| 1. |
- Kristan, Matej, et al.
(författare)
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The Visual Object Tracking VOT2015 challenge results
- 2015
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Ingår i: Proceedings 2015 IEEE International Conference on Computer Vision Workshops ICCVW 2015. - : IEEE. - 9780769557205 ; , s. 564-586
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge 2015, VOT2015, aims at comparing short-term single-object visual trackers that do not apply pre-learned models of object appearance. Results of 62 trackers are presented. The number of tested trackers makes VOT 2015 the largest benchmark on short-term tracking to date. For each participating tracker, a short description is provided in the appendix. Features of the VOT2015 challenge that go beyond its VOT2014 predecessor are: (i) a new VOT2015 dataset twice as large as in VOT2014 with full annotation of targets by rotated bounding boxes and per-frame attribute, (ii) extensions of the VOT2014 evaluation methodology by introduction of a new performance measure. The dataset, the evaluation kit as well as the results are publicly available at the challenge website(1).
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| 2. |
- Miao, Xiujuan, et al.
(författare)
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Aerodynamic performance of a high-speed train passing through three standard tunnel junctions under crosswinds
- 2020
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Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- The aerodynamic performance of a high-speed train passing through tunnel junctions under severe crosswind condition was numerically investigated using improved delayed detached-eddy simulations (IDDES). Three ground scenarios connected with entrances and exits of tunnels were considered. In particular a flat ground, an embankment, and a bridge configuration were used. The numerical method was first validated against experimental data, showing good agreement. The results show that the ground scenario has a large effect on the train's aerodynamic performance. The bridge case resulted in generally smaller drag and lift, as well as a lower pressure coefficient on both the train body and the inner tunnel wall, as compared to the tunnel junctions with flat ground and embankment. Furthermore, the bridge configuration contributed to the smallest pressure variation in time in the tunnel. Overall, the study gives important insights on complicated tunnel junction scenarios coupled with severe flow conditions, that, to the knowledge of the authors, were not studied before. Beside this, the results can be used for further improvements in the design of tunnels where such crosswind conditions may occur.
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| 3. |
- Ma, Ruijie, et al.
(författare)
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Adding a Third Component with Reduced Miscibility and Higher LUMO Level Enables Efficient Ternary Organic Solar Cells
- 2020
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 5:8, s. 2711-2720
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Tidskriftsartikel (refereegranskat)abstract
- It is widely known that the miscibility between donor and acceptor is a crucial factor that affects the morphology and thus device performance of nonfullerene organic solar cells (OSCs). In this Letter, we show that incorporating a third component with lower miscibility and higher lowest unoccupied molecular orbital (LUMO) level into the state-of-the-art PM6:Y6 system can significantly enhance the performance of devices. The best results of the ternary devices are achieved by adding a small molecular acceptor named ITCPTC (similar to 5% w/w), which significantly improves the power conversion efficiency (PCE) of the host system from 16.44% to 17.42%. The higher LUMO of the third component increases the open-circuit voltage (V-oc), while the low miscibility enlarges the domains and leads to improved short-circuit current density (J(sc)) and fill factor (FF). The efficacy of this strategy is supported by using other nonfullerene third components including an asymmetric small molecule (N7IT) and a polymer acceptor (PF2-DTC), which play the same role as ITCPTC and boost the PCEs to 16.96% and 17.04%, respectively. Our approach can be potentially applied to a wide range of OSC material systems and should facilitate the development of the OSC field.
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| 4. |
- Deng, Na, et al.
(författare)
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Comparative analysis of optimal operation strategies for district heating and cooling system based on design and actual load
- 2017
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 205, s. 577-588
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Tidskriftsartikel (refereegranskat)abstract
- Computational load significantly influences energy and cost savings when developing an operation strategy for a district heating and cooling system. In this study, a model was identified to study the effects of the difference between design load and actual load on an optimal operation strategy. The established model is strongly dependent on the economy principle, and the proposed optimal strategy could achieve a dynamic balance between the users' load and the system energy supply. This model was validated at 30% load rate, which demonstrated an obvious cost saving of 63.6% under the actual load and 42.2% under the design load. Based on the current strategy, the optimal strategy at different load rates was analyzed with respect to two characteristics of each subsystem: energy outputs and operation costs. Furthermore, in the optimal strategy, changes in total operation costs and cost savings rates under different load rates are also discussed. The results showed that, when the load rate was changed from 30 to 75%, the savings rates based on the design load were 42.2, 17.9, 2.5, and 12.6%, and the savings rates based on the actual load were 63.6, 49.8, 34.3, and 25.7%, respectively. Based on the actual load, the energy savings advantage of the optimal operation strategy could be maximized, in particular, during the initial stage of project construction. Furthermore, the commercial software MATLAB was used for programming and calculations. The simulation results indicated that the application of the combined cooling, heating, and power system could significantly improve the cost-effectiveness.
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| 5. |
- Zhao, Fuwen, et al.
(författare)
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Highly efficient fused ring electron acceptors based on a new undecacyclic core
- 2021
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Ingår i: Materials Chemistry Frontiers. - : ROYAL SOC CHEMISTRY. - 2052-1537. ; 5:4, s. 2001-2006
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Tidskriftsartikel (refereegranskat)abstract
- Two FREAs, IUIC-O and IUIC-T, based on an undecacyclic core were developed. IUIC-T having a higher extinction coefficient affords aligned energy levels with PBDB-T, finer nanoscale morphology and more orderly molecular stacking, thus achieving more efficient exciton dissociation and charge transport. Therefore, the PBDB-T:IUIC-T based OSC gains a higher PCE of 13.05%.
