| 1. |
- Aad, G., et al.
(författare)
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- 2012
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Ingår i: The European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6052. ; 72:7
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Överstam, Henrik
(författare)
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Evaluation of the improvement of rolling analysis by means of modern technology
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Modern wire rod rolling is characterised by high rolling speed and requirements on well-defined mechanical properties as well as close tolerances. Traditional methods for analyses of this kind of processes, such as the slip line field theory and the upper bound analysis, have proven not to be sufficient. Different methods for rolling analysis have been evaluated. Several FE approaches were compared to classical methods such as the upper bound and the slip line theory and the results was validated by practical experiments. The finite element method has proven to be a powerful tool in order understand the metal working process, it also gives the possibility to study phenomena not yet clarified.
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| 3. |
- Ridderstad, Per S
(författare)
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Kring några Tessinska småtryck i Ericsbergsarkivet
- 2001
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Ingår i: Biblis. - 1403-3313. ; 3(2000):3/4, s. 54-57
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Tidskriftsartikel (refereegranskat)abstract
- A folder in the Ericsberg archive contains a rare collection of small ephemera printed to be used as theatre posters, advertisements for fanciful shops, pharmaceutical labels on imaginary medicines, lottery tickets etc. at a 1749 christmas party at the court of Queen Lovisa Ulrika of Sweden. The festivity was organized as a street market inside the palace by the Chancellor Count Tessin, and the texts were humourous, symbolic, sometimes surrealistic. That they are all printed can be seen to mirror that the public sphere in 18th century European towns began to be filled with printed messages af all kinds, which is the real breakthrough of print culture.
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| 4. |
- Thiyam, Priyadarshini
(författare)
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A study of finite-size, non-perturbative and anisotropic effects on the Lifshitz-van der Waals forces and torque with material dielectric responses from first-principles calculations
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The van der Waals and the Casimir-Lifshitz forces are forces of attraction that exist between neutral polarizable bodies due to quantum fluctuations. They can be repulsive depending on the material properties and the geometry of the system. Since they are pervasive in nature, they encompass a great deal of relevance in the study of interaction between bodies in several different scenarios and background geometrical settings. This doctoral thesis first addresses the important aspects of finite-size and the non-perturbative effects of the van der Waals interactions between two atoms or molecules. Going beyond the usual assumption of atoms and molecules as point particles and adopting a description of finite size, the divergence inherent in such interaction energies in the limit of zero separation distance between the two interacting atoms or molecules is removed. The attainment of finite interaction energy at such close separation distance facilitates the estimation of van der Waals force contribution to the binding energy of the molecules, and towards surfaces. This is particularly important for noble atoms. The interaction between a pair of helium (He) atoms and krypton (Kr) atoms, and between a pair of methane (CH$_4$) molecules considering its environmental relevance, is investigated in detail. The application of finite size further leads to finite self energies of the atoms. The full expression of the interaction energy, as is discussed in detail in this thesis, typically contains a logarithmic factor of the form $\ln(1 \pm x)$. Formerly, in evaluating the interaction energies, this factor is customarily series-expanded and truncated in the leading order with certain assumptions. This thesis explores the effect of using the full expression, which is referred herein as the non-perturbative (or, the non-expanded) theory, analytically wherever possible as well as numerically. The combined application of the finite-size theory and the non-perturbative theory results in as much as 100\,\% correction in the self energy of atoms in vacuum. This may give rise to significant physical consequences, for example, in the permeabilities of atoms across dielectric membranes. The thesis next addresses the aspect of anisotropy in the Casimir-Polder interaction between a completely polarizable molecule and a dielectric slab polarizable in the normal direction. The formalism is applied to the study of preferential adsorption in the specific case of carbon dioxide (CO$_2$) and methane (CH$_4$) molecules interacting with amorphous silica slabs and thin gold films. Owing to its greater polarizability, the linearly polarizable CO$_2$ molecule is found to attract more towards the surfaces than the isotropically polarizable CH$_4$ molecule. In addition, the stable orientation of the CO$_2$ molecule with respect to the surface is determined to be the one in which the long, linear axis of the molecule is perpendicular to the surface. Further, the feature of Casimir torque which is a consequence of anisotropy in the interacting dielectric slabs is explored in the case of biaxial materials, in particular the bulk black phosphorus and its novel 2D counterpart phosphorene. The torque between a pair of phosphorus slabs, one face rotated with respect to the other, is observed to change sign at a particular separation distance which is determined by the crossing frequency of its planar dielectric components. This distance-dependent reversal of the sign of torque has never been observed before. The observation is verified with several other biaxial materials. This finding will help assist in the experimental detection of the Casimir torque, and can potentially be exploited in the future for designing nanodevices. Another remarkable effect that is uncovered is the submersion of ice microcrystals under water governed by the balance of repulsive Lifshitz force from the vapor-water interface and the buoyant force of water. The repulsive effect is found to be enhanced by the presence of salt ions in the system. An exclusion zone ranging from 2 nm to 1 ${\mu}$m devoid of small ice particles is formed below the water surface. As the ice sphere grows in size, the buoyant force overcomes the Lifshitz force, and the ice sphere starts to float with a fraction of its volume above the water surface in accordance with the classical Archimedes principle. The combined impact of Lifshitz forces and double-layer interactions is further investigated in ice-water-CO$_2$ and vapor-water-CO$_2$ systems employing different models of effective polarizability for ions, {\it viz.} the hardsphere model and Onsager's model. The CO$_2$ bubble is found to be repelled by the vapor-water interface and attracted towards the ice-water interface. The equilibrium thin film of water formed between vapor and ice surfaces varies in thickness depending on the model of effective polarizability and the type of salt present in the system. Further studies of the interaction energy in geometries comprising two molecules near an interface and molecule in a three-layer geometry are conducted which may be relevant for potential energy storage applications. The density functional theory (DFT) is employed to generate the frequency-dependent dielectric functions required for Lifshitz energy and force calculations. Summing up, in the numerous contexts outlined above, the importance of the van der Waals and Lifshitz forces has been demonstrated. The studies in this thesis enable significant predictions related to these forces which may be verifiable by experiments.
