| 1. |
- Andreasson, Eskil, et al.
(författare)
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Simulation of thin aluminium-foil in the packaging industry
- 2017
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Ingår i: AIP Conference Proceedings. - : American Institute of Physics Inc.. - 0094-243X. - 9780735415805
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Konferensbidrag (refereegranskat)abstract
- This work present an approach of how to account for the anisotropic mechanical material behaviour in the simulation models of the thin aluminium foil layer (≈10 μm) used in the Packaging Industry. Furthermore, the experimental results from uniaxial tensile tests are parameterised into an analytical expression and the slope of the hardening subsequently extended way beyond the experimental data points. This in order to accommodate the locally high stresses present in the experiments at the neck formation. An analytical expression, denominated Ramberg-Osgood, is used to describe the non-linear mechanical behaviour. Moreover it is possible with a direct method to translate the experimental uniaxial tensile test results into useful numerical material model parameters in Abaqus™. In addition to this the extended material behaviour including the plastic flow i.e. hardening, valid after onset of localisation, the described procedure can also capture the microscopic events, i.e. geometrical thinning, ongoing in the deformation of the aluminium foil. This method has earlier successfully been applied by Petri Mäkelä for paperboard material [1]. The engineering sound and parameterised description of the mechanical material behaviour facilitates an efficient categorisation of different aluminium foil alloys and aid the identification of the correct anisotropic (RD/TD/45°) mechanical material behaviour derived from the physical testing. © 2017 Author(s).
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| 2. |
- Khodaee, Alireza, 1984-, et al.
(författare)
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Evaluation of effects of geometrical parameters on density distribution in compaction of PM gears
- 2017
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Ingår i: AIP Conference Proceedings. - : Author(s). - 0094-243X. - 9780735415805
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Konferensbidrag (refereegranskat)abstract
- The usage of powder metallurgy (PM) for manufacturing of transmission components in automotive industries has been studied by many researchers. PM components have become of interest in recent years due to advancements in post processing possibilities such as hot isostatic pressing (HIP). Still in many of the forming process routes for making components from PM materials, the compaction of the powder into green component is the first step. Compaction is required to put the powder into the near net shape of the desired component and it causes a density gradient in the body of the green component. Basically the friction between powder particles and between the powder particles and die walls are the well-known roots for such density gradients in the compacted component. Looking at forming of PM gears, the gradient in density is one of the most important roots of problems in the processing of PM gears as well. That is because making a gear with full density and no pores will be very costly if large density gradients exist in the green component. The purpose of this study is to find the possible relations between the gear geometry and the density gradients in the green component after compaction in addition to the friction effects. For this purpose several gears should be tested. To reduce the research costs, the finite element (FE) method is used. First a FE model of the compaction process is developed and verified. To investigate the relations between the density gradients and the gear parameters such as addendum diameter (da) and the face width (b) several gear geometries have been studied. The compaction of selected gears is simulated using the FE model. The simulations results which are the distribution of density in the green component are evaluated and discussed and conclusion are made based on them. © 2017 Author(s).
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| 3. |
- Amloy, Supaluck, et al.
(författare)
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Polarized emission from single GaN quantum dots grown by molecular beam epitaxy
- 2011
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Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735410022 ; 1399, s. 541-542
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Konferensbidrag (refereegranskat)abstract
- Polarization resolved microphotoluminescence measurements of single MBE-grown GaN/Al(Ga)N quantum dots (QDs) have been performed. The exciton and biexciton peaks with full width at half maximum as narrow as
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| 4. |
- Abel, Martin, et al.
(författare)
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Collision-induced absorption by supermolecular complexes from a new potential energy and induced dipole surface, suited for calculations up to thousands of kelvin
- 2010
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Ingår i: 20th International Conference on Spectral Line Shapes. - Melville, NY : American Institute of Physics (AIP). - 9780735408456 ; , s. 251-257
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Konferensbidrag (refereegranskat)abstract
- Absorption by pairs of H2 molecules is an important opacity source in the atmospheres of the outer planets, and thus of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra, amongst other reasons due to absorption by H2-H2, H2-He, and H2-H collisional complexes in the stellar atmospheres. To model the radiative processes in these atmospheres, which have temperatures of several thousand kelvin, one needs accurate knowledge of the induced dipole (ID) and potential energy surfaces (PES) of such collisional complexes. These come from quantum-chemical calculations with the H2 bonds stretched or compressed far from equilibrium. Laboratory measurements of collision-induced (CI) absorption exist only at much lower temperature. For H2 pairs at room temperature, the calculated spectra of the rototranslational band, the fundamental band, and the first overtone match the experimental data very well. In addition, with the newly obtained IDS it became possible to reproduce the measurements in the far blue wing of the rototranslational spectrum of H2 at 77.5 K, as well as at 300 K. Similarly good agreement between theory and measurement is seen in the fundamental band of molecular deuterium at room temperature. Furthermore, we also show the calculated absorption spectra of H2-He at 600 K and of H2-H2 at 2,000 K, for which there are no experimental data for comparison
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| 5. |
- Abgrall, N., et al.
