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• 51.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
A new approach for studying cavitation in lubrication2014Inngår i: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 136, nr 1, artikkel-id 11706Artikkel i tidsskrift (Fagfellevurdert)

The underlying theory, in this paper, is based on clear physical arguments related to conservation of mass flow and considers both incompressible and compressible fluids. The result of the mathematical modeling is a system of equations with two unknowns, which are related to the hydrodynamic pressure and the degree of saturation of the fluid. Discretization of the system leads to a linear complementarity problem (LCP), which easily can be solved numerically with readily available standard methods and an implementation of a model problem in matlab code is made available for the reader of the paper. The model and the associated numerical solution method have significant advantages over today's most frequently used cavitation algorithms, which are based on Elrod-Adams pioneering work

• 52.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Reynolds equation flow factor estimates by means of homogenization2010Inngår i: ASIATRIB 2010: Frontiers in tribology - knowledge & friendship . proceedings of the fourth Asia International Conference on Tribology, 5-9 December 2010, Perth, Western Australia, 2010, s. 185-Konferansepaper (Fagfellevurdert)
• 53.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Flow in thin domains with a microstructure: Lubrication and thin porous media2017Inngår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1798, artikkel-id 020172Artikkel i tidsskrift (Fagfellevurdert)

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.

• 54.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Similarities and differences between the flow factor method by Patir and Cheng and homogenization2011Inngår i: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 133, nr 3, s. 031702-1Artikkel i tidsskrift (Fagfellevurdert)

Different averaging techniques have proved to be useful for analyzing the effects of surface roughness in hydrodynamic lubrication. This paper compares two of these averaging techniques, namely the flow factor method by Patir and Cheng (P&C) and homogenization. It has been rigorously proved by many authors that the homogenization method provides a correct solution for arbitrary roughness. In this work it is shown that the two methods coincide if and only if the roughness exhibits certain symmetries. Hence, homogenization is always the preferred method.

• 55.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Homogenization of a Reynolds equation describing compressible flow2011Rapport (Annet vitenskapelig)
• 56.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Homogenization of a Reynolds equation describing compressible flow2012Inngår i: Journal of Mathematical Analysis and Applications, ISSN 0022-247X, E-ISSN 1096-0813, Vol. 390, nr 2, s. 456-471Artikkel i tidsskrift (Fagfellevurdert)

We homogenize a Reynolds equation with rapidly oscillating film thickness function hε, assuming a constant compressiblity factor in the pressure-density relation. The oscillations are due to roughness on the bounding surfaces of the fluid film. As shown by previous studies, homogenization is an effective approach for analyzing the effects of surface roughness in hydrodynamic lubrication. By two-scale convergence theory we obtain the limit problem (homogenized equation) and strong convergence in L2 for the unknown density ρε. By adding a small corrector term we also obtain strong convergence in the Sobolev norm.

• 57.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Homogenization of Reynolds equation2005Rapport (Annet vitenskapelig)
• 58.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
The homogenization process of the time dependent Reynolds equation describing compressible liquid flow2007Inngår i: Tribologia : Finnish Journal of Tribology, ISSN 0780-2285, Vol. 26, nr 4, s. 30-44Artikkel i tidsskrift (Fagfellevurdert)

To increase the hydrodynamic performance in different machine elements during lubrication, e.g. journal bearings and thrust bearings, it is important to understand the influence of surface roughness. In this connection one encounters different approaches commonly based on some form of the Reynolds equation. They may generally be divided into deterministic- and averaging- techniques. The former regards all surface roughness information and provides a detailed understanding of the local effects that arise. The latter method is suitable when investigating how the surface roughness affects performance of the machine element as a whole. Homogenization is a rigorous mathematical concept that when applied to a certain problem may be thought of as an averaging technique also providing information about local effects. In this work the compressible time dependent Reynolds equation is homogenized. Related problems have recently been analyzed by homogenization techniques under various assumptions. In the present paper the compressibility is modeled assuming a constant lubricant bulk modulus. The formal method of multiple scale expansion is used to derive a so-called homogenized equation and a numerical solution method to solve both the deterministic problem and the homogenized problem is implemented. The numerical results clearly show that the solution of the homogenized equation is a suitable approximation to the solution of the deterministic problem. It is also demonstrated that for small values of the roughness wavelength, the homogenization technique is superior, since the solution of the deterministic problem requires an extremely fine discretization mesh. More over, the solution of the time dependent homogenized problem may in some cases be reduced to solve a stationary problem that facilitates the solution process and interpretation of results.

