| 1. |
- Shen, Yong-Feng, et al.
(författare)
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Deformation mechanisms of a 20Mn TWIP steel investigated by in situ neutron diffraction and TEM
- 2013
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Ingår i: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 61:16, s. 6093-6106
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Tidskriftsartikel (refereegranskat)abstract
- The deformation mechanisms and associated microstructure changes during tensile loading of an annealed twinning-induced plasticity steel with chemical composition Fe-20Mn-3Si-3Al-0.045C (wt.%) were systematically investigated using in situ time-of-flight neutron diffraction in combination with post mortem transmission electron microscopy (TEM). The initial microstructure of the investigated alloy consists of equiaxed gamma grains with the initial alpha'-phase of similar to 7% in volume. In addition to dislocation slip, twinning and two types of martensitic transformations from the austenite to alpha'- and epsilon-martensites were observed as the main deformation modes during the tensile deformation. In situ neutron diffraction provides a powerful tool for establishing the deformation mode map for elucidating the role of different deformation modes in different strain regions. The critical stress is 520 MPa for the martensitic transformation from austenite to alpha'-martensite, whereas a higher stress (>600 MPa) is required for actuating the deformation twin and/or the martensitic transformation from austenite to epsilon-martensite. Both epsilon- and alpha'-martensites act as hard phases, whereas mechanical twinning contributes to both the strength and the ductility of the studied steel. TEM observations confirmed that the twinning process was facilitated by the parent grains oriented with < 1 1 1 > or < 1 1 0 > parallel to the loading direction. The nucleation and growth of twins are attributed to the pole and self-generation formation mechanisms, as well as the stair-rod cross-slip mechanism.
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| 2. |
- Zhang, Yuelan, et al.
(författare)
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Two-Step Grain-Growth Kinetics of Sub-7 nm SnO2 Nanocrystal under Hydrothermal Condition
- 2015
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Ingår i: Journal of Physical Chemistry C. - 1932-7447 .- 1932-7455. ; 119:33, s. 19505-19512
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the grain growth kinetics of SnO2 quantum dots under hydrothermal conditions was investigated. By varying the reaction temperature and duration, SnO2 particle sizes were tuned from 2 to 7 nm. It is demonstrated that the growth behavior of subnanometer-sized SnO2 underwent two distinct processes: below the critical size of 5.5 nm, about double of Bohr radius, the grain growth kinetics obeys an Ostwald ripening mechanism, while above that, an oriented attachment process governs the particle growth. For the former cases, the activation energies were Ea1 = 61.94 kJ/mol at 200 °C and Ea1′ = 62.84 kJ/mol at 160 °C, which greatly differs from that of Ea2 = 131.32 kJ/mol for the latter case. High-resolution transmission electron microscope, X-ray diffraction as well as UV–vis diffuses reflectance, photoluminescence, Fourier transmission infrared, and Raman spectra were employed to reveal the size-dependent properties. As the particle size of SnO2 reduces, there occurred a lattice expansion, band gap broadening, and an abnormal blue shift. All these characteristics are closely related to the size changing in a narrow range from quantum dots to several nanometers. The findings reported here may shed light on further understanding the unique behaviors of quantum dots.
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| 3. |
- Fu, Jiahong, et al.
(författare)
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Heat transfer and field synergy characteristics in a rectangular unit channel under mechanical vibration
- 2022
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Ingår i: International Communications in Heat and Mass Transfer. - : Elsevier BV. - 0735-1933. ; 136
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Tidskriftsartikel (refereegranskat)abstract
- The internal heat exchangers of a vehicle in driving are excited by forced vibration due to road bumps. But the effect of this phenomenon on the thermal-hydraulic performance of the heat exchanger has not been systematically studied. To investigate the influence of this vibration on the heat transfer characteristics, a numerical model of the rectangular heat exchanger unit channel under vibration excitation was established and verified by experiments. It is found that compared to frequency, amplitude of vibration has a greater effect in enhancing heat transfer but when it is more than 4 mm, which leads to a rapid increase in the friction factor f. An index (j/js)/(f/fs) and a thermal-vibration performance factor (TVPF) considering the frequency and amplitude are proposed to evaluate the effect of vibration on the heat transfer, and it is indicated that for real vehicle operation, an amplitude of 2 mm and frequency of 25 Hz can effectively enhance heat transfer. Besides, it was found that the velocity gradient field perpendicular to the main flow direction caused by vibration synergizes with the temperature gradient field. This work is meaningful and of significance to the practical design of the actual heat exchangers in the automotive application.