(författare)
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The large enriched germanium experiment for neutrinoless double beta decay (LEGEND)
- 2017
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Ingår i: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. ; 1894
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Konferensbidrag (refereegranskat)abstract
- The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neu-trinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of ∼0.1 count /(FWHM·t·yr) in the region of the signal. The current generation 76Ge experiments GERDA and the Majorana Demonstrator, utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years, using existing resources as appropriate to expedite physics results.
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| 6. |
- Abou-Taouk, Abdallah, 1982, et al.
(författare)
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Evaluation of Optimized 3-step Global Reaction Mechanism for CFD Simulations on Sandia Flame D
- 2011
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Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735409569 ; 1389, s. 66-69
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Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to evaluate a new optimized 3-step global reaction mechanism (opt) [1] for a methane-air mixture for industry purpose. The global reaction mechanism consists of three reactions corresponding to the fuel oxidation into CO and H2O, and the CO–CO2 equilibrium reaction. Correction functions that are dependent on the local equivalence ratio are introduced into the global mechanism. The optimized 3-step global reaction scheme is adapted into the Computational Fluid Dynamics (CFD) analysis of a partially-premixed piloted methane jet flame. The burner consists of a central nozzle (for premixed fuel/air), surrounded by a premixed pilot flame, and an annular co-flow stream. Both steady-state RANS (Reynolds Averaged Navier Stokes) and time-averaged hybrid URANS/LES (Unsteady RANS/Large Eddy Simulation) results have been computed and compared with experimental results obtained from the Sydney burner at Sandia National Laboratories, Sandia Flame D [2]. The CFD results with the optimized 3-step global reaction mechanism show reasonable agreement with the experimental data based on emission, velocity and temperature profiles, while the 2-step Westbrook Dryer (WD2) [3] global reaction mechanism shows poor agreement with the emission profiles. ©2011 American Institute of Physics
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| 7. |
- Abramowicz, Marek A, 1945, et al.
(författare)
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Interpreting black hole QPOs
- 2004
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Ingår i: AIP Conference Proceedings. - 0094-243X. ; 714, s. 21-28
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- n all the microquasars with two hHz QPOs, the ratio of the frequencies is 3:2, supporting our suggestion that a non-linear resonance between two modes of oscillation in the accretion disk plays a role in exciting the observed modulations of the X-ray flux. We discuss the evidence in favor of this interpretation, and we relate the black hole spin to the frequencies expected for various types of resonances that may occur in nearly Keplerian disks in strong gravity. For those microquasars where the mass of the central X-ray source is known, the black hole spin can be deduced from a comparison of the observed and expected frequencies.
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| 8. |
- Abrikosov, Alexei I., et al.
(författare)
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Multiscale study of crystal and electronic structure of Al defects in concrete
- 2018
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Ingår i: International Conference of Computational Methods in Sciences and Engineering 2018, ICCMSE 2018. - : Author(s). - 9780735417663 ; 2040
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Konferensbidrag (refereegranskat)abstract
- Possible crystal structures of aluminium defects in concrete materials are tested with reactive force filed ReaxFF. The ongoing project includes further refinement of the structures by semiempirical and ab initio methods.
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| 9. |
- Adenier, Guillaume, et al.
(författare)
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Double Blinding-Attack on Entanglement-Based Quantum Key Distribution Protocols
- 2012
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. - 9780735410046 ; 1424:1, s. 9-16
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Tidskriftsartikel (refereegranskat)abstract
- We propose a double blinding-attack on entangled-based quantum key distribution protocols. The principle of the attack is the same as in existing blinding attack except that instead of blinding the detectors on one side only, Eve is blinding the detectors of both Alice and Bob. In the BBM92 protocol, the attack allows Eve to get a full knowledge of the key and remain undetected even if Alice and Bob are using 100% efficient detectors. The attack can be easily extended to Ekert protocol, with an efficiency as high as 85.3%.
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| 10. |
- Ahn, Kyungjin, et al.
(författare)
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The Inhomogeneous Background of H2 Dissociating Radiation During Cosmic Reionization
- 2008
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Ingår i: FIRST STARS III. - : American Institute of Physics.
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Konferensbidrag (refereegranskat)abstract
- The first, self-consistent calculations of the cosmological H2 dissociating UV background produced during the epoch of reionization by the sources of reionization are presented. Large-scale radiative transfer simulations of reionization trace the impact of all the ionizing starlight on the IGM from all sources in our simulation volume down to dwarf galaxies of mass ~108 Msolar, identified by very high-resolution N-body simulations, including the self-regulating effect of IGM photoheating on dwarf galaxy formation. The UV continuum emitted below 13.6 eV by each source is then transferred through the same IGM, attenuated by atomic H Lyman series resonance lines, to predict the evolution of the inhomogeneous background in the Lyman-Werner band of H2 between 11 and 13.6 eV.
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