• 59. Almqvist, Andreas
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
The homogenization process of the time dependent Reynolds equation describing compressible liquid flow2006Rapport (Annet vitenskapelig)
• 60.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Narvik University College, 8505 Narvik, Norway. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
New concepts of homogenization applied in rough surface hydrodynamic lubrication2007Inngår i: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197, Vol. 45, nr 1, s. 139-154Artikkel i tidsskrift (Fagfellevurdert)

This work introduces a new concept of homogenization that enables efficient analysis of the effects of surface roughness representations obtained by measurements in applications modeled by the Reynolds equation. Examples of such applications are trust- and journal-bearings. The numerical analysis of these types of applications requires an extremely dense computational mesh in order to resolve the surface roughness, suggesting some type of averaging. One such method is homogenization, which has been applied to Reynolds type equations with success recently. This approach is similar to the technique proposed by Patir and Cheng, who introduced flow factors determining the hydrodynamic action due to surface roughness. The difference is, however, that the present technique has a rigorous mathematical support. Moreover, the recipe to compute the averaged coefficients is simple without any ambiguities. Using either the technique proposed by Patir and Cheng or homogenization, the coefficients determining the averaged Reynolds equation are obtained by solving differential equations on a local scale. Unfortunately, this is detrimental when investigating the effects induced by real, measured, surface roughness, even though these local problems may be solved in parallel. The present work presents a solution by applying the technique based on bounds. This technique transforms the stationary Reynolds equation into two computationally feasible forms, one for the upper bound and one for the lower bound, where the flow factors are obtained by straightforward integration. Together with the preciseness of these bounds, the bounds approach becomes an eminent tool suitable for investigating the effect of real, measured, surface roughness on hydrodynamic performance.

• 61.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
A new concept in cavitation modelling2013Inngår i: Tribo Lyon 2013: book of abstracts : a joint event of WTC 2013, Lyon, 2013, s. 170-Konferansepaper (Fagfellevurdert)
• 62.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Homogenization applied in rough surface hydrodynamic lubrication2007Inngår i: Svenska Mekanikdagar 2007: Program och abstracts / [ed] Niklas Davidsson; Elianne Wassvik, Luleå: Luleå tekniska universitet, 2007, s. 31-Konferansepaper (Annet vitenskapelig)
• 63.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Homogenization of the Reynolds equation2013Inngår i: Encyclopedia of Tribology, Berlin: Springer-Verlag New York Inc. , 2013, s. 1685-1690Kapittel i bok, del av antologi (Fagfellevurdert)
• 64.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Modelling cavitation in (elasto)hydrodynamic lubrication2016Inngår i: Advances in tribology / [ed] Pranav H. Darji, Croatia: INTECH, 2016, s. 198-213Kapittel i bok, del av antologi (Fagfellevurdert)

In this chapter we will present a derivation of a mathematical model describing how cavitation influences the pressure distribution in a thin lubricant film between two moving surfaces. The main idea in the derivation is to first describe the influence of cavitation on the mass flow and thereafter using a conservation law for the mass. This leads to a nonlinear system with two complementary variables: one is the pressure distribution and the other is related to the density, i.e. a nonlinear complementarity problem (NLCP). The proposed approach is used to derive a mass conserving cavitation model considering that density, viscosity and film thickness of the lubricant depend on the pressure. To demonstrate the applicability and evaluate the proposed model and the suggested numerical implementation, a few model problems are analysed and presented.