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| 5. |
- Arnborg, Stefan, et al.
(författare)
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Seeing Arboretum for the (partial k-) Trees
- 2020
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Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Royal Institute of Technology, Stockholm, Sweden : Springer. ; , s. 3-6
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The idea of applying a dynamic programming strategy to evaluating certain objective functions on trees is fairly straightforward. The road for this idea to develop into theories of width parameters has been not so straight. Hans Bodlaender has played a major role in the process of mapping out that road. In this sentimental journey, we will recount our collective road trip over the past decades.
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| 6. |
- Arnborg, Stefan
(författare)
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Robust Bayesianism : Imprecise and Paradoxical Reasoning
- 2004
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Ingår i: Proceedings of the Seventh International Conference on Information Fusion, FUSION 2004. - 917056115X ; , s. 407-414
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Konferensbidrag (refereegranskat)abstract
- We are interested in understanding the relationship between Bayesian inference and evidence theory, in particular imprecise and paradoxical reasoning. The concept of a set of probability distributions is central both in robust Bayesian analysis and in some versions of Dempster-Shafer theory. Most of the literature regards these two theories as incomparable. We interpret imprecise probabilities as imprecise posteriors obtainable from imprecise likelihoods and priors, both of which can be considered as evidence and represented with, e.g., DS-structures. The natural and simple robust combination operator makes all pairwise combinations of elements from the two sets. The DS-structures can represent one particular family of imprecise distributions, Choquet capacities. These are not closed under our combination rule, but can be made so by rounding. The proposed combination operator is unique, and has interesting normative and factual properties. We compare its behavior on Zadeh's example with other proposed fusion rules. We also show how the paradoxical reasoning method appears in the robust framework.
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| 7. |
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| 8. |
- Adloff, C, et al.
(författare)
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A measurement of the t dependence of the helicity structure of diffractive rho meson electroproduction at HERA
- 2002
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 539:1-2, s. 25-39
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Tidskriftsartikel (refereegranskat)abstract
- The helicity structure of the diffractive electroproduction of rho mesons, e + p --> e + rho + Y, is studied in a previously unexplored region of large four-momentum transfer squared at the proton vertex, t: 0 < t' < 3 GeV2, where t' = - min. The data used are collected with the HI detector at HERA in the kinematic domain 2.5 < Q(2) < 60 GeV2, 40 < W < 120 GeV No t dependence of the r(00)(04) spin density matrix element is found. A significant t dependent helicity non-conservation from the virtual photon to the rho meson is observed for the spin density matrix element combinations r(00)(5) + 2r(11)(5) and r(00)(1) + 2r(11)(1). These t dependences are consistently described by a perturbative QCD model based on the exchange of two gluons.
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| 9. |
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| 10. |
- Adlmann, Franz Alois
(författare)
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Opportunities and challenges of surface scattering at next generation neutron sources
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Complex fluids and soft matter are ubiquitously found in the world and all contacts in life are made over surfaces. To describe the mechanical behavior of such substances, rheological methods are used. Flow instabilities are a big challenge in rheology since they will be reflected in the macroscopic variables probed, like e. g. the viscosity. Many such discontinuities may actually originate at the surface. Investigating the properties of liquids in contact with the surface under mechanical load is the main course of the thesis. Neutron reflectometry and GISANS are perfect tools in this context to access the solid liquid interfaces, since they can penetrate many engineering materials and show a comparably large scattering potential at deuterated samples. In this thesis shear was applied on a model solution and neutron scattering techniques were used to investigate the structure under load. The focus was set on the development of the measurement methods themselves to enable new scientific insights in the future. First, by stroboscopic measurements the flux limitations are overcome for oscillatory rheology. By reintegration in the post processing it is shown that kinetic measurements with neutrons are possible with a time resolution below one millisecond. Second, the transformation of grazing incidence data from the laboratory system into q-space is strongly non-linear resulting in a need for re-binning. In this thesis a universal tool has been developed for this purpose. Finally, there is an ongoing discussion on depth sensitive neutron scattering experiments from solid-liquid boundaries. By using emission densities we show that such experiments face severe limitations due to the low absorption cross section of the neutron.
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