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  • 951. Akhtar, Sifa
    et al.
    Claug, Sanna
    Hur skiftarbetare upplever aktivitetsbalans2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to describe shiftworkers experience of occupational balance. A qualitative design was used to focus the individuals’ thoughts and experiences. Data were collected through semistructured interviews and were analyzed by qualitative content analysis. Seven participants were included in the study, six men and one woman. The analysis resulted in three categories. Those were: Changes in time use, planning and daily routines, Changes in everyday activities together with others and Changes in the ability to perform activities. The results showed that shift work effects sleep, time use and planning of daily activities as well as daily routines. After working nightshift, the time is used for sleep and recovery, and there is not much time for daily activities. The everyday activities together with others was effected in a negative way and time together with family and friends were limited. Furthermore, the results showed that shift work causes a range of consequences such as lack of energy, tiredness and fatigue which affects the activity performance. Fatigue was a significant part that affected the shift workers occupational balance. The results of this study may contribute to future research as there is a lack of knowledge regarding how occupational balance is experienced among a healthy population working shifts. The results may contribute to an increased understanding of how occupational balance is affected by shift work that can be used by occupational therapists meeting these clients in their practice.

  • 952. Akhter, Shakeela
    et al.
    Bashir, Muhammad Khalid
    Importance of Web site design and customer support services in online purchase2008Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study was to provide a deeper understanding on the role of Website design in online purchase. Multiple case study method was chosen and two web sites from Pakistan were selected as cases for this research study which are doing business online. Data is collected through observations and from interviews. Four customers of these web sites were interviewed from United States and United Kingdom in order to find out detailed information about customer services. This study identifies important elements of web site design which are undertaken by users while interaction with the web sites, keeping in mind two important aspects of the websites, ease of use and customer confidence. Moreover, the perceptions of customers about services of the web site are described. Finding and conclusions of this research thesis indicates that there are several important factors to be considered while designing a web site, and different variables were found important in enhancing customer services through web.

  • 953.
    Akimaya, Muhammad
    et al.
    Colorado School of Mines.
    Dahl, Carol
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences. Mineral and Energy Economics Program and Payne Institute of Earth Resources, Division of Economics and Business, Colorado School of Mines, Golden, CO .
    Estimating the Cross-Price Elasticity of Regular Gasoline with Respect to the Price of Premium Gasoline2018In: Journal of Transport Economics and Policy, ISSN 0022-5258, E-ISSN 1754-5951, Vol. 52, no 2, p. 157-180Article in journal (Refereed)
    Abstract [en]

    Gasoline demand has been extensively researched, yet there has been no attempt to estimate cross-price elasticities of different grades of gasoline. Such knowledge will allow accurate determination of the impact of a fuel pricing policy that has different rates of tax or subsidy depending on the gasoline grade. Using monthly data on the Mexican gasoline market from 1999 to 2014, regular gasoline demand is estimated with an ARDL model. Endogeneity of the price and structural break are also investigated. The cross-price elasticity between regular and premium gasoline is found to be 0.875, confirming high substitutability among gasoline with different grades.

  • 954.
    Akimaya, Muhammad
    et al.
    Colorado School of Mines.
    Dahl, Carol
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences. Mineral and Energy Economics Program and Payne Institute of Earth Resources, Division of Economics and Business, Colorado School of Mines, Golden, CO .
    Simulation of price controls for different grade of gasoline: The case of Indonesia2017In: Energy Economics, ISSN 0140-9883, E-ISSN 1873-6181, Vol. 68, p. 373-382Article in journal (Refereed)
    Abstract [en]

    A gasoline subsidy is one of the most prevalent strategies for distributing welfare to the people in oil-producing countries. However well-intentioned, the policy will distort the gasoline market with the resulting inefficiencies. Furthermore, the gasoline subsidy takes a great amount of government's budget. Arguably, these funds could be spent elsewhere with a greater impact on economic growth. These governments are aware of the cost of such a policy, yet face difficulties in removing the policy because of strong resistance from the public. This paper looks at the unique case of Indonesia that only provides a subsidy for regular gasoline and in turn proposes an alternative policy that introduces a subsidy for premium gasoline at a lower rate to reduce the overall gasoline subsidy cost. There has yet to be any research that simulates price controls for gasoline with different grades. The aggregate demand for gasoline in Indonesia is replicated using a translog cost calibration approach. Simulations based on the calibrated demand are then performed and the results confirm the existence of potential savings that are largely determined by the cross-price elasticities between regular and premium gasoline. The benchmark scenario, based on a recent study of substitutability between gasoline by grades, results in an 11.5% reduction in subsidy cost of around 950 million USD with a subsidy rate of Rp 2254/liter. Furthermore, the optimal rate of subsidy for premium gasoline results in a reduction of inefficiency as consumers' welfare increase by 6.8 trillion rupiahs (or 560 million USD).

  • 955.
    Akita, Munehira
    et al.
    Nibon Fukushi University.
    Lee, Kwan Suk
    Hong-ik University.
    Noy, Ian Y.
    Transport Canada.
    Shahnavaz, Houshang
    Helander, Martin
    Nanyang Technological University.
    Hendrick, Hal W.
    University of Southern California.
    Lee, Kwan S.
    Hong-ik University.
    Kogi, Kazutaka
    Institute for Science of Labour.
    Sugiyama, Sadao
    Kansei Gakuin University.
    Asian ergonomics in the new millennium2000In: Ergonomics for the New Millenium: proceedings of the XIVth Triennial Congress of the International Ergonomics Association and 44th Annual Meeting of the Human Factors and Ergonomics society, July 29 through August 4, 2000, San Diego, California USA, Human Factors and Ergonomics Society, 2000, Vol. Vol. 6, p. 690-691Conference paper (Refereed)
    Abstract [en]

    Asia has more than a half of the world population. However, ergonomics has not been widely applied with exceptions of Japan and Korea. Recently, the excitement of ergonomics is being spread to other countries such as Hong Kong, Taiwan, and Indonesia. Although there have been two regional conferences, PPCOE and SEA Conference, Asian ergonomists have not met together to discuss their activities in a world conference. Therefore, the objectives of this symposium is to provide the opportunities for them to discuss the current status of ergonomics and possibly joints efforts to promote ergonomics in Asia. At the same time, this symposium intends to introduce the ergonomics activities in Asia to Western and non-Asian ergonomists and to look for new guidance to enhance its activities from the world renowned exports who have experienced in working in Asia with Asian ergonomists. This syposium consists of two sessions: one panel session and one technical session

  • 956.
    Akkaya, Kemal
    et al.
    Southern Illinois University.
    Aust, Stefan
    NEC Communication Systems, Ltd..
    Hollick, Matthias
    TU Darmstadt.
    Itaya, Satoko
    Smart Wireless Laboratory, NICT.
    Kantarci, Burak
    University of Ottawa.
    Pfeiffer, Tom
    TU Berlin.
    Senel, Fatih
    International Antalya University.
    Strayer, Tim
    BBN Technologies.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science. Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Distance- Spanning Technology.
    Message from the demonstrations chair2014Conference paper (Other academic)
    Abstract [en]

    It is my pleasure to welcome you to the sixth Demonstration Session at the IEEE Conference on Local Computer Networks (LCN) 2014. We were looking for demonstrations for all topics covered by the main conference as well as all the workshops held in conjunction with the conference. The technical demonstrations were strongly encouraged to show innovative and original research. The main purpose of the demo session is to provide demonstrations that validate important research issues and/or show innovative prototypes.

