| 41. |
- Cook, G. A. S., et al.
(författare)
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Clustering, MNEs, and Innovation : Who Benefits and How?
- 2013
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Ingår i: International Journal of the Economics of Business. - : Informa UK Limited. - 1357-1516 .- 1466-1829. ; 20:2, s. 203-227
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Tidskriftsartikel (refereegranskat)abstract
- This paper explores three under-researched questions in the literature on multinational enterprises (MNEs), clustering, and innovation. First, to what extent does multinationality lead to higher rates of innovation activity and performance? Second, what, if any, is the link between MNE cluster location and innovation inputs and outputs? Third, are there any significant differences between enterprises belonging to domestic and overseas MNEs in these regards? Evidence is based primarily on 11,775 firms derived from the UK Community Innovation Survey 2007. Diversity in the regional economy exerts the most consistent positive influence, followed by the scale of employment in the enterprise's own industry. Enterprises belonging to domestic MNEs appear to exert higher levels of innovation effort. However, evidence regarding their superiority in innovation outputs was weaker. Contrary to Michael Porter's work, it appears that enterprises belonging to overseas firms benefit more than domestic firms.
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| 42. |
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| 43. |
- Cook, Gary, et al.
(författare)
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Geographic Clustering and Outward Foreign Direct Investment
- 2012
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Ingår i: International Business Review. - : Elsevier. - 0969-5931 .- 1873-6149. ; 21:6, s. 1112-1121
-
Tidskriftsartikel (refereegranskat)abstract
- This study addresses an important neglected question: To what extent do geographic clusters promote outward foreign direct investment (ODI)? We find evidence that clusters do promote ODI and so support Porter’s argument that advantages gained in clusters can be the foundations of successful internationalisation. Digging deeper, we find that certain cluster incumbents promote more ODI than others, with more experienced firms and firms with stronger resource bases accounting for more ODI. We also find that firms located in clusters within major global nodes/cities engage in more ODI. Finally, we find that both localisation and urbanisation economies promote ODI. However, the former, within-industry effects, are more important. Overall, this study echoes Dunning’s call for more focus on the ‘L’ component of the OLI paradigm and particularly on the advantages that reside in clusters that make them not only attractive destinations for FDI but also fertile environments from which FDI can spring.
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| 44. |
- Davis, Sergio, et al.
(författare)
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Model for diffusion at the microcanonical superheating limit from atomistic computer simulations
- 2011
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 84:6, s. 064102-
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Tidskriftsartikel (refereegranskat)abstract
- The diffusion statistics of atoms in a crystal close to the critical superheating temperature was studied in detail using molecular dynamics and Monte Carlo simulations. We present a continuous random-walk model for diffusion of atoms hopping through thermal vacancies. The results obtained from our model suggest that the limit of superheating is precisely the temperature for which dynamic percolation happens at the time scale of a single individual jump. A possible connection between the critical superheating limit and the maximization of the Shannon entropy associated with the distribution of jumps is suggested. As a practical application of our results, we show that an extrapolation of the critical superheating temperature (and therefore an estimation of the melting point) can be performed using only the dynamical properties of the solid state.
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| 45. |
- Davis, Sergio, et al.
(författare)
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Molecular dynamics simulation of zirconia melting
- 2010
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Ingår i: Central European Journal of Physics. - : Walter de Gruyter GmbH. - 1895-1082 .- 1644-3608. ; 8:5, s. 789-797
-
Tidskriftsartikel (refereegranskat)abstract
- The melting point for the tetragonal and cubic phases of zirconia (ZrO2) was computed using Z-method microcanonical molecular dynamics simulations for two different interaction models: the empirical Lewis-Catlow potential versus the relatively new reactive force field (ReaxFF) model. While both models reproduce the stability of the cubic phase over the tetragonal phase at high temperatures, ReaxFF also gives approximately the correct melting point, around 2900 K, whereas the Lewis-Catlow estimate is above 6000 K.
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| 46. |
- Davis, Sergio, et al.
(författare)
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SearchFill : A stochastic optimization code for detecting atomic vacancies in crystalline and non-crystalline systems
- 2011
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Ingår i: Computer Physics Communications. - : Elsevier BV. - 0010-4655 .- 1879-2944. ; 182:5, s. 1105-1110
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Tidskriftsartikel (refereegranskat)abstract
- We present an implementation of a stochastic optimization algorithm applied to location of atomic vacancies. Our method labels an empty point in space as a vacancy site, if the total spatial overlap of a "virtual sphere", centered around the point, with the surrounding atoms (and other vacancies) falls below a tolerance parameter. A Metropolis-like algorithm displaces the vacancies randomly, using an "overlap temperature" parameter to allow for acceptance of moves into regions with higher overlap, thus avoiding local minima. Once the algorithm has targeted a point with low overlap, the overlap temperature is decreased, and the method works as a steepest descent optimization. Our method, with only two free parameters, is able to detect the correct number and coordinates of vacancies in a wide spectrum of condensed-matter systems, from crystals to amorphous solids, in fact in any given set of atomic coordinates, without any need of comparison with a reference initial structure.
