| 1. |
- Hansson, Linus, et al.
(författare)
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Development and implementation of a dynamic TES dispatch control component in a PV-CSP techno-economic performance modelling tool
- 2017
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Ingår i: AIP Conference Proceedings. - : American Institute of Physics (AIP). - 0094-243X. - 9780735415225
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Konferensbidrag (refereegranskat)abstract
- The dispatchability offered by thermal energy storage (TES) in concentrated solar power (CSP) and solar hybrid plants based on such technology presents the most important difference compared to power generation based only on photovoltaics (PV). This has also been one reason for recent hybridization efforts of the two technologies and the creation of Power Purchase Agreement (PPA) payment schemes based on offering higher payment multiples during daily hours of higher (peak or priority) demand. Recent studies involving plant-level thermal energy storage control strategies are however to a large extent based on pre-determined approaches, thereby not taking into account the actual dynamics of thermal energy storage system operation. In this study, the implementation of a dynamic dispatch strategy in the form of a TRNSYS controller for hybrid PV-CSP plants in the power-plant modelling tool DYESOPT is presented. In doing this it was attempted to gauge the benefits of incorporating a day-ahead approach to dispatch control compared to a fully pre-determined approach determining hourly dispatch only once prior to annual simulation. By implementing a dynamic strategy, it was found possible to enhance technical and economic performance for CSP-only plants designed for peaking operation and featuring low values of the solar multiple. This was achieved by enhancing dispatch control, primarily by taking storage levels at the beginning of every simulation day into account. The sequential prediction of the TES level could therefore be improved, notably for evaluated plants without integrated PV, for which the predicted storage levels deviated less than when PV was present in the design. While also featuring dispatch performance gains, optimal plant configurations for hybrid PV-CSP was found to present a trade-off in economic performance in the form of an increase in break-even electricity price when using the dynamic strategy which was offset to some extent by a reduction in upfront investment cost. An increase in turbine starts for the implemented strategy however highlights that this is where further improvements can be made.
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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- Aichmayer, Lukas, et al.
(författare)
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Performance Improvements of the KTH High-Flux Solar Simulator
- 2017
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Ingår i: AIP Conference Proceedings 1850. - : American Institute of Physics (AIP). - 9780735415225
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Konferensbidrag (refereegranskat)abstract
- This paper presents the performance improvements implemented in the KTH high-flux solar simulator to deliver a total power on target closer to the working conditions of real CSP systems. Therefore, additional rectifiers were installed in the power conversion unit of the high-power lamps as well as the back reflector was coated providing more favorable spectral reflectance properties. The results of a single lamp/lens-combination show that the power on target in an aperture of 280mm in diameter was increased from 831W to 1446W while the peak flux was increased from 675kW/m² to 905kW/m².
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