Dynamic Capture Using a Traplike Soft Gripper With Stiffness Anisotropy

Dynamic capture is a common skill that humans have practiced extensively but is a challenging task for robots in which sensing, planning, and actuation must be tightly coordinated to deal with targets of diverse shapes, sizes, and velocity. In particular, the impact force may cause serious damage to a rigid gripper and even its carrier, e.g., a robotic arm. Existing soft grippers suffer from low speed and force to actively respond to capturing dynamic targets. In this article, we propose a soft gripper capable of efficient capture of dynamic targets, taking inspiration from the biological structures of multitentacled animals or plants. The presented gripper uses a cluster of tentacles to achieve an omnidirectional envelope and high tolerance to dynamic target during the capturing process. In addition, a stiffness anisotropy property is implemented to the tentacle structure to form a “trap” making it easy for the targets to enter yet difficult to escape. We also present an analytical model for the tentacle structure to describe its deformation during the collision with a target. In experiments, we construct a robotic prototype and demonstrate its ability to capture dynamic targets

Comparative Transcriptome Analysis between Embryogenic and Non-Embryogenic Callus of <i>Davidia involucrata</i>

Davidia involucrata Baill. (D. involucrata), a rare and endangered wild plant, is native to China and is globally recognized as an ornamental tree species. However, D. involucrata exhibits inherent biological characteristics that contribute to its low reproductive efficiency. To address this challenge, somatic embryogenesis, a biotechnological method, offers numerous advantages, including enhanced reproductive efficiency, a large reproductive coefficient, and a complete structural composition. Consequently, somatic embryogenesis holds significant value in the propagation and genetic improvement of this particular tree species. In a previous study, we utilized immature zygotic embryos of D. involucrata as explants and induced somatic embryogenesis from embryogenic callus, thereby establishing a rapid propagation and plant regeneration scheme. In this study, we utilized Illumina RNA sequencing to compare the transcriptomes of the embryogenic callus (EC) and non-embryogenic callus (NEC) of D. involucrata. The analysis revealed 131,109 unigenes assembled from EC and NEC, and 12,806 differentially expressed genes (DEGs) were identified. To verify the authenticity of the transcriptome sequencing results, qRT-PCR was performed and 16 DEGs were screened, with the stable reference gene UBQ being selected. Our analysis focused on genes related to plant growth regulators and somatic embryogenesis, such as the Aux, IAA, ARF, GH3, AHP, ARR, CYCD, BBM, WUS, GRF, SERK, and WOX gene families. We found that certain genes in these families were significantly upregulated in EC induction compared to NEC, indicating that they play crucial roles in D. involucrata cell proliferation, differentiation, and cell totipotency. These results offer new insights into the role of these gene families in EC, and may guide efforts to improve the somatic embryo induction, culture conditions, and genetic transformation efficiency of D. involucrata

Plants as highly diverse sources of construction wood, handicrafts and fibre in the Heihe valley (Qinling Mountains, Shaanxi, China): the importance of minor forest products

Abstract Background Chinese rural communities living among species-rich forests have little documentation on species used to make handicrafts and construction materials originating from the surrounding vegetation. Our research aimed at recording minor wood uses in the Heihe valley in the Qinling mountains. Methods We carried out 37 semi-structured interviews in seven villages. Results We documented the use of 84 species of plants. All local large canopy trees are used for some purpose. Smaller trees and shrubs which are particularly hard are selectively cut. The bark of a few species was used to make shoes, hats, steamers and ropes, but this tradition is nearly gone. A few species, mainly bamboo, are used for basket making, and year-old willow branches are used for brushing off the chaff during wheat winnowing. Conclusions The traditional use of wood materials documented suggests that some rare and endangered tree species may have been selectively cut due to their valuable wood, e.g. Fraxinus mandshurica and Taxus wallichiana var. chinensis. Some other rare species, e.g. Dipteronia sinensis, are little used and little valued

Frequency Modulation and Erosion Performance of a Self-Resonating Jet

The self-resonating water jet offers the advantages of both a cavitation jet and a pulsed jet, and thus has been widely used for many practical applications. In the present study, the 120° -impinging edge Helmholtz nozzle was investigated for better erosion performance. The oscillating mechanism was analyzed from both numerical and experimental perspectives. The results showed that the cavitation clouds in the chamber dominate the oscillating frequency. The frequency resulting from the non-linear interaction was also observed in the simulation. The dominant frequency increases linearly as pressure decreases without entrained air. The frequency modulation was achieved through various inspiratory methods, and the modulation range was dependent on the pressure drop. The erosion performance was improved with entrained air, and the improvement was effected by the inspiratory method. The oscillating frequency was determined by the forced frequency of entrained air, and the best erosion performance was achieved at the frequency closest to the fundamental frequency. A feasible method to improve the erosion performance was investigated in this preliminary study, which could provide a guide for practical applications

Improved estimation of motion blur parameters for restoration from a single image

This paper presents an improved method to estimate the blur parameters of motion deblurring algorithm for single image restoration based on the point spread function (PSF) in frequency spectrum. We then introduce a modification to the Radon transform in the blur angleestimation scheme with our proposed difference value vs angle curve. Subsequently, theauto-correlation matrix is employed to estimate the blur angle by measuring the distancebetween the conjugated-correlated troughs. Finally, we evaluate the accuracy, robustnessand time efficiency of our proposed method with the existing algorithms on the public benchmarks and the natural real motion blurred images. The experimental results demonstratethat the proposed PSF estimation scheme not only could obtain a higher accuracy for theblur angle and blur length, but also demonstrate stronger robustness and higher time efficiency under different circumstances