• 65.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Near-boundary asymptotics for correlation kernels2013Inngår i: Journal of Geometric Analysis, ISSN 1050-6926, E-ISSN 1559-002X, Vol. 23, nr 1, s. 73-95Artikkel i tidsskrift (Fagfellevurdert)

We discuss asymptotic formulas for the correlation kernel corresponding to a (more or less) general potential Q in the plane. If Kn is such a kernel, there is a known asymptotic formula Kn(z, z)=nΔQ(z)+B1(z)+n-1B2(z)+⋯ valid for z in the interior of a certain compact set known as the "droplet" corresponding to Q (on which ΔQ>0). On the other hand, if z is in the exterior of the droplet, Kn(z, z) converges to zero exponentially in n. Results of this type are useful in random matrix theory and conformal field theory; they have recently been used to prove the Gaussian field convergence in the interior of the droplet for fluctuations of eigenvalues of random normal matrices. To be able to extend such results beyond the interior, it becomes necessary to have a certain uniformity of estimates as z approaches the boundary either from the interior or from the exterior. Such estimates have to our knowledge hitherto not been known on a rigorous level. This note intends to fill this gap. We will consider applications in later publications. Our treatment of the (interior) asymptotics relies in an essential way on previous work due to Berman, Berndtsson, and Sjöstrand (Ark. Mat. 46, 2008), and Berman (Indiana Univ. Math. J. 58, 2009). We hope that this note can to some extent be regarded as a contribution to that work.

• 66.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Royal Institute of Technology, Department of Mathematics. CALTECH, Department of Mathematics, Pasadena.
Fluctuations of eigenvalues of random normal matrices2011Inngår i: Duke mathematical journal, ISSN 0012-7094, E-ISSN 1547-7398, Vol. 159, nr 1, s. 31-81Artikkel i tidsskrift (Fagfellevurdert)

In this article, we consider a fairly general potential in the plane and the corresponding Boltzmann-Gibbs distribution of eigenvalues of random normal matrices. As the order of the matrices tends to infinity, the eigenvalues condensate on a certain compact subset of the plane-the "droplet." We prove that fluctuations of linear statistics of eigenvalues of random normal matrices converge on compact subsets of the interior of the droplet to a Gaussian field, and we discuss various ramifications of this result.

• 67.
Centre for Electronic Materials, University of Manchester.
Centre for Electronic Materials, University of Manchester. Centre for Electronic Materials, University of Manchester. Institute of Physics and Astronomy, University of Aarhus. Department of Physics, University of Exeter. Department of Physics, University of Exeter. Department of Physics, University of Newcastle. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Piezospectroscopic analysis of the hydrogen-carbon complexes in silicon2001Inngår i: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308, s. 139-142Artikkel i tidsskrift (Fagfellevurdert)

We have observed the donor (Ec-0.22 eV) and acceptor (Ec-0.16 eV) levels related to hydrogen-carbon complexes in silicon. The donor level is only detected at low temperatures after proton implantation. This hydrogen-carbon complex irreversibly reconfigures at temperatures above 225 K to a configuration characterized by the acceptor level, which is stable up to room temperature. The same acceptor level is also observed after atomic hydrogen diffusion. We have used Laplace transform deep level transient spectroscopy (DLTS) to show the influence of uniaxial stress on the electron emission process and the effect of the stress-induced alignment for the acceptor state. The pattern of the Laplace DLTS peak splittings indicate a trigonal symmetry of the defect. First principles calculations were carried out on the hydrogen-carbon defects with a view of determining their electrical levels and stress response for comparison with the experimental results.

• 68.
Centre for Electronic Materials, University of Manchester.
Centre for Electronic Materials, University of Manchester. Centre for Electronic Materials, University of Manchester. Institute of Physics and Astronomy, University of Aarhus. School of Physics, University of Exeter. School of Physics, University of Exeter. Department of Physics, University of Newcastle. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Electrical activity of carbon-hydrogen centers in Si2002Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, nr 23, s. 235205-1Artikkel i tidsskrift (Fagfellevurdert)

The electrical activity of Cs-H defects in Si has been investigated in a combined modeling and experimental study. High-resolution Laplace capacitance spectroscopy with the uniaxial stress technique has been used to measure the stress-energy tensor and the results are compared with theoretical modeling. At low temperatures, implanted H is trapped as a negative-U center with a donor level in the upper half of the gap. However, at higher temperatures, H migrates closer to the carbon impurity and the donor level falls, crossing the gap. At the same time, an acceptor level is introduced into the upper gap making the defect a positive-U center.