  • 957.
    Akos, Dennis
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Ene, A.
    Stanford University.
    Thor, Jonas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    A prototyping platform for multi-frequency GNSS receivers2003In: ION GPS/GNSS Proceedings, Institute of Navigation, The , 2003Conference paper (Refereed)
    Abstract [en]

    The future satellite positioning/navigation systems (i.e. GPS and Galileo) will provide civil signals on multiple frequencies, similar to those currently available for military purposes only. This paper presents a direct RF sampling front end design well suited for multiple frequency satellite navigation receiver design. No frequency downconversion is necessary; rather the particular frequency bands of interest are intentionally aliased using a wide band analog-to-digital converter (ADC). The resulting samples are passed to the memory space of a host PC for storage, and are saved to disk for eventual processing of the multiple frequency transmissions. The present paper describes the design of the front-end, validates its concept with collected data, and discusses the variations on the design of a generic multiple frequency GPS front end. Methods for processing the data obtained by the front end design are also presented.

  • 958.
    Akos, Dennis
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    From, Markus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Karlsson, Mattias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Larsson, Kjell
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Receiver measured time in the VDL mode 4 system2000In: IEEE 2000 Position Location and Navigation Symposium: San Diego, California, March 13 - 16, 2000, Piscataway, NJ: IEEE Communications Society, 2000, p. 309-316Conference paper (Refereed)
    Abstract [en]

    This paper details an investigation into the receiver measured time (RMT) concept of VDL Mode 4, basically the ability to derive estimates of time from the transmission of the VDL Mode 4 signals themselves. The RMT concept is based on determining the accurate time of transmission by measuring the time of arrival (TOA) of a received signal. The reverse aspect, or that of user position, can also be computed in the same manner and all computed simulations hold for errors in position. If synchronized time is available, or can be derived, then the user position can be computed based on signals from known transmitter locations. A complete, end-to-end RMT simulation model for the Gaussian filtered frequency shift keying (GFSK) and differential 8-phase shift keying (D8PSK) modulation techniques has been developed in which various transmitters, channels and receiver models as well as an RMT measurement system have been included. The timing results, which are included, are described in terms of two-sigma errors as a function of signal-to-noise ratios (SNRs). The performance varies for the different receiver structures over the typical operation region and for a 1-bit differential GFSK detector the two-sigma error is as low as 0.40 microseconds, corresponding to a ranging error of approximately 120 meters. When incorporating co-channel interference (CCI), multipath and Doppler frequency shifts the RMT performance has been shown to decrease in terms of higher two-sigma errors

  • 959.
    Akos, Dennis
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Stockmaster, Michael
    Rockwell Collins, Cedar Wells.
    Tsui, James B.Y.
    Wright-Patterson Air Force Base, Dayton.
    Caschera, Joe
    Wright-Patterson Air Force Base, Dayton.
    Direct bandpass sampling of multiple distinct RF signals1999In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 47, no 7, p. 983-988Article in journal (Refereed)
    Abstract [en]

    A goal in the software radio design philosophy is to place the analog-to-digital converter as near the antenna as possible. This objective has been demonstrated for the case of a single input signal. Bandpass sampling has been applied to downconvert, or intentionally alias, the information bandwidth of a radio frequency (RF) signal to a desired intermediate frequency. The design of the software radio becomes more interesting when two or more distinct signals are received. The traditional approach for multiple signals would be to bandpass sample a continuous span of spectrum containing all the desired signals. The disadvantage with this approach is that the sampling rate and associated discrete processing rate are based on the span of spectrum as opposed to the information bandwidths of the signals of interest. Proposed here is a technique to determine the absolute minimum sampling frequency for direct digitization of multiple, nonadjacent, frequency bands. The entire process is based on the calculation of a single parameter-the sampling frequency. The result is a simple, yet elegant, front-end design for the reception and bandpass sampling of multiple RF signals. Experimental results using RF transmissions from the US Global Positioning System-Standard Position Service (GPS-SPS) and the Russian Global Navigation Satellite System (GLONASS) are used to illustrate and verify the theory

  • 960.
    Akpalu, Wisdom
    et al.
    Department of History, Economics and Politics, State University of New York, Farmingdale, UNU-WIDER, University of Ghana, Legon-Accra.
    Abidoye, Babatunde
    CEEPA, University of Pretoria.
    Muchapondwa, Edwin
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Simbanegavi, Witness
    African Economic Research Consortium (AERC), Nairobi.
    Public disclosure for carbon abatement: African decision-makers in a PROPER public good experiment2017In: Climate and Development, ISSN 1756-5529, E-ISSN 1756-5537, Vol. 9, no 6, p. 548-558Article in journal (Refereed)
    Abstract [en]

    linear public good experiment adopted from Holt and Laury [1997. Classroom games: Voluntary provision of a public good. Journal of Economic Perspectives, 11(4), 209–215.] has been employed to investigate strategic behaviour in pollution abatement among African climate decision-makers. The experiment consisted of three groups, of which groups 2 and 3 received one and two treatments, respectively. The first treatment entailed publicly disclosing the pollution of each member of a group by placing a corresponding colour-coded card in front of each subject, while the second involved the withdrawal of the public disclosure. Group 2 received the first treatment; Group 3 received both the first and second treatments in succession. We found that the untreated group (baseline) polluted more than the two treated groups, and there was no statistically significant difference between the pollution abatement of the two treated groups. These results suggest that public disclosure potentially drives pollution abatement and that its eventual withdrawal does not obliterate abatement behaviour. We did not observe conditional cooperation but average pollution declined over time. Furthermore, individuals who thought it was unfair for Africa to reduce emissions polluted more. We also found that pollution levels differ significantly between males and females.

