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  • 451.
    Abrahamsson, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Positionering av last hos gantrykranar via direktverkan på last1988Report (Other academic)
  • 452. Abrahamsson, Terese
    et al.
    Taavo, Therese
    Manliga och kvinnliga förskollärares uppfattningar om sitt arbete: ur ett genusperspektiv2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 453. Abrahamsson, Thérese
    et al.
    Sundström, Charlotte
    Man behöver inte göra det märkvärdigare än vad det är: en studie om lärares uppfattningar av skriftliga omdömen i den individuella utvecklingsplanen.2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 454.
    Abramov, A.A.
    et al.
    Moscow State Mining University, Moscow.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Chemistry and optimal conditions for copper minerals flotation: theory and practice2005In: Mineral Processing and Extractive Metallurgy Review, ISSN 0882-7508, E-ISSN 1547-7401, Vol. 26, no 2, p. 77-143Article in journal (Refereed)
    Abstract [en]

    Reliable information on the surface state of sulphide copper minerals and regularities of sulphidization and flotation of oxidized copper minerals, the composition of sorption layer on the mineral surface forming during its interaction with xanthate or dixanthogen, and the influence of collector forms sorption on the copper minerals floatability and on the optimal conditions for these minerals flotation and depression has been obtained at present. The determined physicochemical models in the form of quantitative equations have been derived for the optimal conditions of flotation and depression of copper minerals under changing pH value and of sodium sulphide, lime, cyanide, zinc–cyanide complexes additions. The equations derived were proven in the laboratory and industrial scale and can be used both in automatic control systems at plants and for improvement of technological processes of selective flotation of copper containing ores.

  • 455.
    Abramovic, Shoshana
    et al.
    University of Haifa.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science. University of Tromsø ; The Arctic University of Norway, Narvik.
    Fejer and Hermite–Hadamard Type Inequalitiesfor N-Quasiconvex Functions2017In: Mathematical notes of the Academy of Sciences of the USSR, ISSN 0001-4346, E-ISSN 1573-8876, Vol. 102, no 5-6, p. 599-609Article in journal (Refereed)
    Abstract [en]

    Abstract—Some new extensions and refinements of Hermite–Hadamard and Fejer type inequali-ties for functions which are N-quasiconvex are derived and discussed.

  • 456.
    Abramovich, S.
    et al.
    Department of Mathematics, University of Haifa, Haifa, Israel.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science. UIT The Arctic University of Norway, Narvik, Norway.
    Extensions and Refinements of Fejer and Hermite–Hadamard Type Inequalities2018In: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 21, no 3, p. 759-772Article in journal (Refereed)
    Abstract [en]

    In this paper extensions and refinements of Hermite-Hadamard and Fejer type inequalities are derived including monotonicity of some functions related to the Fejer inequality and extensions for functions, which are 1-quasiconvex and for function with bounded second derivative. We deal also with Fejer inequalities in cases that p, the weight function in Fejer inequality, is not symmetric but monotone on [a, b] .

  • 457.
    Abramovich, Shosana
    et al.
    Department of Mathematics, University of Haifa.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Some New Refined Hardy Type Inequalities with Breaking Points p = 2 or p = 32014In: Concrete Operators, Spectral Theory, Operators in Harmonic Analysis and Approximation: 22nd International Workshop in Operator Theory and its Applications, Sevilla, July 2011 / [ed] Manuel Cepedello Boiso; Håkan Hedenmalm; Marinus A. Kaashoek; Alfonso Montes Rodríguez; Sergei Treil, Basel: Encyclopedia of Global Archaeology/Springer Verlag, 2014, p. 1-10Conference paper (Refereed)
    Abstract [en]

    For usual Hardy type inequalities the natural “breaking point” (the parameter value where the inequality reverses) is p = 1. Recently, J. Oguntuase and L.-E. Persson proved a refined Hardy type inequality with breaking point at p = 2. In this paper we show that this refinement is not unique and can be replaced by another refined Hardy type inequality with breaking point at p = 2. Moreover, a new refined Hardy type inequality with breaking point at p = 3 is obtained. One key idea is to prove some new Jensen type inequalities related to convex or superquadratic funcions, which are also of independent interest

  • 458.
    Abramovich, Shoshana
    et al.
    Department of Mathematics, University of Haifa.
    Krulić, Kristina
    Faculty of Textile Technology, University of Zagreb.
    Pečarić, Josip
    Faculty of Textile Technology, University of Zagreb.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Some new refined Hardy type inequalities with general kernels and measures2010In: Aequationes Mathematicae, ISSN 0001-9054, E-ISSN 1420-8903, Vol. 79, no 1-2, p. 157-172Article in journal (Refereed)
    Abstract [en]

    We state and prove some new refined Hardy type inequalities using the notation of superquadratic and subquadratic functions with an integral operator Ak defined by, where k: Ω1 × Ω2 is a general nonnegative kernel, (Ω1, μ1) and (Ω2, μ2) are measure spaces and,. The relations to other results of this type are discussed and, in particular, some new integral identities of independent interest are obtained.

  • 459.
    Abramovich, Shoshana
    et al.
    Department of Mathematics, University of Haifa.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Inequalities for averages of quasiconvex and superquadratic functions2016In: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 19, no 2, p. 535-550Article in journal (Refereed)
    Abstract [en]

    For n ε ℤ+ we consider the difference Bn-1 (f)-Bn(f):= 1/an n-1/ηi=0 f(ai/an-1)-1/an+1 nηi=0f(ai/an) where the sequences{ai} and {ai-ai-1} are increasing. Some lower bounds are derived when f is 1-quasiconvex and when f is a closely related superquadratic function. In particular, by using some fairly new results concerning the so called "Jensen gap", these bounds can be compared. Some applications and related results about An-1 (f)-An(f):= 1/an n-1/ηi=0 f(ai/an-1)-1/an+1 nηi=0f(ai/an) are also included.