• 69.
Luleå tekniska universitet.
Luleå tekniska universitet. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet.
Linjär algebra med geometri1990 (oppl. 2)Bok (Annet (populærvitenskap, debatt, mm))
• 70.
Luleå tekniska universitet.
Luleå tekniska universitet. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet.
Linjär algebra med geometri1986Bok (Annet (populærvitenskap, debatt, mm))
• 71.
Luleå tekniska universitet.
Luleå tekniska universitet. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Linjär algebra med geometri1999Bok (Annet (populærvitenskap, debatt, mm))
• 72.
University of L'Aquila (Italy).
Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB. Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
On the passivity of the Delay-Rational Green’s-function-based model for Transmission Lines2019Inngår i: Analysis, Probability, Applications, and Computation: Proceedings of the 11th ISAAC Congress / [ed] Karl‐Olof Lindahl,Torsten Lindström, Luigi G. Rodino, Joachim Toft, Patrik Wahlberg, 2019, s. 71-81Konferansepaper (Fagfellevurdert)

In this paper, we study the delay-rational Green’s-function-based (DeRaG) model for transmission lines. This model is described in terms of impedance representation and it contains a rational and a hyperbolic part. The crucial property of transmission lines models is to be passive. The passivity of the rational part has been studied by the authors in a previous work. Here, we extend the results to the rational part of the DeRaG model. Moreover, we prove the passivity of the hyperbolic part.

• 73.
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. New Boliden AB. New Boliden AB. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. LKAB.
Interactions in multi-component mineral systems2011Konferansepaper (Annet vitenskapelig)
• 74.
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. New Boliden AB. New Boliden AB. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. LKAB.
Interactions in multi-component mineral systems2010Konferansepaper (Annet vitenskapelig)
• 75.
Department of Fundamental and Applied Mathematics, Eurasian National University, Munaitpasov str. 4, Astana.
Department of Fundamental and Applied Mathematics, Eurasian National University, Munaitpasov str. 4, Astana. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some New Hardy-type Integral Inequalities on Cones of Monotone Functions2013Inngår i: Advances in Harmonic Analysis and Operator Theory: The Stefan Samko Anniversary Volume, Basel: Encyclopedia of Global Archaeology/Springer Verlag, 2013, s. 77-89Kapittel i bok, del av antologi (Fagfellevurdert)

Some new Hardy-type inequalities with Hardy-Volterra integral operators on the cones of monotone functions are obtained. The case 1 < p ≤ q < ∞ is considered and the involved kernels satisfy conditions which are less restrictive than the classical Oinarov condition.

• 76.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Estimates for Hardy-type integral operators in weighted Lebesgue spaces2013Doktoravhandling, med artikler (Annet vitenskapelig)

This PhD thesis deals with the theory of Hardy-type inequalities in a new situation, namely when the classical Hardy operator is replaced by a more general operator with a kernel. The kernels we consider belong to the new classes $\mathcal{O}^+_n$ and $\mathcal{O}^-_n$, $n=0,1,...$, which are wider than co-called Oinarov class of kernels. This PhD thesis consists of four papers (papers A, B, C and D), two complementary appendixes (A$_1$, C$_1$) and an introduction, which put these publications into a more general frame. This introduction also serves as a basic overview of the field. In paper A some boundedness criteria for the Hardy-Volterra integral operators are proved and discussed. The case $1<q<p<\infty$ is considered and the involved kernels are from the classes $\mathcal{O}^+_1$ and $\mathcal{O}^-_1$. A complete solution of the problem is presented and discussed. The appendix to paper A contains the proof of Theorem 3.1, which is not included in the paper. In paper B even more complicated (than in paper A) case with variable limits on the Hardy operator is investigated. The main results of the paper are proved by applying the block-diagonal method given by Batuev and Stepanov and the results from paper A. Paper C deals with Hardy-type inequalities restricted to the cones of monotone functions. The case $1<p\le q<\infty$ is considered and the involved kernels satisfy conditions, which are less restrictive than the usual Oinarov condition. Also in this case a complete solution is obtained and some concrete applications are pointed out. In particular, in paper C some open questions are raised. These questions are discussed and solved in an appendix to Paper C. In paper D we study superpositions of the Hardy-Volterra integral operator and its adjoint. The boundedness and compactness criteria in the range of parameters $1<p\le q<\infty$ are obtained and discussed. Moreover, some new properties of the classes $\mathcal{O}^+_n$ and $\mathcal{O}^-_n$ are proved.