  • 961.
    Akpalu, Wisdom
    et al.
    Department of History, Economics and Politics, State University of New York, Farmingdale.
    Muchapondwa, Edwin
    School of Economics, University of Cape Town.
    Zikhali, Precious
    Centre for World Food Studies (SOW-VU), Vrije Universiteit.
    Can the restrictive harvest period policy conserve mopane worms in southern Africa?: A bioeconomic modelling approach2009In: Environment and Development Economics, ISSN 1355-770X, E-ISSN 1469-4395, Vol. 14, no 5, p. 587-600Article in journal (Refereed)
    Abstract [en]

    The mopane worm, which is the caterpillar form of the Saturnid moth Imbrasia belina Westwood, is like other edible insects and caterpillars a vital source of protein in southern African countries. The worms live and graze on mopane trees, which have alternative uses. With increasing commercialization of the worm, its management, which was hitherto organized as a common property resource, has been degraded to almost open access. This paper uses a bioeconomic modelling approach to show that for some optimal allocation of the mopane forest stock, the restrictive harvest period policy advocated by community leaders may not lead to sustainable harvesting of the worm

  • 962.
    Akselsen, Odd M.
    et al.
    SINTEF, Trondheim.
    Wiklund, Greger
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Østby, Erling
    SINTEF, Trondheim.
    Sörgjärd, Arve
    Kværner Verdal.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A first assessment of laser hybrid welding of 420 mpa steel for offshore structure application2013In: 14th NOLAMP Conference: The 14th Nordic Laser Materials Processing Conference, August 26th – 28th 2013, Gothenburg, Sweden / [ed] Alexander Kaplan; Hans Engström, Luleå: Luleå tekniska universitet, 2013, p. 171-182Conference paper (Other academic)
    Abstract [en]

    For many years, laser hybrid welding has been used in various industries to increaseproductivity and reduce costs. One example is the adaption of the hybrid process inshipbuilding. The next natural step is to further develop the process for the oil and gasindustry, where the welded joint properties requirements are more severe, and the ability tohandle tolerance deviations is more critical. As a first attempt to develop hybrid laser processfor the use in offshore structures, the present investigation addresses preliminary weldingtrails carried out with 15 kW fibre laser with appropriate gas metal arc welding equipment,using double Y joint geometry and 20 mm thick 420 MPa steel plates. The subsequent weldtesting included both Charpy V notch impact and CTOD fracture mechanical testing at -30°C.The results indicate that the heat affected zone (HAZ) of the examined steel appeared withsatisfactory Charpy and CTOD toughness (> 200 J, > 0.2 mm) while the weld metal hadinsufficient toughness (20-40 J, < 0.2 mm). With a better welding wire, designed for lowtemperature applications, it is reasonable to suggest that laser hybrid arc welding can be usedfor applications even below a temperature of -30°C.

  • 963.
    Akselsen, Odd Magne
    et al.
    SINTEF, Trondheim.
    Wiklund, Greger
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Østby, Erling
    SINTEF, Trondheim.
    Sørgjerd, Arve
    Kværner Verdal.
    Kaplan, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Properties of laser hybrid butt welds of 420 MPa steel2013In: The proceedings of the Twenty-third (2013) International Offshore and Polar Engineering Conference: Anchorage, Alaska, June 30-July 5, 2013 : ISOPE-2013 Anchorage / [ed] Jin S. Chung, Cupertino, Calif.: International Society of Offshore and Polar Engineers , 2013, p. 290-294Conference paper (Refereed)
    Abstract [en]

    Laser hybrid welding has been used in European shipbuilding for many years due to its high productivity. In order to qualify the process for the oil and gas industry, an extensive welding and testing programme is needed, and the properties must satisfy more severe requirements than in shipbuilding. This is particularly the case when these activities are moving to the Arctic regions, where low temperature toughness may be the primary challenge. The present investigation addressed preliminary welding trials carried out with 15 kW fibre laser-gas metal arc (GMA) hybrid welding using double Y joint of 20 mm thick 420 MPa steel plates. Both Charpy V notch impact and CTOD fracture mechanical testing were included with test temperature of -30°C. The results indicate that the heat affected zone (HAZ) of the examined steel appeared with satisfactory toughness (> 200 J, > 0.2 mm) while the employed weld metal had insufficient impact properties. The weld metal CTOD toughness approached 0.2 mm. With a better welding wire, designed for low temperature applications, it is reasonable to suggest that laser hybrid arc welding can be used for applications even below -30 to -40°C

  • 964.
    Akselsson, K. Roland
    et al.
    Lund University, Division of Working Environment, Depatment of Industrial Engineering, Lund Institute of Technology.
    Bengtsson, Peter
    Eriksson, J.
    Lund University, Division of Working Environment, Depatment of Industrial Engineering, Lund Institute of Technology.
    Johansson, Curt R.
    Lund University, Department of Psychology/Work Science Division.
    Johansson, G.I.
    Lund University, Division of Working Environment, Depatment of Industrial Engineering, Lund Institute of Technology.
    Klercker, Jonas af
    Lund Institute of Technology, School of Architecture.
    Computer aided planning of production and working environment1994In: Human factors in organizational design and management - IV: development, introduction and use of new technology : challenges for human organization and human resource development in a changing world : proceedings of the Fourth International Symposium on Human Factors in Organizational Design and Management held in Stockholm, Sweden, May 29-June 2, 1994 / [ed] Gunilla Bradley; Hal W. Hendrick, Amsterdam: Elsevier, 1994, p. 499-504Conference paper (Refereed)
    Abstract [en]

    The success of design projects depends on their quality from a technical and economic point of view and on the quality of their implementation and use. This paper discusses a computer aided planning (CAP) technique and its applicability and quality in both these respects. One version of the CAP-technique is developed for planning of industrial working environments and another version for planning of residential and working environments for the physically handicapped

