Hesitant fuzzy linguistic term sets (HFLTSs) are used to deal with situations in which the decision makers (DMs) think of several possible linguistic values or richer expressions than a single term ...for an indicator, alternative, variable, etc. Compared with fuzzy linguistic approaches, they are more convenient and flexible to reflect the DMs' preferences in decision making. For further applications of HFLTSs to decision making, we develop a concept of hesitant fuzzy linguistic preference relations (HFLPRs) as a tool to collect and present the DMs' preferences. Due to the importance of the consistency measures using preference relations in decision making, we develop some consistency measures for HFLPRs to ensure that the DMs are being neither random nor illogical. A consistency index is defined to establish the consistency thresholds of HFLPRs to measure whether an HFLPR is of acceptable consistency. For HFLPRs with unacceptable consistency, we develop two optimization methods to improve the consistency until they are acceptable. Several illustrative examples are given to validate the consistency measures and the optimization methods.
Silicon, because of its high specific capacity, is intensively pursued as one of the most promising anode material for next‐generation lithium‐ion batteries. In the past decade, various ...nanostructures are successfully demonstrated to address major challenges for reversible Si anodes related to pulverization and solid‐electrolyte interphase. However, the electrochemical performance is still limited by challenges that stem from the use of nanomaterials. In this progress report, the focus is on the challenges and recent progress in the development of Si anodes for lithium‐ion battery, including initial Coulombic efficiency, areal capacity, and material cost, which call for more research effort and provide a bright prospect for the widespread applications of silicon anodes in the future lithium‐ion batteries.
Silicon, because of its high specific capacity, is intensively pursued as one of the most promising anode material for next‐generation lithium‐ion batteries. In this progress report, the focus is on the challenges and recent progress in the development of Si anodes for the widespread applications of lithium‐ion battery, including initial Coulombic efficiency, areal capacity, and material cost.
In order to improve the comprehensive properties of titanium alloys to meet the requirements for the production of engines, the micro - arc deposition technology was used to modify the surface of ...titanium alloys for engines. Three different micro - arc deposited Al2O3 - TiO2 coatings were prepared with different pulse duty cycles (30%, 40% and 50%). The surface morphology of coatings was observed by field emission electron microscope, the thickness of coatings was measured by metallographic microscope, the surface roughness of coatings was measured by laser confocal microscope, the elastic modulus and hardness of coatings were measured by nanoindenter, and the effect of duty cycle on the structure and mechanical properties of micro - arc deposited Al2O3 - TiO2 coatings on titanium alloys for engines were investigated systematically. Results showed that the average thickness of the Al2O3 - TiO2 coating increased as the duty cycle increased from 30% to 40% and 50%. With the increase of pulse duty cycle, the sur
Precarious work in China has drawn increasing attention, and this paper examines its changing trends from 2006 to 2017. It finds that as the state intensifies its intervention in the labor market, ...employers face a conflicting institutional environment with the demands of the technological environment. Employers meet the legitimacy requirements of state policy by increasing the number of stable jobs on the one hand and reducing the labor costs of unstable workers on the other hand to smooth out the increase in labor costs caused by the increase in stable workers, resulting in a stronger segmentation of the “stable–unstable” dichotomy. These two processes are more pronounced in the private sector because of the stronger tensions between legitimization and performance maximization.
A sequential cross‐coupling/annulation of ortho‐vinyl bromobenzenes with aromatic bromides was realized, providing a direct and modular approach to access polycyclic aromatic compounds. A ...vinyl‐coordinated palladacycle was proposed as the key intermediate for this sequential process. Excellent chemoselectivity and regioselectivity were observed in this transformation. The practicability of this method is highlighted by its broad substrate scope, excellent functional group tolerance, and rich transformations associated with the obtained products.
Palladium catalysis: A sequential cross‐coupling/annulation of ortho‐vinyl bromobenzenes with aromatic bromides is realized in a direct and modular approach to access polycyclic aromatic compounds. A C(vinyl), C(aryl)‐palladacycle species is proposed as the key intermediate. High chemo‐ and regioselectivity, broad substrate scope, and excellent functional group tolerance are observed for this transformation.
