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As an important future development direction, unmanned agent formation has considerable research value. Therefore, path planning is the key technology for unmanned platforms to realize intelligent navigation, and the scheme combining A* and DWA algorithm has a wide range of applications, but this method has the following problems in the navigation of USV formation: First, the speed of USV are uncontrollable when it reaches the target position; Second, the navigation success rate is low when the global paths of three USVs cross; Third, USV tends to deviate from the global path when turning. Based on the above problems, this paper proposes an improved algorithm. By adjusting the global path and improving the decision strategy, the algorithm solves the shortcomings of the original algorithm and improves the performance. The improved algorithm is simulated and evaluated, which fully proves the effectiveness of the improved measures and puts forward a solution for the intelligent navigation of USV formation. [ABSTRACT FROM AUTHOR]

In order to further enhance the performance of the AlSi10Mg parts fabricated by selective laser melting, the WC/AlSi10Mg composite with 0.1%WC(mass fraction) was obtained by mixing the nano-WC and AlSi10Mg in mixing machine, and the specimen block was fabricated by the selective laser melting machine. By comparing the AlSi10Mg specimens fabricated by the same process, the effects of nano-WC on the microstructure formation and evolution of the microstructure and the mechanical properties of the microstructure were investigated. The results show that the WC/AlSi10Mg powder has good sphericity and the particle size distribution is concentrated in 20-60 μm. The WC/AlSi10Mg sample has the density of over 99% and hardness of about 158.89HV, which is 14.58% higher than that of the AlSi10Mg sample. The WC/AlSi10Mg samples grow uniformly and densely, with obvious molten pool lines. The inside of the crystal grain is α-Al matrix, and the boundary is a eutectic Si phase interposed with WC. The yield strength of the WC/AlSi10Mg sample reaches 337.75 MPa, the ultimate strength is as high as 514.00 MPa, and the elongation is 3.78%. Compared with the same process, AlSi10Mg samples are increased by 4.73%, 6.25% and 35.97%, respectively. Therefore, SLM-processed WC/AlSi10Mg composite parts have better application prospects than AlSi10Mg parts.

Examining the pollination biology of plant species is not only crucial for enhancing our understanding of their reproductive biology, but also essential for elucidating their adaptation and evolutionary history. Here, we investigated the breeding system and pollination biology of two closely related species in Actaea. The flower of A. purpurea is unique in the genus with purple and chartaceous (paper-like) sepals, fewer stamens with yellow anthers and purple filaments. Through three seasons of field observation and exclusion experiments, we determined that A. purpurea was primarily pollinated by a hornet species, Vespa bicolor , which also served as the most efficient pollinator. In contrast, A. japonica was primarily pollinated by large flies. Actaea purpurea exhibited a significantly higher cumulative nectar volume than A. japonica , which could be a crucial factor in attracting V. bicolor. A control experiment further demonstrated that removing the nectar leaf (petal) significantly decreased the visiting frequency of V. bicolor. Breeding system studies revealed that both species were self-compatible, yet they primarily underwent outcrossing in natural habitats. Our study presents a compelling case of possible pollinator shift in A. purpurea accompanied by morphological divergence. A more in-depth investigation of this system would offer crucial insights into the extent to which pollinators are involved in the plant speciation process and whether they contribute to reproductive isolation between closely related species. [ABSTRACT FROM AUTHOR]

In order to further enhance the performance of the AlSi10Mg parts fabricated by selective laser melting, the WC/AlSi10Mg composite with 0.1%WC(mass fraction) was obtained by mixing the nano-WC and AlSi10Mg in mixing machine, and the specimen block was fabricated by the selective laser melting machine. By comparing the AlSi10Mg specimens fabricated by the same process, the effects of nano-WC on the microstructure formation and evolution of the microstructure and the mechanical properties of the microstructure were investigated. The results show that the WC/AlSi10Mg powder has good sphericity and the particle size distribution is concentrated in 20-60 μm. The WC/AlSi10Mg sample has the density of over 99% and hardness of about 158.89HV, which is 14.58% higher than that of the AlSi10Mg sample. The WC/AlSi10Mg samples grow uniformly and densely, with obvious molten pool lines. The inside of the crystal grain is α-Al matrix, and the boundary is a eutectic Si phase interposed with WC. The yield strength of the WC/AlSi10Mg sample reaches 337.75 MPa, the ultimate strength is as high as 514.00 MPa, and the elongation is 3.78%. Compared with the same process, AlSi10Mg samples are increased by 4.73%, 6.25% and 35.97%, respectively. Therefore, SLM-processed WC/AlSi10Mg composite parts have better application prospects than AlSi10Mg parts.