• 77.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some new Hardy-type Inequalities for integral operators with kernels2011Licentiatavhandling, med artikler (Annet vitenskapelig)

This Licentiate thesis deals with the theory of Hardy-type inequalities in anew situation, namely when the classical Hardy operator is replaced by amore general operator with kernel. The kernels we consider belong to thenew classes O+ n and O-n , n = 0; 1; :::, which are wider than co-called Oinarovclass of kernels.The thesis consists of three papers (papers A, B and C), an appendix topaper A and an introduction, which gives an overview to this specific fieldof functional analysis and also serves to put the papers in this thesis into amore general frame.In paper A some new Hardy-type inequalities for the case with Hardy-Volterra integral operators involved are proved and discussed. The case 1

• 78.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
L.N. Gumilyov Eurasian National University. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
On the boundedness of some classes of integral operators in Lebesgue spaces2011Rapport (Annet vitenskapelig)
• 79.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
On the boundedness of some classes of integral operators in weighted Lebesgue spaces2012Inngår i: Eurasian Mathematical Journal, ISSN 2077-9879, Vol. 3, nr 1, s. 5-17Artikkel i tidsskrift (Fagfellevurdert)
• 80.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some new inequalities on cones of monotone functions2011Rapport (Annet vitenskapelig)
• 81.
Department of Mathematics, Cukurova University.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Algorithms to compute CM - and S-estimates for regression2003Inngår i: International Conference on Robust Statistics: ICORS / [ed] Rudolf Dutter; P. Filzmoser; U. Gather; P. J. Pousseeuw, Physica-Verlag Rudolf Liebig GmbH , 2003, s. 62-76Konferansepaper (Fagfellevurdert)

Constrained M-estimators for regression were introduced by Mendes and Tyler in 1995 as an alternative class of robust regression estimators with high breakdown point and high asymptotic efficiency. To compute the CM-estimate, the global minimum of an objective function with an inequality constraint has to be localized. To find the S-estimate for the same problem, we instead restrict ourselves to the boundary of the feasible region. The algorithm presented for computing CM-estimates can easily be modified to compute S-estimates as well. Testing is carried out with a comparison to the algorithm SURREAL by Ruppert

• 82.
Växjö universitet.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Interpolation of Besov and Sobolev Spaces in the non-diagonal case2006Inngår i: Constructive Theory of Functions: Proceedings of International Conference, Varna / [ed] R. Bojanov, Sofia: Prof. Marin Drinov Academic Publishing House, 2006, s. 45-50Konferansepaper (Fagfellevurdert)
• 83. Asekritova, Irina
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Interpolation of Besov spaces in the nondiagonal case2006Inngår i: St. Petersburg Mathematical Journal, ISSN 1061-0022, E-ISSN 1547-7371, Vol. 18, nr 4, s. 1-9Artikkel i tidsskrift (Fagfellevurdert)
• 84.
School of Mathematics and Systems Engineering.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Invertibility of operators in spaces of real interpolation2008Inngår i: Revista Matematica Complutense, ISSN 1139-1138, Vol. 21, nr 1, s. 207-217Artikkel i tidsskrift (Fagfellevurdert)