  • 965.
    Akselsson, K Roland
    et al.
    Lunds tekniska högskola, LTH.
    Bengtsson, Peter
    Eriksson, Joakim
    Lunds tekniska högskola, LTH.
    Johansson, Gerd
    Lunds tekniska högskola, LTH.
    Computer-aided planning of new production lines in mechanical industries and of working environments for disabled persons1993In: Production research 1993: of the 12th International Conference on Production Research, Lappeenranta, Finland, 16 - 20 August, 1993 / [ed] V Orpana; A Lukka, Amsterdam: Elsevier, 1993, p. 85-86Conference paper (Other academic)
  • 966.
    Akselsson, K Roland
    et al.
    Lunds tekniska högskola, LTH.
    Bengtsson, Peter
    Johansson, Curt R
    Lunds universitet.
    Karlsson, Torsten
    Lunds universitet.
    Klercker, Jonas af
    Lunds tekniska högskola, LTH.
    Lundahl, Anders
    Lunds tekniska högskola, LTH.
    Lloyd, Rick
    Lunds tekniska högskola, LTH.
    Dynamisk beskrivning med datorstödd bild1988Conference paper (Other academic)
  • 967.
    Akselsson, K. Roland
    et al.
    Lund Institute of Technology.
    Bengtsson, Peter
    Johansson, Curt R.
    Lund University, Department of Psychology/Work Science Division.
    Klercker, Jonas af
    Lund Institute of Technology, School of Architecture.
    Computer aided participatory planning1990In: Ergonomics of hybrid automated systems I: proceedings of the second International Conference on Human Aspects of Advanced Manufacturing and Hybrid Automation, Honolulu, Hawaii, U.S.A., August 12-16, 1990 / [ed] Waldemar Karwowski; Mansour Rahimi, Amsterdam: Elsevier, 1990, p. 69-76Conference paper (Refereed)
  • 968. Aksenova, N.A.
    et al.
    Isakina, A.P.
    Prokhvatilov, A.N.
    Strzhemechny, M.A.
    Soldatov, Alexander
    Sundqvist, Bertil
    Structural studies of C60 polymerized at high pressure1997In: Proceedings of the Symposium on Recent Advances in the Chemistry and Physics of Fullerenes and Related Materials: : [based on papers presented at the fourth symposium of the Fullerenes Group of the Electrochemical Society, held at the 192nd Meeting of the Electrochemical Society in Paris, France, from August 31 to September 5, 1997. This symposium, entitled Fullerenes: Chemistry, Physics and New Directions X ...] / [ed] Karl M. Kadish, Pennington, NJ: Electrochemical Society, Incorporated , 1997Conference paper (Refereed)
  • 969.
    Akshantala, Nagendra V.
    et al.
    School of Aerospace Engineering, Georgia Institute of Technology, Atlanta.
    Talreja, Ramesh
    A mechanistic model for fatigue damage evolution in composite laminates1998In: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 29, no 2, p. 123-140Article in journal (Refereed)
    Abstract [en]

    We propose a mechanistic model which is capable of describing the evolution of transverse cracking in cross ply laminates subjected to cyclic tension in the longitudinal direction. The key feature of the model is that it incorporates delamination associated with transverse cracks in a manner that induces further formation of transverse cracks as delamination grows in fatigue. A variational approach is taken to estimate the stresses in the region between transverse cracks, and these are found to be accurate away from the crack planes when comparison is made with finite element computations. The evolution of transverse crack density and the associated overall elastic moduli changes predicted by the model are in agreement with experimental results

  • 970.
    Akshantala, Nagendra V.
    et al.
    Goodyear Tire and Rubber Company, Akron, OH.
    Talreja, Ramesh
    A micromechanics based model for predicting fatigue life of composite laminates2001In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 285, no 1-2, p. 303-313Article in journal (Refereed)
    Abstract [en]

    The current practice, as well as the hitherto proposed models, for assessment of fatigue life of composite laminates rely largely on experimental fatigue life data. In this paper, we propose a methodology for fatigue life prediction that utilizes a micromechanics based evaluation of damage evolution in conjunction with a semi-empirical fatigue failure criterion. The specific case treated is that of cross ply laminates under cyclic tension. The predicted results are compared with experimental data for several glass/epoxy and carbon/epoxy laminates, and good agreement is found. Published by Elsevier Science S.A. The current practice, as well as the hitherto proposed models, for assessment of fatigue life of composite laminates rely largely on experimental fatigue life data. In this paper, we propose a methodology for fatigue life prediction that utilizes a micromechanics based evaluation of damage evolution in conjunction with a semi-empirical fatigue failure criterion. The specific case treated is that of cross ply laminates under cyclic tension. The predicted results are compared with experimental data for several glass/epoxy and carbon/epoxy laminates, and good agreement is found.

  • 971.
    Aksoy, A. G.
    et al.
    Department of Mathematics, Claremont McKenna College.
    Maligranda, Lech
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Real interpolation and measure of weak noncompactness1995In: Mathematische Nachrichten, ISSN 0025-584X, E-ISSN 1522-2616, Vol. 175, no 1, p. 5-12Article in journal (Refereed)
    Abstract [en]

    Behavior of weak measures of noncompactness under real interpolation is investigated. It is shown that "convexity type" theorems hold true for weak measures of noncompactness.

  • 972.
    Aksoy, A.G.
    et al.
    Department of Mathematics, Claremont McKenna College.
    Maligranda, Lech
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Lipschitz-Orlicz spaces and the Laplace equation1996In: Mathematische Nachrichten, ISSN 0025-584X, E-ISSN 1522-2616, no 178, p. 81-101Article in journal (Refereed)
  • 973.
    Akter, Shamima
    et al.
    International Islamic University, Chittagong, Bangladesh.
    Nahar, Nazmun
    University of Chittagong, Bangladesh.
    Hossain, Mohammad Shahadat
    University of Chittagong, Bangladesh.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    New Crossover Technique to Improve Genetic Algorithm and Its Application to TSP2019In: Proceedings of 2019 International Conference on Electrical, Computer and Communication Engineering (ECCE), IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    Optimization problem like Travelling Salesman Problem (TSP) can be solved by applying Genetic Algorithm (GA) to obtain perfect approximation in time. In addition, TSP is considered as a NP-hard problem as well as an optimal minimization problem. Selection, crossover and mutation are the three main operators of GA. The algorithm is usually employed to find the optimal minimum total distance to visit all the nodes in a TSP. Therefore, the research presents a new crossover operator for TSP, allowing the further minimization of the total distance. The proposed crossover operator consists of two crossover point selection and new offspring creation by performing cost comparison. The computational results as well as the comparison with available well-developed crossover operators are also presented. It has been found that the new crossover operator produces better results than that of other cross-over operators.

  • 974.
    Akter, Shamima
    et al.
    Department of Computer Science and Engineering, International Islamic University, Chittagong, Bangladesh.
    Nahar, Nazmun
    Department of Computer Science and Engineering, International Islamic University, Chittagong, Bangladesh.
    Hossain, Mohammad Shahadat
    Department of Computer Science and Engineering, International Islamic University, Chittagong, Bangladesh.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    A New Crossover Technique to Improve Genetic Algorithm and Its Application to TSP2019In: 2019 International Conference on Electrical, Computer and Communication Engineering (ECCE), IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    Optimization problem like Travelling Salesman Problem (TSP) can be solved by applying Genetic Algorithm (GA) to obtain perfect approximation in time. In addition, TSP is considered as a NP-hard problem as well as an optimal minimization problem.Selection, crossover and mutation are the three main operators of GA. The algorithm is usually employed to find the optimal minimum total distance to visit all the nodes in a TSP. Therefore, the research presents a new crossover operator for TSP, allowing the further minimization of the total distance. The proposed crossover operator consists of two crossover point selection and new offspring creation by performing cost comparison. The computational results as well as the comparison with available well-developed crossover operators are also presented. It has been found that the new crossover operator produces better results than that of other cross-over operators.

