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| 2. |
- Abdallah, Nancy, et al.
(author)
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Combinatorial invariance of Kazhdan-Lusztig-Vogan polynomials for fixed point free involutions
- 2018
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In: Journal of Algebraic Combinatorics. - : SPRINGER. - 0925-9899 .- 1572-9192. ; 47:4, s. 543-560
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Journal article (peer-reviewed)abstract
- When acts on the flag variety of , the orbits are in bijection with fixed point free involutions in the symmetric group . In this case, the associated Kazhdan-Lusztig-Vogan polynomials can be indexed by pairs of fixed point free involutions , where denotes the Bruhat order on . We prove that these polynomials are combinatorial invariants in the sense that if is a poset isomorphism of upper intervals in the Bruhat order on fixed point free involutions, then for all v amp;gt;= u.
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| 3. |
- Abdallah, Nancy, et al.
(author)
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Topology of posets with special partial matchings
- 2019
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In: Advances in Mathematics. - : Academic Press. - 0001-8708 .- 1090-2082. ; 348, s. 255-276
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Journal article (peer-reviewed)abstract
- Special partial matchings (SPMs) are a generalisation of Brentis special matchings. Let a pircon be a poset in which every non-trivial principal order ideal is finite and admits an SPM. Thus pircons generalise Mariettis zircons. We prove that every open interval in a pircon is a PL ball or a PL sphere. It is then demonstrated that Bruhat orders on certain twisted identities and quasiparabolic W-sets constitute pircons. Together, these results extend a result of Can, Cherniaysky, and Twelbeck, prove a conjecture of Hultman, and confirm a claim of Rains and Vazirani.
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| 4. |
- Abrikosov, Igor, et al.
(author)
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Phase Stability and Elasticity of TiAlN
- 2011
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In: Materials. - : MDPI. - 1996-1944 .- 1996-1944. ; 4:9, s. 1599-1618
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Journal article (peer-reviewed)abstract
- We review results of recent combined theoretical and experimental studies of Ti1−xAlxN, an archetypical alloy system material for hard-coating applications. Theoretical simulations of lattice parameters, mixing enthalpies, and elastic properties are presented. Calculated phase diagrams at ambient pressure, as well as at pressure of 10 GPa, show a wide miscibility gap and broad region of compositions and temperatures where the spinodal decomposition takes place. The strong dependence of the elastic properties and sound wave anisotropy on the Al-content offers detailed understanding of the spinodal decomposition and age hardening in Ti1−xAlxN alloy films and multilayers. TiAlN/TiN multilayers can further improve the hardness and thermal stability compared to TiAlN since they offer means to influence the kinetics of the favorable spinodal decomposition and suppress the detrimental transformation to w-AlN. Here, we show that a 100 degree improvement in terms of w-AlN suppression can be achieved, which is of importance when the coating is used as a protective coating on metal cutting inserts.
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| 5. |
- Alling, Björn, et al.
(author)
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Metastability of fcc-related Si-N phases
- 2008
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 78:13, s. 132103-132103
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Journal article (peer-reviewed)abstract
- The phenomenon of superhardening in TiN/SiNx nanocomposites and the prediction of extreme hardness in bulk gamma-Si3N4 have attracted a large interest to this material system. Attempts to explain the experimental findings by means of first-principles calculations have so far been limited to static calculations. The dynamical stability of suggested structures of the SiNx tissue phase critical for the understanding of the nanocomposites is thus unknown. Here, we present a theoretical study of the phonon-dispersion relations of B1 and B3 SiN. We show that both phases previously considered as metastable are dynamically unstable. Instead, two pseudo-B3 Si3N4 phases derived from a L1(2)- or D0(22)-type distribution of Si vacancies are dynamically stable and might explain recent experimental findings of epitaxial SiNx in TiN/SiNx multilayers.
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| 6. |
- Björner, Anders, et al.
(author)
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A note on blockers in posets
- 2004
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In: Annals of Combinatorics. - : Springer Science and Business Media LLC. - 0218-0006 .- 0219-3094. ; 8:2, s. 123-131
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Journal article (peer-reviewed)abstract
- The blocker A* of an antichain A in a finite poset P is the set of elements minimal with the property of having with each member of A a common predecessor. The following is done: (1) The posets P for which A** = A for all antichains are characterized.(2) The blocker A* of a symmetric antichain in the partition lattice is characterized.(3) Connections with the question of finding minimal size blocking sets for certain set families are discussed.
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| 7. |
- Elg, Ulf, et al.
