leaching properties of the minerals in the slag. However, the leaching/dissolution properties of individual slag minerals are usually not studied. One common slag mineral that can contribute to the leaching of chromium is magnesiowüstite. The object of this study is to determine whether magnesiowüstite can be modified to avoid chromium leaching. Magnesiowüstite samples with different FeO/MgO ratios with and without chromium content are manufactured. The dissolution is evaluated at pH 7 and 10 using the magnesiowüstite samples without chromium, at size fraction 20–38 μm, by measuring the acid consumption required to maintain constant pH level. The magnesiowüstite samples with chromium content are leached at pH 10; the leachate is analyzed for chromium. The results are unanimous, with increasing FeO content the dissolution of magnesiowüstite and leaching of chromium decrease. At pH 10 the magnesiowüstite, with ≥60 wt% FeO show no sign of dissolution and no chromium leaching could be detected with ≥70 wt% FeO. The results prove that the FeO content can stabilize magnesiowüstite and, thereby, prevent chromium leaching

  • 12.
    Saintilan, Nicholas J.
    et al.
    Section of Earth and Environmental Sciences, University of Geneva.
    Stephens, Michael
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Spikings, Richard A.
    Section of Earth and Environmental Sciences, University of Geneva.
    Schneider, Jens C.
    Department of Mineralogy, Technische Universität Bergakademie Freiberg.
    Chiaradia, Massimo
    Section of Earth and Environmental Sciences, University of Geneva.
    Spangenberg, Jorge E.
    Institute of Earth Surface Dynamics, University of Lausanne.
    Ulianov, Alexey
    Institute of Earth Sciences, University of Lausanne.
    Fontboté, Lluis
    Section of Earth and Environmental Sciences, University of Geneva.
    Polyphase vein mineralization in the Fennoscandian Shield at Åkerlandet, Järvsand, and Laisvall along the erosional front of the Caledonian orogen, Sweden2017In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866Article in journal (Refereed)
    Abstract [en]

    The Åkerlandet, Järvsand, and Laisvall deposits in Sweden are calcite-fluorite-sulfide vein deposits and occurrences located close to the current erosional front of the Caledonian orogen and hosted by crystalline basement rocks in the Fennoscandian Shield. At Laisvall, basement-hosted veinlets occur beneath Ediacaran to Cambrian sandstones that host a strata-bound Pb-Zn deposit. The mineralized fractures at Åkerlandet and Järvsand occur along fault systems oriented N–S to NNW–SSE. Veins or veinlets strike NNW–SSE and NW–SE at Åkerlandet, NNE–SSW at Järvsand, and NNW–SSE and NNE–SSW to NE–SW at Laisvall. At Åkerlandet and Järvsand, fractures acted as conduits for hydrothermal fluids of variable composition and formed during separate tectonic events. At Åkerlandet, the fault zone with NNW–SSE strike shows kinematic indicators consistent with ~NE–SW bulk horizontal extension. At Järvsand, the calcite-fluorite-galena veins formed along R-Riedel shears related to the host N–S to NNW–SSE fault system. The kinematic indicators are consistent with ~NW–SE bulk horizontal extension, similar to the extensional deformation during the later part of the Caledonian orogeny (Silurian to Devonian). At Åkerlandet, adularia-quartz deposition was followed by sphalerite ± galena and finally by precipitation of fluorite and calcite. 40Ar-39Ar thermochronology of a single adularia sample did not yield a well-defined plateau age but the gas released at higher temperatures suggests an early Tonian (980 to 950 Ma) crystallization age, i.e., during the later part of the Sveconorwegian orogeny, although the data do not exclude other less likely interpretations. Previous fluid inclusion microthermometry and geochronological studies and new petrographic and geochemical results suggest that sphalerite ± galena mineralization formed from saline, relatively oxidizing, moderate-temperature, and slightly acidic hydrothermal fluids, either during the Ediacaran or the Middle Ordovician. Metals and H2S were derived from local basement rocks. Based on petrographic evidence, rare earth element composition, and S, C, and O isotope data, fluorite and calcite precipitated under near neutral and relatively reducing conditions. Occurrence of solid bitumen in veins at Åkerlandet and C and O isotope data of calcite at Åkerlandet and in the Laisvall basement veinlets suggest that the precipitation of calcite and fluorite was triggered by interaction of hot and evolved hydrothermal fluids (87Sr/86Sr = 0.718–0.732) with organic matter. Structural, petrographic, and geochemical data at Laisvall suggest that the basement structures hosting calcite-fluorite ± pyrite veinlets were utilized in the Middle Ordovician as the plumbing system for the oxidizing, slightly acidic, metal-bearing brines that caused the economic Pb-Zn mineralization in the overlying sandstones

  • 13.
    Bergmark, Ulrika
    et al.
    Luleå University of Technology, Department of Arts, Communication and Education, Education, Language, and Teaching.
    Kostenius, Catrine
    Luleå University of Technology, Department of Health Sciences, Health and Rehab.
    Students’ Experiences of Meaningful Situations in School2017In: Scandinavian Journal of Educational Research, ISSN 0031-3831, E-ISSN 1470-1170Article in journal (Refereed)
    Abstract [en]

    This paper focuses on school situations students experienced as meaningful and how these experiences can guide educational improvement. Participants included 15 students in grade 3 from a Swedish school. In this qualitative study, the data consisted of drawings, multimodal productions, interviews, and field notes. The analysis resulted in four themes: Having the opportunity to learn in different spaces; Being free and able to participate; Experiencing caring and sharing, and Recognizing one’s own growth and achievement. The findings suggest that situations students find meaningful involve aspects of both learning and wellbeing. The practical implication for these results is that student-generated qualitative data can help indicate needs for educational improvement.

