| 1. |
- Pecunia, Vincenzo, et al.
(författare)
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Roadmap on energy harvesting materials
- 2023
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Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.
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| 2. |
- Li, Chenglei, et al.
(författare)
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Room-temperature direct regeneration of spent LiFePO4 cathode using the external short circuit strategy
- 2023
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Ingår i: Next Sustainability. - : Elsevier. - 2949-8236. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Lithium iron phosphate batteries (LFP), widely used as power sources, are forecasted to reach the terawatt-hour scale, inevitably leading to battery waste and expediating the urgency for effective recycling processes for LFP. The modern recycling methodologies based on material recovery face significant economic, environmental, and energy consumption challenges. This research attempts to resolve these challenges by providing direct cathode regeneration based on the principles of an external short-circuit to replenish lithium lost in the spent cathode with lithiated materials (LiC6, Li metal). Given that most active lithium loss in the cathode is caused by the growth of the solid electrolyte interphase rather than structural damage, restoring the lost lithium can revitalize a spent cathode battery’s electrochemical performance to a near-original state. The lithium loss in LFP cathodes ranging from 20% to 80% was renewed by supplementing lithium. Relithiation of 10Ah commercial LFP spent cathode showed revitalized electrochemical performance. Compared to the modern recycling methods, direct cathode regeneration improves the economic benefits of recycling by 33%, decreases energy consumption by 48%, and reduces carbon emissions by 62%. Direct cathode regeneration provides a scaffold for the next generation of recycling methods to improve recycling efficiency while reducing their environmental footprint.
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| 3. |
- Gao, Qiang, et al.
(författare)
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Femtosecond-laser electronic-excitation tagging velocimetry using a 267 nm laser
- 2019
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Ingår i: Sensors and Actuators, A: Physical. - : Elsevier BV. - 0924-4247. ; 287, s. 138-142
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Tidskriftsartikel (refereegranskat)abstract
- Femtosecond (fs)-laser electronic-excitation tagging velocimetry (FLEET) in a nitrogen flow field using a 267 nm laser was performed under the condition of fs-laser filamentation. The filamentous properties and their effects on velocity measurements were investigated and were compared with those of an 800 nm fs-laser. The results show that the required energy of the 267 nm laser pulse is as low as hundreds of μJ, and this is beneficial for reducing the potential perturbations to the flow flied. The filaments induced by the 267 nm laser are longer and thinner than are those induced by the 800 nm laser, which enlarges the velocity measurements region, and a precision of 1.3% was achieved.
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| 4. |
- Guo, Xuewen, et al.
(författare)
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Understanding the effect of N2200 on performance of J71 : ITIC bulk heterojunction in ternary non-fullerene solar cells
- 2019
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Ingår i: Organic electronics. - : Elsevier. - 1566-1199 .- 1878-5530. ; 71, s. 65-71
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Tidskriftsartikel (refereegranskat)abstract
- None-fullerene solar cells with ternary architecture have attracted much attention because it is an effective approach for boosting the device power conversion efficiency. Here, the crystalline polymer N2200 as the third component is integrated into J71: ITIC bulk heterojunction. A series of characterizations indicate that N2200 could increase photo-harvesting, balanced hole and electron mobilities, enhanced exciton dissociation, and suppressed charge recombination, which result in the comprehensive improvement of open circuit voltage, short circuit current and fill factor in the device. Moreover, after introduction of N2200, the morphology of the ternary active layer is optimized, and the film crystallinity is improved. This work demonstrates that adding a small quantity of high crystallization acceptor into non-fullerene donor: acceptor mixture is a promising strategy toward developing high-performance organic solar cells.
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| 5. |
- Han, Lei, et al.
(författare)
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Simultaneous measurements of velocity and concentration of gas flow using femtosecond laser-induced chemiluminescence
- 2022
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Ingår i: Optics and Lasers in Engineering. - : Elsevier BV. - 0143-8166. ; 155
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Tidskriftsartikel (refereegranskat)abstract
- The mixing process in a gas flow plays a crucial role in chemical reactions, and simultaneous measurements of both velocity and mixture fraction are desired to fathom the process. Here, we report a scheme for simultaneously measuring both velocity and concentration by femtosecond laser-induced chemiluminescence. The femtosecond laser would induce chemical reactions that generate CN radicals in the B state. The transition of CN (X-B) would emit fluorescence with both strong intensity and long duration, and the decay of the fluorescence versus time showed prominent benefits for the simultaneous measurement. This measurement was accomplished by an ICCD camera worked in the on-chip multi-exposure mode, i.e., the camera had two exposures in succession to capture two luminescent lines on one image. The first line was used to measure the methane concentration and hence, the mixture fraction through a calibration procedure. The second line was the first line displaced by the flow in a known time interval and we demonstrate an algorithm to derive the one dimensional-two components velocity fields from the line shapes of the luminescent lines. The detection limit of the concentration is estimated to be 152 ppm and the minimum measurable velocity is estimated to be 5 m/s.
