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  • 1.
    Almqvist, Andreas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Fabricius, John
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Lundström, Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Wall, Peter
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Flow in thin domains with a microstructure: Lubrication and thin porous media2017Ingår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1798, artikel-id 020172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper is devoted to homogenization of different models of flow in thin domains with a microstructure. The focus is on applications connected to the effect of surface roughness in full film lubrication, but a parallel to flow in thin porous media is also discussed. Mathematical models of such flows naturally include two small parameters. One is connected to the fluid film thickness and the other to the microstructure. The corresponding asymptotic analysis is a delicate problem, since the result depends on how fast the two small parameters tend to zero relative to each other. We give a review of the current status in this area and point out some future challenges.

  • 2.
    Bin Asad, S M Sayeed
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Andersson, Anders G.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Experimental study of the flow past submerged half-cylinders2017Ingår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1851, artikel-id 020001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This investigation studies the details of the flow behind and over two identical semicircular cylinderspositioned in tandem. Laser Doppler Velocimetry (LDV) measurements are carried out in a laboratory waterflume using two different gap ratios (Sp/d = 1 and Sp/d = 0.5; where Sp indicates distance between the cylindersand d indicates cylinder diameter) under two different flow situations. These LDV measurement are used toderive velocities, formation length and Power spectral density for the various flow conditions. Flowvisualizations are also added in this investigation. The results indicate that the flow is significantly affected dueto gap ratios.

  • 3. Burtseva, Evgeniya
    et al.
    Lundberg, Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Persson, Lars-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Samko, Natasha
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Potential type operators in PDEs and their applications2017Ingår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1798, artikel-id 020178Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     We prove the boundedness of Potential operator in weighted generalized Morrey space in terms of Matuszewska-Orlicz indices of weights and apply this result to the Hemholtz equation in r3 with a free term in such a space. We also give a short overview of some typical situations when Potential type operators arise when solving PDEs.

  • 4.
    Nukala, Madhuri
    et al.
    Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, SE 851 70, Sundsvall, Sweden.
    Mendrok, Jana
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Analysis of light scattering by two-dimensional inhomogeneities in paper using general radiative transfer theory2014Ingår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1637, s. 750-758Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lateral light scattering simulations of printed dots are analyzed using general radiative transfer theory. We investigated the appearance of a printed paper in relation to the medium parameters like thickness of the paper sample, its optical properties, and the asymmetry factor. It was found that the appearance of a print greatly depends on these factors making it either brighter or darker. A thicker substrate with higher single scattering albedo backed with an absorbing surface makes the dots brighter due to increased number of scattering events. Additionally, it is shown that the optical effects of print also depend on illuminating and viewing angles along with the depth of ink penetration. A larger single scattering angle implies less intensity and the dots appear much blurred due to the shadowing effect prominent when viewed from sides. A fully penetrated dot of the same extinction coefficient as a partial penetrated one is darker due to increased absorption. These results can be used in applications dealing with lateral light scattering.

  • 5.
    Paembonan, Andri Yadi
    et al.
    Master Program of Geotechnology, Khon Kaen University.
    Arjwech, Rungroj
    Master Program of Geotechnology, Khon Kaen University.
    Davydycheva, Sofia N.
    KMS Technologies.
    Smirnov, Maxim
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Strack, Kurt M.
    KMS Technologies.
    An application of LOTEM around salt dome near Houston, Texas2017Ingår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1861, artikel-id 030006Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A salt dome is an important large geologic structure for hydrocarbon exploration. It may seal a porous reservoir of rocks that form petroleum reservoirs. Several techniques such as seismic, gravity, and electromagnetic including magnetotelluric have successfully yielded salt dome interpretation. Seismic has difficulties seeing through the salt because the seismic energy gets trapped by the salt due to its high velocity. Gravity and electromagnetics are more ideal methods. Long Offset Transient Electromagnetic (LOTEM) and Focused Source Electromagnetic (FSEM) were tested over a salt dome near Houston, Texas. LOTEM data were recorded at several stations with varying offset, and the FSEM tests were also made at some receiver locations near a suspected salt overhang. The data were processed using KMS's processing software: First, for assurance, including calibration and header checking; then transmitter and receiver data are merged and microseismic data is separated; Finally, data analysis and processing follows. LOTEM processing leads to inversion or in the FSEM case 3D modeling. Various 3D models verify the sensitivity under the salt dome. In addition, the processing was conducted pre-stack, stack, and post-stack. After pre-stacking, the noise was reduced, but showed the ringing effect due to a low-pass filter. Stacking and post-stacking with applying recursive average could reduce the Gibbs effect and produce smooth data

  • 6.
    Persson, Lars-Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Samko, Natasha
    Session-workshop on analysis, inequalities and homogenization theory and applications2010Ingår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1281, s. 489-Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Analysis, Inequalities and Homogenization Theory are increasingly important areas for various kinds of applications both to other fields of Mathematics and to other sciences, e.g. physics, material science, numerical analysis and geophysics.The main aim of the session is to bring together researchers with different backgrounds and interests in all aspects of these areas of mathematics and plan for future cooperation and new directions of joint research. As background the participants will present the newest developments and present “status of the art” of their research fields. Special meetings with informal discussions will be organized, where in particular various kinds of applications will be highlighted. The topics of interest include (but are not limited to): General Inequalities, Hardy type inequalities, Real and complex analysis, Functional analysis, q-analysis, Interpolation theory, Function Spaces and Homogenization Theory

  • 7.
    Tsandzana, Afonso Fernando
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Homogenization of a mathematical model for cavitation in thin film flow2017Ingår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1798, artikel-id 020163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper is a contribution to mathematical modeling of thin film flow between two surfaces which are in relative motion. In particular such flows are important in lubrication theory. For many shapes of the surfaces and boundary conditions the pressure in the fluid will be so low that the continuous fluid film ruptures and air bubbles are formed. This phenomenon is known as cavitation and have a huge impact on the hydrodynamic performance. We derive a mathematical model of thin film flow between two close surfaces which takes into account cavitation, surface roughness and pressure dependent density. Moreover, we use two-scale convergence to homogenize the model. In addition, we compute the coefficients of the homogenized equation for a simple class of functions that describe the film thickness.

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