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Discrete element modelling (DEM) is a numerical method for examining the dynamic behavior of granular media. In order to build an accurate simulation model and provide more comprehensive soil characteristic parameters for the design and optimization of various soil contact machinery, in this paper, the discrete element simulation method (EDEM) combined with experimental approach is used to investigate the soil contact characteristic parameters in East Asia. In this study, Hertze-Mindlin (no slip) was used as a particle contact model by taking particle contact parameters and soil JKR (Johnson-Kendall-Roberts) surface energy as determinants, and repose angle, internal friction angle, and cohesive force as evaluation indexes. The method of Plackett-Burman, Stepest ascent, and Box-Behnken were used to gradually reduce the range of parameters needed for simulation until the most accurate value was determined. The results show that the restitution coefficient, static friction coefficient, and rolling friction coefficient between soil particles have significant effects on the DEM model, and their value of them are 0.596, 0.725, and 0.16, respectively. Based on these parameters used for the repose angle test and direct shear stress test, the value of repose angle is 31.97°, the internal friction angle is 27.61°, and the cohesive force is 33.06 kPa. The relative errors with the actual measured values are 9.54%, 1.87%, and 2.31%, respectively. In order to further test whether the simulation parameters of soil obtained by repose angle test and direct shear stress test are consistent with the real soil, comparison test between field test and discrete element simulation was used. The results show that the error in height of ridge between the simulated soil and the actual soil is 4.06%, which is within the acceptable range. It also indicates that the calibrated and optimized soil simulation model can accurately represent the real soil. The research provides theoretical basis and technical support for the study of soil contact parts by using the discrete element method, combined with repose angle test and direct shear stress test. [ABSTRACT FROM AUTHOR]

Flammulina filiformis, as one of the most popular edible fungi in East Asia, is produced in an industrialized and standardized way. However, its monotonous variety and product convergence have seriously restricted the development of the industry. In this study, 11 cultivated strains and 13 wild strains of F. filiformis were collected from multiple regions of China and Japan and were performed genome sequencing. Together with genome data of six strains previously released, in total 23 dikaryons (formed by two monokaryons mating, can making fruiting body), 35 monokaryons (formed by protoplast-regenerating of dikaryon and isolating) were used for genetic diversity and population structure analysis based on the high-throughput genotyping. Firstly, a set of SNP markers with intrapopulation polymorphism including 849,987 bi-allelic SNPs were developed and basically covered all of 11 chromosomes with a high distribution density of 24.16 SNP markers per kb. The cultivated dikaryotic strains were divided into three subgroups, and their breeding history was made inferences, which is consistent with the available pedigree records. The wild dikaryotic strains were divided into two subgroups and showed varied contributions of genetic components with high genetic diversity. All the investigated dikaryons have a symmetric distribution pattern with their two constituent monokaryons in principal component analysis. Finally, we summarized the pedigree relationship diagram of F. filiformis main strains including six modules, and the genotypes of hybrids can be directly phased by the known parental allele according to it. This study provides a method to distinguish two sets of monokaryon haplotypes, and several valuable genetic resources of wild F. filiformis, and an effective strategy for guiding F. filiformis breeding based on the population structure and pedigree relationship in future. [ABSTRACT FROM AUTHOR]

Population migrations in Southwest and South China have played an important role in the formation of East Asian populations and led to a high degree of cultural diversity among ethnic minorities living in these areas. To explore the genetic relationships of these ethnic minorities, we systematically surveyed the variation of 10 autosomal STR markers of 1,538 individuals from 30 populations of 25 ethnic minorities, of which the majority were chosen from Southwest China, especially Yunnan Province. With genotyped data of the markers, we constructed phylogenies of these populations with both DA and DC measures and performed a principal component analysis, as well as a clustering analysis by structure. Results showed that we successfully recovered the genetic structure of analyzed populations formed by historical migrations. Aggregation patterns of these populations accord well with their linguistic affiliations, suggesting that deciphering of genetic relationships does in fact offer clues for study of ethnic differentiation. [ABSTRACT FROM AUTHOR]