| 1. |
- He, Liang, et al.
(författare)
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Discrete element simulation of porous asphalt mixture clogging law
- 2023
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Ingår i: Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering. - : Chang'an University. - 1671-1637. ; 23:2, s. 78-91
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Tidskriftsartikel (refereegranskat)abstract
- To reveal the pore clogging law of porous asphalt mixture, the combination study of model experiment and simulation of porous asphalt mixture clogging was conducted. The pore characteristics of the porous asphalt mixture were analyzed based on the CT-scanning and discrete element software PFC3D V5. 0, and the pore data of the porous asphalt mixture were obtained. The aggregates of different particle sizes were put into PFC3D V5. 0, and the compacted virtual specimens were generated according to the pore characteristics. The accuracy of the model was verified by comparing the pore images of actual specimens with the MATLAB slices. In the self-weight condition, the simulation was set with the porous asphalt mixture specimen being intruded by clogging particles with specific gradation composition. The data of indoor experiments were compared and verified. The particle sizes of clogging particles were changed, and the pore decay rates of the specimen were analyzed. The clogging-sensitive particles were identified. In the self-weight condition, the fluid simulation experiment was introduced, and the change law of specimen clogging was analyzed by changing the seepage rate of fluid. Analysis results show that the virtual specimen generated by PFC3D V5. 0 has high accuracy, and the simulation reveals the clogging law of the specimen. The small particles not only accumulate at the throat position causing clogging, but also congregate and interlock with the particles of larger sizes resulting in clogging too. In the self-weight condition, the clogging is mainly concentrated at the upper 30 mm of the mixture specimen, and the size distribution of corresponding clogging-sensitive particles is 0. 150-0. 600 mm. The size distribution of clogging particles has a great impact on the clogging results. In the conditions of gravity and fluid, with the seepage rate increasing from 0. 005 m • s-1 to 0. 030 m • s-1, the changing rate of pore decay rate increases. In addition, the clogging particles remaining in the mixture decrease, accompanied by the reduction of the pore decay rate. Therefore, the local rainfall conditions should also be considered in the design and maintenance of drainage asphalt pavement. 2 tabs, 20 figs, 30 refs. © 2023 Chang'an University. All rights reserved.
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| 2. |
- Wu, Zhongbin, et al.
(författare)
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Achieving Extreme Utilization of Excitons by an Efficient Sandwich-Type Emissive Layer Architecture for Reduced Efficiency Roll-Off and Improved Operational Stability in Organic Light-Emitting Diodes
- 2016
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:5, s. 3150-3159
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Tidskriftsartikel (refereegranskat)abstract
- It has been demonstrated that the efficiency roll-off is generally caused by the accumulation of excitons or charge carriers, which is intimately related to the emissive layer (EML) architecture in organic light-emitting diodes (OLEDs). In this article, an efficient sandwich-type EML structure with a mixed-host EML sandwiched between two single-host EMLs was designed to eliminate this accumulation, thus simultaneously achieving high efficiency, low efficiency roll-off and good operational stability in the resulting OLEDs. The devices show excellent electroluminescence performances, realizing a maximum external quantum efficiency (EQE) of 24.6% with a maximum power efficiency of 105.6 lm W-1 and a maximum current efficiency of 93.5 cd A(-1). At the high brightness of 5 000 cd m(-2), they still remain as high as 23.3%, 71.1 lm W-1, and 88.3 cd A(-1), respectively. And, the device'lifetime is up to 2000 h at initial luminance of 1000 cd m(-2), which is significantly higher than that of compared devices with conventional EML structures. The improvement mechanism is systematically studied by the dependence of the exciton distribution in EML and the exciton quenching processes. It can be seen that the utilization of the efficient sandwich-type EML broadens the recombination zone width, thus greatly reducing the exciton quenching and increasing the probability of the exciton recombination. It is believed that the design concept, provides a new avenue for us to achieve high-performance OLEDs.
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| 3. |
- Jaskorzynska, Bozena, et al.
(författare)
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Dielectric and Plasmon Slot Waveguides for Photonic Integration
- 2009
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Ingår i: ICTON 2009: 11th International Conference on Transparent Optical Networks. - NEW YORK : IEEE. ; , s. 653-656
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Konferensbidrag (refereegranskat)abstract
- Slot waveguides formed either in high-index dielectrics or in metals attract great interest because they provide sub-wavelength confinement in the slot region. While this feature is very attractive for devices relying on stimulated emission or nonlinear effects, it does not necessarily improve the integration density. The spacing between dielectric slot waveguides is still limited by diffraction. Although for metal (plasmon) waveguides the total field can be shrunk far beyond the diffraction limit, the associated increase in propagation loss will set practical limits on both the minimum waveguide width and edge-to-edge separation. Here we compare the packing densities for 3D slot waveguides in silicon and plasmon waveguides in gold with a silicon slot. As a reference we also consider silicon photonic wire. We calculate center-to-center waveguide separations (pitch) versus cross-talk level. We show that at ca 24 dB/mu m cross-talk and requiring the attenuation length of at least 5 mu m, plasmon slot waveguides can be packed ca 3.5 times denser than silicon slot waveguides, and ca 2.5 times denser than photonic wires. We also show examples of the fabricated devices.
