| 471. |
- Wan, Xin Yu, et al.
(author)
-
Similarity-Based Optimal Operation of Water and Sediment in a Sediment-Laden Reservoir
- 2010
-
In: Water resources management. - 0920-4741 .- 1573-1650. ; 24:15, s. 4381-4402
-
Journal article (peer-reviewed)abstract
- Reservoir sedimentation is a severe problem because it leads to the loss of reservoir storage capacity Therefore, the sustainable management of water and sediment constitutes a critical measure in reservoir operation In this research, a model of similarity-based operation method of water and sediment which can improve the efficiency of reservoir operation strategies is presented Two parts comprise this method a similarity-based forecasting model for the sediment process at the dam, and a new operation mode of water and sediment based on the sediment process at the dam The similarity-based forecasting model is built on the total flow model of water and sediment, which requires less data Using the similarity among flood cases, the parameters of the model are calibrated by group, and are dynamically selected, an approach which enforces the suitability of parameters and improves the forecasting accuracy In terms of the sediment process at the dam the proposed optimal operation model of water and sediment improves the sediment venting efficiency and saves the water resource.
|
|
| 472. |
- Wang, Anci, et al.
(author)
-
Performance optimization of electric vehicle battery thermal management based on the transcritical CO2 system
- 2023
-
In: Energy. - : Elsevier BV. - 0360-5442. ; 266
-
Journal article (peer-reviewed)abstract
- Thermal management of electric vehicles, especially battery thermal management, is critical to driving range and operational safety. To find a vehicle thermal management system with higher energy efficiency and environmental protection, an environmentally-friendly and efficient battery and cabin parallel cooling thermal management system was evaluated with CO2 as the working fluid. First, different control strategies of the evaporation temperature were compared regarding the battery cooling performance. Then, the effect of the battery cooling evaporation temperature on the coefficient of performance (COP) was explored. It was found that the maximum COP increased by 8.38% as the evaporation temperature decreased from 17 to 5.8 °C. Besides, it was found that the optimal battery cooling evaporation temperature range is 10.2–11 °C when the battery heating power is 0.4 kW. The vapor quality at the cold plate outlet should be lower than 0.95. Finally, the battery cooling performance under variable operating conditions was investigated. The influence of operating parameters on the battery cooling evaporation temperature and CO2 outlet vapor quality was also analyzed. Simulation results showed that the optimum evaporation temperature range varied significantly under different working conditions. The vapor quality at the cold plate outlet decreased slightly with the evaporation temperature.
|
|
| 473. |
- Wang, Bolin, et al.
(author)
-
Palladium-Catalyzed Dehydrogenative Carbonylative Esterification of Allenoic Acids for the Synthesis of γ-Butyrolactone Derivatives
- 2024
-
In: Organic Letters. - 1523-7060 .- 1523-7052. ; 26:12, s. 2430-2434
-
Journal article (peer-reviewed)abstract
- A highly efficient dehydrogenative carbonylative esterification of allenoic acids using Pd-catalysis was developed, providing a novel approach to synthesizing esterified γ-butyrolactone derivatives with consistently good to excellent results demonstrated across over 50 examples. Additionally, we used a heterogeneous catalyst known as Pd-AmP-MCF and harnessed biomimetic-aerobic-oxidation conditions to facilitate the practical execution of this reaction. Furthermore, our detailed study of γ-butyrolactone products highlighted their potential in synthesizing bioactive compounds.
|
|
| 474. |
- Wang, Bei, et al.
(author)
-
Sandwiched Polyethylene Shrink Film Masking with Tunable Resolution and Shape for Liquid Alloy Patterning
- 2019
-
In: ACS APPLIED POLYMER MATERIALS. - : American Chemical Society (ACS). - 2637-6105. ; 1:2, s. 145-151
-
Journal article (peer-reviewed)abstract
- Among numerous patterning techniques, masked liquid alloy printing is one of the most promising techniques for scalable fabrication of liquid-alloy-based stretchable electronics. Like any other mask-based process, its resolution is often constrained by the quality of the mask, and the fabrication cost increases drastically with increased resolution. In this work, by introducing a sandwiched thermal shrink polymer film masking technique and a corresponding intermediate release agent, fine liquid alloy patterns were demonstrated by using a mechanical cutting plotter together with a common oven. The final resolution and shape of the mask could be tuned based on the anisotropy of the shrink polymer film and other operational parameters of the technique. After shrinkage, the width of the patterned liquid alloy lines and space in-between could be tuned to less than one third of the original cut pattern, to about 35 and 60 mu m, respectively, according to requirements. To better predict the final structure, several parameters were investigated experimentally and numerically. Finally, a liquid alloy strain sensor and three-dimensional conformal masking were demonstrated, showing the potential of the developed technique.
|
|
| 475. |
- Wang, Chao, et al.
