A homogeneous high precision direct integration based on Chebyshev interpolation

Based on Chebyshev’s interpolation theory, the non-homogeneous term of the second-order linear differential equations is interpolated, and a precise integration algorithm with easy programming, high computational efficiency and precision design is realized. The method does not involve inverse operation, and does not need to additionally calculate the matrix index on the integration point, and can control the error boundary based on different precision requirements, so it has high stability and controllability. Numerical examples of periodic loads common in vibration engineering show the effectiveness of the method

MeetDurian: A Gameful Mobile App to Prevent COVID-19 Infection

The COVID-19 problem has not gone away with the passing of the seasons. Even though most countries have achieved remarkable results in fighting against epidemic diseases and preventing and controlling viruses, the general public is still far from understanding the new crown virus and lacks imagination on its transmission law. In this paper, we propose MeetDurian: a cross-platform mobile application that exploits a location-based game to improve users' hygiene habits and reduce virus dispersal. We present its main features, its architecture, and its core technologies. Finally, we report a set of experiments that prove the acceptability and usability of MeetDurian. An illustrative demo of the mobile app features is shown in the following video: https://youtu.be/Vqg7nFDQuOU.Comment: 4 pages, 4 figure

Exploring the roles of horizotnal gene transfer in metazoans

Horizontal gene transfer (HGT; also known as lateral gene transfer, LGT) refers to the movement of genetic information between distinct species by overcoming normal mating barriers. Historically HGT is only considered to be important in prokaryotes. Some researchers believe that eukaryotes have sexual recombination and HGT is insignificant. However, HGT has also been found to play roles in many aspects of eukaryotic evolution, like parasitism and the colonization of land by plants, although at lower frequencies than in prokaryotes. In this dissertation, I first estimated the scope of HGT in 16 selected metazoan species by genome screening using AlienG. These species are sampled to represent major lineages of metazoans. Among all the 16 species, Nematostella vectensis (4.08%) has the highest percentage of HGT genes, while parasitic Schistosoma japonicum (0.47%) ranks the lowest. In order to find out which factors are correlated with HGT rates in different species, living habitat, diet, lineage group and reproductive type were analyzed in a statistical framework. In Chapter 3 and Chapter 4, Ciona intestinalis and Trichoplax adhaerens were chosen as models to investigate horizontally acquired genes. Tunicate cellulose synthase was discovered to originate from green algae, instead from bacteria as found in previous studies. 43 genes of 21 families in T. adhaerens were found to be horizontally acquired. The functions and impacts of acquired genes on T. adhaerens are also discussed

Superconductivity induced by doping Ru in SrFe2-xRuxAs2

Using one-step solid state reaction method, we have successfully synthesized the superconductor SrFe1-xRuxAs. X-ray diffraction indicates that the material has formed the ThCr2Si2-type structure with a space group I4/mmm. The systematic evolution of the lattice constants demonstrates that the Fe ions are successfully replaced by the Ru. By increasing the doping content of Ru, the spin-density-wave (SDW) transition in the parent compound is suppressed and superconductivity emerges. The maximum superconducting transition temperature is found at 13.5 K with the doping level of x = 0.7. The temperature dependence of DC magnetization confirms superconducting transitions at around 12 K. Our results indicate that similar to non-isoelectronic substitution, isoelectronic substitution contributes to changes in both the carrier concentration and internal pressure, and superconductivity could be induced by isoelectronic substitution.Comment: 14 pages, 4 figure

Fabrication and characterization of iron pnictide wires and bulk materials through the powder-in-tube method

The recent discovery of superconductivity in the iron based superconductors with very high upper critical fields presents a new possibility for practical applications, but fabricating fine-wire is a challenge because of mechanically hard and brittle powders and the toxicity and volatility of arsenic. In this paper, we report the synthesis and the physical characterization of iron pnictide wires and bulks prepared by the powder-in-tube method (PIT). A new class of high-Tc iron pnictide composite wires, such as LaFeAsO1-xFx, SmFeAsO1-xFx and Sr1-xKxFeAs, has been fabricated by the in situ PIT technique using Fe, Ta and Nb tubes. Microscopy and x-ray analysis show that the superconducting core is continuous, and retains phase composition after wire drawing and heat treatment. Furthermore, the wires exhibit a very weak Jc-field dependence behavior even at high temperatures. The upper critical field Hc2(0) value can exceed 100 T, surpassing those of MgB2 and all the low temperature superconductors and indicating a strong potential for applications requiring very high field. These results demonstrate the feasibility of producing superconducting pnictide composite wire. We also applied the one step PIT method to synthesize the iron-based bulks, due to its convenience and safety. In fact, by using this technique, we have successfully discovered superconductivity at 35 K and 15 K in Eu0.7Na0.3Fe2As2 and SmCoFeAsO compounds, respectively. These clearly suggest that the one-step PIT technique is unique and versatile and hence can be tailored easily for other rare earth derivatives of novel iron-based superconductors.Comment: Review for the special issue of Physica C on iron-based pnictide superconductor