  • 14.
    Pelcastre, Leonardo
    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.
    Prakash, Braham
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological behaviour of Zn coated UHSS sliding against hot-work tool steel at high temperatures2017In: Wear, ISSN 0043-1648, E-ISSN 1873-2577Article in journal (Refereed)
    Abstract [en]

    The increasing demands for light-weight components in vehicles contribute to the global expansion of hot sheet metal forming technologies. Structural components are typically produced using hot stamping of ultra-high strength steel (UHSS). This process allows forming of complex shapes whilst enabling control of the mechanical properties of the end product. Interest in zinc coated UHSS has increased in recent years in view of the corrosion protection it provides to the final components. There is a need for increased understanding of its tribological behaviour during the interaction with tool steel at elevated temperatures. In this work, tribological studies have been carried out in a novel hot strip tribometer. The aim was to study the effect of different operating conditions on the tribological behaviour of zinc coated UHSS sliding against a hot-work tool steel under un-lubricated conditions. The parameters studied in this work were; temperature, ranging from 400˚C to 700˚C; and contact pressure, from 5 to 30 MPa. The UHSS was initially heated up to austenitising temperature (840˚C) and then cooled down to the testing temperature. Upon stabilisation of temperature, the load was applied and sliding was carried out for a total of 1500 mm at 100 mm/s. The results showed a trend towards decreasing average coefficient of friction as temperature and contact pressure increased. Unstable friction behaviour was observed at low temperature (400˚C) and high contact pressure (30 MPa) whilst higher temperatures (600˚C) facilitated the development of a low and stable friction behaviour. It is proposed that the friction behaviour is controlled by the properties of the zinc phases in the coating developed during heating of the UHSS. The combination of high temperature and sliding conditions result in the removal of the uppermost oxide layer and the phases beneath control the friction behaviour.

  • 15.
    Källström, Elisabeth
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Volvo Construction Equipment, Eskilstuna, Sweden.
    Olsson, Tomas
    SICS Swedish ICT, Kista, Sweden.
    Lindström, John
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Håkansson, Lars
    Linnaeus University, Växjö, Sweden.
    Larsson, Jonas
    Volvo Construction Equipment, Eskilstuna, Sweden.
    On-board Clutch Slippage Detection and Diagnosis in Heavy Duty Machine2017In: International Journal of Prognostics and Health Management, ISSN ISSN2153-2648Article in journal (Refereed)
    Abstract [en]

    In order to reduce unnecessary stops and expensive downtime originating from clutch failure of construction equipment machines; adequate real time sensor data measured on the machinein combination with feature extraction and classification methods may be utilized.This paper, based on a study at Volvo Construction Equipment,presents a framework with feature extraction methods and an anomaly detection module combined with Case-Based Reasoning (CBR) for on-board clutch slippage detection and diagnosis in a heavy duty equipment. The feature extraction methods used are Moving Average Square Value Filtering (MASVF) and a measure of the fourth order statistical properties of the signals implemented as continuous queries over data streams. The anomaly detection module has two components,the Gaussian Mixture Model (GMM) and the Logistics Regression classifier. CBR is a learning approach that classifies faults by creating a new solution for a new fault case from the solution of the previous fault cases. Through use of a data stream management system and continuous queries (CQs), the anomaly detection module continuously waits for a clutch slippage event detected by the feature extraction methods, the query returns a set of features which activates the anomaly detection module. The first component of the anomaly detection module trains a GMM to extracted features while the second component uses a Logistic Regression classifier for classifying normal and anomalous data. When an anomalyis detected, the Case-Based diagnosis module is activated for fault severity estimation.

  • 16.
    Sandström, Linda
    et al.
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    Nilsson, Carina
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    Juuso, Päivi
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    Engström, Åsa
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    CCNs experiences of nursing trauma patients2017Conference paper (Refereed)
  • 17.
    Sandström, Linda
    et al.
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    Juuso, Päivi
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    Engström, Åsa
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    The helicopter as a caring context: trauma patients’ experiences2017Conference paper (Refereed)
  • 18.
    Strömbäck, Ulrica
    et al.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Vikman, Irene
    Luleå University of Technology, Department of Health Sciences, Health and Rehab.
    Lundblad, Dan
    Sunderby Research Unit, Department of Public Health and Clinical Medicine, Umeå University.
    Lundqvist, Robert
    Department of Research, Norrbotten County Council, Luleå.
    Engström, Åsa
    Luleå University of Technology, Department of Health Sciences, Nursing Care.
    The second myocardial infarction: Higher risk factor burden and earlier second myocardial infarction in women compared to men : The Northern Sweden MONICA study2017In: European Journal of Cardiovascular Nursing, ISSN 1474-5151, E-ISSN 1873-1953Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    Several studies have examined various parameters and experiences when patients suffer their first myocardial infarction (MI), but knowledge about when they suffer their second MI is limited.

    AIM:

    To compare risk factors for MI, that is, diabetes, hypertension and smoking, for the first and second MI events in men and women affected by two MIs and to analyse the time intervals between the first and second MIs.

    METHODS:

    A retrospective cohort study of 1017 patients aged 25-74 years with first and second MIs from 1990 through 2009 registered in the Northern Sweden MONICA registry.

    RESULTS:

    More women than men have diabetes and hypertension and are smokers at the first MI. Similar differences between the genders remain at the time of the second MI for diabetes and hypertension, although both risk factors have increased. Smoking decreased at the second MI without any remaining difference between genders. Women suffer their second MI within a shorter time interval than men do. Within 16 months of their first MI, 50% of women had a second MI. The corresponding time interval for men was 33 months.

    CONCLUSION:

    Patients affected by an MI should be made aware of their risk of recurrent MI and that the risk of recurrence is highest during the first few years after an MI. In patients affected by two MIs, women have a higher risk factor burden and suffer their second MI earlier than men do and thus may need more aggressive and more prompt secondary prevention.