  • 460.
    Abramovich, Shoshana
    et al.
    Department of Mathematics, University of Haifa.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Some new estimates of the ‘Jensen gap’2016In: Journal of inequalities and applications (Print), ISSN 1025-5834, E-ISSN 1029-242X, Vol. 2016, article id 39Article in journal (Refereed)
    Abstract [en]

    Let (μ,Ω) be a probability measure space. We consider the so-called ‘Jensen gap’ J(φ,μ,f)=∫ Ω φ(f(s))dμ(s)−φ(∫ Ω f(s)dμ(s)) for some classes of functions φ. Several new estimates and equalities are derived and compared with other results of this type. Especially the case when φ has a Taylor expansion is treated and the corresponding discrete results are pointed out.

  • 461.
    Abramovich, Shoshana
    et al.
    University of Haifa.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Some new scales of refined Hardy type inequalities via functions related to superquadracity2013In: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 16, no 3, p. 679-695Article in journal (Refereed)
    Abstract [en]

    For the Hardy type inequalities the "breaking point" (=the point where the inequality reverses) is p = 1. Recently, J. Oguntoase and L. E. Persson proved a refined Hardy type inequality with a breaking point at p = 2. In this paper we prove a new scale of refined Hardy type inequality which can have a breaking point at any p ≥ 2. The technique is to first make some further investigations for superquadratic and superterzatic functions of independent interest, among which, a new Jensen type inequality is proved

  • 462.
    Abramovich, Shoshana
    et al.
    University of Haifa, Department of Mathematics.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Pecaric, Josip
    University of Zagreb.
    Varosanec, Sanja
    University of Zagreb.
    General inequalities via isotonic subadditive functionals2007In: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 10, no 1, p. 15-28Article in journal (Refereed)
    Abstract [en]

    In this manuscript a number of general inequalities for isotonic subadditive functionals on a set of positive mappings are proved and applied. In particular, it is pointed out that these inequalities both unify and generalize some general forms of the Holder, Popoviciu, Minkowski, Bellman and Power mean inequalities. Also some refinements of some of these results are proved.

  • 463.
    Abramovich, Shoshana
    et al.
    University of Haifa.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Samko, Natasha
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    On some new developments of Hardy-type inequalities2012In: 9th International Conference on Mathematical Problems in Engineering, Aerospace and Sciences: ICNPAA 2012 / [ed] Seenith Sivasundaram, Melville, NY: American Institute of Physics (AIP), 2012, p. 739-746Conference paper (Refereed)
    Abstract [en]

    In this paper we present and discuss some new developments of Hardy-type inequalities, namely to derive (a) Hardy-type inequalities via a convexity approach, (b) refined scales of Hardy-type inequalities with other “breaking points” than p = 1 via superquadratic and superterzatic functions, (c) scales of conditions to characterize modern forms of weighted Hardy-type inequalities.

  • 464.
    Abramovich, Shoshana
    et al.
    Department of Mathematics, University of Haifa.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Samko, Natasha
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    On γ-quasiconvexity, superquadracity and two-sided reversed Jensen type inequalities2015In: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 18, no 2, p. 615-627Article in journal (Refereed)
    Abstract [en]

    In this paper we deal with γ -quasiconvex functions when −1γ 0, to derive sometwo-sided Jensen type inequalities. We also discuss some Jensen-Steffensen type inequalitiesfor 1-quasiconvex functions. We compare Jensen type inequalities for 1-quasiconvex functionswith Jensen type inequalities for superquadratic functions and we extend the result obtained forγ -quasiconvex functions to more general classes of functions.

  • 465.
    Abramovich, Shoshana
    et al.
    Department of Mathematics, University of Haifa.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Samko, Natasha
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Some new scales of refined Jensen and Hardy type inequalities2014In: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 17, no 3, p. 1105-1114Article in journal (Refereed)
    Abstract [en]

    Some scales of refined Jensen and Hardy type inequalities are derived and discussed. The key object in our technique is ? -quasiconvex functions K(x) defined by K(x)x-? =? (x) , where Φ is convex on [0,b) , 0 < b > ∞ and γ > 0.

  • 466. Abramsson, Ida
    et al.
    Johansson, Krister
    Internet - informationskälla och kommunikationsmedel: ett försök att utveckla elevernas förmåga att använda Internet i skolarbetet1999Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 467. Abramsson, MaiGreth
    et al.
    Byström, Eva
    Personers upplevelser av att lära sig leva med typ-2 diabetes2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 468.
    Abrishambaf, Reza
    et al.
    Department of Engineering Technology, Miami University, Hamilton, OH.
    Bal, Mert
    Department of Engineering Technology, Miami University, Hamilton, OH.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Distributed home automation system based on IEC61499 function blocks and wireless sensor networks2017In: Proceedings of the IEEE International Conference on Industrial Technology, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1354-1359, article id 7915561Conference paper (Refereed)
    Abstract [en]

    In this paper, a distributed home automation system will be demonstrated. Traditional systems are based on a central controller where all the decisions are made. The proposed control architecture is a solution to overcome the problems such as the lack of flexibility and re-configurability that most of the conventional systems have. This has been achieved by employing a method based on the new IEC 61499 function block standard, which is proposed for distributed control systems. This paper also proposes a wireless sensor network as the system infrastructure in addition to the function blocks in order to implement the Internet-of-Things technology into the area of home automation as a solution for distributed monitoring and control. The proposed system has been implemented in both Cyber (nxtControl) and Physical (Contiki-OS) level to show the applicability of the solution

