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Comparative analysis among the capabilities of the RANS, DES, and LES models to predict flow and turbulence distribution was conducted to come up with guidelines for hydraulic torque converter (TC) transient simulation. To ensure the accuracy of calculation, the complex geometry of hydrodynamic elements was accurately represented and the computational meshes of the structured hexahedron were appropriately distributed. Wall shear stress, pressure-streamline structure were analyzed. Compared with RANS, the transient vorticity features, including the birth, development, formation of a scroll; transportation along the blade surface; shedding and rupture at the trailing edge could be clearly captured by the LES and DES models. Rothalpy was used to quantitatively evaluate the hydraulic loss and a new computational formula was proposed to predict the efficiency of each element in TC. After the comparison of relative computing time, DES model was proved be a feasible method for efficiently and accurately simulating 3D unsteady turbulent flow of TC.

A permanent advanced population containing 388 SSSLs was used for genetic analysis of seed dormancy; 25 QTLs including eight stable, six major and five new were identified. Seed dormancy (SD) is not only a complex biological phenomenon, but also a key practical problem in agricultural production closely related with pre-harvest sprouting (PHS). However, the genetic mechanisms of SD remain elusive. Here, we report the genetic dissection of SD in rice using 388 single segment substitution lines (SSSLs) derived from 16 donor parents. Continuous variation and positive correlations in seed germination percentages were observed in seven seasons. Genetic analysis revealed the narrow sense heritability in different seasons varied from 31.4 to 82.2% with an average value of 56.8%. In addition, 49 SSSLs exhibited significant difference to recipient parent HJX74 on SD in at least two seasons, and 12 of them were stably identified with putative QTLs in all of their corresponding cropping seasons. Based on substitution mapping, a total of 25 dormancy QTLs were detected on 11 chromosomes except the chromosome 5 with an interval length of 1.1 to 31.3 cM. The additive effects of these QTLs changed from -0.31 to -0.13, and the additive effect contributions ranged from 16.7 to 41.4%. Six QTLs, qSD3-2, qSD4-1, qSD7-1, qSD7-2, qSD7-3 and qSD11-2, showed large additive effect contributions (≥30%). Five QTLs, qSD3-3, qSD7-1, qSD7-4, qSD9-1 and qSD10-1, may represent novel ones. Furthermore, linkage and recombinant analysis delimited qSD7-1 to a locus 1.5 cM away from marker Oi2 and a 355-kb fragment flanked by RM1134 and Ui159, respectively. Taken together, this work conducts a comprehensive genetic dissection of SD and will provide more selections for breeding elite PHS-resistant rice varieties.

Highlights: (1) Fluid dynamics and CFD were combined to investigate the flow state in the tibia-metatarsus joint. (2) The mechanism of flow inside the leg was analysed. (3) A bio-inspired hydraulic system was devised based on the flow path of haemolymph in the channel obtained from simulations.

Nature has always inspired human achievements in industry, and biomimetics is increasingly being applied in fluid power technology. Arachnida use hydraulic forces, rather than muscle, for leg extensions during locomotion. Many cold-blooded and soft-bodied organisms rely on a hydrostatic skeleton to transmit force, which involves a hydraulic mechanism. Biological hydraulic transmission differs from engineering hydraulic transmission in many aspects, such as in energy transfer and transformation, the movement mode, environmental friendliness, system pressure level, and energy supplement mode. The existence of a hydraulic mechanism in a biological drive requires 3 features: a power source, cavity, and working medium. The power source is similar to a hydraulic pump, and the cavity is similar to a hydraulic cylinder, both of which are necessary for producing deformation. The working medium is similar to a hydraulic fluid. Under these 3 conditions, a biological flow is generated inside or outside the body to meet the needs of a biological drive. This paper reviews the biological organisms that employ hydraulic systems, identifies related studies on these biological hydraulic systems, and summarizes the mechanisms involved in using hydraulic pressure to achieve graceful and agile movements. This in-depth study and exploration of biological hydraulic systems can provide a good reference for solving the challenges of using hydraulic systems, such as increasing the energy efficiency, improving reliability, building smart components and systems, reducing the size and weight of components, reducing the environmental impact of systems, and improving and applying energy storage and redeployment capabilities. This paper also includes a detailed discussion of new ideas and innovative sources for the future development of hydraulic systems. In contrast with the bio-inspired designs used in other engineering fields, very few studies have reported on using bio-inspired methods for hydraulic transmission techniques. The aim of this work is to attract the attention of researchers to help address this gap and to promote the use of biologically-inspired methods to improve engineering fluid power systems.