  • 19.
    Nygren Zotterman, Anna
    Luleå University of Technology, Department of Health Sciences.
    Encounters in primary healthcare from the perspectives of people with long-term illness, their close relatives and district nurses2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    People with a long-term illness and their close relatives regard encounters as the foundation of their relationshipwith the district nurses within the primary healthcare setting. The overall aim of this doctoral thesis was todescribe and elucidate the experiences of encounters for people with long-term illness, their close relatives anddistrict nurses within a primary healthcare setting. From the overall aim, specific aims were formulated asfollows: to describe district nurses’ views on quality of healthcare encounters in primary healthcare (I), toelucidate meanings of encounters for patients with long-term illness within the primary healthcare setting (II), toelucidate meanings of encounters for close relatives of people with a long-term illness within a primaryhealthcare setting (III) and to describe the experiences of dignity encounters from the perspective of people withlong-term illness and their close relatives within a primary healthcare setting (IV). Data were collected fromfocus group interviews (I), narrative interviews (II, III), and semi-structured interviews (IV). The interviewswere analysed using thematic content analysis (I, IV) and phenomenological hermeneutics (II, III). The findingsshow that encounters are given great importance among people who have a long-term illness, their closerelatives, and district nurses in the setting of primary healthcare. The manner in which the encounter wasexperienced in the relationship with healthcare personnel was, at many times, crucial for the whole careexperience to be viewed as beneficial or not. The findings show that district nurses described that the encountersformed the basis of their work as an important aspect and that many times they were difficult because of stressand lack of time. The first meeting with the patient was important since it was unique and unrepeatable. Districtnurses considered themselves as being the patients ‘advocate’ who helped them and protected their interests.They indicated the importance of confirming the patient as a person deserving of respect, and if a meeting turnedout poorly, it was their duty to give the patient an apology (I). The findings also show that patients with a longtermillness experienced that good encounters had health-promoting effects on their health and recovery. Patientsfelt well when they were welcomed as a person with respect, interest, and attention by the healthcare personnel.They wanted to participate in their own care by receiving regular information and follow-up dialogues abouttheir status with the healthcare personnel. Continuity with the healthcare personnel laid the foundation for apersonal and a trustful relationship (II). Close relatives of people with a long-term illness wanted to beencountered as part of the ill person’s family as they accompanied him or her to the healthcare centre. To beconfirmed as a family was important, as it gave meaning to their lives and strengthened their well-being. A goodencounter was characterised by aspects of being involved in the care of the ill person and being respected as avaluable person (III). The findings show that people with a long-term illness and their close relatives experienceddignity in the encounter when they had access to care. They experienced that it was important to be encounteredwith dignity, as it meant receiving help with their needs from the healthcare personnel. To be confirmed by beingseen and listened to was important. When the couples experienced dignity in the encounter, they felt satisfiedwith the care they received. To be encountered with dignity made they feel valuable; this facilitated their healthand well-being, and it contributed to a good impression of the healthcare personnel within primary healthcare(IV). In conclusion, the findings of this thesis show that healthcare encounters are more than just meetings; theyalso mean being confirmed as a human being by being treated with respect, engagement and dignity. Healthcarepersonnel should promote encounters for people with long-term illness and their close relatives in order tosupport their feelings of being regarded as persons and to feel that they are welcomed to primary healthcare withtheir needs, which can empower their health and well-being.

  • 20.
    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.

  • 21.
    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.

  • 22.
    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. 

  • 23.
    Bhardwaj, Anshuman
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Singh, Shaktiman
    Institut für Kartographie, Technische Universität Dresden.
    Sam, Lydia
    Institut für Kartographie, Technische Universität Dresden.
    Bhardwaj, Akanksha
    Banaras Hindu University, Varanasi.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Singh, Atar
    Department of Environmental Science, Sharda University.
    Kumar, Rajesh
    Department of Environmental Science, Sharda University.
    MODIS-based estimates of strong snow surface temperature anomaly related to high altitude earthquakes of 20152017In: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 188, 1-8 p.Article in journal (Refereed)
    Abstract [en]

    The high levels of uncertainty associated with earthquake prediction render earthquakes some of the worst natural calamities. Here, we present our observations of MODerate resolution Imaging Spectroradiometer (MODIS)-derived Land Surface Temperature (LST) anomaly for earthquakes in the largest tectonically active Himalayan and Andean mountain belts. We report the appearance of fairly detectable pre-earthquake Snow Surface Temperature (SST) anomalies. We use 16 years (2000–2015) of MODIS LST time-series data to robustly conclude our findings for three of the most destructive earthquakes that occurred in 2015 in the high mountains of Nepal, Chile, and Afghanistan. We propose the physical basis behind higher sensitivity of snow towards geothermal emissions. Although the preliminary appearance of SST anomalies and their amplitudes vary, we propose employing a global-scale monitoring system for detecting and studying such spatio-temporal geophysical signals. With the advent of improved remote sensors, we anticipate that such efforts can be another step towards improved earthquake predictions.

  • 24.
    Pusch, Roland
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kasbohm, Jörn
    GeoENconLtd, Institute of Geography and Geology, Univ. of Greifswald, Germany.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Yang, Ting
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Two genuinely geological alternatives for disposal of highly radioactive waste (HLW)2017In: Communicacaoes Geologicas, ISSN 0873-948X; e-ISSN: 1647-581XArticle in journal (Refereed)
    Abstract [en]

    Disposal of highly radioactive waste (HLW) can be environmentally acceptable if radionuclides are kept isolated from the groundwater, which has inspired planners of repositories to work out multibarrier concepts that postulate defined functions of the host rock and engineered waste confinements. Assessment of the role of the host rock involves groundwater flow modelling and rock mechanical analysis, which are both highly speculative and ignore future changes in rock structure, stress conditions, and groundwater flow. Widening the perspective by considering the integrated physical performance of contacting geological strata respecting groundwater flow conditions can provide excellent isolation of HLW with a minimum of engineered barriers as illustrated by the principle of very deep boreholes (VDH) for which the very high salt content of deep water is the primary barrier by maintaining possibly contaminated groundwater at depth. Such isolation of groundwater regimes can also be obtained by constructing relatively shallow repositories in crystalline rock covered by clay-containing sedimentary rock in regions with no or very low hydraulic gradients. The paper describes a possible case of this type, showing that effective isolation of HLW in repositories of commonly discussed types, KBS-3H and VDH, can be achieved under present climatic conditions.

    The paper compares the short- and long-term functions of repositories located at the southern end of the Swedish island Gotland, being an example of desired geological conditions that are found also in other parts of Sweden and in Lithuania, Germany, Holland and the UK. Here, 500 m of sediment rock series cover gneiss bedrock in which a KBS-3H repository of SKB-type can be built under virtually “dry” conditions because of the tightness of the overlying sedimentary rock and lack of hydraulic gradients in the crystalline rock. Shafts leading down from the ground surface to the repository level are constructed by use of freezing technique and lined with low-pH concrete before installation of waste after which they have to be sealed with expanding clay. Use of initially largely water-saturated clay provides suitable physical properties of the embedment of waste containers. Alternatively, a VDH repository consisting of a number of steep 4 km deep boreholes with about 8oo mm diameter can be driven for installing waste below 2 km depth, leaving the upper 2 km for sealing with clay. The geological conditions, which are also believed to provide acceptable rock pressure conditions for construction of a KBS-3H repository at about 600 m depth, are believed to be suitable for the construction and short- and long-term performance of either repository type. 