  • 469.
    Abudayyeh, H.A.
    et al.
    Department of Physics, Al-Quds University, Jerusalem.
    Barghouthi, I.A.
    Department of Physics, Al-Quds University, Jerusalem.
    Slapak, Rikard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Nilsson, Hans
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Centrifugal acceleration at high altitudes above the polar cap: A Monte Carlo simulation2015In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 120, no 8, p. 6409-6426Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo simulation was used to study the outflow of O+ and H+ ions along three flight trajectories above the polar cap up to altitudes of about 15 RE. Barghouthi (2008) developed a model on the basis of altitude and velocity-dependent wave-particle interactions and a radial geomagnetic field which includes the effects of ambipolar electric field and gravitational and mirror forces. In the present work we improve this model to include the effect of the centrifugal force, with the use of relevant boundary conditions. In addition, the magnetic field and flight trajectories, namely, the central polar cap (CPC), nightside polar cap (NPC), and cusp, were calculated using the Tsyganenko T96 model. To simulate wave-particle interactions, the perpendicular velocity diffusion coefficients for O+ ions in each region were determined such that the simulation results fit the observations. For H+ ions, a constant perpendicular velocity diffusion coefficient was assumed for all altitudes in all regions as recommended by Nilsson et al. (2013). The effect of centrifugal acceleration was simulated by considering three values for the ionospheric electric field: 0 (no centrifugal acceleration), 50, and 100 mV/m. It was found that the centrifugal acceleration increases the parallel bulk velocity and decreases the parallel and perpendicular temperatures of both ion species at altitudes above about 4 RE. Centrifugal acceleration also increases the temperature anisotropy at high altitudes. At a given altitude, centrifugal acceleration decreases the density of H+ ions while it increases the density of O+ ions. This implies that with higher centrifugal acceleration more O+ ions overcome the potential barrier. It was also found that aside from two exceptions centrifugal acceleration has the same effect on the velocities of both ions. This implies that the centrifugal acceleration is universal for all particles. The parallel bulk velocities at a given value of ionospheric electric field were highest in the cusp followed by the CPC followed by the NPC. In this study a region of no wave-particle interaction was assumed in the CPC and NPC between 3.7 and 7.5 RE. In this region the perpendicular temperature was found to decrease with altitude due to perpendicular adiabatic cooling.

  • 470. Abulkheir, Jasmine
    et al.
    Olldén, Lisa
    Reliabilitet och validitet av mätmetoder vid vila och aktivering av Transversus abdominis och Multifidus: en systematisk litteraturstudie om EMG och ultraljud2010Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 471. Abushaar, Ubah
    Papperslösa flyktingars rätt till subventionerad hälso- och sjukvård2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 472. Abyareh, Reza
    Tourism attractions and their influence on handicraft employment in Isfahan2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Tourism attractions and handicrafts are the main and important factors in attraction of tourist and following it increasing occupation in the present societies. Isfahan, as one of the most important historical cities in our country has special position both from viewpoint of tourism attractions [Ancient Works] and also from viewpoint of handicrafts [variety, quality and oldness of handicrafts] has special position. In this thesis I made effort to research for the relation between tourism attractions and increasing occupation in the handicrafts section. In this thesis it was determined that there is direct relation between tourism attractions and attracting tourist as well as increasing occupation in the handicrafts section [training and establishment of workshop].

  • 473.
    Abylayeva, Akbota
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Inequalities for some classes of Hardy type operators and compactness in weighted Lebesgue spaces2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This PhD thesis is devoted to investigate weighted differential Hardy inequalities and Hardy-type inequalities with the kernel when the kernel has an integrable singularity, and also the additivity of the estimate of a Hardy type operator with a kernel.The thesis consists of seven papers (Papers 1, 2, 3, 4, 5, 6, 7) and an introduction where a review on the subject of the thesis is given. In Paper 1 weighted differential Hardy type inequalities are investigated on the set of compactly supported smooth functions, where necessary and sufficient conditions on the weight functions are established for which this inequality and two-sided estimates for the best constant hold. In Papers 2, 3, 4 a more general class of -order fractional integrationoperators are considered including the well-known classical Weyl, Riemann-Liouville, Erdelyi-Kober and Hadamard operators. Here 0 <  < 1. In Papers 2 and 3 the boundedness and compactness of two classes of such operators are investigated namely of Weyl and Riemann-Liouville type, respectively, in weighted Lebesgue spaces for 1 < p ≤ q < 1 and 0 < q < p < ∞. As applications some new results for the fractional integration operators of Weyl, Riemann-Liouville, Erdelyi-Kober and Hadamard are given and discussed.In Paper 4 the Riemann-Liouville type operator with variable upper limit is considered. The main results are proved by using a localization method equipped with the upper limit function and the kernel of the operator. In Papers 5 and 6 the Hardy operator with kernel is considered, where the kernel has a logarithmic singularity. The criteria of the boundedness and compactness of the operator in weighted Lebesgue spaces are given for 1 < p ≤ q < ∞ and 0 < q < p < ∞, respectively. In Paper 7 we investigated the weighted additive estimates for integral operators K+ and K¯ defined by

    K+ ƒ(x) := ∫ k(x,s) ƒ(s)ds,  K¯ ƒ(x) := ∫ k(x,s)ƒ(s)ds.

    It is assumed that the kernel k of the operators K+and K- belongs to the general Oinarov class. We derived the criteria for the validity of these addittive estimates when 1 ≤ p≤ q < ∞

  • 474.
    Abylayeva, Akbota M.
    et al.
    Department of Mechanics and Mathematics, L.N. Gumilyov Eurasian National University, Astana .
    Oinarov, Ryskul
    Department of Mechanics and Mathematics, L.N. Gumilyov Eurasian National University, Astana.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Boundedness and compactness of a class of Hardy type operators2016In: Journal of inequalities and applications (Print), ISSN 1025-5834, E-ISSN 1029-242X, no 1, article id 324Article in journal (Refereed)
    Abstract [en]

    We establish characterizations of both boundedness and of compactness of a general class of fractional integral operators involving the Riemann-Liouville, Hadamard, and Erdelyi-Kober operators. In particular, these results imply new results in the theory of Hardy type inequalities. As applications both new and well-known results are pointed out.