(author)
-
Rebuilding the vibrational wavepacket in TRAS using attosecond X-ray pulses
- 2024
-
In: Communications Physics. - : Springer Nature. - 2399-3650. ; 7:1
-
Journal article (peer-reviewed)abstract
- Time-resolved X-ray photoelectron spectroscopy (TXPS) is a well-established technique to probe coherent nuclear wavepacket dynamics using both table-top and free-electron-based ultrafast X-ray lasers. Energy resolution, however, becomes compromised for a very short pulse duration in the sub-femtosecond range. By resonantly tuning the X-ray pulse to core-excited states undergoing Auger decay, this drawback of TXPS can be mitigated. While resonant Auger-electron spectroscopy (RAS) can recover the vibrational structures not hidden by broadband excitation, the full reconstruction of the wavepacket is a standing challenge. Here, we theoretically demonstrate how the complete information of a nuclear wavepacket, i.e., the populations and relative phases of the vibrational states constituting the wavepacket, can be retrieved from time-resolved RAS (TRAS) measurements. Thus, TRAS offers key insights into coupled nuclear and electronic dynamics in complex systems on ultrashort timescales, providing an alternative to leverage femtosecond and attosecond X-ray probe pulses.
|
|
| 476. |
- Wang, Dianzheng, et al.
(author)
-
Dense Pure Tungsten Fabricated by Selective Laser Melting
- 2017
-
In: Applied Sciences. - : MDPI AG. - 2076-3417. ; 7:4
-
Journal article (peer-reviewed)abstract
- Additive manufacturing using tungsten, a brittle material, is difficult because of its high melting point, thermal conductivity, and oxidation tendency. In this study, pure tungsten parts with densities of up to 18.53 g/cm(3) (i.e., 96.0% of the theoretical density) were fabricated by selective laser melting. In order to minimize balling effects, the raw polyhedral tungsten powders underwent a spheroidization process before laser consolidation. Compared with polyhedral powders, the spherical powders showed increased laser absorptivity and packing density, which helped in the formation of a continuous molten track and promoted densification.
|
|
| 477. |
|
|
| 478. |
- Wang, Dan, et al.
(author)
-
On the phases of a semi-sectorial matrix and the essential phase of a Laplacian
- 2023
-
In: Linear Algebra and its Applications. - : Elsevier BV. - 0024-3795 .- 1873-1856. ; 676, s. 441-458
-
Journal article (peer-reviewed)abstract
- In this paper, we extend the definition of phases of sectorial matrices to those of semi-sectorial matrices, which are possibly singular. Properties of the phases are also extended, including those of the Moore-Penrose generalized inverse, compressions and Schur complements, matrix sums and products. In particular, an interlacing relation is established between the phases of A+B and those of A and B combined. Also, a majorization relation is established between the phases of the nonzero eigenvalues of AB and the phases of the compressions of A and B, which leads to a generalized matrix small phase theorem. For the matrices which are not necessarily semi-sectorial, we define their (largest and smallest) essential phases via diagonal similarity transformation. An explicit expression for the essential phases of a Laplacian matrix of a directed graph is obtained.
|
|
| 479. |
- Wang, Duo, et al.
(author)
-
Unraveling complex magnetism in two-dimensional FeS2
- 2021
-
In: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 104:24
-
Journal article (peer-reviewed)abstract
- Atomically thin two-dimensional (2D) magnets have given rise to emergent phenomena due to magnetic exchange and spin-orbit coupling showing great promise for realizing ultrathin device structures. In this paper, we critically examine the magnetic properties of 2D FeS2, a non van der Waals magnet, which has been recently claimed to exhibit room-temperature ferromagnetism in the (111) orientation. Our ab initio study based on collinear density functional theory has revealed the ground state as an antiferromagnetic one with an ordering temperature of around 100 K along with a signature of spin-phonon coupling, which may trigger a ferromagnetic coupling via strain. Moreover, our calculations based on spin spirals indicate the possibility of noncollinear magnetic structures, which is also supported by Monte Carlo simulations based on ab initio magnetic exchange parameters. This opens up an excellent possibility to manipulate magnetic structures by the application of directional strain.
|
|
| 480. |
- Wang, Guang, et al.
(author)
-
Controlling phase and rheological behaviours of hexagonal lyotropic liquid crystalline templates for nanostructural administration and retention
- 2022
-
In: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 607, s. 816-825
-
Journal article (peer-reviewed)abstract
- Introducing polymerizable monomers into a binary hexagonal lyotropic liquid crystalline (LLC) template is a straightforward way for retaining the nanostructure but will decrease attractive intra-and inter aggregate interactions. It is therefore crucial to understand the interfacial interactions at nanoscale after introducing the monomers but prior to polymerization. Herein, active species, poly (ethylene glycol) diacrylate (PEGDA) and 2-hydroxyethyl methacrylate (HEMA), were introduced into hexagonal LLC of dodecyl trimethylammonium bromide and water to explore the structural variables, dimensional stabil-ity, and dynamic property. At a proper volume ratio of PEGDA/HEMA (1/4), the system presents excellent homogeneity with a higher dimensional stability and lower dynamic property from rheological assess-ments, thereby achieving robust, free-standing, and transparent membranes after photo -polymerization. The unique property of the system also lies in the much lower order-disorder transition temperature (45 degrees C) that facilitates the reorientation of mesochannels. They are in contrast inaccessible for the ternary system only with PEGDA, though the nanostructure for both systems could be retained. An insight into subtle variations in these parameters allows us to prepare a polymerizable template possess-ing higher dimensional stability and suitable flexibility via molecular design, thereby enabling simulta-neous structural alignment and retention for the development of functional nanomaterials. (c) 2021 Elsevier Inc. All rights reserved.
|
|