  • 25.
    Ntuli, Herbert
    et al.
    School of Economics, University of Cape Town, Private Bag, Rondebosch .
    Muchapondwa, Edwin
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Effects of wildlife resources on community welfare in Southern Africa2017In: Ecological Economics, ISSN 0921-8009, E-ISSN 1873-6106, Vol. 131, 572-583 p.Article in journal (Refereed)
    Abstract [en]

    This paper demonstrates the importance of wildlife in the portfolio of environmental income in the livelihoods of poor rural communities living adjacent to a national park. The results show that wealthier households use more wildlife resources in total than do relatively poor households. However, poorer households derive greater proportional benefit than wealthier households from the use of wildlife resources. Excluding wildlife understates the relative contribution of environmental resources while at the same time overstating the relative contribution of farm and wage income. Wildlife income alone accounts for about a 5.5% reduction in the proportion of people living below the poverty line. Furthermore, wildlife income has an equalizing effect, bringing about a 5.4% reduction in measured inequality. Regression analysis suggests that the likelihood of belonging to a wealthier category of income increases with an increase in environmental income. As expected, household wealth significantly and positively affects environmental income generated by households. This seems to suggest that wildlife-based land reform also needs to empower poor households in the area of capital accumulation while imposing restraints on the use of capital investments by well-off households to harvest wildlife.

  • 26.
    Rao Vuddanda, Parameswara
    et al.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Montenegro-Nicolini, Miguel
    Department of Pharmaceutical Sciences and Technology, University of Chile, Santiago.
    Morales, Javier O.
    Department of Pharmaceutical Sciences and Technology, University of Chile, Santiago.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Effect of plasticizers on the physico-mechanical properties of pullulan based pharmaceutical oral films2017In: European Journal of Pharmaceutical Sciences, ISSN 0928-0987, E-ISSN 1879-0720, Vol. 96, 290-298 p.Article in journal (Refereed)
    Abstract [en]

    The effect of different plasticizers (glycerol, vitamin E TPGS and triacetin) and their concentrations on the physico-mechanical properties of pullulan based oral films was studied. A full factorial (32) design of experiments was used. Elastic modulus, tensile strength, elongation at break and disintegration time were selected as response variables. Modulated differential scanning calorimeter (MDSC) was used for determining glass transition temperature (Tg) of pullulan films. The surface morphology of films was evaluated by SEM, while ATR-FTIR was used to obtain a molecular level understanding of polymer-plasticizer interactions. The DoE analysis allowed for the modelling of tensile strength and elongation at break. The highest elongations were observed in glycerol at 20% w/w. Majority of the films disintegrated within one minute without significant differences. ATR-FTIR spectra of pullulan alone and different plasticizer blend films show characteristic molecular interactions. The present study concluded that glycerol is suitable plasticizer compared to others for manufacturing pullulan based oral films.

  • 27.
    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.

  • 28.
    Zrida, Hana
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Fernberg, Patrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ayadi, Zoubir
    Institut Jean Lamour, Ecole Européenne d’Ingénieurs en Génie des Matériaux, Université de Lorraine.
    Varna, Janis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Microcracking in thermally cycled and aged Carbon fibre/polyimide laminates2017In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 94, no 1, 121-130 p.Article in journal (Refereed)
    Abstract [en]

    Carbon fibre T650 8-harness satin weave fabric composites with thermosetting polyimide resin designed for high service temperatures are solidified at 340 °C. High thermal stresses develop after cooling down to room temperature, which lead to multiple cracking in bundles of the studied quasi-isotropic composite. The composites are subjected to two thermal cycling ramps and the increase of crack density in each bundle is quantified. Comparison of two ramps with the same lowest temperature shows that the highest temperature in the cycle has a significant effect on thermal fatigue resistance. During thermal aging tests at 288 °C the mechanical properties are degrading with time and the crack density after certain aging time is measured. Aging and fatigue effects are separately analysed showing that part of the cracking in thermal cycling tests is related to material aging during the high temperature part of the cycle. Numerical edge stress analysis and fracture mechanics are used to explain observations. The 3-D finite element edge stress analysis reveals that there is large edge effect that induces a large difference in the damage state between the different layers on the edge. The linear elastic fracture mechanics explains the higher initiated and propagated crack density in the surface layers comparing to the inner layers.

  • 29.
    Ma, Chunyan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. College of Chemical Engineering, Nanjing Tech University.
    Guo, Yanhua
    College of Chemical Engineering, Nanjing Tech University.
    Li, Dongxue
    College of Chemical Engineering, Nanjing Tech University.
    Zong, Jianpeng
    College of Chemical Engineering, Nanjing Tech University.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Liu, Chang
    College of Chemical Engineering, Nanjing Tech University.
    Molar enthalpy of mixing and refractive indices of choline chloride-based deep eutectic solvents with water2017In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 105, 30-36 p.Article in journal (Refereed)
    Abstract [en]

    The molar enthalpies of mixing were measured for binary systems of choline chloride-based deep eutectic solvents (glycerol, ethylene glycol and malonic acid) with water at 298.15 K and 308.15 K, and atmospheric pressure with an isothermal calorimeter. Refractive indices were also measured at 303.15 K and atmospheric pressure. The binary mixtures of {chcl/glycerol (1:2) + water, chcl/ethylene glycol (1:2) + water} showed exothermic behaviour over the entire range of composition, while the binary mixture of {chcl/malonic acid (1:1) + water} showed endothermic behaviour at first and then changed to be exothermic with the increasing content of chcl/malonic acid (1:1). Experimental refractive indices were fitted with the Redlich–Kister equation, and experimental molar enthalpies of mixing were correlated with the Redlich–Kister equation and the non-random two-liquid (NRTL) model. The NRTL model with the fitted parameters was used to predict the vapour pressures of these three mixtures. For mixtures of {chcl/glycerol (1:2) + water} and {chcl/ethylene glycol (1:2) + water}, the predicted vapour pressures agreed well with the experimental reults from the literature. While for mixture of {chcl/malonic acid (1:1)+water}, the predicted vapour pressures showed deviation at the high concentration of chcl/malonic acid (1:1), and this was probably because of the complex molecular interaction between chcl/malonic acid (1:1) and water

  • 30.
    Sanda, Mohammed-Aminu
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Dynamics of National Culture and Employee Characteristics on Organizational Commitment in Retail Banks in Ghana2017In: Advances in Cross-Cultural Decision Making: Proceedings of the AHFE 2016 International Conference on Cross-Cultural Decision Making (CCDM), July 27-31,2016, Walt Disney World®, Florida, USA / [ed] Sae Schatz; Mark Hoffman, London: Encyclopedia of Global Archaeology/Springer Verlag, 2017, 71-83 p.Conference paper (Refereed)
    Abstract [en]

