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A high-precision marine gravity gradient reference map is key to enabling underwater gravity gradient matching navigation. At present, the construction of the reference maps is based on quadrilateral geographic grids. However, quadrilateral grids lead to detriangulation at high latitudes, which limits the global applicability of such maps to underwater gravity navigation. To circumvent the limitations of quadrilateral grids, a hexagonal grid is introduced for constructing the reference map. This paper analyzes the characteristics of the icosahedral Snyder equal area aperture 4 hexagon (ISEA4H) and H3 grid systems and selects an appropriate grid system. In addition, we calculate and analyze the grid model errors and matching positioning errors of hexagonal and quadrilateral grids at the same resolution. The experimental results show that the grid model and matching positioning errors of a hexagonal grid system are more than 14% and 15% less than those of a quadrilateral grid system, respectively, indicating the feasibility and effectiveness of applying hexagonal grids to gravity gradient matching navigation. Given the low construction efficiency of a marine hexagonal grid gravity gradient reference map, we propose an efficient CPU+GPU hybrid parallel scheme. A global total tensor marine hexagonal grid gravity gradient reference map model is then constructed.

Lepidopteran species are mostly pests, causing serious annual economic losses. High-quality genome sequencing and assembly uncover the genetic foundation of pest occurrence and provide guidance for pest control measures. Long-read sequencing technology and assembly algorithm advances have improved the ability to timeously produce high-quality genomes. Lepidoptera includes a wide variety of insects with high genetic diversity and heterozygosity. Therefore, the selection of an appropriate sequencing and assembly strategy to obtain high-quality genomic information is urgently needed. This research used silkworm as a model to test genome sequencing and assembly through high-coverage datasets by de novo assemblies. We report the first nearly complete telomere-to-telomere reference genome of silkworm Bombyx mori (P50T strain) produced by Pacific Biosciences (PacBio) HiFi sequencing, and highly contiguous and complete genome assemblies of two other silkworm strains by Oxford Nanopore Technologies (ONT) or PacBio continuous long-reads (CLR) that were unrepresented in the public database. Assembly quality was evaluated by use of BUSCO, Inspector, and EagleC. It is necessary to choose an appropriate assembler for draft genome construction, especially for low-depth datasets. For PacBio CLR and ONT sequencing, NextDenovo is superior. For PacBio HiFi sequencing, hifiasm is better. Quality assessment is essential for genome assembly and can provide better and more accurate results. For chromosome-level high-quality genome construction, we recommend using 3D-DNA with EagleC evaluation. Our study references how to obtain and evaluate high-quality genome assemblies, and is a resource for biological control, comparative genomics, and evolutionary studies of Lepidopteran pests and related species. [ABSTRACT FROM AUTHOR]