Let A be a linear bounded operator from a couple X→ = (X0, X1) to a couple Y→ = (Y0, Y1) such that the restrictions of A on the spaces X0 and X1 have bounded inverses. This condition does not imply that the restriction of A on the real interpolation space (X0, X 1)θ, q has a bounded inverse for all values of the parameters θ and q. In this paper under some conditions on the kernel of A we describe all spaces (X0, X1)θ,q such that the operator A : (x0,X1)θ,q → (Y0, Y1) has a bounded inverse

• 85. Asekritova, Irina
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Lions-Peetre reiteration formulas for triples and their applications2001Inngår i: Studia Mathematica, ISSN 0039-3223, E-ISSN 1730-6337, Vol. 145, nr 3, s. 219-254Artikkel i tidsskrift (Fagfellevurdert)

Two reiteration theorems for triples of quasi-Banach function lattices are given. As a by-product of these, some interpolation results are obtained for block-Lorentz spaces and triples of weighted $L_p$-spaces.

• 86.
Matematiska och Systemtekniska Institutionen, Växjö University.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Department of Mathematics, Kliment Ohridski University of Sofia.
The Lizorkin-Freitag formula for several weighted Lp spaces and vector-valued interpolation2005Inngår i: Studia Mathematica, ISSN 0039-3223, E-ISSN 1730-6337, Vol. 170, nr 3, s. 227-239Artikkel i tidsskrift (Fagfellevurdert)

A complete description of the real interpolation space L = (L p0(ω0), . . ., Lpn(ω n))θ,q is given. An interesting feature of the result is that the whole measure space (Ω, μ) can be divided into disjoint pieces Ωi (i ε I) such that L is an l q sum of the restrictions of L to Ωi, and L on each Ωi is a result of interpolation of just two weighted L p spaces. The proof is based on a generalization of some recent results of the first two authors concerning real interpolation of vector-valued spaces.

• 87.
Yaroslavl Pedagogical Institute.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Distribution and rearrangement estimates of the maximal function and interpolation1997Inngår i: Studia Mathematica, ISSN 0039-3223, E-ISSN 1730-6337, Vol. 124, nr 2, s. 107-132Artikkel i tidsskrift (Fagfellevurdert)
• 88.
Interdisciplinary Research Centre for Semiconductor Materials, The Blackett Laboratory, Imperial College of Science, Technology and Medicine, London.
Interdisciplinary Research Centre for Semiconductor Materials, The Blackett Laboratory, Imperial College of Science, Technology and Medicine, London. Interdisciplinary Research Centre for Semiconductor Materials, The Blackett Laboratory, Imperial College of Science, Technology and Medicine, London. Department of Materials Science and Engineering, Liverpool University. Department of Materials Science and Engineering, Liverpool University. Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastrasse 72, D-79108 Freiburg. Department of Electronic and Electrical Engineering, University of Surrey, Guildford. Department of Physics, University of Exeter. Department of Physics, University of Exeter. Department of Physics, University of Newcastle. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
The bonding of CAs acceptors in InxGa1-xAs grown by chemical beam epitaxy using carbon tetrabromide as the source of carbon1996Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 80, nr 12, s. 6754-6760Artikkel i tidsskrift (Fagfellevurdert)

InxGa1-xAs layers (0≤x≤0.37) doped with carbon (>1020 cm-3) were grown on semi-insulating GaAs substrates by chemical beam epitaxy using carbon tetrabromide (CBr4) as the dopant source. Hall measurements imply that all of the carbon was present as CAs for values x up to 0.15. The C acceptors were passivated by exposing samples to a radio frequency hydrogen plasma for periods of up to 6 h. The nearest-neighbor bonding configurations of CAs were investigated by studying the nondegenerate antisymmetric hydrogen stretch mode (A-1 symmetry) and the symmetric XH mode (A+1 symmetry) of the H-CAs pairs using IR absorption and Raman scattering, respectively. Observed modes at 2635 and 450 cm-1 had been assigned to passivated Ga4CAs clusters. New modes at 2550 and 430 cm-1 increased in strength with increasing values of x and are assigned to passivated InGa3CAs clusters. These results were compared with ab initio local density functional theory. Modes due to AlInGaCAs clusters were detected in samples containing grown in Al and In. These results demonstrate that for InGaAs, CBr4 is an efficient C doping source since both In-CAs bonds as well as Ga-CAs bonds are formed, whereas there is no evidence for the formation of In-CAs bonds in samples doped with C derived from trimethylgallium or solid sources