  • 475.
    Abylayeva, Akbota M.
    et al.
    Department of Mechanics and Mathematics, L.N. Gumilyov Eurasian National University, Astana, Kazakhstan .
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science. UiT, Tromso, Norway. RUDN University, Moscow, Russia.
    Hardy type inequalities and compactness of a class of integral operators with logarithmic singularities2018In: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 21, no 1, p. 201-215, article id 21-16Article in journal (Refereed)
    Abstract [en]

    We establish criteria for both boundedness and compactness for some classes of integraloperators with logarithmic singularities in weighted Lebesgue spaces for cases 1 < p 6 q <¥ and 1 < q < p < ¥. As corollaries some corresponding new Hardy inequalities are pointedout.1

  • 476.
    Abylayeva, A.M.
    et al.
    L. N.Gumilev Eurasian National University, Khazakstan.
    Baiarystanov, A.O.
    L. N.Gumilev Eurasian National University, Khazakstan.
    Persson, Lars-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Wall, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Additive weighted Lp estimates of some classes of integral operators involving generalized Oinarov Kernels2017In: Journal of Mathematical Inequalities, ISSN 1846-579X, E-ISSN 1848-9575, Vol. 11, no 3, p. 683-694Article in journal (Refereed)
    Abstract [en]

    Abstract. Inequalities of the formkuK f kq 6C(kr f kp +kvH f kp) , f > 0,are considered, where K is an integral operator of Volterra type and H is the Hardy operator.Under some assumptions on the kernel K we give necessary and sufficient conditions for suchan inequality to hold.1

  • 477.
    Acar, Sevil
    et al.
    Department of Economics, Istanbul Kemerburgaz University, Bagcilar, Turkey.
    Söderholm, Patrik
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Social Sciences.
    Brännlund, Runar
    Centre for Environmental and Resource Economics, Umeå School of Business and Economics, Umeå University.
    Convergence of per capita carbon dioxide emissions: implications and meta-analysis2018In: Climate Policy, ISSN 1469-3062, E-ISSN 1752-7457, Vol. 18, no 4, p. 512-525Article in journal (Refereed)
    Abstract [en]

    There is a rich empirical literature testing whether per capita carbon dioxide emissions tend to converge over time and across countries. This article provides a meta-analysis of the results from this research, and discusses how carbon emissions convergence may be understood in, for instance, the presence of international knowledge spillovers and policy convergence. The results display evidence of either divergence or persistent gaps at the global level, but convergence of per capita carbon dioxide emissions between richer industrialized countries. However, the results appear sensitive to the choice of data sample and choice of convergence concept, e.g. stochastic convergence versus β-convergence. Moreover, peer-reviewed studies have a higher likelihood of reporting convergence in carbon dioxide emissions compared to non-refereed work. POLICY RELEVANCE The empirical basis for an egalitarian rule of equal emissions per capita in the design of global climate agreements is not solid; this supports the need to move beyond single allocation rules, and increase knowledge about the impacts of combined scenarios. However, even in the context of the 2015 Paris Agreement with its emphasis on voluntary contributions and ‘national circumstances’, different equity-based principles could serve as useful points of reference for how the remaining carbon budget should be allocated

  • 478. Achani, D.
    et al.
    Eriksson, Magnus
    SINTEF Materials and chemistry, Applied mechanics and corrosion, Trondheim, Norway.
    Hopperstad, O.S.
    Lademo, O.-G.
    Modelling of local necking and fracture in aluminium alloys2007In: Materials processing and design : modeling, simulation and applications ; NUMIFORM '07: proceedings of the 9th International Conference on Numerical Methods in Industrial Forming Processes, Porto, Portugal, 17 - 21 June 2007 / [ed] J.M.A. Cesar de Sa; Abel D. Santos, American Institute of Physics (AIP), 2007, p. 111-116Conference paper (Refereed)
  • 479.
    Acharya, Soam
    et al.
    Cornell University, Ithaca.
    Smith, Brian P
    Cornell University, Ithaca.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Characterizing user access to videos on the World Wide Web1999In: Multimedia computing and networking 2000 / [ed] Klara Nahrstedt, Bellingham, Wash: SPIE - International Society for Optical Engineering, 1999, p. 130-141Conference paper (Refereed)
    Abstract [en]

    Despite evidence of rising popularity of video on the web (or VOW), little is known about how users access video. However, such a characterization can greatly benefit the design of multimedia systems such as web video proxies and VOW servers. Hence, this paper presents an analysis of trace data obtained from an ongoing VOW experiment in Lulea University of Technology, Sweden. This experiment is unique as video material is distributed over a high bandwidth network allowing users to make access decisions without the network being a major factor. Our analysis revealed a number of interesting discoveries regarding user VOW access. For example, accesses display high temporal locality: several requests for the same video title often occur within a short time span. Accesses also exhibited spatial locality of reference whereby a small number of machines accounted for a large number of overall requests. Another finding was a browsing pattern where users preview the initial portion of a video to find out if they are interested. If they like it, they continue watching, otherwise they halt it. This pattern suggests that caching the first several minutes of video data should prove effective. Lastly, the analysis shows that, contrary to previous studies, ranking of video titles by popularity did not fit a Zipfian distribution.

