| 1. |
- Wang, Jiabin, et al.
(författare)
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The Effect of Bogie Positions on the Aerodynamic Behavior of a High-Speed Train: An IDDES Study
- 2021
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Ingår i: Flow, Turbulence and Combustion. - : Springer Science and Business Media LLC. - 1573-1987 .- 1386-6184. ; 107:2, s. 257-282
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Tidskriftsartikel (refereegranskat)abstract
- In this study, an improved delayed detached-eddy simulation method has been used to investigate the aerodynamic behavior of the CRH2 high-speed trains (HST) with different first and last bogie positions. The results of the numerical simulations have been validated against experimental data obtained from a previous wind tunnel test, a full-scale field test and a reduced-scale moving model test. The results of the flow prediction are used to explore the effects of the bogie positions on the slipstream, wake flow, underbody flow and aerodynamic drag. Compared with the original HST model, the downstream movement of the first bogie, has a great effect on decreasing the slipstream velocity and pressure fluctuation aside the HST, especially around the lower part of the HST. Furthermore, the size of the longitudinal vortex structure and slipstream velocity in the near wake region also decrease significantly by moving the last bogie upstream. Additionally, the movement of the first and last bogies toward the HST center, effectively decreases the drag values of the head and tail car, while a lower effect is observed on the intermediate cars.
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| 2. |
- Wang, Tiantian, et al.
(författare)
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Microstructural probing of phosphonium-based ionic liquids on a gold electrode using colloid probe AFM
- 2022
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 24:41, s. 25411-25419
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Tidskriftsartikel (refereegranskat)abstract
- Atomic force microscopy (AFM) with a gold colloid probe modeled as the electrode surface is employed to directly capture the contact resonance frequency of two phosphonium-based ionic liquids (ILs) containing a common anion [BScB]− and differently lengthened cations ([P6,6,6,14]+ and [P4,4,4,8]+). The comparative interfacial studies are performed by creating IL films on the surface of gold, followed by measuring the wettability, thickness of the films, adhesion forces, surface morphology and AFM-probed contact resonance frequency. In addition, the cyclic voltammetry and impedance spectroscopy measurements of the neat ILs are measured on the surface of the gold electrode. The IL with longer cation alkyl chains exhibits a well-defined thin film on the electrode surface and enhanced the capacitance than the shorter chain IL. The AFM contact resonance frequency and force curves reveal that the longer IL prefers to form stiffer ion layers at the gold electrode surface, suggesting the “…anion–anion–cation–cation…” bilayer structure, in contrast, the shorter-chain IL forms the softer cation–anion alternating structure, i.e., “…anion–cation–anion–cation…”.
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| 3. |
- Fang, Tao, et al.
(författare)
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Perovskite QLED with an external quantum efficiency of over 21% by modulating electronic transport
- 2021
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Ingår i: Science Bulletin. - : ELSEVIER. - 2095-9273. ; 66:1, s. 36-43
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite quantum-dot-based light-emitting diodes (QLEDs) are highly promising for future solid-state lightings and high-definition displays due to their excellent color purity. However, their device performance is easily affected by charge accumulation induced luminescence quenching due to imbalanced charge injection in the devices. Here we report green perovskite QLEDs with simultaneously improved efficiency and operational lifetime through balancing the charge injection with the employment of a bilayered electron transport structure. The charge-balanced QLEDs exhibit a color-saturated green emission with a full-width at half-maximum (FWHM) of 18 nm and a peak at 520 nm, a low turn-on voltage of 2.0 V and a champion external quantum efficiency (EQE) of 21.63%, representing one of the most efficient perovskite QLEDs so far. In addition, the devices with modulated charge balance demonstrate a nearly 20-fold improvement in the operational lifetime compared to the control device. Our results demonstrate the great potential of further improving the device performance of perovskite QLEDs toward practical applications in lightings and displays via rational device engineering. (C) 2020 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.
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| 4. |
- Han, Tiantian, et al.
(författare)
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Structural analysis of dilute-nitride zinc blende InxGa1−xNyAs1−y cluster by a semiempirical quantum chemistry study
- 2007
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 101:12, s. 123707-1-123707-6
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the total energy of a series of dilute-nitride zinc blende Inx Ga1-x Ny As1-y cluster configurations using a semiempirical quantum chemistry method. It was found that In-N bonding is favorable from an energy point of view when the N atom is substitutional (replacing an As atom at the regular zinc blende lattice site) and the In mole fraction is smaller than 25%. In-N bonding is always favorable when the N atom is interstitial. Furthermore, an analysis of the incorporation of N-N pairs showed that substitutional incorporation is favored over interstitial. In addition, the dissociation of a N-N pair was found to depend on the local environment, being either In rich or In-free, along the dissociation trajectory when the average In mole fraction is high. The theoretical results are in agreement with experimental results.
