| 1. |
- Laksman, Efraim, et al.
(författare)
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Generalized upper bounds on the minimum distance of PSK block codes
- 2015
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Ingår i: IMA Journal of Mathematical Control and Information. - : Oxford Journals. - 0265-0754 .- 1471-6887. ; 32:2, s. 305-327
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Forskningsöversikt (refereegranskat)abstract
- This paper generalizes previous optimal upper bounds on the minimum Euclidean distance for phase shift keying (PSK) block codes, that are explicit in three parameters: alphabet size, block length and code size. The bounds are primarily generalized from codes over symmetric PSK to codes over asymmetric PSK and also to general alphabet size. Furthermore, block codes are optimized in the presence of other types of noise than Gaussian, which induces also non-Euclidean distance measures. In some instances, codes over asymmetric PSK prove to give higher Euclidean distance than any code over symmetric PSK with the same parameters. We also provide certain classes of codes that are optimal among codes over symmetric PSK.
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| 2. |
- Gosson, Maurice de
(författare)
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The Principles of Classical and Quantum Mechanics
- 2002
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Ingår i: Hardcover. - London-Singapore : Imperial College Press.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This book is devoted to a symplectic approach of classical and quantum mechanics
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| 3. |
- Nedic, Mitja, et al.
(författare)
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Herglotz functions and applications in electromagnetics
- 2020
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Ingår i: Advances in Mathematical Methods for Electromagnetics. - : Institution of Engineering and Technology. - 9781785613845 - 9781785613852 ; , s. 491-514
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Herglotz functions inevitably appear in pure mathematics, mathematical physics, and engineering with a wide range of applications. In particular, they are the pertinent functions to model passive systems, and thus appear in modeling of electromagnetic phenomena in circuits, antennas, materials, and scattering. In this chapter, we review the basic theory of Herglotz functions and its applications to determine sum rules and physical bounds for passive systems.
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| 4. |
- Nystedt, Patrik, 1971-, et al.
(författare)
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Artinian and noetherian partial skew groupoid rings
- 2018
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Ingår i: Journal of Algebra. - : Academic Press. - 0021-8693 .- 1090-266X. ; 503, s. 433-452
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Tidskriftsartikel (refereegranskat)abstract
- Let α={α_g : R_{g^{−1}}→R_g}_{g∈mor(G)} be a partial action of a groupoid G on a (not necessarily associative) ring R and let S=R⋆G be the associated partial skew groupoid ring. We show that if α is global and unital, then S is left (right) artinian if and only if R is left (right) artinian and R_g={0}, for all but finitely many g∈mor(G). We use this result to prove that if α is unital and R is alternative, then S is left (right) artinian if and only if R is left (right) artinian and R_g={0}, for all but finitely many g∈mor(G). This result applies to partial skew group rings, in particular. Both of the above results generalize a theorem by J. K. Park for classical skew group rings, i.e. the case when R is unital and associative, and G is a group which acts globally on R. We provide two additional applications of our main results. Firstly, we generalize I. G. Connell's classical result for group rings by giving a characterization of artinian (not necessarily associative) groupoid rings. This result is in turn applied to partial group algebras. Secondly, we give a characterization of artinian Leavitt path algebras. At the end of the article, we relate noetherian and artinian properties of partial skew groupoid rings to those of global skew groupoid rings, as well as establish two Maschke-type results, thereby generalizing results by M. Ferrero and J. Lazzarin for partial skew group rings to the case of partial skew groupoid rings.
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| 5. |
- Nystedt, Patrik, 1971-, et al.
(författare)
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EPSILON-STRONGLY GROUPOID-GRADED RINGS, THE PICARD INVERSE CATEGORY AND COHOMOLOGY
- 2020
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Ingår i: Glasgow Mathematical Journal. - : CAMBRIDGE UNIV PRESS. - 0017-0895 .- 1469-509X. ; 62:1, s. 233-259
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Tidskriftsartikel (refereegranskat)abstract
- We introduce the class of partially invertible modules and show that it is an inverse category which we call the Picard inverse category. We use this category to generalize the classical construction of crossed products to, what we call, generalized epsilon-crossed products and show that these coincide with the class of epsilon-strongly groupoid-graded rings. We then use generalized epsilon-crossed groupoid products to obtain a generalization, from the group-graded situation to the groupoid-graded case, of the bijection from a certain second cohomology group, defined by the grading and the functor from the groupoid in question to the Picard inverse category, to the collection of equivalence classes of rings epsilon-strongly graded by the groupoid.
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| 6. |
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| 7. |
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Archives of ALGA, volume 1
- 2004
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Volume 1 contains 3 articles: Nail H. Ibragimov, Equivalence groups and invariants of linear and non-linear equations; Nail H. Ibragimov and Sergey V. Meleshko, Linearization of third-order ordinary differential equations; Nail H. Ibragimov, Gazanfer Ünal and Claes Jogreús, Group analysis of stochastic differential systems: Approximate symmetries and conservation laws.
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| 8. |
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Archives of ALGA. Volume 2
- 2005
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Volume 2 contains 3 articles: Ilir Berisha, Translation of Bäcklunds paper ”Surfaces of constant negative curvature”; Johan Erlandsson, "Survey of mathematical models in biology from point of view of Lie group analysis"; Niklas Säfström, "Group analysis of a tumour growth model"
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| 9. |
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Archives of ALGA. Volume 3
- 2006
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Volume 3 contains 6 articles: Lars Haikola, Louise Petrén-Overton, min mormor; Lars Haikola, Louise Petr´en-Overton, my grandmother. Traslations: Louise Petrén, Extension of Laplace's method to the equations...; E. Bessel-Hagen, On conservation laws of electrodynamics. Nail H. Ibragimov, The answer to the question put to me by L.V. Ovsyannikov 33 years ago; Nail H. Ibragimov, Raisa Khamitova, Bo Thidé, Adjoint system and conservation laws for symmetrized electromagnetic equations with a dual Ohm's law.
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| 10. |
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Archives of ALGA. Volume 4
- 2007
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Volume 4 contains articles: Nail H. Ibragimov, Ewald J.H. Wessels and George F.R. Ellis, Group classication of the Sachs equations for a radiating axisymmetric, non-rotating, vacuum space-time; Nail H. Ibragimov A discussion of conservation laws for over-determined systems with application to the Maxwell equations in vacuum; Nail H. Ibragimov, Quasi-self-adjoint differential equations; Nail H. Ibragimov and Salavat V. Khabirov, Existence of integrating factors for higher-order ordinary differential equations; Nail H. Ibragimov, Integration of second-order linear equations via linearization of Riccati's equations; Nail H. Ibragimov and Sergey V. Meleshko Linearization of second-order ordinary differential equations by changing the order; Nail H. Ibragimov and Sergey V. Meleshko Second-order ordinary differential equations equivalent to y''= H(y); Nail H. Ibragimov, Sergey V. Meleshko and Supaporn Suksern, Linearization of fourth-order ordinary differential equations by point transformations; Nail H. Ibragimov and Emrullah Yasar, Non-local conservation laws in fluid dynamics
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