  • 480. Acheampong, Roland
    et al.
    Gyawu, Peter
    E-commerce and Internet Adoption among SMEs Non-traditional Exporters: A Case Study of Ghanaian Fruit Exporters2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 481. Achereiner, Frédéric
    New polymer foams and their applications2003Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master’s Thesis deals with the development of new polymer foams with very small cell size, the PolyHIPEs, and their applications. The area of application studied was papermaking. The porous polymers were used as filler material in paper sheets, with the purpose of increasing light scattering in light-weight paper grades, and thus their brightness and opacity. The work was divided in two parts: The first part concerns the development of the polymer foams themselves. Since this is a rather novel area, only few research teams in the world are currently working with these. So the development had to be started nearly from scratch. This implies starting with the preparation of a High Internal Phase Emulsion (HIPE) with 90% of water and a styrene-based oil phase. This was done by using the Phase-Inversion Temperature method. The composition of the system and all the other parameters were tailored to obtain the smallest droplet size possible. Then the oil phase of the HIPE was polymerised, to form the PolyHIPE. After washing and drying, this gave a dry monolith of highly porous polymer. The internal structure, observed by Scanning Electron Microscopy, was very specific to PolyHIPE: polyhedral cells interconnected through holes in the cells walls. The cell size was in the range of 1 to 2 µm and the connecting holes were mainly between 0.1 and 0.6 µm in diameter. The second part deals with the application of PolyHIPEs to papermaking. To be used in paper, the new polymer foam had first to be reduced into a powder, while keeping intact the specific internal structure. This was done by crushing it in ethanol using an Ultraturrax apparatus. Then test were done to determine the quantity of filler retained in the paper. The results indicated that only 40 to 50% of the filler was mechanically trapped in the paper. Retention agents were of no real use. Finally, paper sheets containing filler were prepared. Observation with Scanning Electron Microscopy confirmed that the filler was retained in the paper. Reflectance measurements indicated a positive effect on brightness and opacity. More experiments have to be done to determine exactly the effects of PolyHIPEs in paper, but these new polymer foams have definitely a future in this area.

  • 482.
    Achi, Elif
    et al.
    Eurocopter Deutschland GmbH (ECD), Stress and Dynamic System Department.
    Talreja, Ramesh
    Characterization of viscoelasticity and damage in high temperature polymer matrix composites2006In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 66, no 14, p. 2506-2519Article in journal (Refereed)
    Abstract [en]

    This paper describes a thermodynamics based model for viscoelastic composites with damage and illustrates its use in characterization of viscoelastic response of polymer matrix woven fabric composites subjected to loading at high temperatures. The characterization is conducted by an experimental method aided by finite element (FE) modeling. The experimental characterization is based on creep data obtained under constant loads of different magnitudes and at different temperatures, and on recovery data collected after unloading. A carbon fiber/polyamide resin woven composite with glass transition temperature (Tg) of around 380 °C was used in the experimental program. A FE model was developed to determine the non-linear viscoelastic response by implementing incremental constitutive relations into an ABAQUS® code. The laminate viscoelastic properties were obtained by finite element micromechanics analysis using the neat resin data as input. Comparing its results with creep-recovery test data at different temperature and stress levels validated the FE model. There are several factors affecting the viscoelastic behavior of polymer matrix composites such as temperature, moisture and stress level. Accordingly, a large number of tests need to be performed to characterize the viscoelastic response experimentally for each fiber-matrix combination. For this purpose an efficient and systematic experimental procedure was used to understand the effects of temperature and stress level on the viscoelastic response, to clarify the damage-viscoelasticity coupling and to determine the viscoelastic properties of the material system

  • 483.
    Achleitner, Stefan
    et al.
    Unit of Hydraulic Engineering, University of Innsbruck.
    Schröber, Johannes
    AlpS - Centre for Climate Change Adaptation Technologies, Innsbruck.
    Rinderer, Michael
    Hydrology and Climate Unit, Department of Geography, University of Zurich.
    Leonhardt, Günther
    Unit of Environmental Engineering, University of Innsbruck.
    Schöberl, Friedrich
    Institute of Geography, University of Innsbruck.
    Kirnbauer, Robert
    Institute of Hydraulic Engineering and Water Resources Management, Vienna University of Technology.
    Schönlaub, Helmut
    TIWAG - Tiroler Wasserkraft AG.
    Analyzing the operational performance of the hydrological models in an alpine flood forecasting system2012In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 412-413, p. 90-100Article in journal (Refereed)
    Abstract [en]

    During recent years a hybrid model has been set up for the operational forecasting of flood discharges in the 6750km 2 Tyrolean part of the River Inn catchment in Austria. The catchment can be characterized as a typical alpine area with large variations in altitude. The paper is focused on the error analysis of discharge forecasts of four main tributary catchments simulated with hydrological water balance models. The selected catchments cover an area of 2230km 2, where the non-glaciated and glaciated parts are modeled using the semi-distributed HQsim and the distributed model SES, respectively.The forecast errors are evaluated as a function of forecast lead time and forecasted discharge magnitude using 14 events from 2007 to 2010. The observed and forecasted precipitation inputs were obtained under operational conditions. The mean relative bias of the forecasted discharges revealed to be constant with regard to the forecast lead time, varying between 0.2 and 0.25 for the different catchments. The errors as a function of the forecasted discharge magnitude showed large errors at lower values of the forecast hydrographs, where errors decreased significantly at larger discharges being relevant in flood forecasting

  • 484. Acimovic, Tomislav
    Kartläggning och stabilisering av ASEA-SKF processen vid Erasteel Kloster AB, Söderfors2002Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 485.
    Ackeby, Susanne
    et al.
    STRI AB.
    Ohlsson, Lars
    Falbygdens Energi AB.
    Etherden, Nicholas
    STRI.
    Regulatory Aspects of Energy Storage in Sweden2013Conference paper (Refereed)
    Abstract [en]

    This paper highlights the possibilities and limitations of investing in energy storage for use at distribution level under the existing regulatory framework in Sweden. The paper further gives a brief overview of possible applications and ownership models for energy storage in a distribution grid. It was concluded that it is allowed for a network operator to own an energy-storage installation; there are however restrictions in the use of the installation for trade in electricity. A general observation from the study was that there are uncertainties in the interpretation of the laws and regulations due to the complete absence of experience in the use of grid-size energy storage.

