South China University of Technology

About: South China University of Technology is a education organization based out in Guangzhou, China. It is known for research contribution in the topics: Catalysis & Adsorption. The organization has 62343 authors who have published 69468 publications receiving 1251592 citations. The organization is also known as: SCUT & Huánán Lǐgōng Dàxué.

Weyl points and Fermi arcs in a chiral phononic crystal

Abstract: Acoustic Weyl points are realized in a three-dimensional chiral phononic crystal that breaks inversion symmetry, with the topological nature of the associate surface states providing robust modes that propagate along only one direction.

Site Occupancy Preference, Enhancement Mechanism, and Thermal Resistance of Mn4+ Red Luminescence in Sr4Al14O25: Mn4+ for Warm WLEDs

Abstract: Red phosphors play an indispensable role in phosphor-based warm white light-emitting diodes (WLEDs). We demonstrated recently that the non-rare-earth phosphor Sr4Al14O25:Mn4+ exhibits red luminescence even more intensely than the commercial Mn4+ phosphor 3.5MgO.0.5MgF2.GeO2:Mn4+ upon blue excitation. Herein, on the basis of crystal field calculations employing the exchange charge model, we identify the energy levels of three types of Mn4+ ions situated at Al3+ sites in the Sr4Al14O25 crystal lattice and find that the doped manganese ions occupy preferentially the Al4 and Al5 more covalent sites rather than the Al6 site. We report that the Mn4+ luminescence can be enhanced upon the inclusion of Mg2+ in the synthesis reaction. The mechanisms for this effect comprise the lower nonradiative decay rate from the 2Eg state because of the reduction in energy migration along Mn4+ ions to killer sites and the morphology evolution from orderly layered smooth nanosheets to irregular nanoparticles disorderly compacted...

Viewpoint Invariant Texture Description Using Fractal Analysis

Abstract: Image texture provides a rich visual description of the surfaces in the scene. Many texture signatures based on various statistical descriptions and various local measurements have been developed. Existing signatures, in general, are not invariant to 3D geometric transformations, which is a serious limitation for many applications. In this paper we introduce a new texture signature, called the multifractal spectrum (MFS). The MFS is invariant under the bi-Lipschitz map, which includes view-point changes and non-rigid deformations of the texture surface, as well as local affine illumination changes. It provides an efficient framework combining global spatial invariance and local robust measurements. Intuitively, the MFS could be viewed as a "better histogram" with greater robustness to various environmental changes and the advantage of capturing some geometrical distribution information encoded in the texture. Experiments demonstrate that the MFS codes the essential structure of textures with very low dimension, and thus represents an useful tool for texture classification.

Enhancing the Regeneration Process of Consumed NaBH4 for Hydrogen Storage

Abstract: Sodium borohydride (NaBH4) is regarded as an excellent hydrogen-generated material, but its irreversibility of hydrolysis and high cost of regeneration restrict its large-scale application. In this study a convenient and economical method for NaBH4 regeneration is developed for the first time without hydrides used as starting materials for the reduction process. The real hydrolysis by-products (NaBO2·2H2O and NaBO2·4H2O), instead of dehydrated sodium metaborate (NaBO2), are applied for the regeneration of NaBH4 with Mg at room temperature and atmospheric pressure. Therefore, the troublesome heat-wasting process to obtain NaBO2 using a drying procedure at over 350 °C from NaBO2·xH2O is omitted. Moreover, the highest regeneration yields of NaBH4 are achieved to date with 68.55% and 64.06% from reaction with NaBO2·2H2O and NaBO2·4H2O, respectively. The cost of NaBH4 regeneration shows a 34-fold reduction compared to the previous study that uses MgH2 as the reduction agent, where H2 is obtained from a separate process. Furthermore, the regeneration mechanism of NaBH4 is clarified and the intermediate compound, NaBH3(OH), is successfully observed for the first time during the regeneration process.