  • 975. Al Ali, Syamendi
    Förslag och metoder för minimering av ställtider2006Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 976.
    Al Amli, Ali
    et al.
    Civil Engineering Department, AlMu stansiriyah Engineering College, ALMust ansiriyah University, Baghdad .
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Shejiri, Sabah Jasim Dahboosh
    Department of Civil Engin eering, AL-Farabi University College, Baghdad.
    Repairing of RC T-Section Beams with Opening by CFRP for Cracks and Ultimate Torque2018In: Journal of Civil Engineering and Architecture, ISSN 1934-7359, E-ISSN 1934-7367, Vol. 12, p. 83-90Article in journal (Refereed)
    Abstract [en]

    The repair of reinforced concrete (RC) beams with carbon fiber reinforced polymers (CFRP) is experimentally investigated in this study. The four T-section reinforced reactive powder concrete beams with many locations of circular opening were repaired by CFRP and investigated under pure torsion. The repairing beams were tested to obtain the effect of the amount of CFRP laminate on beams cracking and ultimate torque behavior, angle of twist and failure modes. The results obtained from the adopted repairing technique showed a significant effect of external high strength CFRP laminates on effectively restore of section solid of 85% of crack torsional strength effectively restored. In addition, the results show that effectively restoring of section opening by 82%-80% of crack torsional strength, and the adopted repairing technique gives a good strength to the beams.

  • 977.
    Al Amli, Ali Sabah Ahmed
    et al.
    Civil Engineering Department, Al Mustansiriyah Engineering College, Al Mustansiriyah University, Baghdad.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Abtan, Yaarub G.
    Civil Engineering Department, Al Mustansiriyah Engineering College, Al Mustansiriyah University, Baghdad.
    Behavior of Repairing Composite I-SectionBeams with Opening under Ultimate Torque2018In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 10, no 4, p. 202-214Article in journal (Refereed)
    Abstract [en]

    An experimental study was conducted to investigate the behavior of composite concrete beams damaged and cracked under pure torsion, and then repaired by external strengthening. This was achieved using high strength Carbon Fiber Reinforced Polymer (CFRP) laminates bonded with epoxy four composite modify reactive powder concrete (MRPC) I-beams. Different types of section (Solid & with opening) were tested to obtain the effect of amount of CFRP laminate on beams ultimate torque behavior, angle of twist and failure modes. The results obtained showed that a significant effect of external high strength CFRP laminates on effectively restore of section solid, the range of 89.8% to 91.2% of ultimate torsional strength effectively restored as well as effectively restoring of section opening by 83.48% - 86.67% of ultimate torsional strength. The repaired beams give high efficiency in ultimate torsional strength, and indicate that the adopted technique gives a good torsional strength.

  • 978.
    Al Dahaan, Saadi
    et al.
    University of Kufa, Kufa, Iraq.
    Al-Ansari, Nadhir
    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.
    Influence of Groundwater Hypothetical Salts on Electrical Conductivity Total Dissolved Solids2016In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 8, no 11, p. 823-830Article in journal (Refereed)
    Abstract [en]

    A relationship between electrical conductivity (EC) and total dissolved solids (TDS) was tested for solutions of same salinity levels with respect to different artificial salts with their combinations. Results showed remarkable jumping at the order of the artificial salt sequence specially that of the magnesium type. A computer model is designed with an input of EC and TDS. The output will be the possible prevailing artificial salts. The accuracy of the model was tested by using the groundwater data of Safwan-Zubair area south of Iraq and it proved to be significant at 95% matching. The 5% unmatched results are due to the possibility of having more than one type of prevailing salt.

  • 979.
    Al Haiany, Haidar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Reliability Centered Maintenance: Different Implementation Approaches2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mining equipment are becoming very sophisticated and complex. At the same time, mining companies modernise its operation by increased mechanisation and automation (Dhillon, 2008). That requires well-developed and planned maintenance strategy. A proper maintenance strategy and appropriate maintenance actions, are essential to keep equipment safe & reliable, decrease the overall costs, and it helps to eliminate workplace hazards. Maintenance strategies and maintenance actions, in turn, are changed and developed more than any technology (Moubray, 1997). Changing and developing of the maintenance can be due to many factors, perhaps due to the complexity of the systems or due to the development of the technology. One of the best research (developed technology) that has been done in this area is the research by Nowlan and Heap about Reliability Centered Maintenance (RCM) in 1978. RCM is defined as, “a zero-based, structured process used to identify the failure management strategies required to ensure an asset meets its mission requirements in its operational environment in the safest and cost – effective manner” (Regan, 2012). The RCM is one of the best powerful asset management strategies. RCM can be applied to any asset, nuclear power plant, aeroplane, or truck ship. According to (Nowlan & Heap, 1978), the main goal of implementation an RCM process is to provide the stated function of the facility with required reliability and availability at the lowest cost. In this master thesis, an RCM analysis process has been described in details. Moreover, two types of implementation approaches of an RCM analysis process have also been described. The intention of describing these two approaches is to see what the differences between them are and which one can be recommended for using in mining. The first approach is according to (Hinchcliffe & Smith, 2004) and the second approach is according to (Regan, 2012). Moreover, in this master thesis, there are also two case studies that have been analysed. The intention of analysing these two case-studies is to see how the RCM has been implemented. As a result of the research carried out in this master thesis, some basic streamline RCM analysis process has been recommended for using in mining. This recommended RCM analysis process could be applicable to be used in every industry section. The result of this work can be summarised that RCM is an applicable tool which can be used in mining for selecting the right maintenance approach for different equipment, systems or subsystem. RCM analysis process is discussed from different perspective. In the discussion, the misconceptions about the implementation of an RCM analysis process have been discussed. Altogether, Reliability Centered Maintenance is one of the most powerful asset management strategies that can be used in every industry section. If the RCM is applied by right people and by the right way, the result can be profitable for the mining companies.