SUMMARY: Rhodiola L. is a genus that has undergone rapid radiation in the mid‐Miocene and may represent a typic case of adaptive radiation. Many species of Rhodiola have also been widely used as an important adaptogen in traditional medicines for centuries. However, a lack of high‐quality chromosome‐level genomes hinders in‐depth study of its evolution and biosynthetic pathway of secondary metabolites. Here, we assembled two chromosome‐level genomes for two Rhodiola species with different chromosome number and sexual system. The assembled genome size of R. chrysanthemifolia (2n = 14; hermaphrodite) and R. kirilowii (2n = 22; dioecious) were of 402.67 and 653.62 Mb, respectively, with approximately 57.60% and 69.22% of transposable elements (TEs). The size difference between the two genomes was mostly due to proliferation of long terminal repeat‐retrotransposons (LTR‐RTs) in the R. kirilowii genome. Comparative genomic analysis revealed possible gene families responsible for high‐altitude adaptation of Rhodiola, including a homolog of plant cysteine oxidase 2 gene of Arabidopsis thaliana (AtPCO2), which is part of the core molecular reaction to hypoxia and contributes to the stability of Group VII ethylene response factors (ERF‐VII). We found extensive chromosome fusion/fission events and structural variations between the two genomes, which might have facilitated the initial rapid radiation of Rhodiola. We also identified candidate genes in the biosynthetic pathway of salidroside. Overall, our results provide important insights into genome evolution in plant rapid radiations, and possible roles of chromosome fusion/fission and structure variation played in rapid speciation. [ABSTRACT FROM AUTHOR]

A wideband circularly polarized (CP) dipole antenna with compact size and wide beamwidth is proposed. To achieve a wide half‐power beamwidth (HPBW), the dipole is designed to be a folded bowtie, and four rotationally symmetric vertical metal plates are placed on the square ground plane. A circular parasitic patch above the dipole arms improves the impedance bandwidth. By using a 3‐dB coupler, the proposed antenna achieves wideband CP performance. The measured results show that an impedance bandwidth for VSWR ≤ 2 and a 3‐dB axial‐ratio (AR) bandwidth are from 0.76 to 2.1 GHz (93.7%). Moreover, a bandwidth of HPBW ≥ 102° is from 0.76 to 1.8 GHz (81.2%). [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) is an important tool for hybrid production and a good system for studying the interaction between nucleus and cytoplasm, but its mechanism is still unclear. The relationship between stamen abnormality and the relative expression levels of flower development genes in tobacco CMS line K326 was studied. The CMS line K326 was derived from a natural variation in Nicotiana tabacum and was bred by continuous backcross of flue-cured tobacco variety K326. It has not only stamens with carpelloid, but also stamens with petaloid, and the base of abnormal stamens is fused into a whole. In this study, we identified MADS-box genes and SUPERMAN genes of whole genome, which controlled the flower development in N. tabacum and analyzed their chromosomal localization and collinearity. The cis-acting elements of B genes and SUPERMAN genes were predicted, and their expression characteristics in flower buds at different stages in both CMS line and its maintainer line were studied. The results showed that 160 MADS-box genes and 5 SUPERMAN genes were identified in the genome of tobacco, including 4 PI genes, 3 AP3 genes, and 7 B genes. There were 79 MADS-box genes scattered on 22 chromosomes, and 3 SUPERMAN genes distributed on 3 chromosomes. Collinearity analysis showed that tandem and fragment DNA duplication and multiplication were the driving forces of the expansion of MADS- box gene family in tobacco. The abnormal stamens of CMS line K326 appeared at small bud stage, suggesting that the abnormal stamens in CMS line K326 were the result of early meristem development defects. The qRT-PCR showed that 7 B genes and 1 SUPERMAN gene were expressed both in CMS line K326 and its maintainers. The relative expression level of PI gene NitMADS115 in the maintainer line was higher than that in CMS line at all stages. The relative expression levels of AP3 genes NitMADS72 and NitMADS100 in maintainer lines were lower than those in CMS lines. Other genes were down-regulated at small bud stage and large bud stage, and up-regulated at middle bud stage. The SUPERMAN gene could only be detected at small bud and middle bud stage of the maintainer line, but not at bud stages of CMS line. Analysis of cis-acting elements showed that NitMADS115 had an auxin response element AuxRR. The study indicates that auxin might play an important role in cytoplasmic retrograde regulation of nucleus in tobacco. [ABSTRACT FROM AUTHOR]