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| 4. |
- Jacobsson, T. Jesper, 1984-, et al.
(författare)
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An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles
- 2022
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Ingår i: Nature Energy. - : Springer Nature. - 2058-7546. ; 7:1, s. 107-115
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Tidskriftsartikel (refereegranskat)abstract
- Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences.
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| 5. |
- Jia, Xue, et al.
(författare)
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CsPb(IxBr1-x)(3) solar cells
- 2019
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Ingår i: Science Bulletin. - : ELSEVIER. - 2095-9273. ; 64:20, s. 1532-1539
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Tidskriftsartikel (refereegranskat)abstract
- Owing to its nice performance, low cost, and simple solution-processing, organic-inorganic hybrid perovskite solar cell (PSC) becomes a promising candidate for next-generation high-efficiency solar cells. The power conversion efficiency (PCE) has boosted from 3.8% to 25.2% over the past ten years. Despite the rapid progress in PCE, the device stability is a key issue that impedes the commercialization of PSCs. Recently, all-inorganic cesium lead halide perovskites have attracted much attention due to their better stability compared with their organic-inorganic counterpart. In this progress report, we summarize the properties of CsPb(IxBr1-x)(3) and their applications in solar cells. The current challenges and corresponding solutions are discussed. Finally, we share our perspectives on CsPb(IxBr1-x)(3) solar cells and outline possible directions to further improve the device performance. (C) 2019 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.
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| 6. |
- Jiang, Cong, et al.
(författare)
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F-doped LiNi0.8Co0.15Al0.05O2-? : cathodes with enhanced ORR catalytic activity for LT-SOFCs
- 2023
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 940
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Tidskriftsartikel (refereegranskat)abstract
- Developing highly effective catalysts for oxygen reduction reaction (ORR) is crucial to enable the low-temperature operation of solid oxide fuel cells (SOFCs). Recent studies have proposed a promising O2-/H+/e- conducting oxide, LiNi0.8Co0.15Al0.05O2-delta (LNCA) with good ORR catalytic activity for SOFC cathode uses. Herein, to further optimize the cathode functionality of LNCA, a fluorine anion (F-) doping strategy is ap-plied to develop highly active LNCAF0.1 and LNCAF0.2 cathodes for Sm-doped ceria (SDC) electrolyte-based SOFCs. It is found the successful doping of F- in the oxygen site of LNCA leads to improved oxygen ionic conductivity and facilitated surface exchange and bulk diffusion of oxygen in LNCAF0.1 and LNCAF0.2, which thus gain distinctly promoted ORR catalytic activity at 450-550 degrees C, as confirmed by the decreased area specific resistances (ASR) and activation energy on symmetrical cells. The as-fabricated two SDC-based SOFCs with LNCAF0.1 and LNCAF0.2 cathodes exhibit peak power densities of 497 and 591 mW cm-2 at 550 degrees C, respectively, which are higher than that of the cell with LNCA cathode. Furthermore, the single cell with the best-performing LNCAF0.2 cathode demonstrates a good stability for 110 h at 550 degrees C. The present study thus provides a feasible strategy of F anion doping to promote the ORR catalytic activity of LNCA cathode for developing low-temperature SOFCs.
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| 7. |
- Wang, Yan, et al.
(författare)
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Bimetallic hybrids modified with carbon nanotubes as cathode catalysts for microbial fuel cell: Effective oxygen reduction catalysis and inhibition of biofilm formation
- 2021
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Ingår i: Journal of Power Sources. - Amsterdam, Netherlands : Elsevier. - 0378-7753 .- 1873-2755. ; 485
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Tidskriftsartikel (refereegranskat)abstract
- As a promising energy conversion equipment, the performance of microbial fuel cell (MFC) is affected by slow kinetics of oxygen reduction reaction (ORR). It is of great significance to explore electrocatalysts with high activity for sustainable energy applications. Herein, we synthesize the in-situ grown carbon nanotubes decorated electrocatalyst derived from copper-based metal organic frameworks (MOFs) co-doped with cobalt and nitrogen (CuCo@NCNTs) through straightforward immersion and pyrolysis process. The carbon nanotubes produced by metallic cobalt and high-activity bimetallic active sites formed by nitrogen doping enable CuCo@NCNTs to have the best oxygen reduction reaction (ORR) performance in alkaline electrolyte, with limit current density of 5.88 mA cm-2 and onset potential of 0.91 V (vs. RHE). Moreover, CuCo@NCNTs nanocomposite exhibits obvious antibacterial activity, and inhibiting the biofilm on cathode surface in antibacterial test and biomass quantification. The maximum power density (2757 mW m-3) of MFC modified with CuCo@NCNTs is even higher than Pt/C catalyst (2313 mW m-3). In short, CuCo@NCNTs nanocomposite can be an alternative cathode catalyst for MFC.