    Firms operating in high growth sectors are known to face the challenges of hiring and assimilating large numbers of new employees, providing new knowledge and skills to existing employees, and addressing the need for a rapid expansion of leadership capability. In the Ghanaian situation, such a challenge is known to prevail, since the country implemented major financial sector reforms starting in the late 1980s as part of its broad market reforms, key of which is the deregulation of the financial sub-sector. The banking sector in Ghana is therefore, faced with human resource management challenges, which includes the finding of the right caliber of employees to employ, and how to ensure that employees get committed to their organizations in order to reduce their desire to switch to competitor firms, due to apparent dissatisfaction with their jobs. This study therefore, examined a conceptual model that sought to hypothesize the impact of national culture and employee characteristics on employees’ organizational commitment in retail banks in Ghana. The purpose is to understand the extent to which Ghanaian national cultural values and employee characteristics impact on employee organizational commitment in Retail Banks operating in Ghana. Quantitative data was collected from 282 bank employee across nine different retail banks in Ghana, and analyzed stepwise, using the analysis of moment structures (AMOS) program. Firstly, path analysis was conducted to test the individual measurement models that constitute the various components of the conceptual structural model. In this analysis, the factor score weights and model fit estimates for the indicator variables in the various latent variables (i.e. national culture, employee characteristics, and organizational commitment,) were appraised. Results from the path analysis identified four measurable indicators for organizational commitment. The analysis showed that all the measurable indicators tested for national culture and employee characteristics did not have significant loads to serve as measurable indicators. It is concluded that employees’ organizational commitment in retail banks in Ghana is neither influenced by the Ghanaian national culture nor the employee’s characteristics.

  • 31.
    Rogdakis, Ioannis
    et al.
    School of Production Engineering and Management, Technical University of Crete.
    Marinaki, Magdalene
    School of Production Engineering and Management, Technical University of Crete.
    Marinakis, Yannis
    School of Production Engineering and Management, Technical University of Crete, Decision Support Systems Laboratory, Department of Production Engineering and Management, Technical University of Crete.
    Migdalas, Athanasios
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    An Island Memetic Algorithm for Real World Vehicle Routing Problems2017In: Operational Research in Business and Economics: 4th International Symposium and 26th National Conference on Operational Research, Chania, Greece, June 2015 / [ed] Evangelos Grigoroudis ; Michael Doumpos, Encyclopedia of Global Archaeology/Springer Verlag, 2017, 205-223 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, a new algorithm is presented which is applied to a real world Vehicle Routing Problem (VRP) of a provision company in the island of Crete in Greece. The company serves 116 customers located in Crete. This real world problem is solved effectively by a hybrid Island Memetic Algorithm (IMA) which employs Greedy Randomized Adaptive Search Procedure (GRASP) and Iterated Local Search (ILS). The proposed algorithm is also compared to five other approaches both on the real world problem and on classic benchmark instances from the literature. Methods such as GRASP, local search and Iterated Local Search (ILS) are employed as subroutines with certain probabilities in the algorithms. Furthermore, it is also demonstrated how premature convergence can be prevented by adopting specific strategy. Computational results show the superiority of the proposed hybrid Island Memetic Algorithm

  • 32.
    Sanda, Mohammed Aminu
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    An organizational activity framework for effective business practices implementation in research-oriented organizations in developing economies2017In: Advances in Human Factors, Business Management, Training and Education: Proceedings of the AHFE 2016 International Conference on Human Factors, Business Management and Society, July 27-31, 2016, Walt Disney World®, Florida, USA / [ed] Jussi Ilari Kantola; Tibor Barath; Salman Nazir; Terence Andre, London: Encyclopedia of Global Archaeology/Springer Verlag, 2017, 993-1006 p.Conference paper (Refereed)
    Abstract [en]

    This paper explored the constraints to business practices implementation by Research-Oriented Organizations in Developing Economies. Guided by organizational activity, sociotechnical and macroergonomic theories, data was collected from four research-oriented organizations in four developing countries, and analyzed using actions of identified groups in each organization’s activity system as the unit of analysis. It was found that the emergence of multivoicedness in the organizations’ activity systems created misfits among the organizations components which created systemic problems, ruptures, and breakdowns which constrained the effectiveness of the organizations’ business practices implementations. It is concluded that in the process of business practices implementation, an activity in the organization must be understood not as one activity with its peculiarities, but rather as a real aggregate of several activities and relations arising from the interacting components of the organization. A framework for understanding effective business practices implementation in research-oriented organizations is thus formulated.

  • 33.
    Duenas Dobrowolski, Jan
    et al.
    Wrocław University of Science and Technology.
    Gawlinski, Marek
    Department of Design Fundamentals and Fluid-Flow Machinery, Wrocław University of Technology.
    Paszkowski, Maciej
    Department of Fundamentals of Machine Design and Tribology, Wrocław University of Technology.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Höglund, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Experimental study of lubricating grease flow inside the gap of a labyrinth seal using micro Particle Image Velocimetry2017In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397XArticle in journal (Refereed)
    Abstract [en]

    In this study the flow of lubricating greases in a labyrinth seal geometry is studied using micro Particle Image Velocimetry (µPIV). The aim is to evaluate the grease velocity distribution inside the gap of a labyrinth seal and to find a relationship between the grease consistency and the transferred speed from the rotating ring in order to choose the correct grease as a sealing medium. Also, the grease flow characteristics are important for the understanding of fracture due to grease layer displacement. For these purposes, four greases with different rheological properties were used in µPIV experiments. It was found that not only the grease consistency plays a crucial role in speed development but also the grease composition and the slip effect presence at the grease-rotating wall interface.