  • 980.
    Al Maliki, Ali
    et al.
    Environment Research Centre, Ministry of Since and Technology, Jadriah, Baghdad.
    Al-lami, Ahmed Kadhim
    Department of Physics, College of Science, Al-Nahrain University, Jadriah, Baghdad.
    Hussain, H.M.
    Faculty of Science, University of Kufa.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Comparison between inductively coupled plasma and X-ray fluorescence performance for Pb analysis in environmental soil samples2017In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 76, no 12, article id 433Article in journal (Refereed)
    Abstract [en]

    Comparison of two conventional analytical techniques such as X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) for measuring Pb concentrations in soil samples was achieved using field and laboratory work. Seventy-three samples were collected from urban areas surrounding the large lead smelter at South Australia, as an indicator of the environment impact of smelter activity. Soil Pb concentrations were determined using hand-held XRF analyser under laboratory conditions. ICP-MS analysis on digested soils (using a microwave-assisted nitric acid digestion-extraction) was applied to validate p-XRF data. The analysis showed that Pb concentrations determined by XRF correlated with high linearity with Pb concentrations determined by ICP-MS measurements (R2 = 0.89). Statistical test (t test) was applied to the data of both methods applied without any significant difference between the two techniques. These results indicated that ICP-MS corroborated XRF for Pb soil measurements and suggests that XRF was a reliable and quick alternative to traditional analytical methods in studies of environmental health risk assessment, allowing for much larger sampling regimes in relatively shorter times and could be applied in the field.

  • 981.
    Al Maliki, Ali
    et al.
    Environment Research Centre, Ministry of Since and Technology, Naghdad.
    Owens, Gary
    University of South Australia, Adelaide.
    Hussain, Hussain M.
    Remote Sensing Centre, University of Kufa, Al-Najf.
    Al-Dahaan, Saadi
    Environment and Geomorphology Department, University of Kufa, Al-Najf.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Chemometric Methods to Predict of Pb in Urban Soil from Port Pirie, South Australia, using Spectrally Active of Soil Carbon2018In: Communications in Soil Science and Plant Analysis, ISSN 0010-3624, E-ISSN 1532-2416, Vol. 49, no 11, p. 1370-1383Article in journal (Refereed)
    Abstract [en]

    A total of 73 soil samples were initially analyzed for lead (Pb) concentration as an indicator of the environment impact of smelter activity in the Port Pirie, South Australia. Chemometric techniques were used to assess the ability of near-infrared (NIR) reflectance spectroscopy to predict soil Pb using spectrally active soil characteristics such as soil carbon (C). The result indicated a strong linear relationship between log-transformed data of soil Pb and spectral reflectance in the range between 500 and 612 nm with R2 = 0.54 and a low root-mean-square error (RMSEv = 0.38) for the validation mode with an acceptable ratio of performance to deviation and ratio of error range (1.6 and 7.7, respectively). This study suggested that NIR spectroscopy based on auxiliary spectrally active components is a rapid and noninvasive assessment technique and has the ability to determine Pb contamination in urban soil to be useful in environmental health risk assessment.

  • 982. Al Shakarchi, Fatima
    Byggnad på ofri grund: Ett område med ett oklart sakrättsligt skydd vid köp, pantsättning samt säkerhetsöverlåtelse2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 983. Ala, Patrik
    et al.
    Åström, Mikael
    Analys av TM-korg2000Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 984. Alagheband, Parisa
    Adoption of electronic banking services by Iranian customers2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Banking has always been a highly information intensive activity particularly over the last few decades that information technology (IT) has affected the banking industry heavily. The appearance of electronic banking services has changed the nature of financial services delivered to customers. By providing these services, banks can get notable cost savings, reduce their branch networks, and downsize the number of their service staff. But since customers do not adopt and use these services, banks can not profit from these new services. Recently, a number of Iranian banks have started to offer electronic banking services to their customers but still electronic banking is an unknown concept from customers’ point of view. The purpose of this study is to gain a deep understanding of the factors which influence the adoption and usage of these services by customers in Iran. In this study, based on the review of literature, a model of the perceived innovation attributes and the personal characteristics of adopters have been developed. Then the model has been tested using a questionnaire concerned with Iran market for electronic banking services. The results are presented in details which indicate that the model is a proper predictor of adoption behavior. In particular, perceptions of relative advantages, compatibility and trailability of the service, cost and risk as well as gender and social character were found to influence the adoption of electronic banking services. The practical implications of the study are discussed and suggestions for future research are presented.

  • 985. Alagöz, Sait Fatih
    Development of design guidelines for underground platinum mine regional support pillars2007Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Assessment of pillar stability is one of the most crucial steps in mine design (Sjöberg, 1992). South African platinum mines has reached a point where layouts made for shallow operations are insufficient due to increased depth, creating a necessity for new design layouts for medium depth mines (>1000 m). In this thesis, a design criterion for medium depth platinum mines’ regional support pillars is presented. Frank2 Shaft was chosen because it is the deepest and most seismically active mine in the region. The design methodology is refining the actual mine plan with the designed regional support pillars. Average pillar stress was designed to be 1000 MPa during shallow operations. Increased levels of seismicity and signs of failure in regional support pillars showed the necessity for reducing the stress levels on these pillars. It was assumed to reduce the 1000 MPa value by half, i.e. 500 MPa, as an empirical approach based on experience. Future regional support pillars will therefore be designed according to this criterion: however it was not supported by the theory. This thesis project aims to support this design with theory, or refine it if the theory proposes a different design criterion. The primary source of information for the refining process was literature review and observations of failed pillars. It was unfortunate that none of the newly designed regional pillars were cut by the time this study was conducted. However, old design regional pillars were observed for back analysis. Crush pillars as well as potholes were also visited. As a starting point, the current design of 108 regional support pillars at Frank2 shaft was taken into consideration. Average pillar stress (APS) levels calculated for different dimensions of pillars using Tributary Area Method and Coates Method. Numerical modeling was done using Besol/MS, a linear elastic modeling program. However, only 30 of these pillars were modeled due to the limitations of the program. These results were used for comparison with foundation strength, which appeared to be a more limiting parameter than pillar strength itself. As a result of comparisons of these results combined with back analysis of old type regional support pillars with estimated APS levels: a design criterion has been developed. The design criterion is: Design APS ≤ 2.0 x UCS of the weakest foundation strata As stated, new design regional support pillars have not yet been cut, this result and hence the criterion has not been verified completely. Nevertheless, literature review and observations along with numerical modeling justified the design criterion as an applicable one for the time being.

  • 986. Alahakoon, O.
    et al.
    Loke, Seng Wai
    Zaslavsky, Arkady
    User profiles with common modules for multiple domains2005In: IPSI-2005 Hawaii, January 6 - 8, 2005: [Book of Abstracts], IPSI Belgrade , 2005, p. 9-Conference paper (Other academic)
    Abstract [en]

    Personalization using profiles of the users has become an important feature in the fast growing number of e-commerce applications. In current applications, these profiles are usually tailored to the application domains. Therefore separate profiles have to be generated and maintained for each different application domain. Each time a new need arises, users have to reveal their personal details or/and needs to new applications. To overcome this limitation we propose a novel modular user profile, which has layers of information enabling these to be used across multiple application domains. The proposed model consists of three layers where information related to a particular user is separated according to "domain dependence".