• 89.
Samara State University.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
On interpolation in Lp spaces2003Inngår i: Mathematical notes of the Academy of Sciences of the USSR, ISSN 0001-4346, E-ISSN 1573-8876, Vol. 74, nr 5-6, s. 734-739Artikkel i tidsskrift (Fagfellevurdert)
• 90.
Department of Mathematics, Samarkand State University.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
On interpolation in Lp-spaces2003Inngår i: Mathematical notes of the Academy of Sciences of the USSR, ISSN 0001-4346, E-ISSN 1573-8876, Vol. 74, nr 5, s. 782-786Artikkel i tidsskrift (Fagfellevurdert)
• 91.
Samara State University.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Samara State University.
Sequences of independent Walsh functions in BMO2013Inngår i: Siberian mathematical journal, ISSN 0037-4466, E-ISSN 1573-9260, Vol. 54, nr 2, s. 205-211Artikkel i tidsskrift (Fagfellevurdert)

Under examination are the sequences of independent Walsh functions in the space of functions of bounded mean oscillation. We study geometric properties of the subspaces spanned by the sequences; in particular, some necessary and sufficient conditions are found for such a subspace to be complemented

• 92.
Samara State Univ, Dept Math & Mech, , Samara, Russia.Samara State Aerosp Univ, Samara , Russia .
Poznan Univ Tech, Inst Math, Poznan, Poland. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Isomorphic structure of Cesàro and Tandori spaces2019Inngår i: Canadian Journal of Mathematics - Journal Canadien de Mathematiques, ISSN 0008-414X, E-ISSN 1496-2479, Vol. 71, nr 3, s. 501-532Artikkel i tidsskrift (Fagfellevurdert)

We investigate the isomorphic structure of the Cesàro spaces and their duals, the Tandori spaces. The main result states that the Cesàro function space Ces∞ and its sequence counterpart ces∞ are isomorphic. This is rather surprising since Ces∞ (like Talagrand’s example) has no natural lattice predual. We prove that ces∞ is not isomorphic to ℓ∞ nor is Ces∞ isomorphic to the Tandori space L1 with the norm ∥f∥L1 = ∥f∥L1, where f(t) = esssups≥tf(s). Our investigation also involves an examination of the Schur and Dunford–Pettis properties of Cesàro and Tandori spaces. In particular, using results of Bourgain we show that a wide class of Cesàro–Marcinkiewicz and Cesàro–Lorentz spaces have the latter property.

• 93. Astashkin, Sergey
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Cesaro function spaces fail the fixed point property2008Inngår i: Proceedings of the American Mathematical Society, ISSN 0002-9939, E-ISSN 1088-6826, Vol. 136, nr 12, s. 4289-4294Artikkel i tidsskrift (Fagfellevurdert)

The Cesaro sequence spaces ces(p), 1 < p < infinity, are reflexive but they have the fixed point property. In this paper we prove that in contrast to these sequence spaces the corresponding Cesaro function spaces Ces(p) on both [0, 1] and [0, infinity) for 1 < p < infinity are not reflexive and they fail to have the fixed point property.

• 94.
Samara State University.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Geometry of Cesaro function spaces2011Inngår i: Functional analysis and its applications, ISSN 0016-2663, E-ISSN 1573-8485, Vol. 45, nr 1, s. 64-68Artikkel i tidsskrift (Fagfellevurdert)

Geometric properties of CesA ro function spaces Ces (p) (I), where I = [0,a) or I = [0, 1], are investigated. In both cases, a description of their dual spaces for 1 < p < a is given. We find the type and the cotype of CesA ro spaces and present a complete characterization of the spaces l (q) that have isomorphic copies in Ces (p) [0, 1] (1 a (c) 1/2 p < a).