  • 486.
    Ackelid, Emma
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Stenmark, Gabriella
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Konsumenters uppfattning av hållbarhetsmärkningar i dagligvaruhandeln: Hur köpbeslutet påverkas2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Hållbarhet är en stark faktor som påverkar både konsumenter och företag i växande utsträckning. Att medvetet konsumera i enlighet med hållbara riktlinjer ligger i många konsumenters intresse, och företag utvecklar kontinuerligt strategier för att bemöta konsumentbehov och höja sin försäljning. I takt med detta ökar utbudet av hållbart märkta produkter och hållbarhetsmärkningar. För konsumenter innebär detta större valmöjligheter men också eventuella svårigheter då hållbarhetsmärkningar ofta upplevs snarlika och svåra att förstå betydelsen bakom, vilket i sin tur kan ha en motverkande effekt på konsumenters köpbeslut. Syftet med denna studie var därför att undersöka hur konsumenter i dagligvaruhandeln ställer sig till svenskt etablerade hållbarhetsmärkningar på likvärdiga produkter, för att utforska hur hållbarhetsmärkningar påverkar konsumenters köpbeslut vid köptillfället. Studien eftersträvade att identifiera de starkaste faktorerna som ligger bakom konsumenters beslut att köpa eller inte köpa hållbart märkta produkter. Avsikten var att ge företag/varumärken en bild av vad konsumenterna behöver för att effektivt vägledas i sitt köpbeslut. Insamling av data genomfördes genom enkäter med kvalitativ karaktär då studien avsåg att belysa konsumentåsikter kopplade till konsumentbeteende. Urvalet som inkluderades i studien utgjordes av individer som köper produkter i dagligvaruhandeln. Analys av data skedde med utgångspunkt i grundad teori där nyckelord och mönster mellan respondenter och svar identifierades och tolkades. Resultatet av studien visade att konsumenter främst påverkas i köpriktning vid köp av hållbart märkta produkter till följd av miljömässiga omvärldseffekter och personliga effekter på den egna hälsan, men även till viss del till följd av omvärldseffekter kopplade till socialt ansvarstagande samt tillgänglighet av information. Bristande tilltro som skapar associationer till opålitlighet samt bristande förståelse till följd av dålig kunskap är de enda faktorerna som har påverkan på köpbeslut i icke-köpriktningen enligt resultatet av studien. Genom att belysa de faktorer som påverkar konsumenter i köpriktning och motverka de faktorer som påverkar konsumenter i icke-köpriktning, kan företag/varumärken uppnå företagsnytta.

  • 487. Ackermann, Cecilia
    Rekryteringscenter: En centralisering av Skellefteå kommuns rekryteringsarbete2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 488. Ackermann, Christina
    Bending of high strength steel2008Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this project, which was done in cooperation with the company SSAB Hard and Special Steels, was to find the minimal bending radius for five different steels with two different bending methods. In order to realise that, the project was divided into two different parts, the material characterisation and the forming operations. The material characterization was composed of different methods, optical and scanning electron microscopy, hardness and tensile test and x-ray diffraction. During the forming part two different methods were used, the corner bending and the press bending, which were performed respectively in the SSAB laboratory in Borlänge and at the company Svetjänst in Arnemark. During the material characterisation various findings were made, eg the deformation level varied with depth into the materials, a high deformation and a strong texture was found at the surface layer of the material, which decreases by going deeper into the middle of the material. Also cracks in the surface layer of the materials were found. The high deformation with the cracks caused the failure during the bending operations, as the surface layer was also the most loaded during bending and consequently, cracks can open and be easily formed. The direction of the surface texture in cooperation with the crack orientation can also explain the different behaviour of the samples bended in different directions. The tensile and hardness test delivered uniform results with a small standard deviation, which would indicate consistency, however this result must be taken with caution, because the tests were made only with material from one position in one roll and therefore may not be representative of a full roll or take into account production variations. A difference in bending behaviour was seen between the different bending directions in both tests, however the magnitude of this difference was very different between the two test methods. This is difficult to explain because the two tests were made in different places and by different people without providing detailed information about the test procedure and without my direct oversight. Therefore it is difficult to directly compare the two tests and thus isolate the method specific factors that influence the results. Some factors that may have a big influence, for example the forming speed, were not controlled in these tests. For the press bending a study was also made about the springback in the materials, which is dependent on the strength and the residual stresses in the material. In general one can say that the springback increases with the increasing strength in the material. But there were also exceptions, which can be explained via defects in the material, which were found in the base and also in the cold rolled material. Also the material with the highest deformation degree by cold rolling had the highest springback despite of the lowest strength, but there the main influence has to be the residual stresses which are already introduced during rolling. The conclusions of this project are the as follows: - The highly deformed surface layer is responsible for defects during the bending sequence - The texture is the highest in the surface layer, which causes the different results in different bending directions - The low statistical variation for the few tests performed here in this project are expected to grow with larger testing sequences with samples taken from across the roll and from different production lines. - The different testing sequences make it difficult to compare the bending methods. These conclusions make it difficult to give a general minimal bending radius for these materials because the radius found is specific to a particular material and a particular test. The results for the tests performed here are given in the body of the report.

