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| 2. |
- Du, Chun-Xia, et al.
(författare)
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Si/SiGe/Si : Er
- 2001
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 78:12, s. 1697-1699
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Tidskriftsartikel (refereegranskat)abstract
- Si/SiGe/Si:Er:O heterojunction bipolar transistor (HBT) type light-emitting devices with Er3+ ions incorporated in the collector region have been fabricated using a layered structure grown by differential molecular-beam epitaxy. Electroluminescence measurements on processed light-emitting HBTs can be performed in either constant driving current mode or constant applied bias mode, which is an important advantage over conventional Si:Er light-emitting diodes. Intense room-temperature light emission at the Er3+ characteristic wavelength of 1.54 µm has been observed at low driving current density, e.g., 0.1 A cm-2, and low applied bias, e.g., 3 V, across the collector and emitter. © 2001 American Institute of Physics.
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| 3. |
- Jin, Yingzhi, et al.
(författare)
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Investigation on voltage loss in organic triplet photovoltaic devices based on Ir complexes
- 2019
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 7:47, s. 15049-15056
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Tidskriftsartikel (refereegranskat)abstract
- Voltage losses in singlet material-based organic photovoltaic devices (OPVs) have been intensively studied, whereas, only a few investigations on triplet material-based OPVs (T-OPVs) are reported. To investigate the voltage loss in T-OPVs, two homoleptic iridium(iii) complexes based on extended pi-conjugated benzo[g]phthalazine ligands, Ir(Ftbpa)(3) and Ir(FOtbpa)(3), are synthesized as sole electron donors. T-OPVs are fabricated by mixing two donors with phenyl-C-71-butyric acid methyl ester (PC71BM) as an electron acceptor. Insertion of oxygen-bridges as flexible inert delta-spacers in Ir(FOtbpa)(3) has slightly elevated both the lowest unoccupied molecular orbital and the highest occupied molecular orbital levels compared to those of Ir(Ftbpa)(3), which results in a lower charge transfer (CT) state energy (E-CT) for Ir(FOtbpa)(3)-based devices. However, a higher V-oc (0.88 V) is observed for Ir(FOtbpa)(3)-based devices than those of Ir(Ftbpa)(3) (0.80 V). To understand the above result, the morphologies of the two blend films are studied, which excludes the influence of morphology. Furthermore, radiative and non-radiative recombination in two devices is quantitatively investigated, which suggests that a higher V-oc can be attributed to reduced radiative and non-radiative recombination loss for the Ir(FOtbpa)(3)-based devices.
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| 4. |
- Li, Hongxia, et al.
(författare)
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Microscopic insights of phase-transition-induced vapor transport enhancement in porous media
- 2024
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Ingår i: International Journal of Multiphase Flow. - 0301-9322. ; 177
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Tidskriftsartikel (refereegranskat)abstract
- Vapor transport in porous media, often associated with liquid-vapor phase change, is an fundamental process in many emerging underground energy storage and extraction processes (i.e., seasonal solar thermal aquifer storage, geothermal extraction, extraterrestrial in-situ water extraction). By jointly using experimental imaging and numerical modeling at the micro-scale, we conduct mechanistic pore scale investigation of capillarity-dominated phase change dynamics and its influence on vapor transport in partially saturated porous rock micromodel. Strongly linked to surface roughness and wettability condition, the capillarity hinders water vaporization from rock surface micro/nano-structures as observed under the environmental scanning electron microscope. By varying the contact angle of 0°, 60°, and 120°, the lattice Boltzmann simulation shows the wettability-dependent vaporization process of capillary-hold water, where pores with hydrophilic surfaces contains significantly more liquid water than that of the hydrophobic ones under the same temperature. When saturated vapor flows through rock porous patterns, capillarity further induces water condensation on the strongly water-wet surfaces. Water condensation, yet forming water bridges/islands and causing the blockage of vapor diffusion, enhances the vapor diffusion ability counterintuitively. The reduction of diffusion path is revealed as the main reason by assessing the local vapor pressure distribution before and after the pore filling by condensate. The findings support the debatable enhancement mechanisms postulated by Philip and de Vries. This work offers the insightful interfacial hydrodynamics of vapor transport in porous media and potentially provides operational guidance for geothermal applications and beyond.
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| 6. |
- Sörlin, Sverker
(författare)
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The Anxieties of a Science Diplomat : Field Coproduction of Climate Knowledge and the Rise and Fall of Hans Ahlmann's "Polar Warming"
- 2011
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Ingår i: Osiris. - Chicago : University of Chicago Press. - 0369-7827 .- 1933-8287. ; 26, s. 66-88, s. 66-88
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Tidskriftsartikel (refereegranskat)abstract
- In the decades between the world wars there were several attempts to document and explain perceived tendencies of atmospheric warming. Hans Ahlmann, a seminal figure in modern glaciology and a science policy adviser and diplomat, constructed a theory of "polar warming" using field results from glacier melting in the Arctic. This article aims to link the rise and fall of "polar warming" with Ahlmann's style of fieldwork. In Ahlmann's view, fieldwork should (1) enhance credibility of polar climate science by emulating laboratory methods and (2) secure knowledge in remote places through collaboration with local residents and fieldworkers. The bodily nature of this style of knowledge production turned out to be an asset in establishing Ahlmann's theory of polar warming but ultimately proved nonresilient to theories of anthropogenic climate change, which became influential from the 1950s onward.
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| 8. |
- Zhang, Chi, 1992, et al.
(författare)
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Pedestrian Behavior Prediction Using Deep Learning Methods for Urban Scenarios: A Review
- 2023
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Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 24:10, s. 10279-10301
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Tidskriftsartikel (refereegranskat)abstract
- The prediction of pedestrian behavior is essential for automated driving in urban traffic and has attracted increasing attention in the vehicle industry. This task is challenging because pedestrian behavior is driven by various factors, including their individual properties, the interactions with other road users, and the interactions with the environment. Deep learning approaches have become increasingly popular because of their superior performance in complex scenarios compared to traditional approaches such as the social force or constant velocity models. In this paper, we provide a comprehensive review of deep learning-based approaches for pedestrian behavior prediction. We review and categorize a large selection of scientific contributions covering both trajectory and intention prediction from the last five years. We categorize existing works by prediction tasks, input data, model features, and network structures. Besides, we provide an overview of existing datasets and the evaluation metrics. We analyze, compare, and discuss the performance of existing work. Finally, we point out the research gaps and outline possible directions for future research. Marie Skłodowska-Curie Actions; Innovative Training Network (ITN); Project name: SHAPE-IT; Grant number: 860410; Publication date: 12 June 2023; DOI: 10.1109/TITS.2023.3281393
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