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| 6. |
- Zhao, Yufeng, et al.
(författare)
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Synthesis of hierarchically porous LiNiCuZn-oxide and its electrochemical performance for low-temperature fuel cells
- 2014
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 39:23, s. 12317-12322
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Tidskriftsartikel (refereegranskat)abstract
- In this work, hierarchically porous composite metal oxide LiNiCuZn-oxide (LNCZO) was successfully synthesized through a sol-gel method with a bio-Artemia cyst shell (AS) as a hard template. The phase and morphology of the products were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM). The as-synthesized material was used as symmetrical electrodes, anode and cathode, for the SDC-LiNaCO3 (LNSDC) electrolyte based low temperature solid oxide fuel cell (LTSOFCs), achieving a maximum power density of 132 mW cm(-2) at 550 degrees C. Besides, a single-component fuel cell device was also demonstrated using a mixture of as-prepared LNCZO and ionic conductor LNSDC, and a corresponding peak power output of 155 mW cm(-2) was obtained, suggesting that the hierarchically porous product has high prospective in the single-component fuel cell.
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| 7. |
- Zhang, Jie, et al.
(författare)
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Assessment of URANS, SAS, and IDDES on the bi-stable wake flow of a generic ship
- 2023
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Ingår i: Ocean Engineering. - 0029-8018. ; 286
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims to assess the prediction ability of URANS (unsteady Reynolds-averaged Navier-Stokes), SAS (scale-adaptive simulation), and IDDES (improved delayed detached-eddy simulation) on the naturally asymmetric flow of a generic ship model. The inlet velocity gives a Reynolds number of 8 × 104 based on the ship width. Experimental results are used as the baseline to judge the accuracy of these modelling techniques. The findings indicate that all techniques can predict the flow asymmetry of the ship wake, although URANS is less accurate due to its inability to resolve small-scale flow structures. Furthermore, IDDES is found to be more accurate than SAS considering the extent of wake asymmetry. Therefore, IDDES is recommended when higher accuracy is needed despite its higher computational demand.
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| 8. |
- He, Kan, et al.
(författare)
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Assessment of LES, IDDES and RANS approaches for prediction of wakes behind notchback road vehicles
- 2021
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- The capability of Large Eddy Simulations (LES), Improved Delayed Detached Eddy Simulations (IDDES) and Reynolds-Averaged Navier–Stokes Equations (RANS) to predict the flow behind notchback Ahmed body is investigated in the present paper. Simulations consider two specific models, with effective backlight angles of β1=17.8° and β2=21.0°, respectively. The focus of the study is on the prediction of the expected lateral asymmetry or symmetry of the near-wake flows. Results show that IDDES using coarse computational grids predicts the flow in agreement with LES using finer computational grids. RANS results in inaccurate flow predictions, attributed to its steady formulation relying on turbulence modelling being incapable of dealing with the studied flow. Modal analysis applying Proper Orthogonal Decomposition (POD) suggests the consistency of the wake dynamics between IDDES and LES. The presence of the wake bi-stability is validated by the wind tunnel experiment.
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| 9. |
- He, Kan, 1991, et al.
(författare)
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Blockage influence on bi-stable flows of a notchback bluff body
- 2021
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Ingår i: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 33:12
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Tidskriftsartikel (refereegranskat)abstract
- The expected flow asymmetry behind a three-dimensional notchback Ahmed body is numerically investigated using large-eddy simulations with different blockage ratios of 0%, 5 %, 10 %, and 20 %. The focus of the study is on the natural bi-stable flow influenced by the blockage ratio. Although the wake asymmetry can be observed under the blockage ratio within 0 % - 10 %, the significant blockage influence on the sensitive bi-stability is indicated by the wake structures, pressure gradients, and wake dynamics achieved with the proper orthogonal decomposition. The higher blockage ratio increases the turbulence kinetic energy, velocity, and negative pressure in the near-wake region, resulting in the decrease in the asymmetry degree. The consistency of the asymmetric wake is found with blockage ratios between 0% and 5 %. However, a 20 % blockage ratio symmetrizes the bi-stable wake. Several existing drag corrections for the blockage influence are discussed. The wind tunnel experiment verifies the bi-stable flow with low blockage ratios and the wake symmetrization with a 20 % blockage ratio.
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| 10. |
- He, Kan, et al.
(författare)
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Evaluation of LES, IDDES and URANS for prediction of flow around a streamlined high-speed train
- 2022
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 223
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Tidskriftsartikel (refereegranskat)abstract
- The turbulent flow past a simplified Intercity-Express 3 high-speed train at ReH=6×104 is investigated by a combination of wind tunnel experiments and numerical simulations using the large-eddy simulation (LES), the improved delayed detached eddy simulation (IDDES) and the unsteady Reynolds-averaged Navier-Stokes (URANS) simulation. This work aims to compare the predictive capabilities of LES, IDDES and URANS for the flow over a streamlined high-speed train. Numerical simulations are compared to experimental data for validation. Results show that the well-resolved LES is more accurate among the numerical methods used. Compared to the well-resolved LES, IDDES and URANS using the coarser mesh can produce similar mean flow, although IDDES and URANS are found to be slightly inaccurate for the coherent wake structures near the wall. However, for the near-wall flow instability concerning wake dynamics, Reynolds stresses, turbulence kinetic energy and the fluctuation of pressure, IDDES is found to be inapplicable. Overall, this study suggests that the well-resolved LES is appropriate to the flow of a streamlined high-speed train. Moreover, IDDES and URANS are proved to apply to the mean field of the studied flow.
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