4,047 research outputs found
Collective octahedral tilting in ultrathin Ruddlesden-Popper perovskite under terahertz light
Perovskites have been applied in a wide range of fields such as solar cells
and non-volatile memories due to their multiferroic nature and excellent
photo-electric conversion capabilities. Recently, two-dimensional (2D)
perovskites with a few atomic layers have been successfully synthesized,
attracting significant attention for potential applications. In this work, we
perform first-principles calculations to investigate an ultrathin prototypical
Ruddlesden-Popper phase, , with its thickness down
to one unit cell. We show that this compound could exist in two (meta-)stable
octahedral tilting phases, belonging to and space groups,
respectively. Using the optomechanical theory, we suggest that reversible and
non-volatile phase switching can be triggered using non-destructive terahertz
light. In addition, the two phases show distinct optical reflectance spectrum
in the visible light range, which can be used as an optical probe for phase
transformation. This enables both "write" and "read" in an all-optical route.Comment: 5 figures, accepted in Appl. Phys. Let
Research on Early-Warning Method and its Application of Complex System of Circular Economy for Oil and Gas Exploitation
AbstractIt is a very important link to determine the reference in the warning of circular economy development, because it's the key to ensure the accuracy of warning result. To establish reference not only have to consider the convenience of data calculation, but also have to consider patterns of economic exploitation complied with the principle of circular economy when choosing criterion-referenced indexes. Only in this way can we ensure the warning results as accurate as possible, give timely warning to the exploitation methods which can’t meet the circular economy and guide the formulation of regulatory policies.In this paper, on the basis of operational early-warning Indexes system of complex system of circular economy for oil and gas exploitation, early-warning method with fuzzy ISODATA cluster analysis has been established. Furthmore, decision analysis of warning outcome has been analyzed, which is combined with practice of LN oil field of T Company. The author believes that the fuzzy ISODATA cluster analysis based early warning system and decision analysis would be practicability
Bid Optimization by Multivariable Control in Display Advertising
Real-Time Bidding (RTB) is an important paradigm in display advertising,
where advertisers utilize extended information and algorithms served by Demand
Side Platforms (DSPs) to improve advertising performance. A common problem for
DSPs is to help advertisers gain as much value as possible with budget
constraints. However, advertisers would routinely add certain key performance
indicator (KPI) constraints that the advertising campaign must meet due to
practical reasons. In this paper, we study the common case where advertisers
aim to maximize the quantity of conversions, and set cost-per-click (CPC) as a
KPI constraint. We convert such a problem into a linear programming problem and
leverage the primal-dual method to derive the optimal bidding strategy. To
address the applicability issue, we propose a feedback control-based solution
and devise the multivariable control system. The empirical study based on
real-word data from Taobao.com verifies the effectiveness and superiority of
our approach compared with the state of the art in the industry practices
TiO2 -Based Surfaces with Special Wettability – From Nature to Biomimetic Application
Super-wetting/antiwetting surfaces with extremely high contrast of surface energy and liquid adhesion have attracted a lot of interest in both fundamental research and industry. Various types of special wetting surfaces can be constructed by adjusting the topographical structure and chemical composition. In this chapter, recent advance of the super-wetting/antiwetting surfaces with special solid/liquid adhesion has been reviewed, with a focus on the biomimetic fabrication and applications of TiO2-based surfaces. Special super-wettability examples include lotus-leaf-inspired surfaces with low adhesion, rose-petal-inspired surfaces with high adhesion, spider silk bio-inspired surfaces with directional adhesion, fish-scale-inspired underwater superoleophobic surface, and artificial surfaces with controllable or stimuli-responsive liquid adhesion. In addition, we will review some potential applications related to artificial antiwetting surface with controllable adhesion, e.g., self-cleaning, antifogging/anti-icing, micro-droplet manipulation, fog/water collection, water/oil separation, anti-bioadhesion, micro-template for patterning, and friction reduction. Finally, the difficulty and prospects of this renascent and rapidly developing field are also briefly proposed and discussed
Comparison of Chebyshev and Legendre Polynomial Expansion of Phase Function of Cloud and Aerosol Particles
Chebyshev and Legendre polynomial expansion is used to reconstruct the Henyey-Greenstein phase function and the phase functions of spherical and nonspherical particles. The result of Legendre polynomial expansion is better than that of Chebyshev polynomial for around 0-degree forward angle, while Chebyshev polynomial expansion produces more accurate results in most regions of the phase function. For large particles like ice crystals, the relative errors of Chebyshev polynomial can be two orders of magnitude less than those of Legendre polynomial
- …