  • 34.
    Sanda, Mohammed Aminu
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Charismatic influence and organizing capability as unique managerial self-efficacies for effective small firm performance in developing economy2017In: Advances in Human Factors, Business Management, Training and Education: Proceedings of the AHFE 2016 International Conference on Human Factors, Business Management and Society, July 27-31, 2016, Walt Disney World®, Florida, USA / [ed] Jussi Ilari Kantola; Tibor Barath; Salman Nazir; Terence Andre, London: Encyclopedia of Global Archaeology/Springer Verlag, 2017, 419-431 p.Conference paper (Refereed)
    Abstract [en]

    In the past two decades, changes in the industrial environment of most developing countries and the increasing competition among firms has greatly influenced executives’ attitudes and behaviours in the effective management of their firms. There is evidence in the extant literature that the sustained superior performances of most firms is attributable to the unique capabilities used in managing their human resources, and which capabilities are rare, valuable, non-substitutable and imitable. This study therefore, explored the requisite self-efficacies that are exhibited by executives of small firms in Ghana in their day-to-day management of their businesses that leads to increase firm performance, since such self-efficacies are human-oriented capabilities that are rare, valuable, non-substitutable and imitable. This was necessitated by the observation that most executives of small firms in Ghana have not been able to achieve much for their firms, in terms of increasing their businesses productive efficiencies and effectiveness, because the requisite self-efficacies required of such executives for improved performances are unknown and unexplored. Guided by the self-efficacy theorization, data was collected from executives of seventy-two small firms in Ghana using a standardised questionnaire. Factor analysis was conducted to identify the plausible factors with the requisite weight to predict the executives’ self-efficacy, and the attribution of such factors. The factor analyses, with Kaiser-Meyer-Olkin as well as Bartlett’s tests, were initiated to measure the factorability of the data, using the statistical package for the social sciences (SPSS) as the analytic tool. Principal Component Analysis was then used as a data reduction technique using the Rotation Method (Varimax with Kaiser Normalization). Indicator predictiveness was interpreted using Schumacker and Lomax’s (2004) recommendation that estimated factor loading must be 0.7 or higher. Based on the analysis, it is found that the executives of small firms in Ghana exhibit self-efficacies which they manifest variously as charismatic influences and organizing capabilities. The executives showed high levels of organizing capabilities and charismatic influences on the work they manage as a result of their self-efficacies. It is also found that the self-efficacy indicators reflecting the executives’ exertion of charismatic influences on their employees correlated significantly with their self-efficacy indicators reflecting their capabilities to organize their firms’ activities. It is concluded that the executives’ use of their charismatic influence-oriented and organizing capability-oriented self-efficacies has a positive influence on their abilities to manage their small firms. It is also concluded that, the executives ability to handle the time demands and the paper work required of their managerial jobs, on the one hand, and their ability to maintain control of their personal daily schedule, and cope with the stress aspect of their managerial job, on the other, had a direct positive impact on their abilities to carry out the following functions. The findings in this study contribute to knowledge in the management of small firms. Specifically, for Ghana, this research provides a platform for the development of a database that will help inform policy-makers on the requisite self-efficacies to be required of small firms’ executives in the daily management of their businesses.

  • 35.
    Sanda, Mohammed-Aminu
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Cognitive and Emotional-Motivational Implications in the Job Design of Digitized Production Drilling in Deep Mines2017In: Advances in Neuroergonomics and Cognitive Engineering: Proceedings of the AHFE 2016 International Conference on Neuroergonomics and Cognitive Engineering, July 27-31, 2016, Walt Disney World®, Florida, USA / [ed] Kelly S. Hale; Kay M. Stanney, London: Encyclopedia of Global Archaeology/Springer Verlag, 2017, 211-222 p.Conference paper (Refereed)
    Abstract [en]

    The aim of this paper was to understand the influence of cognitive and emotional-motivational aspects of task complexity on workers performances in high-technology driven drilling activity in a deep mine. Data was collected by observing and video recording miners’ engaged in two separate production drilling activities, using two Boomers simultaneously. Based on the analysis, it is found that the workers encounter cognitive challenges in their ability to process information marked on rock surfaces for the positioning of the boomers, resulting in added complexity to their drilling tasks. The workers’ were also found to have issues with the quality of their designed job environment, and which emotional-motivational challenge also added to their tasks complexity. It is concluded that by understanding the emerging cognitive and emotional-motivational aspects of task complexities, future design processes of a friendly and performance enhancing work environments and technologies could evolve for efficient and effective human work.

  • 36.
    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.

  • 37.
    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.

  • 38.
    Booth, Todd
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Critical Infrastructure Network DDoS Defense, via Cognitive Learning2017In: / [ed] Pietro Manzoni, Universitat Politècnica de València, Spain, 2017Conference paper (Refereed)
    Abstract [en]

    Some public and private services are called part of the Critical Infrastructure (CI), which are considered as the most important services to protect the functioning of a society and the economy.  Many CIs provide services via the Internet and thus cyber-attacks can be performed remotely.  It is now very simple and free to find and download software, which automates performing cyber-attacks.  A recent example is that two teenagers, with close to no security knowledge, created an on-line business. They would run cyber-attacks (online booter service called vDOS, as reported by Brian Krebs) for a small fee. They reportedly earned over 600,000 USD in a short period of time by conducting a large number of automated DDoS cyber-attacks. Then Krebs was retaliated against, and the highest DDoS attack bandwidth ever recorded, 620 Gbps, was launched against Krebs. In this paper we show how cognitive learning can be used to significantly mitigate any effects of DDoS network attacks, against the critical infrastructure.

  • 39.
    Häggquist, Elisabeth
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    The interrelated use of geological information and other types of geoinformation in local governments2017In: Transactions on GIS, ISSN 1361-1682, E-ISSN 1467-9671Article in journal (Refereed)
    Abstract [en]

    There is a growing interest in the use of geoinformation in government decision-making. Studies on the usability of geological information, which is one type of geoinformation, have however been scarce in the literature. A system built for an efficient organization may, therefore, not be catering to the needs of the individual user and understanding the perceived barriers to using geological information should be an important goal of geodata implementation. The objectives of this article are to: (1) investigate whether the analyses of user patterns are improved by considering an interrelated estimation with two types of geoinformation, and (2) explore whether there are gender differences in how peer advice affects the use of geoinformation. The data were collected in 2014 through a web survey, and the sample consisted of 390 women and 287 men working in Swedish municipalities. The results indicates a more accurate prediction pattern when a secondary geoinformation decision was included, thus suggesting that different types of geoinformation should be jointly analyzed. The officials tend to use both types of geoinformation, alluding to a demand for combined geoinformation products among the target population. Finally, there is evidence of women's decision to use geoinformation being affected by peer advice