  • 489.
    Ackermann, N.L.
    et al.
    Clarkson University, Department of Civil and Environmental Engineering, Potsdam, NY.
    Shen, Hung Tao
    Clarkson University, Department of Civil and Environmental Engineering, Potsdam, NY.
    Olsson, P.
    Luleå tekniska universitet.
    Local scour around circular piers under ice covers2002In: Ice in the environment: proceedings 16th International Symposium on Ice, Dunedin, New Zealand, 2 - 6 December 2002 / [ed] Vernon A. Squire, Dunedin: Dep. of Physic, Univ. of Otago , 2002, p. 149-155Conference paper (Refereed)
    Abstract [en]

    This paper presents a laboratory investigation on the effect of ice cover on local scour around circular bridge piers. Experiments were performed in a 12-meter flume with recirculating sediment discharge. Both smooth and rough artificial covers were used. The bed material consisted of uniform ripple-forming sand. The tests were run for both clear water as well as live bed conditions. The results showed that for equivalent averaged flow velocities the existence of an ice cover could increase the local scour depth scour by 25 to 35 % from the free surface condition. The largest difference occurs at a live bed condition when the flow velocity, U, is in the rage of 1.5 to 2 times of the critical velocity for bed movement, U (sub c) . A rough cover gives slightly larger scour depth than a smooth cover. The movement of bed forms led to variations of scour depth with time.

  • 490.
    Acosta, April Anne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Behaviour of the Cold-formedTrapezoidal Sheet Overlap Jointin a Gerber Lapped Connection2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 491.
    Adalat, Mohsin
    et al.
    COSMOSE Research Group, Department of Computer Science, COMSATS University Islamabad, Islamabad, Pakistan.
    Niazi, Muaz A.
    COSMOSE Research Group, Department of Computer Science, COMSATS University Islamabad, Islamabad, Pakistan.
    Vasilakos, Athanasios
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Variations in power of opinion leaders in online communication networks2018In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 5, no 10, article id 180642Article in journal (Refereed)
    Abstract [en]

    Online social media has completely transformed how we communicate with each other. While online discussion platforms are available in the form of applications and websites, an emergent outcome of this transformation is the phenomenon of ‘opinion leaders’. A number of previous studies have been presented to identify opinion leaders in online discussion networks. In particular, Feng (2016 Comput. Hum. Behav. 54, 43–53. (doi:10.1016/j.chb.2015.07.052)) has identified five different types of central users besides outlining their communication patterns in an online communication network. However, the presented work focuses on a limited time span. The question remains as to whether similar communication patterns exist that will stand the test of time over longer periods. Here, we present a critical analysis of the Feng framework both for short-term as well as for longer periods. Additionally, for validation, we take another case study presented by Udanor et al. (2016 Program 50, 481–507. (doi:10.1108/PROG-02-2016-0011)) to further understand these dynamics. Results indicate that not all Feng-based central users may be identifiable in the longer term. Conversation starter and influencers were noted as opinion leaders in the network. These users play an important role as information sources in long-term discussions. Whereas network builder and active engager help in connecting otherwise sparse communities. Furthermore, we discuss the changing positions of opinion leaders and their power to keep isolates interested in an online discussion network.

  • 492.
    Adaldo, Antonio
    et al.
    Department of Automatic Control, School of Electrical Engineering, KTH Royal Institute of Technology.
    Mansouri, Sina Sharif
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Kanellakis, Christoforos
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Dimarogonas, Dimos V.
    Department of Automatic Control, School of Electrical Engineering, KTH Royal Institute of Technology.
    Johansson, Karl H.
    Department of Automatic Control, School of Electrical Engineering, KTH Royal Institute of Technology.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Cooperative coverage for surveillance of 3D structures2017In: IEEE International Conference on Intelligent Robots and Systems, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1838-1845, article id 8205999Conference paper (Refereed)
    Abstract [en]

    In this article, we propose a planning algorithm for coverage of complex structures with a network of robotic sensing agents, with multi-robot surveillance missions as our main motivating application. The sensors are deployed to monitor the external surface of a 3D structure. The algorithm controls the motion of each sensor so that a measure of the collective coverage attained by the network is nondecreasing, while the sensors converge to an equilibrium configuration. A modified version of the algorithm is also provided to introduce collision avoidance properties. The effectiveness of the algorithm is demonstrated in a simulation and validated experimentally by executing the planned paths on an aerial robot.

    The full text will be freely available from 2019-12-14 11:35
  • 493.
    Adam, A.
    et al.
    University of Salford.
    Howcroft, Debra
    Richardson, H.
    University of Salford.
    A decade of neglect: Reflecting on gender and IS2004In: New technology, work and employment, ISSN 0268-1072, E-ISSN 1468-005X, Vol. 19, no 3, p. 222-240Article in journal (Refereed)
    Abstract [en]

    This paper presents the case that research on gender and information systems (IS), from both quantitative and qualitative traditions, is problematic as the concept of gender continues to remain under-theorised. This will be elaborated upon with a critique of some recent qualitative and quantitative research papers that have been published in key IS journals within a ten-year period.

  • 494.
    Adam, Jonsson
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    On permutations and equity among generationsIn: Article in journal (Other academic)
    Abstract [en]

    In the literature on intergenerational justice, there is a widely held view that in order to live up to the utilitarian ideal of equal regard for all individuals, including those who have not yet been born, we must impose infinite permutation invariance conditions known as axioms of extended anonymity. I argue that such conditions do not bear relevance to the utilitarian ideal. I do so by showing that all examples that have been used to motivate extended anonymity axioms can be accounted for with an alternative principle that is supported independently.

  • 495.
    Adamo, Nasrat
    et al.
    LTU team.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mosul Dam Full Story: Safety Evaluations of Mosul Dam2016In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 6, no 3, p. 185-212Article in journal (Refereed)
    Abstract [en]

    Mosul Dam is the second biggest dam in the Middle East due to the capacity of its reservoir. Since the operation of this dam in 1986, it is suffering from seepage problems in the foundation of the dam due to the dissolution of gypsum and anhydrite layers under the foundation. This phenomenon has raised concern about the safety of the dam. Studies done during the recent years showed that grouting works can only be considered as a temporary solution at its best. It is clear now that while grouting must be continued search for long term solution must be sought if dam failure consequences are to be avoided. This must be done as soon as possible as the dam is showing more and more signs of weakness. It is further considered that the suggestions and recommendations forwarded by the team of Lulea University of Technology and the Panel of Experts in the Stockholm Workshop 24-25 May, 2016 give the most practical and suitable solutions for this problem.

