x. y. liu

The hollow projectile is a new type of projectile that has complex water entry hydrodynamics characteristics and has attracted significant attention in recent years. As such, it is important to investigate the effects of different entry velocities and aperture diameters on the cavity morphology, cavitation, dynamics, and motion characteristics of hollow projectiles when entering water at high speeds. In this study, four stages of an open cavity, cavity stretching, cavity closure, and cavity contraction in the water entry processes of a hollow projectile at 50–200 m/s and four aperture diameter projectiles at 100 m/s were studied using the volume of fluid (VOF), realizable k-ε turbulence, and Schnerr-Sauer cavitation model. With an increase in the speed, the depth of the cavity closure increases, thereby advancing the closure time. The timing of the surface closure at 50 m/s is clearly different from that at 100–200 m/s. Cavitation is not obvious and is near the cavity wall at 50 m/s, although the entire cavity is almost filled with vapor at 100–200 m/s. The friction resistance has two step points when impacting the water surface and entering the water completely. As the velocity increases or the aperture ratio reduces, the splash is higher, the cavity volume is larger, the cavitation phenomenon is more obvious, the cavity closure time is delayed, and the frictional resistance of the projectile is greater. The results of this study can guide the production and application of hollow projectiles in the future.

Randomness and fuzziness of argumentation have attracted the interest of many researchers.However, though each of these two properties is discussed in the past, seldom literature considers both of them.The purpose of this paper aims to explore semantics of the argumentation frameworks with these two attributes at the same time.Firstly, we introduce probabilistic-fuzzy matrices to describe the arguments with randomness and fuzziness,and define the mathematical form of the probabilistic-fuzzy argumentation frameworks.In these frameworks, an argument has finite fuzzy states and each fuzzy state has a probability.This provides a mathematical foundation for the follow-up work.Then, we introduce a method of modifying the probabilities of the fuzzy states,which proposes a feasible way to revise the probabilities.Formally, it is the revision of the probabilistic-fuzzy matrices of arguments.Finally, based on this process, we set up an extension semantics system for probabilistic-fuzzy frameworks.The semantics enriches the theory of argumentation, and propose a way to check the probabilities.

High-throughput sequencing of intestinal microbial DNA using the Illumina platform was implemented to clarify the structure and function of intestinal flora and antibiotic resistance genes (ARGs) abundances in yellow catfish (Pelteobagrus fulvidraco). Species annotation and gene function analysis were performed on the metagenomic sequencing data. Intestinal bacteria were isolated and identified by 16sRNA. The results showed that intestinal flora was highly similar in the three P. fulvidraco. A total of 37 phyla and 788 genera of intestinal bacteria were identified. Proteobacteria, Streptomyces, and Clostridium are the dominant flora with the average relative abundance of 25.71%, 14.75%, and 5.15%, respectively. Six strains were successfully isolated and identified in our experiment. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the primary metabolic pathway is dominated by metabolism and organic systems, while the secondary metabolic pathway is dominated by sensory system, carbohydrate metabolism, replication, and repair. In addition, 499 ARGs of 37 resistance types were identified based on Antibiotic Resistance Genes Database. Tetracycline, polypeptide, macrolide, glycopeptide, and multiple drug resistance were highly abundant. The intestinal ARGs of P. fulvidraco were macB, bcrA, and evgS. In general, rich bacterial diversity and many types of ARG were detected in the intestine of P. fulvidraco. Moreover, probiotics are potentially a good alternative to antibiotic abuse in aquaculture industry. Therefore, analysis of intestinal flora, intestinal flora ARGs and gene functions is beneficial for the artificial farming of P. fulvidraco.