  • 987. Alahakoon, O.
    et al.
    Loke, S.W.
    Monash University, Melbourne, VIC.
    Zaslavsky, Arkady
    Modular and hierarchical user profile instantiation for e-commerce applications using mobile software agents2003In: 14th Australasian Conference on Information Systems: delivering IT and e-Business value in networked environments, Edith Cowan University , 2003Conference paper (Refereed)
  • 988.
    Alahakoon, Oshadi
    et al.
    Monash University, Melbourne, VIC.
    Bartolini, Claudio
    Boulmakoul, Abdel
    Burstein, Frada
    Monash University, Melbourne, VIC.
    Loke, Seng Wai
    Zaslavsky, Arkady
    Enhancing the IT service desk function through unobtrusive user profiling, personalization and stereotyping2007In: Proceedings of the 14th Annual Workshop of HP Software University Association: hosted by the Leibniz Computing Center and the Munich Network Management Team, July 8-11, 2007 / [ed] H-G Hegering; H. Reiser; M. Schiffers; Th. Nebe, Stuttgart: Infonomic-Consulting , 2007Conference paper (Other academic)
  • 989. Alahakoon, Oshadi
    et al.
    Cruz, Lito
    Jayaputera, Glenn
    Loke, Seng Wai
    Zaslavsky, Arkady
    Assembling agents on-demand for pervasive wireless services2003In: Wireless Information Systems: Proceedings of the 2nd International Workshop on Wireless Information Systems, WIS 2003 In conjunction with ICEIS 2003, Angers, France, April 2003 / [ed] Qusay H. Mahmoud, ICEIS Press , 2003, p. 21-30Conference paper (Refereed)
  • 990.
    Alahakoon, Oshadi
    et al.
    Caulfield School of Information Technology, Monash University.
    Loke, Seng Wai
    Department of Computer Science and Computer Engineering, La Trobe University.
    Zaslavsky, Arkady
    Capturing buying behaviour using a layered user model2007In: E-Commerce and Web Technologies: 8th International Conference, EC-Web 2007, Regensburg, Germany, September 3-7, 2007. Proceedings / [ed] Giuseppe Psaila; Roland Wagner, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2007, p. 109-118Conference paper (Refereed)
    Abstract [en]

    User models are important tools for personalization, especially in ecommerce applications. But capturing dynamically changing user needs is a challenge. One of the reasons for such difficulty is that the purchasing behavior of an individual is based on a number of different aspects. In this paper we identify these aspects as a combination of demographics, domain based expectations and transactions. Since each individual can demonstrate a unique combination of these aspects, to achieve finer personalization, such individuality will have to be captured in user models. In this paper we propose such a user model architecture, which also has the ability to self-improve adapting to changes of individual behavior and long term modeling possibilities.

  • 991. Alahakoon, Oshadi
    et al.
    Loke, Seng Wai
    Zaslavsky, Arkady
    Personalization across de-centralized domains with a modular user profile architecture2005In: Proceedings of the International Conference on Information and Automation, 2005Conference paper (Refereed)
  • 992.
    Alahakoon, Oshadi
    et al.
    Monash University, Melbourne, VIC.
    Loke, Seng Wai
    Monash University, Melbourne, VIC.
    Zaslavsky, Arkady
    Unobtrusive acqusition of user information for e-commerce applications2005In: Proceedings of the Sixth International Conference on Enterprise Information Systems: Porto, Portugal, April 14 - 17, 2004 / [ed] Isabel Seruca, Setúbal: INSTICC Press, 2005, p. 3-8Conference paper (Refereed)
    Abstract [en]

    E-commerce has become a common activity among many people. Although widely used, the interfaces which users communicate with e-commerce systems are still at an early stage of development in terms of intelligence and user-friendliness. Unobtrusiveness is recognized as one of the most important desired attributes of an intelligent and friendly interface. In this paper we describe our work on an information architecture to minimize obtrusiveness. A layered information architecture supported by a structured user profile model is described in the paper. As example scenario is presented to clarify the new architecture and the development of a cost model for measuring the level of obtrusiveness is discussed

