| 1. |
- Ning, Dezhi, et al.
(författare)
-
Hydrodynamic performance of a pile-restrained WEC-type floating breakwater : An experimental study
- 2016
-
Ingår i: Renewable energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 95, s. 531-541
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a system which integrates an oscillating buoy type wave energy converter with a vertical pile-restrained floating breakwater is introduced. A preliminary experimental study on the hydrodynamic performance of the system is carried out in a wave flume under the action of regular waves. A current controller-magnetic powder brake system is used to simulate the power generation system. The design is verified against published results. The power-take off damping characteristics are investigated, and the current controller-magnetic powder brake system can simulate the (approximate) Coulomb damping force very well. The effects of various parameters, including wave period and wave height, dimensions of the system and excitation current, on the hydrodynamic performance are investigated. Results indicate that the power take-off damping force, draft and relative width between the floating breakwater and the wavelength have a significant influence on the hydrodynamic performance of the system. A range can be observed for which the capture width ratio of the system can achieve approximately 24% while transmission coefficient was kept lower than 0.50 with the proper adjustment of power take-off damping force, and the floating breakwater performs in an effective manner. The new concept provides a promising way to utilize wave energy cost-effectively.
|
|
| 2. |
- Ning, Dezhi, et al.
(författare)
-
Hydrodynamic performance of an oscillating wave surge converter in regular and irregular waves : an experimental study
- 2017
-
Ingår i: Journal of Marine Science and Technology. - 0948-4280 .- 1437-8213. ; 25:5, s. 520-530
-
Tidskriftsartikel (refereegranskat)abstract
- A series of physical experiments are carried out to investigate the hydrodynamic performance of a bottom-hinged flap-type oscillating wave surge converter (OWSC). The power take-off (PTO) system in the OWSC is achieved with the magnetic powder brake. Both regular and irregular wave conditions are considered. It is observed that the capture width ratio (CWR) of the proposed OWSC is strongly affected by the PTO damping torque, incident wave amplitude, inertia of the structure and wave spectrum etc.
|
|
| 3. |
- Ning, Dezhi, et al.
(författare)
-
Near Trapping Effect on Wave-Power Extraction by Linear Periodic Arrays
- 2020
-
Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Near trapping is a kind of strong hydrodynamic interaction phenomenon in a regular array under specific incident wave conditions, which causes the excitation force on the structures in the array to change suddenly. In this paper, based on linear potential flow theory, the effects of near trapping on the hydrodynamic interaction and wave-power extraction characteristics of linear periodic arrays composed of the oscillating float type wave energy converters are studied by using the higher-order boundary element method in a frequency domain. The parameters considered include the separation spacing, number of devices, and incident wave direction. It is found that the near trapping significantly reduces the overall wave-power extraction, especially for the cases with a large number of devices, and changes the trend of the power distribution. The occurrence of the near trapping phenomenon depends on the ratio of the separation spacing to the wavelength and the incident wave direction. The results highlight the effective layout of linear arrays under the influence of near trapping, which not only ensures the total production power, but also reduces the power difference among wave energy converters.
|
|
| 4. |
|
|
| 5. |
- Wu, Zhongbin, et al.
(författare)
-
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
-
Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:5, s. 3150-3159
-
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.
|
|
| 6. |
- Wu, Zhongbin, et al.
(författare)
-
High-Performance Hybrid White Organic Light-Emitting Diodes with Superior Efficiency/Color Rendering Index/Color Stability and Low Efficiency Roll-Off Based on a Blue Thermally Activated Delayed Fluorescent Emitter
- 2016
-
Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 26:19, s. 3306-3313
-
Tidskriftsartikel (refereegranskat)abstract
- Thermally activated delayed fluorescence (TADF)-based white organic light-emitting diodes (WOLEDs) are highly attractive because the TADF emitters provide a promising alternative route to harvest triplet excitons. One of the major challenges is to achieve superior efficiency/color rendering index/color stability and low efficiency roll-off simultaneously. In this paper, high-performance hybrid WOLEDs are demonstrated by employing an efficient blue TADF emitter combined with red and green phosphorescent emitters. The resulting WOLED shows the maximum external quantum efficiency, current efficiency, and power efficiency of 23.0%, 51.0 cd A(-1), and 51.7 lm W-1, respectively. Moreover, the device exhibits extremely stable electroluminescence spectra with a high color rendering index of 89 and Commission Internationale de L'Eclairage coordinates of (0.438, 0.438) at the practical brightness of 1000 cd m(-2). The achievement of these excellent performances is systematically investigated by versatile experimental and theoretical evidences, from which it is concluded that the utilization of a blue-green-red cascade energy transfer structure and the precise manipulation of charges and excitons are the key points. It can be anticipated that this work might be a starting point for further research towards high-performance hybrid WOLEDs.
|
|
| 7. |
|
|