• 95. Astashkin, Sergey
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Interpolation between L1 and Lp, 12004Inngår i: Proceedings of the American Mathematical Society, ISSN 0002-9939, E-ISSN 1088-6826, Vol. 132, nr 10, s. 2929-2938Artikkel i tidsskrift (Fagfellevurdert)

The main result of this paper is that if $X$ is an interpolation rearrangement invariant space on $[0,1]$ between $L_1$ and $L_\infty$, for which the Boyd index $\alpha(X)>1/p$, \$1

• 96. Astashkin, Sergey
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Rademacher functions in Cesaro type spaces2010Inngår i: Studia Mathematica, ISSN 0039-3223, E-ISSN 1730-6337, Vol. 198, nr 3, s. 235-247Artikkel i tidsskrift (Fagfellevurdert)

The Rademacher sums are investigated in the Cesaro spaces Ces(p) (1 <= p <= infinity) and in the weighted Korenblyum-Krein-Levin spaces K-p,K-w on [0,1]. They span l(2) space in Ces(p) for any 1 <= p < infinity and in K-p,K-w if and only if the weight w is larger than t log(2)(p/2)(2/t) on (0,1). Moreover, the span of the Rademachers is not complemented in Ces(p) for any 1 <= p < infinity or in K-1,K-w for any quasi-concave weight w. In the case when p > 1 and when w is such that the span of the Rademacher functions is isomorphic to l(2), this span is a complemented subspace in K-p,K-w.

• 97. Astashkin, Sergey
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Structure of Cesaro function spaces2009Inngår i: Indagationes mathematicae, ISSN 0019-3577, E-ISSN 1872-6100, Vol. 20, nr 3, s. 329-379Artikkel i tidsskrift (Fagfellevurdert)

The structure of the Cesàro function spaces Cesp on both [0,1] and [0, ∞) for 1 < p ≤ ∞ is investigated. We find their dual spaces, which equivalent norms have different description on [0, 1] and [0, ∞).The spaces Cesp for 1 < p < ∞ are not reflexive but strictly convex. They are not isomorphic to any Lq space with 1 ≤ q ≤ ∞. They have "near zero" complemented subspaces isomorphic to lp and "in the middle" contain an asymptotically isometric copy of l1 and also a copy of L1[0, 1]. They do not have Dunford-Pettis property but they do have the weak Banach-Saks property. Cesàro function spaces on [0, 1] and [0, ∞) are isomorphic for 1 < p ≤ ∞. Moreover, we give characterizations in terms of p and q when Cesp[0, 1] contains an isomorphic copy of lq.

• 98. Astashkin, Sergey
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Ultrasymmetric Orlicz spaces2008Inngår i: Journal of Mathematical Analysis and Applications, ISSN 0022-247X, E-ISSN 1096-0813, Vol. 347, nr 1, s. 273-285Artikkel i tidsskrift (Fagfellevurdert)

It is proved that ultrasymmetric reflexive Orlicz spaces can be described exactly as all those Orlicz spaces which can be written as some Lorentz spaces. This description is an answer to the problem posed by Pustylnik in [E. Pustylnik, Ultrasymmetric spaces, J. London Math. Soc. (2) 68 (1) (2003) 165-182]. On the other hand, the Lorentz-Orlicz spaces with non-trivial indices of their fundamental functions are ultrasymmetric.

• 99. Astashkin, Sergey
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Department of Mathematics, Voronezh State University.
On the complementness of subspaces generated by contractions and shifts of functions. (Russian)2002Inngår i: Doklady Akademii Nauk, ISSN 0869-5652, Vol. 387, nr 5, s. 583-585Artikkel i tidsskrift (Fagfellevurdert)
• 100.
Department of Mathematics and Mechanics, Samara State University.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
A short proof of some recent results related to Cesàro function spaces2013Inngår i: Indagationes mathematicae, ISSN 0019-3577, E-ISSN 1872-6100, Vol. 24, nr 3, s. 589-592Artikkel i tidsskrift (Fagfellevurdert)

We give a short proof of the recent results that, for every 1≤p<∞, the Cesàro function space Cesp(I) is not a dual space, has the weak Banach–Saks property and does not have the Radon–Nikodym property.

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