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| 8. |
- Wang, Yucheng, et al.
(författare)
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Digital twin enhanced fault prediction for the autoclave with insufficient data
- 2021
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Ingår i: Journal of manufacturing systems. - : Elsevier BV. - 0278-6125 .- 1878-6642. ; 60, s. 350-359
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Tidskriftsartikel (refereegranskat)abstract
- Since any faulty operations could directly affect the composite property, making early prognosis is particularly crucial for complex equipment. At present, data-driven approach has been typically used for fault prediction. However, for part of complex equipment, it is difficult to access reliable and sufficient data to train the fault prediction model. To address this issue, this paper takes autoclave as an example. A Digital Twin (DT) model containing multiple dimensions for the autoclave is firstly constructed and verified. Then the characteristics of autoclave under different conditions are analyzed and presented with specific parameters. The data in normal and faulty conditions are simulated by using the DT model. Both the simulated data and extracted historical data are applied to enhance fault prediction. A convolutional neural network for fault prediction will be trained with the generated data which matches the feature of the autoclave in faulty conditions. The effectiveness of the proposed method is verified through result analysis.
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| 9. |
- Zhang, Meng, et al.
(författare)
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Top ten intelligent algorithms towards smart manufacturing
- 2023
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Ingår i: Journal of manufacturing systems. - : Elsevier BV. - 0278-6125 .- 1878-6642. ; 71, s. 158-171
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Forskningsöversikt (refereegranskat)abstract
- Intelligent algorithms can empower the development of smart manufacturing, since they can provide optimal solutions for detection, analysis, prediction and optimization. In recent ten years, publications on intelligent algorithms in smart manufacturing have increased sharply, showing superior performance in solving problems such as shop-floor scheduling, equipment prognosis, product defect detection and manufacturing service composition, etc. In this context, this paper focuses on the selection of commonly used top ten algorithms by providing a sound understanding of how they contribute to improving manufacturing processes. First, it presents a comprehensive survey and bibliometric analysis according to relevant literature. On this basis, the top ten algorithms are highlighted and reviewed. Then three key issues concerning when to use these algorithms in smart manufacturing, how to use them, as well as why to use them are studied. Finally, the challenges for the ten algorithms are summarized.
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| 10. |
- Zuo, Hongyu, et al.
(författare)
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Bioinspired Gradient Covalent Organic Framework Membranes for Ultrafast and Asymmetric Solvent Transport
- 2024
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Ingår i: Advanced Materials. - 0935-9648 .- 1521-4095. ; 36:16
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Tidskriftsartikel (refereegranskat)abstract
- Gradients play a pivotal role in membrane technologies, e.g., osmotic energy conversion, desalination, biomimetic actuation, selective separation, and more. In these applications, the compositional gradients are of great relevance for successful function implementation, ranging from solvent separation to smart devices; However, the construction of functional gradient in membranes is still challenging both in scale and directions. Inspired by the specific function-related, graded porous structures in glomerular filtration membranes, a general approach for constructing gradient covalent organic framework membranes (GCOMx) applying poly (ionic liquid)s (PILs) as template is reported here. With graded distribution of highly porous covalent organic framework (COF) crystals along the membrane, GCOMx exhibts an unprecedented asymmetric solvent transport when applying different membrane sides as the solvent feed surface during filtration, leading to a much-enhanced flux (10–18 times) of the “large-to-small” pore flow comparing to the reverse direction, verified by hydromechanical theoretical calculations. Upon systematic experiments, GCOMx achieves superior permeance in nonpolar (hexane ≈260.45 LMH bar−1) and polar (methanol ≈175.93 LMH bar−1) solvents, together with narrow molecular weight cut-off (MWCO, 472 g mol−1) and molecular weight retention onset (MWRO, <182 g mol−1). Interestingly, GCOMx shows significant filtration performance in simulated kidney dialysis, revealing great potential of GCOMx in bionic applications.
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