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| 6. |
- Li, Bo, et al.
(författare)
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Comprehensive CO detection in flames using femtosecond two-photon laser-induced fluorescence
- 2017
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Ingår i: Optics Express. - 1094-4087. ; 25:21, s. 25809-25818
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a femtosecond two-photon laser-induced fluorescence (fs-TPLIF) technique for sensitive CO detection, using a 230 nm pulse of 9 µJ and 45 fs. The advantages of fs-TPLIF in excitation of molecular species were analyzed. Spectra of CO fs-TPLIF were recorded in stable laminar flames spatially resolved across the flame front. A hot band (1, n) together with the conventional band (0, n) of the B→A transitions were observed in the burned zone and attributed to the broadband nature of the fs excitation. The CO fs-TPLIF signal recorded across the focal point of the excitation beam shows a relatively flat intensity distribution despite of the steep laser intensity variation, which is beneficial for CO imaging in contrast to nanosecond and picosecond TPLIF. This phenomenon can be explained by photoionization, which over the short pulse duration dominates the population depletion of the excited B state due to the high peak power, but only contributes in total a negligible X state depletion due to the low pulse energy. Single-shot CO fs-TPLIF images in methane/air flames were recorded by imaging the broadband fluorescence. The results indicate that fs-TPLIF is a promising tool for CO imaging in flames.
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| 7. |
- Li, Bo, et al.
(författare)
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Femtosecond laser-induced cyano chemiluminescence in methane-seeded nitrogen gas flows for near-wall velocimetry
- 2018
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 51:29
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a velocimetric technique based on femtosecond laser-induced cyano (CN) chemiluminescence (FLICC). High intensity emission originated from CN(B-X) fluorescence was observed in filaments generated by focusing a femtosecond laser in methane-seeded nitrogen gas flows. The emission is strong and can last for hundreds of microseconds with a proper methane concentration. FLICC was adopted for velocity measurements, and promising results were obtained for near-wall measurements.
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| 8. |
- Li, Bo, et al.
(författare)
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Strategy of interference-free atomic hydrogen detection in flames using femtosecond multi-photon laser-induced fluorescence
- 2017
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 42:6, s. 3876-3880
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen atoms are key species in combustion of hydrogen/hydrocarbon fuels. Interference-free detection of hydrogen atoms natively generated in flames using femtosecond laser-induced fluorescence (LIF) was investigated employing two colors, i.e., 243 nm and 486 nm, as excitation source: two-photon excitation followed by a relay one-photon excitation. This strategy was compared with another commonly adopted two-photon LIF strategy using 205 nm for excitation. The potential interferences were investigated, and a direct verification method was proposed to prove this strategy be interference-free, and imaging of hydrogen atoms natively generated in methane/air flames was achieved.
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| 9. |
- Liang, Xifeng, et al.
(författare)
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On the aerodynamic loads when a high speed train passes under an overhead bridge
- 2020
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 202
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Tidskriftsartikel (refereegranskat)abstract
- The aerodynamic loads on the overhead bridge bottom surface induced by train passage are reported in this paper. Both moving model test and numerical simulation approaches at the 1:20 scale are used. The numerical work is validated through both mesh independence tests and comparison with experimental data. Typical pressure variation curves are plotted and compared with previous studies. The peak pressure values’ dependence on the Reynolds number is considered through four sets of experiments with different train running speeds. The peak pressure coefficient distribution law for the bridge bottom surface is presented. Differences in the pressure distribution in different bridge bottom areas are explained based on more detailed flow field information. The influence of the bridge height on the aerodynamic load magnitude and time interval is presented. Moreover, the application of the CEN Standard to practical engineering issues is discussed.
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| 10. |
- Gao, Qiang, et al.
(författare)
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Quantitative and Spatially Resolved Measurement of Atomic Potassium in Combustion Using Diode Laser
- 2018
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Ingår i: Chinese Physics Letters. - 0256-307X. ; 35:2
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Tidskriftsartikel (refereegranskat)abstract
- compact optical setup for quantitative and spatially resolved measurement of atomic alkali concentration in combustion is demonstrated. Tunable diode laser absorption spectroscopy and laser-induced fluorescence are combined using a single continuous wave diode laser to measure the line-integration concentration and the relative distribution simultaneously, thereby obtaining the absolute concentration distribution along the laser beam. The results indicate the good performance of this method for one-dimensional quantitative measurement.
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