In finite element methods, the accuracy of the solution cannot increase indefinitely since the round-off error related to limited computer precision increases when the number of degrees of freedom (DoFs) is large enough. Because a priori information of the highest attainable accuracy is of great interest, we construct an innovative method to obtain the highest attainable accuracy given the order of the elements. In this method, the truncation error is extrapolated when it converges at the asymptotic rate, and the bound of the round-off error follows from a generically valid error estimate, obtained and validated through extensive numerical experiments. The highest attainable accuracy is obtained by minimizing the sum of these two types of errors. We validate this method using a one-dimensional Helmholtz equation in space. It shows that the highest attainable accuracy can be accurately predicted, and the CPU time required is much smaller compared with that using successive grid refinement.

The existence of magnetostatic surface spin waves in ferromagnets, known as the Damon-Eshbach mode, was recently demonstrated to originate from the topology of the dipole-dipole interaction. In this work, we study the topological characteristics of magnons in easy-axis antiferromagnets with uniaxial anisotropy. The dipolar spin waves are found to be, driven by the dipole-dipole interaction, in a topological nodal-line semimetal phase, which hosts Damon-Eshbach-type surface modes due to the bulk-edge correspondence. The long-wavelength character of dipolar spin waves makes our proposal valid for any natural uniaxial easy-axis antiferromagnet and, thus, enriches the candidates of topological magnonic materials. In contrast to the nonreciprocal property in the ferromagnetic case, surface modes with opposite momentum coexist at each surface, but with different chiralities. Such chirality-momentum or spin-momentum locking, similar to that of electronic surface states in topological insulators, offers the opportunity to design novel chirality-based magnonic devices in antiferromagnets.

A magnon spin-orbit coupling, induced by the dipole-dipole interaction, is derived in monoclinic-stacked bilayer honeycomb spin lattice with perpendicular magnetic anisotropy and antiferromagnetic interlayer coupling. Linear crossings are predicted in the magnon spectrum around the band minimum in Γ valley, as well as in the high-frequency range around the zone boundary. The linear crossings in K and K′ valleys, which connect the acoustic and optical bands, can be gapped when the intralayer dipole-dipole or Kitaev interactions exceed the interlayer dipole-dipole interaction, resulting in a phase transition from semimetal to insulator. Our results are useful for analyzing the magnon spin dynamics and transport properties in van der Waals antiferromagnets.

The Belt and Road initiative has a significant focus on infrastructure, trade, and economic development across a vast region, and it also provides significant opportunities for sustainable development. The combined pressure of climate variability, intensified use of resources, and the fragility of ecosystems make it very challenging, however, to achieve future sustainability. To develop the path in a sustainable way, it is important to have a comprehensive understanding of these issues across nations and evaluate them in a scientific and well-informed approach. In this context, the Digital Belt and Road (DBAR) program was initiated as an international venture to share expertise, knowledge, technologies, and data to demonstrate the role of Earth observation science and technology and big Earth data applications to support large-scale development. In this paper, we identify pressing challenges, present the research priorities and foci of the DBAR program, and propose solutions where big Earth data can make significant contributions. This paper calls for further joint actions and collaboration to build a digital silk road in support of sustainable development at national, regional and global levels.

Due to low power consumption, long lifetime and many other advantages, Light-emitting Diode (LED) has increased dramatically all over the world. Chip Scale Package (CSP) LED is a new LED package with small size, high current, and high reliability. For the CSP LED with smaller size and lower thermal resistance, phosphors and silicone are usually combined as the phosphors/silicone composite and prepared by using a high temperature cure process. However, for those CSPs which are not sufficiently cured, their reliability under a harsh environment (e.g. high temperatures and high humidity) will obviously decrease. In this study, the influence of temperature and ultraviolet light on the cure process of phosphor/silicone composites is studied and an optimal cure process is extracted accordingly. According to the cure experiment under different conditions, the results show that ultraviolet light and phosphor can promote the cure reaction of silicone. With the increase of ultraviolet light intensity and phosphor mass fraction, the cure rate of the silicone and phosphor/silicone composite is greatly increased as well.