  • 993. Alahakoon, Oshadi
    et al.
    Loke, Seng Wai
    Zaslavsky, Arkady
    Use of buying behavioural characteristics in long term user models2006In: Adaptive hypermedia and adaptive web-based systems: 4th international conference, AH 2006, Dublin, Ireland, June 21 - 23, 2006 ; proceedings / [ed] Vincent Wade, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2006Conference paper (Refereed)
  • 994. Alain, Valentin
    Mineral Chemistry and Texture Paragenesis of Alteration Minerals in the Pahtohavare Cu-Au Deposit, Sweden2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Proterozoic Pahtohavare Cu-Au deposit in the northernmost part of Sweden within the Fennoscandian shield consists of a syngenetic stratiform sulphide-magnetite mineralisation (East Ore) which is uneconomic and three stratabound to discordant epigenetic Cu-Au mineralisations (Central, South-East and South Ores) hosted by the Viscaria formation. These epigenetic deposits are hosted by fine-grained albite felsite formed by alteration of graphitic schist while the East Ore is hosted by tuffite. The black graphitic schist have acted as a chemical trap for the mineralising fluids explaining the decomposition of the graphite within the schist proximal to mineralised zones and altering it into albite felsite. The past tectonic events made the Kiruna area having a favorable permeability for epigenetic solutions like saline hydrothermal fluids. This favourable permeability is one of the main important characteristic which explains the formation of Pahtohavare ores. A scapolite-biotite alteration is enveloping the albite-altered mineralised zone and occurs in all stratigraphic units. One albite alteration of the tuffite is related to the intrusion of the footwall mafic sill and the other one is an additional ore-related mineralised albitization which is distinguishable by the lack of spatial relationship with the mafic sill and the occurrence of disseminated Ferro-dolomite. Chlorite has been formed by replacement of biotite and amphibole. A negative correlation between Mg and Cl contents of amphiboles is distinguishable which indicates that Mg-Cl avoidance mechanisms can control the incorporation of halogen in the amphibole structure. Scapolite from scapolite-biotite alteration surrounding the ore-bearing albite felsites and ore veins have a dominantly marialitic composition which indicates that the alteration must have been due to highly saline fluids. The occurrence of dipyre in Pahtohavare can be explained by the fact that the formation of the deposit happened in a Na-Cl rich environment. The main ore minerals are chalcopyrite and pyrite occurring disseminated, as veinlet, or filling breccias, and they are often associated with quartz and carbonate. Pyrrhotite is locally significant. Accessory minerals such as sphalerite, galena, millerite, native gold, tellurobismuthite, altaite, molybdenite, tellurides, and native gold in epigenetic ores occur as inclusions in sulphides and quartz.Alteration zones surrounding the Pahtohavare ores have chemical and mineralogical zonations similar to Rakkurijärvi. The Mg-content of biotites decreases toward the ores of the South, East and South East zone. Addition of potassium and depletion of calcium and manganese are characteristic of the biotite-scapolite alteration zone. The ore-bearing albite carbonate alteration zone shows a depletion of K2O and an addition of Na2O, CaO and MnO. The relation between the depletion of Na and scapolitisation-albitisation is close as it is likely due to Na-Ca exchange reactions. Co-variation diagrams are good geochemical discriminants which can be used as exploration tool. The alteration characteristics of the Pahothavare deposit share similar features with other iron oxide and sulphide deposits such as e.g. Bidjovagge, Norway. The sodic alteration is the most important one because of its association to the mineralisation. There are two generations of ore-forming fluids at Pahtohavare. The main physicochemical parameters that controlled hydrothermal alteration and gold mineralisation are pH, ƒO2 and temperature. The decrease of ƒO2 triggered the replacement of pyrite by pyrrhotite and its occurrence is spatially related to the mineralisation. The magnetite-pyrite and hematite-pyrite assemblages may have buffered the pH increase and ƒO2 decrease of the ore fluids. The chloride complexes of copper and gold are the most important one concerning the transport. The destabilization of gold chloride complexes is the main mechanism of gold deposition. This destabilization is due to an increase of pH from CO2 loss, cooling and dilution of the solution. The high salinity of the fluid can be explained by the metasomatic hydration of biotite and amphibole formation. Salinity is an important factor which determines the precipitation of metals from chloride complexes. Pahtohavare is considered as a copper deposit because of the low concentrations of gold due to the low initial concentrations of gases in the ore fluid and the fluids have not reach the native gold solubility 103 ppb limit for Cl complexes but has crossed the copper 100 ppm limit for Cl complexes. The copper content of the hypersaline brines at Pahtohavare have a range of 100-500 ppm which is comparable to saline magmatic fluids of the Cloncurry district in Australia.

  • 995. Alainentalo, Anna-Lena
    et al.
    Ryytty, Maria
    Hantering av lagar och andra krav för Vägverket Region Norr2005Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 996. Alakangas, Ann-Marie
    Minireningsverk i Luleå kommun: en funktionsstudie2007Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 997. Alakangas, Henrik
    Skillnader mellan elgitarrtoner vid olika tonhöjd av LAME MP3-kodning2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 998. Alakangas, Lena
    En studie av tillverkningsprocessen av mangandioxid täckt sand2001Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 999.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Kolarctic ENBI EnviMIne2014Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The objectives of the project are to develop a methodology for environmentally safe mine closure under specific conditions in the Barents region by cross border cooperation, exchange experiences and scientific knowledge.

  • 1000.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sulphide oxidation and geochemical processes in mine tailings2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The generation of acid mine drainage (AMD) from oxidation of sulphide- bearing waste is a world wide problem, due to low pH levels and the release of metals to recipients. It is therefore important to understand the fundamental geochemical processes occurring in mine waste. The geochemistry of the drainage water from the tailings at the abandoned Laver copper mine in Northern Sweden was studied in 2001 and compared with a previous study performed in 1993. All drainage water is collected in a brook, which means that Laver is a favourable site for mass balance studies. The results show a decrease in the amount of sulphide-associated elements such as S, Cu and Zn in the drainage water, and an increase of the pH level. It has been suggested that this is due to the decrease in the sulphide oxidation rate in the tailings. Modelling the oxidation front movement using the shrinking core model gives similar results. This indicates that the sulphur transported in the drainage water could relatively well reflect the oxidation rate in the tailings. Oxygen sampling was also performed in 2001- 2002 to evaluate whether the flux of oxygen into the tailings was restricted by a vegetation cover. The results show that vegetation does not limit oxygen diffusion into the tailings. There is an atmospheric concentration throughout a profile through oxidised grass covered tailings during the whole sampling period. Oxygen concentrations at depths where sulphide oxidation occurs show seasonal variations, probably due to varying water saturation. Cemented layers were sampled at two locations in the Laver impoundment tailings, where they had been formed in spite of the low sulphide content and lack of carbonates. The aim of the study was to determine the effects of cemented layer formation on metal mobility in the tailings. The cementing agents are jarosite and Fe-oxyhydroxides. Arsenic is strongly enriched and somewhat higher concentrations of Pb, V, Mo and Hg, compared to those in unoxidised tailings, occur in these layers. Sequential extraction shows that these metals are mostly adsorbed/co-precipitated with crystalline iron oxyhydroxides. The enriched metals will probably be remobilised if changes towards more reducing conditions occur, for instance as a result of remediation of the tailings impoundment. An attempt was made to use LA-ICP-SMS to quantify the role of pyrite surfaces as scavengers of metals in oxidising mine tailings. Pyrite grains were collected from a profile through the pyrite-rich tailings at the Kristineberg mine in Northern Sweden. At each spot hit by the laser, the surface layer was analysed in the first shot, and a second shot on the same spot indicated the chemical composition of the pyrite immediately below. The crater diameter for a laser shot is known, and by estimating the crater depth and total pyrite surface, the total enrichment on pyrite grains was calculated. Results are presented for As, Cd, Co, Cu, Ni and Zn. The results clearly show that there is an enrichment of As, Cd, Cu and Zn on the pyrite surfaces below the oxidation front in the tailings, but not of Co and Ni. Arsenic is also enriched on the pyrite grains that survived in the oxidised zone. However, only 1.4 to 3.1% of the Cd and Zn released by sulphide oxidation in the oxidised zone had been enriched on the pyrite surfaces in the unoxidised tailings, but for As and Cu the corresponding figures are about 64 and 43%, respectively. The results should not be taken too literally but allow the conclusion that scavenging to pyrite surfaces is an important process for retention of As and Cu below the oxidation front in pyrite-rich tailings. Although only pyrite grains that appeared to be fresh, without surface coatings, were used in this study, the possibility of a thin layer of Fe-hydroxides occurring must be considered. Both adsorption to the pyrite directly, or to Fe-oxyhydroxides, may explain the enrichment of As, Cd, Cu and Zn on the pyrite surfaces, and, in the case of Cu, also replacement of Fe (II) by Cu(II) in pyrite.

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