  • 40.
    Chen, Yuhong
    et al.
    School of Material Science and Engineering, Beifang University for Nationalities Yinchuan, Ningxia.
    Jiang, Liang
    School of Material Science and Engineering, Beifang University for Nationalities Yinchuan, Ningxia.
    Yang, Qixing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Fenglan, Han
    School of Material Science and Engineering, Beifang University for Nationalities Yinchuan, Ningxia.
    Identification of Fe-containing phase in oxidation process of BOF slag2017In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 726, 564-568 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, the Fe-containing phases in BOF slag were identified before and after oxidized with atmospheric air. XRD and SEM with EDS results showed that The element Fe existed in slag in the form of calcium ferrite, wustite solid solution and hematite. Mg solid solute in wustite. After oxidized, magnetite became the major mineral phase in slag and Mg+ replace the Fe2+ of magnetite crystal to form spinel

  • 41.
    Kanellakis, Christoforos
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Survey on Computer Vision for UAVs: Current Developments and Trends2017In: Journal of Intelligent & Robotic Systems, ISSN 0921-0296Article in journal (Refereed)
    Abstract [en]

    During last decade the scientific research on Unmanned Aerial Vehicless (UAVs) increased spectacularly and led to the design of multiple types of aerial platforms. The major challenge today is the development of autonomously operating aerial agents capable of completing missions independently of human interaction. To this extent, visual sensing techniques have been integrated in the control pipeline of the UAVs in order to enhance their navigation and guidance skills. The aim of this article is to present a comprehensive literature review on vision based applications for UAVs focusing mainly on current developments and trends. These applications are sorted in different categories according to the research topics among various research groups. More specifically vision based position-attitude control, pose estimation and mapping, obstacle detection as well as target tracking are the identified components towards autonomous agents. Aerial platforms could reach greater level of autonomy by integrating all these technologies onboard. Additionally, throughout this article the concept of fusion multiple sensors is highlighted, while an overview on the challenges addressed and future trends in autonomous agent development will be also provided.

  • 42.
    Zhang, Qinhong
    et al.
    Sino-US Global Logistics Institute, Shanghai Jiao Tong University.
    Zhang, Dali
    Sino-US Global Logistics Institute, Shanghai Jiao Tong University.
    Segerstedt, Anders
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Luo, Jianwen
    School of Management, Shanghai Jiao Tong University.
    Optimal ordering and pricing decisions for a company issuing product-specific gift cards2017In: Omega, ISSN 0030-2228, E-ISSN 1541-3764Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate gift card's influence on retailers’ ordering decisions and analyse the benefits of issuing product-specific gift cards. We propose an optimal ordering model for retailers’ decision problems with gift cards being issued. We also solve the problem with the analytical forms of optimal order quantities and expected profits. By comparing the results with the classical newsvendor problem, we classify the benefits of issuing gift cards into three categories: (1) the demand stimulating; (2) the pre-payment, and (3) the non-redemption. We step further to explore a retailer's problem on how to determine the optimal discount for gift cards, which is characterized by a joint optimal policy on the ordering quantity and the discount. We derive the optimal condition on this joint policy. Numerical examples are conducted to illustrate the model results and analyse the influences of parameters. A sample average approximation method is also been introduced to solve the optimization model.

  • 43.
    Dold, Bernhard
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pooler, Robert
    SGS Minerals Chile, Geometallurgy Area, Puerto Madero 130, Pudahuel, Santiago.
    Optimization and quality control of automated quantitative mineralogy analysis for acid rock drainage prediction2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 1, 12Article in journal (Refereed)
    Abstract [en]

    Low ore-grade waste samples from the Codelco Andina mine that were analyzed in an environmental and mineralogical test program for acid rock drainage prediction, revealed inconsistencies between the quantitative mineralogical data (QEMSCAN®) and the results of geochemical characterizations by atomic absorption spectroscopy (AAS), LECO® furnace, and sequential extractions). For the QEMSCAN® results, biases were observed in the proportions of pyrite and calcium sulfate minerals detected. An analysis of the results indicated that the problems observed were likely associated with polished section preparation. Therefore, six different sample preparation protocols were tested and evaluated using three samples from the previous study. One of the methods, which involved particle size reduction and transverse section preparation, was identified as having the greatest potential for correcting the errors observed in the mineralogical analyses. Further, the biases in the quantities of calcium sulfate minerals detected were reduced through the use of ethylene glycol as a polishing lubricant. It is recommended that the sample preparation methodology described in this study be used in order to accurately quantify percentages of pyrite and calcium sulfate minerals in environmental mineralogical studies which use automated mineralogical analysis

  • 44.
    Sarkar, Chiranjit
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Westerberg, Lars-Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Höglund, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Numerical simulations of lubricating grease flow in a rectangular channel with- and without restrictions2017In: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397XArticle in journal (Refereed)
    Abstract [en]

    This paper presents numerical simulations of the laminar flow of lubricating greases in a channel with rectangular cross section. Three greases with different consistencies (NLGI grades 00, 1 and 2 respectively) have been considered in three different configurations comprised by a rectangular channel without restrictions, one rectangular step restriction, and one double lip restriction. The driving pressure drop over the channel spans from 30 kPa to 250 kPa. The grease rheology is described by the Herschel-Bulkley rheology model, and both the numerical code and rheology model have been validated with analytical solutions and flow measurements using micro Particle Image Velocimetry.

  • 45.
    Soria-Salinas, Álvaro
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Sánchez-García-Casarrubios, J.
    Department of Signal and Telecommunication Theory, Universidad Autónoma de Madrid.
    Pérez-Díaz, J-L
    Department of Signal and Telecommunication Theory, Universidad Autónoma de Madrid.
    Vakkada Ramachandran, Abhilash
    Luleå tekniska universitet.
    A Xenon Mass Gauging through Heat Transfer Modeling for Electric Propulsion Thrusters2017In: World Academy of Science, Engineering and Technology: An International Journal of Science, Engineering and Technology, ISSN 2010-376X, E-ISSN 2070-3740, Vol. 11, no 1, 94-105 p.Article in journal (Refereed)
    Abstract [en]