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| 5. |
- Jones, Benedict C, et al.
(författare)
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To which world regions does the valence-dominance model of social perception apply?
- 2021
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Ingår i: Nature Human Behaviour. - : Springer Science and Business Media LLC. - 2397-3374. ; 5:1, s. 159-169
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Tidskriftsartikel (refereegranskat)abstract
- Over the past 10 years, Oosterhof and Todorov's valence-dominance model has emerged as the most prominent account of how people evaluate faces on social dimensions. In this model, two dimensions (valence and dominance) underpin social judgements of faces. Because this model has primarily been developed and tested in Western regions, it is unclear whether these findings apply to other regions. We addressed this question by replicating Oosterhof and Todorov's methodology across 11 world regions, 41 countries and 11,570 participants. When we used Oosterhof and Todorov's original analysis strategy, the valence-dominance model generalized across regions. When we used an alternative methodology to allow for correlated dimensions, we observed much less generalization. Collectively, these results suggest that, while the valence-dominance model generalizes very well across regions when dimensions are forced to be orthogonal, regional differences are revealed when we use different extraction methods and correlate and rotate the dimension reduction solution. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 5 November 2018. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.7611443.v1 .
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| 6. |
- Su, Yiqun, et al.
(författare)
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Effect of Electrode Surface Chemistry on Ion Structuring of Imidazolium Ionic Liquids
- 2023
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 39:24, s. 8463-8474
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Tidskriftsartikel (refereegranskat)abstract
- Surface chemistry plays a critical role in the ion structuring of ionic liquids (ILs) at the interfaces of electrodes and controls the overall energy storage performance of the system. Herein, we functionalized the gold (Au) colloid probe of an atomic force microscope with −COOH and −NH2 groups to explore the effect of different surface chemical properties on the ion structuring of an IL. Aided by colloid-probe atomic force microscopy (AFM), the ion structuring of an imidazolium IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6], abbreviated as BP hereafter), on the Au electrode surface and the ion response to the change in the surface chemistry are investigated. AFM morphologies, contact angles, and approaching force–distance curves of the BP IL on the functionalized Au surfaces exhibited that the IL forms a more obvious layering structure on the −COOH-terminated Au surface (Au–COOH), while it forms heterogeneous and aggregating droplets on the −NH2 surface (Au–NH2). The formed uniform and aggregation-free ion layers in the vicinity of the Au–COOH surface are due to the π–π+ stacking interaction between the delocalized π+ electrons from the imidazolium ring in the IL [BMIM]+ cation and the localized π electrons from the sp2 carbon on the −COOH group. The in situ observation of nano-friction and torsional resonance frequency at the IL–electrode interfaces further demonstrated the ion structuring of the IL at Au–COOH, which results in a more sensitive electrochemical response associated with a faster capacitive process.
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| 7. |
- Zhang, Zenglei, et al.
(författare)
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Insulin resistance and its relationship with long-term exposure to ozone : Data based on a national population cohort
- 2024
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Ingår i: Journal of Hazardous Materials. - 0304-3894. ; 472
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Tidskriftsartikel (refereegranskat)abstract
- The relationship of ozone (O3), particularly the long-term exposure, with impacting metabolic homeostasis in population was understudied and under-recognised. Here, we used data from ChinaHEART, a nationwide, population-based cohort study, combined with O3 and PM2.5 concentration data with high spatiotemporal resolution, to explore the independent association of exposure to O3 with the prevalence of insulin resistance (IR). Among the 271 540 participants included, the crude prevalence of IR was 39.1%, while the age and sex standardized prevalence stood at 33.0%. Higher IR prevalence was observed with each increase of 10.0 μg/m3 in long-term O3 exposure, yielding adjusted odds ratios (OR) of 1.084 (95% CI: 1.079–1.089) in the one-pollutant model and 1.073 (95% CI: 1.067–1.079) in the two-pollutant model. Notably, a significant additive interaction between O3 and PM2.5 on the prevalence of IR was observed (P for additive interaction < 0.001). Our main findings remained consistent and robust in the sensitivity analyses. Our study suggests long-term exposure to O3 was independently and positively associated with prevalence of IR. It emphasized the benefits of policy interventions to reduce O3 and PM2.5 exposure jointly, which could ultimately alleviate the health and economic burden related to DM.
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