(author)
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Competing corporate sustainability perceptions in a global retail organization
- 2021
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In: International Journal of Retail and Distribution Management. - 0959-0552. ; 49:4, s. 449-465
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Journal article (peer-reviewed)abstract
- Purpose: The purpose is to explore the different and often contradictory perceptions individual managers have about corporate sustainability within a global retailer. Design/methodology/approach: A qualitative case study method is used, including interviews and document studies. The authors study the global retailer IKEA. In total the authors have interviewed respondents on both the global level and the country level, within the sustainability organization as well as corporate, sales and communication management. The study includes managers in Sweden, the UK and Germany. Findings: The research is based on institutional theory, focusing upon cognitive and normative aspects; the authors propose that managers may have a proactive, forceful view on sustainability or a reactive view. These need to coexist. The authors also show how global retailers can balance sustainability goals with other business considerations, as well as about the implications of the sustainability approach for the retailer's business model. Practical implications: Retail managers need to recognize and integrate the contradictory views on sustainability that managers hold. The authors show how sustainability can be given different impact depending on the context and the strategic issue it is linked to. Originality/value: Most studies have focused on how sustainability is managed on an organizational level and how different goals can co-exist. The authors’ focus is on individual managers and their perceptions of sustainability – what it includes, how they want to manage sustainability issues, and the priority it should be given.
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| 8. |
- Eriksen, Niklas, et al.
(author)
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Estimating the expected reversal distance after a fixed number of reversals
- 2004
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In: Advances in Applied Mathematics. - San Diego, USA : Elsevier. - 0196-8858 .- 1090-2074. ; 32:3, s. 439-453
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Journal article (peer-reviewed)abstract
- We address the problem of computing the expected reversal distance of a genome with n genes obtained by applying t random reversals to the identity. A good approximation is the expected transposition distance of a product of t random transpositions in S-n. Computing the latter turns out to be equivalent to computing the coefficients of the length function (i.e., the class function returning the number of parts in an integer partition) when written as a linear combination of the irreducible characters of Sn. Using symmetric functions theory, we compute these coefficients, thus obtaining a formula for the expected transposition distance. We also briefly sketch how to compute the variance.
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| 9. |
- Eriksen, Niklas, 1974-, et al.
(author)
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Expected reflection distance in G(r, 1, n) after a fixed number of reflections
- 2005
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In: Annals of Combinatorics. - Basel, Switzerland : Springer Science and Business Media LLC. - 0218-0006 .- 0219-3094. ; 9:1, s. 21-33
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Journal article (peer-reviewed)abstract
- Extending to r > 1 a formula of the authors, we compute the expected reflection distance of a product of t random reflections in the complex reflection group G (r, 1, n). The result relies on an explicit decomposition of the reflection distance function into irreducible G (r, 1, n) characters and on the eigenvalues of certain adjacency matrices.
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| 10. |
- Flink, Axel, 1979-
(author)
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Growth and Characterization of Ti-Si-N Hard Coatings
- 2006
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Licentiate thesis (other academic/artistic)abstract
- Metastable (Ti,Si)N alloy and TiN/SiNx multilayer thin solid films as well as SiNx/TiN surfaces have been explored. Cubic Ti1-xSixN (0≤x≤0.14) films deposited onto cemented carbide (WC-Co) substrates by arc evaporation exhibited a competitive columnar growth mode where the structure transforms to a feather-like nanostructure with increasing Si content as revealed by x-ray diffraction and transmission electron microscopy. X-ray photoelectron spectroscopy revealed the presence of Ti-N and Si-N bonding, but no amorphous Si3N4. Band structure calculations showed that phase separation of NaClstructure Ti1-xSixN solid solution into cubic SiN and TiN phases is energetically favorable. The metastable microstructure, however, was maintained for the Ti0.86Si0.14N film annealed at 900°C, while recrystallization in the cubic state took place at 1100°C annealing during 2h. The Si content influenced the film hardness close to linearly, by combination of solid-solution hardening in the cubic state and defect hardening. For x=0 and x=0.14, nanoindentation gave a hardness of 29.9±3.4 GPa and 44.7±1.9 GPa, respectively. The hardness was retained during annealing at 900°C.Nanostructured materials, e.g., nanocomposites and nanolaminates, are defined by internal interfaces, of which the nature is still under debate. In this work two-phase model systems were explored by depositing SiNx/TiN nanolaminate films, including superlattices containing cubic SiNx, by dual target reactive magnetron sputtering. It is demonstrated that the interfacial phase of SiNx onto TiN(001) and TiN(111) can be crystalline, and even epitaxial with complex surface reconstructions. Using in situ structural analyses combined with ab initio calculations, it is found that SiNx layers grow epitaxially, giving rise to strong interfacial bonding, on both TiN(001) and TiN(111) surfaces. In addition, TiN overlayers grow epitaxially on SiNx/TiN(001) bilayers in nanolaminate structures. These results provide insight into the development of design rules for novel nanostructured materials.
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