Silicon and lithium metal are considered as promising alternatives to state-of-the-art graphite anodes for higher energy density lithium batteries because of their high theoretical capacity. However, ...significant challenges such as short cycle life and low coulombic efficiency have seriously hindered their practical applications. In the past decades, various strategies have been proposed to address the major problems of Si and Li anodes. In this review, we summarize the understanding on Si and Li anodes, highlight the recent progress in the development and introduce advanced characterization techniques. We also indicate the remaining challenges of Si and Li anodes requiring more efforts for future widespread applications. We expect that this review provides an overall picture of the recent progress and inspires more efforts in the fundamental understanding and practical applications of Si and Li anodes.
This review summarizes the important progress of Si and Li anodes and discusses the remaining essential issues towards their applications.
Abstract
Interest in low-temperature operation of solid oxide fuel cells is growing. Recent advances in perovskite phases have resulted in an efficient H
+
/O
2-
/e
-
triple-conducting electrode BaCo
...0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
for low-temperature fuel cells. Here, we further develop BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
for electrolyte applications by taking advantage of its high ionic conduction while suppressing its electronic conduction through constructing a BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
-ZnO p-n heterostructure. With this approach, it has been demonstrated that BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
can be applied in a fuel cell with good electrolyte functionality, achieving attractive ionic conductivity and cell performance. Further investigation confirms the hybrid H
+
/O
2-
conducting capability of BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
-ZnO. An energy band alignment mechanism based on a p-n heterojunction is proposed to explain the suppression of electronic conductivity and promotion of ionic conductivity in the heterostructure. Our findings demonstrate that BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
is not only a good electrode but also a highly promising electrolyte. The approach reveals insight for developing advanced low-temperature solid oxide fuel cell electrolytes.
Traditional cooling systems consume tremendous amounts of energy and thus aggravate the greenhouse effect
. Passive radiative cooling, dissipating an object's heat through an atmospheric transparency ...window (8-13 μm) to outer space without any energy consumption, has attracted much attention
. The unique feature of radiative cooling lies in the high emissivity in the atmospheric transparency window through which heat can be dissipated to the universe. Therefore, for achieving high cooling performance, the design and fabrication of selective emitters, with emission strongly dominant in the transparency window, is of essential importance, as such spectral selection suppresses parasitic absorption from the surrounding thermal radiation. Recently, various materials and structures with tailored spectrum responses have been investigated to achieve the effect of daytime radiative cooling
. However, most of the radiative cooling materials reported possess broad-band absorption/emission covering the whole mid-infrared wavelength
. Here we demonstrate that a hierarchically designed polymer nanofibre-based film, produced by a scalable electrostatic spinning process, enables selective mid-infrared emission, effective sunlight reflection and therefore excellent all-day radiative cooling performance. Specifically, the C-O-C (1,260-1,110 cm
) and C-OH (1,239-1,030 cm
) bonding endows the selective emissivity of 78% in 8-13 μm wavelength range, and the design of nanofibres with a controlled diameter allows for a high reflectivity of 96.3% in 0.3-2.5 μm wavelength range. As a result, we observe ~3 °C cooling improvement of this selective thermal emitter as compared to that of a non-selective emitter at night, and 5 °C sub-ambient cooling under sunlight. The impact of this hierarchically designed selective thermal emitter on alleviating global warming and temperature regulating an Earth-like planet is also analysed, with a significant advantage demonstrated. With its excellent cooling performance and a scalable process, this hierarchically designed selective thermal emitter opens a new pathway towards large-scale applications of all-day radiative cooling materials.
We consider Yang-Mills theory with the coupling constant and theta angle determined by the vacuum expectation values of a dynamical (complex, zero mass) dilaton field. We discuss the tree-level ...N-gluon MHV scattering amplitudes in the presence of a nontrivial background dilaton field and construct the corresponding celestial amplitudes by taking Mellin transforms with respect to the light cone frame energies. In this way, we obtain two-dimensional CFT correlators of primary fields on the celestial sphere. We show that the celestial Yang-Mills amplitudes evaluated in the presence of a spherical dilaton shockwave are given by the correlation functions of primary field operators factorized into the holomorphic current operators times the “light” Liouville operators. They are evaluated in the semiclassical limit of Liouville theory (the limit of infinite central charge) and are determined by the classical Liouville field describing metrics on the celestial sphere.
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