  • 496.
    Adamo, Nasrat
    et al.
    LTU team.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mosul Dam Full Story: What If The Dam Fails?2016In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 6, no 3, p. 245-269Article in journal (Refereed)
    Abstract [en]

    Dams are very important infrastructure to any country where they serve for different purposes. Unfortunately, they represent risks to life and property due to their potential to fail and cause catastrophic flooding. Recent studies indicate the possibility of Mosul Dam failure. For this reason different failure models were used to estimate the consequences of such failure. Almost all models applied gave similar results. It is assumed that in case the water level in Mosul Dam reservoir is at its maximum operational level the effected population will reach 6,248,000 (about one million will lose their life) and the inundated area will be 7202 square kilometer. This catastrophe requires prudent emergency evacuation planning to minimize loses.

  • 497.
    Adamo, Nasrat
    et al.
    LTU team.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mosul Dam the Full Story: Engineering Problems2016In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 6, no 3, p. 213-244Article in journal (Refereed)
    Abstract [en]

    The idea of building of Mosul Dam project started in 1950 and it was referred to as Aski Mosul Dam. Since that time, number of companies worked on the site selection and design of the dam. All the above companies suggested that the dam should be Earth-fill type with compressed clay core but there were different views about the exact location of the dam, spillway and electricity generating station. Grouting was suggested to be performed under the dam, spillway and the electricity generating station. In addition, they suggested that detailed geological investigation should be performed before any construction activities. In 1978, the Swiss Consultants Consortium was asked to be the consultants for Mosul Dam project. The consultants suggested that the operational water level at the dam to be 330 m (a.s.l.) while the flood and normal water levels to be 338 and 335 m (a.s.l.), respectively. The work started on 25th January, 1981 and finished 24th July, 1986. The foundation of the dam is built on alternating beds of limestone and gysum. Seepages due to the dissolution of gypsum were noticed and after impounding in 1986, new seepage locations were recognized. Grouting operations continued and various studies were conducted to find suitable grout or technique to overcome this problem. The seepage due to the dissolution of gypsum and anhydrite beds raised a big concern about the safety of the dam and its possible failure. It is believed that grouting will not solve this problem permanently

  • 498.
    Adamo, Nasrat
    et al.
    LTU team.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Issa, Issa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Sissakian, Varoujan
    Consultant Geologist, Erbil.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mystery of Mosul Dam the Most Dangerous Dam in the World: Experts Proposals and Ideas on Mosul Dam2015In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 5, no 3, p. 79-93Article in journal (Refereed)
    Abstract [en]

    During and after the construction of Mosul Dam, in Iraq, all the studies expressed a clear concern on the fact that the region of the dam suffers from extensive presence of soluble rock formations that might undermine the safety of the dam with its large reservoir. Most of the studies dealt with foundation treatment and safety hazards due to the dissolution of gypsum and anhydrite. To overcome the problem, grouting operations were performed. The seepage of water continued and this highlighted the possibility of the dam failure. Different grouting techniques and methods were suggested but the results were the same. Finally, it was decided to limit the maximum operation water level to EL. 319 m (a.s.l.) instead of EL.330 m (a.s.l.). This recommendation has remained in force up to now with the loss of sizable storage of irrigation water and power potential

  • 499.
    Adamo, Nasrat
    et al.
    LTU team.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Issa, Issa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Sissakian, Varoujan
    Consultant Geologist, Erbil.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mystery of Mosul Dam the most Dangerous Dam in the World: Foundation Treatment during Construction2015In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 5, no 3, p. 59-69Article in journal (Refereed)
    Abstract [en]

    Mosul dam was constructed on the beds of Fatha Formation (Middle Miocene). The beds of the formation are about 250 m thick composed of Marls, chalky limestone; gypsum, anhydrite, and limestone form a layered sequence. They are highly karstified. As a consequence, plenty of grouting operations were carried out to fill all the cavities, fractures, joints and to stop the seepage under the foundation of the dam. The main grouting operations were Blanket grouting and deep grout curtain. It was necessary to perform an extensive maintenance program to control the seepage process within the grouted zone to stop dissolution of gypsum and protect the safety of the dam.

  • 500.
    Adamo, Nasrat
    et al.
    LTU team.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Issa, Issa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Sissakian, Varoujan
    Consultant Geologist, Erbil.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mystery of Mosul Dam the Most Dangerous Dam in the World: Maintenance Grouting2015In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 5, no 3, p. 71-77Article in journal (Refereed)
    Abstract [en]

    Dissolution of gypsum and anhydrite at the foundation of Mosul Dam continued after its construction since 1986 onwards. After impounding, acceptable residual permeability could not be reached and new areas of high grout takes appeared in some other locations. New grout mixes were tested and even methods of delivering and injecting large grout quantities were developed. Sandy mixes were developed by adding certain weight of sand to the cement mix. In addition, pouring gravel after completion of grouting in large takes' zones was performed. As a result of gravel addition, it was concluded that it was not effective and very difficult to pour. Massive grouting was used where bentonite was added to the mix. Piezometric observation was used for checking the conditions of the grout curtain and the detection of problematic areas where additional treatment was required. Massive grouting, however, did not stop the dissolution processes altogether and it seems that it is not likely to do so in the future. The continuation of this program year after year does not preclude some bad implications. More research work is required to improve massive grout durability by adding chemicals which may interact with gypsum beds and hinder dissolution. This can help to improve gypsum resistance and increase its stability. Mathematical models might also be used to understand the mechanism of cavities formation and collapsing.

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