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| 4. |
- Shi, Yantao, et al.
(författare)
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A green route and rational design for ZnO-based high-efficiency photovoltaics
- 2014
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 6:10, s. 5093-5098
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Tidskriftsartikel (refereegranskat)abstract
- In this work, at room-temperature and without any organic surfactants we reported two green and facile approaches for rapid synthesis of ZnO nanorods (NRs) and nanosheet-based ZnO hierarchical structures (NSHSs). Based on their structural advantages, the quasi-solid ZnO-DSCs achieved a record photoelectric conversion efficiency (PCE) of 6.83%.
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| 5. |
- Song, Jun, et al.
(författare)
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Analysis method of the effect of fabrication errors on a planar waveguide demultiplexer
- 2006
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Ingår i: Optical and quantum electronics. - : Springer Science and Business Media LLC. - 0306-8919 .- 1572-817X. ; 38:15, s. 1203-1216
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Tidskriftsartikel (refereegranskat)abstract
- The impact of fabrication errors on a planar waveguide demultiplexer is analyzed based on an analytical method. The explicit expression of the transfer function taking into account phase and amplitude errors is presented in order to analyze the loss and crosstalk of the demultiplexer caused by fabrication errors. A basic requirement for the demultiplexer with a certain crosstalk criterion can be easily obtained. Using an etched diffraction grating demultiplexer as an example, it is shown that the analytical results have a good agreement with results from a numerical method.
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| 6. |
- Song, Jun, et al.
(författare)
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Design and fabrication of compact etched diffraction grating demultiplexers based on alpha-Si nanowire technology
- 2008
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 44:13, s. 816-818
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Tidskriftsartikel (refereegranskat)abstract
- alpha-Silicon nanowire waveguides and related techniques are studied. An ultra-compact etched diffraction grating demultiplexer with 10 nm spacing is fabricated and characterised. The dimension of the device is around half a millimetre, which is one to two orders of magnitude smaller than conventional silica based devices.
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| 7. |
- Song, Jun, et al.
(författare)
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Design and fabrication of compact etched diffraction grating demultiplexers based on α-Si nanowire technology
- 2008
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Ingår i: 2008 IEEE/LEOS International Conference on Optical MEMS and Nanophotonics, OPT MEMS. - 9781424419180 ; , s. 148-149
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Konferensbidrag (refereegranskat)abstract
- Silicon nanowire waveguides and related etched diffraction grating (EDG) demultiplexers are studied by α-Si-on-SiO2 technology. Compact EDG demultiplexers with 10 run spacing for both echelle and total-internal- reflection (TIR) facets have been fabricated and characterized.
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| 8. |
- Song, Jun, et al.
(författare)
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Etched diffraction grating demultiplexers with large free-spectral range and large grating facets
- 2006
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 18:24, s. 2695-2697
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Tidskriftsartikel (refereegranskat)abstract
- A design for etched diffraction grating demultiplexers is presented to obtain both large grating facets and a larger free-spectral range (FSR) using the optimal chirped diffraction orders for different facets. The large grating facets by using a large diffraction order contribute to lowering the manufacturing difficulty, and can provide lower polarization-dependent loss. However, usually the large diffraction order must lower the FSR of the device by all means. Based on the present design, the FSR can overlay the whole diffraction envelop for a special order, but avoid the influence of the adjacent diffraction envelops. Calculations indicate that the extinction ratio between the operated order and adjacent orders can attain a 35 dB or so, which makes the crosstalk from channels in adjacent envelops to those in the operated diffraction envelop acceptable.
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| 9. |
- Song, Jun, et al.
(författare)
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High Sensitive Gas Sensor Application Based on a Small Defect in Silicon Waveguide
- 2009
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:1-4, s. 82-84
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Tidskriftsartikel (refereegranskat)abstract
- A small defect in silicon nanowire waveguides is applied for gas sensors. Small defects with some special shapes and indexes can produce strong resonances with the incident light and induce large loss. Since the silicon waveguide has air cladding, the position of resonant peaks will be sensitive for the variation of the ambient air composition. The sensor based on the principle has a high sensitivity. As an example, we monitored the change of the position of the resonance peak as a function of alcohol concentrations in air. Results showed that a similar to 5-mg/L ethanol vapor in the air can result in a similar to 20-nm wavelength shift of the resonance.
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| 10. |
- Wang, Zhechao, et al.
(författare)
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Experimental demonstration of an ultracompact polarization beam splitter based on a bidirectional grating coupler
- 2009
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Ingår i: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009. - 9781557528773 ; , s. 5377257-
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Konferensbidrag (refereegranskat)abstract
- A bidirectional grating serving both as a polarization beam splitter and a vertical coupler for Silicon on Insulator nanophotonic circuits is fabricated and characterized. The measured coupling efficiency is as high as 43%. The demonstrated device has a large 3-dB bandwidth and a high extinction ratio between two orthogonal polarizations.
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