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| 47. |
- Delczeg-Czirjak, Erna Krisztina, 1978-, et al.
(författare)
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Ab initio study of structural and magnetic properties of Si-doped Fe2P
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 82:8, s. 085103-
-
Tidskriftsartikel (refereegranskat)abstract
- Ab initio electronic-structure methods are used to study the properties of Fe2P1-xSix in ferromagnetic and paramagnetic states. The site preference and lattice relaxation are calculated with the projector augmented wave method as implemented in the Vienna ab initio simulation package. The paramagnetic state is modeled by the disordered local magnetic moment scheme, and the chemical and magnetic disorder is treated using the coherent potential approximation in combination with the exact muffin-tin orbital formalism. The calculated lattice parameters, atomic positions, and magnetic properties are in good agreement with the experimental and other theoretical results. In contrast to the observation, for the ferromagnetic state the body centered ortho-rhombic structure (bco, space group I (mm2) under bar) is predicted to have lower energy than the hexagonal structure (hex, space group P (6) over bar 2m). The zero-point spin fluctuation energy difference is found to be large enough to stabilize the hex phase. For the paramagnetic state, the hex structure is calculated to be the stable phase and the computed total energy versus composition indicates a hex to bco crystallographic phase transition with increasing Si content. The phonon vibrational free energy, estimated from the theoretical equation of state, turns out to stabilize the hexagonal phase, whereas the electronic and magnetic entropies favor the low symmetry orthorhombic structure.
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| 48. |
- Delczeg-Czirjak, Erna K., et al.
(författare)
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Magnetic exchange interactions in B-, Si-, and As-doped Fe2P from first-principles theory
- 2012
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 85:22, s. 224435-
-
Tidskriftsartikel (refereegranskat)abstract
- Di-iron phosphide (Fe2P) is a parent system for a set of magnetocaloric materials. Although the magnetic ordering temperature (T-C = 215 K) of the stoichiometric composition is too low for room-temperature magnetic refrigeration, the partial replacement of P with B, Si, or As elements results in a steep increase in the magnetic ordering temperature. Doping leads to different equilibrium volumes and hexagonal axial ratios (c/a) within the same crystallographic phase over a wide concentration range. Here, using first principles theory, we decompose the change in the total magnetic exchange interaction upon doping into chemical and structural contributions, the latter including the c/a-ratio and volume effects. We demonstrate that for the investigated alloys the structural effect can be ascribed mainly to the decrease in the c/a ratio that strengthens the magnetic exchange interactions between the two Fe sublattices.
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| 49. |
- Delczeg-Czirjak, Erna Krisztina, et al.
(författare)
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Microscopic theory of magnetism in the magnetocaloric material Fe2P1-xTx (T = B and Si)
- 2012
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 86:4, s. 045126-
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Tidskriftsartikel (refereegranskat)abstract
- Landau phenomenological theory in combination with first-principles calculations was used to reveal the origin of the metamagnetic nature and the unusually strong dependence of the ordering temperature with doping of the Fe2P compound. We show that the magnetism of the two sublattices occupied by Fe atoms has an entwined codependency, which is strongly influenced by alloying. We furthermore demonstrate that a constrained disordered local moment approach combined with Monte Carlo simulations can only reproduce the experimental ordering temperatures in these technologically important prototype alloys for magnetocaloric refrigeration.
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| 50. |
- Delczeg, Lorand, et al.
(författare)
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Ab initio description of monovacancies in paramagnetic austenitic Fe-Cr-Ni alloys
- 2012
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 85:17, s. 174101-
-
Tidskriftsartikel (refereegranskat)abstract
- Using first-principles alloy theory, we calculate the vacancy formation energies of paramagnetic face-centered-cubic (fcc) Fe-Cr-Ni alloys as a function of chemical composition. These alloys are well-known model systems for low carbon austenitic stainless steels. The theoretical predictions obtained for homogeneous chemistry and relaxed nearest-neighbor lattice sites are in line with the experimental observations. In particular, Ni is found to decrease and Cr to increase the vacancy formation energy of the ternary system. The results are interpreted in terms of effective chemical potentials. The impact of vacancy on the local magnetic properties of austenitic steel alloys is also investigated.
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