    The current state-of-the-art methods of mass gauging of Electric Propulsion (EP) propellants in microgravity conditions rely on external measurements that are taken at the surface of the tank. The tanks are operated under a constant thermal duty cycle to store the propellant within a pre-defined temperature and pressure range. We demonstrate using computational fluid dynamics (CFD) simulations that the heat-transfer within the pressurized propellant generates temperature and density anisotropies. This challenges the standard mass gauging methods that rely on the use of time changing skin-temperatures and pressures. We observe that the domes of the tanks are prone to be overheated, and that a long time after the heaters of the thermal cycle are switched off, the system reaches a quasi-equilibrium state with a more uniform density. We propose a new gauging method, which we call the Improved PVT method, based on universal physics and thermodynamics principles, existing TRL-9 technology and telemetry data. This method only uses as inputs the temperature and pressure readings of sensors externally attached to the tank. These sensors can operate during the nominal thermal duty cycle. The improved PVT method shows little sensitivity to the pressure sensor drifts which are critical towards the end-of-life of the missions, as well as little sensitivity to systematic temperature errors. The retrieval method has been validated experimentally with CO2 in gas and fluid state in a chamber that operates up to 82 bar within a nominal thermal cycle of 38 °C to 42 °C. The mass gauging error is shown to be lower than 1% the mass at the beginning of life, assuming an initial tank load at 100 bar. In particular, for a pressure of about 70 bar, just below the critical pressure of CO2, the error of the mass gauging in gas phase goes down to 0.1% and for 77 bar, just above the critical point, the error of the mass gauging of the liquid phase is 0.6% of initial tank load. This gauging method improves by a factor of 8 the accuracy of the standard PVT retrievals using look-up tables with tabulated data from the National Institute of Standards and Technology.

  • 46.
    Kahanpää, Henrik
    et al.
    Finnish Meteorological Institute, Helsinki.
    Nweman, C.
    Ashima Research Inc.
    Moores, John E.
    Earth and Space Science and Engineering , York University.
    Zorzano Mier, Maria-Paz
    Centro de Astrobiología (CSIC - INTA), Torrejón de Ardoz, Madrid.
    Navarro, Sara
    Centro de Astrobiología (CSIC - INTA), Torrejón de Ardoz, Madrid.
    Lepinette, Alain
    Centro de Astrobiología (CSIC - INTA), Torrejón de Ardoz, Madrid.
    Martin-Torres, Javier
    nstituto Andaluz de Ciencias de la Tierra (CSIC - UGR), Granada.
    Valentin-Serrano, Patricia
    nstituto Andaluz de Ciencias de la Tierra (CSIC - UGR), Granada.
    Cantor, Bruce
    Malin Space Science Systems, San Diego.
    Lemmon, Mark T.
    Department of Atmospheric Sciences , Texas A&M University.
    Ullán, A.
    Departamento de Teoría de la Señal y Comunicaciones, Escuela Politécnica Superior , Universidad de Alcalá, Madrid.
    Schmidt, W.
    Finnish Meteorological Institute, Helsinki.
    Dust Devils and Convective Vortices Detected by MSL2017Conference paper (Other academic)
  • 47.
    Smith, M.D.
    et al.
    NASA Goddard Space Flight Center, Greenbelt.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Lemmon, Mark T.
    Department of Atmospheric Sciences , Texas A&M University.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Mendaza de Cal, Maria Teresa
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Aerosol optical depth as observed by the Mars Science Laboratory REMS UV photodiodes2017Conference paper (Other academic)
  • 48.
    Guzewich, Scott D.
    et al.
    Universities Space Research Association/NASA Goddard Space Flight Center.
    Newman, C.
    Ashima Research Inc.
    De La Torre Juárez, Manuel
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Mason, E.
    Texas A&M University, College Station, TX.
    Battalio, M.
    Texas A&M University, College Station, TX.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Moores, John E.
    Earth and Space Science and Engineering , York University.
    Moore, C.A.
    Earth and Space Science and Engineering , York University.
    Kloos, J.L
    Earth and Space Science and Engineering , York University.
    Martinez, M.D.
    Uni-versity of Michigan, Ann Arbor.
    Smith, M.D.
    NASA Goddard Space Flight Center, Greenbelt.
    The Mars Science Laboratory dust storm campaign2017Conference paper (Other academic)
  • 49.
    Zamani, Mohammadreza
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    Dini, Hoda
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    Svoboda, Ales
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindgren, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Seifeddine, Salem
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    Andersson, Nils-Eric
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    Jarfors, Anders E.W.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University.
    A dislocation density based constitutive model for as-cast Al-Si alloys: Effect of temperature and microstructure2017In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 121, 164-170 p.Article in journal (Refereed)
    Abstract [en]

    The flow stress of an as-cast Al-Si based alloy was modeled using a dislocation density based model. The developed dislocation density-based constitutive model describes the flow curve of the alloy with various microstructures at quite wide temperature range. Experimental data in the form of stress-strain curves for different strain rates ranging from 10−4 to 10−1 s−1 and temperatures ranging from ambient temperature up to 400 °C were used for model calibration. In order to model precisely the hardening and recovery process at elevated temperature, the interaction between vacancies and dissolved Si was included. The calibrated temperature dependent parameters for different microstructure were correlated to the metallurgical event of the material and validated. For the first time, a dislocation density based model was successfully developed for Al-Si cast alloys. The findings of this work expanded the knowledge on short strain tensile deformation behaviour of these type of alloys at different temperature, which is a critical element for conducting a reliable microstructural FE-simulation.

  • 50.
    Abedin, Md. Zainal
    et al.
    University of Science and Technology Chittagong.
    Chowdhury, Abu Sayeed
    University of Science and Technology Chittagong.
    Hossain, Mohammad Shahadat
    University of Chittagong, Bangladesh.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Karim, Razuan
    University of Science and Technology Chittagong.
    An Interoperable IP based WSN for Smart Irrigation Systems2017Conference paper (Refereed)
    Abstract [en]

    Wireless Sensor Networks (WSN) have been highly developed which can be used in agriculture to enable optimal irrigation scheduling. Since there is an absence of widely used available methods to support effective agriculture practice in different weather conditions, WSN technology can be used to optimise irrigation in the crop fields. This paper presents architecture of an irrigation system by incorporating interoperable IP based WSN, which uses the protocol stacks and standard of the Internet of Things paradigm. The performance of fundamental issues of this network is emulated in Tmote Sky for 6LoWPAN over IEEE 802.15.4 radio link using the Contiki OS and the Cooja simulator. The simulated results of the performance of the WSN architecture presents the Round Trip Time (RTT) as well as the packet loss of different packet size. In addition, the average power consumption and the radio duty cycle of the sensors are studied. This will facilitate the deployment of a scalable and interoperable multi hop WSN, positioning of border router and to manage power consumption of the sensors.

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