Structural bionic design for high-speed machine tool working table based on distribution rules of leaf veins

High-speed machine tool working table restrains the machining accuracy and machining efficiency,so lightweight design of the table is an important issue.In nature,leaf has developed a plate structure that maximizes the surface-to-volume ratio.It can be seen as a plate structure stiffened by veins.Compared with a high-speed machine tool working table,leaf veins play a role of supporting part which is similar to that of stiffening ribs,and they can provide some new design ideas for lightweight design of the table.In this paper,distribution rules of leaf veins were investigated,and a structural bionic design for the table was achieved based on regulation of leaf veins.First,statistical analysis on geometric structure of leaf veins was carried out,and four distribution rules were obtained.Then,relevant mechanical models were developed and analyzed in finite element software.Based on the results from mechanical analysis on those relevant models,the four distribution rules were translated into the design rules and a structural bionic design for the working table was achieved.Both simulation and experimental verifications were carried out,and results showed that the average displacement of the working table was reduced by about 33.9%.

Persistent and advanced reddening of sweetgum leaves after major veins severing

The effects of major veins severing on morphological and physiological features of sweetgum （Liquidambar styraciflua L.） leaves were investigated by observing leaf color change and measuring leaf temperature, green/luminance （G/L） value of half-lobes, leaf stomata conductance, and water content in Yamaguchi University, Japan. The palmately veined leaves of sweetgum （Liquidambar styraciflua L.） were found more sensitive to the major vein severing than that of other species Major veins severing resulted in serious water stresses, as indicated by the persistent reddening and/or advanced reddening of local leaf, lower leaf stomatal conductance, and higher leaf temperature, etc. Severed leaf can be clearly divided into non-severed area, transitional area, and stressed area, which the three areas have different colours and temperature. The major vein barrier can also be seen clearly. The persistent reddening and advanced reddening seem consistent with the phenomenon of red crown top of some sweetgum trees and may have similar mechanism.

Analysis of the Hydraulic Performances of a New Liquid Emitter Based on a Leaf Vein Concept

The leaf-vein drip irrigation emitter is a new type of drip emitter based on a bionic structure able to support shunting,sharp turns,and increased dissipation.In the present work,the results of twenty-five tests executed in the framework of an orthogonal design strategy are presented in order to clarify the influence of the geometrical parameters of the flow channel on the hydraulic characteristics of such emitter.The corresponding flow index and head loss coefficient are determined through numerical simulations and model testing.The results show that the flow index of the flow channel is 0.4970∼0.5461,which corresponds to good hydraulic performances.The head loss coefficient of the flow channel is 572.74∼3933.05,which in turn indicates a good energy dissipation effect.The order of influence of the leaf vein flow channel parameters on the flow index can be represented in a synthetic way as a>b>c>d>e,where(a)is the width of the inlet,(b)is the horizontal distance of the front water inlet,(c)is the vertical distance of the inner edge of the front end,(d)is the horizontal distance of the rear water outlet and(e)is the vertical distance of the outer edge of the front end.The flow index increases with d,decreases with a,first decreases,and then increases with b,and first increases and then decreases with the increase of c and e.The coefficient(R^(2))of the fitted model related to geometric parameters and flow index is 0.9986-0.9999.The relative errors among experimental testing,simulation calculation and predictive estimates are shown to be less than 5%.

Leaf Vein Variations and Gene Control Mode of Cyclamen Hederifolium

In order to explore the heredity of leaf veins of Cyclamen Hederifolium and to breed excellent varieties, selling measurement for six types of different leaf veins were carried out and the genetie constitutions of leaf veins were studied according to the separation conditions of their progenies. The results showed that the inbred progenies of B or M types were B or M types with a percentage of 100% while the progenies of F, H, X and L types had character segregations. The separa- tion law illustrated that leaf veins of Cyclamen Hederifolium were eontrolled by minor multiple genes and each locus was consisted of a pair of alleles, RL of Rn. RL was responsible for the green phenotype of leaves and RB was responsible for the silvery white phenotype of leaves, leaves were deep green when the genotype of the locus was RLRL ; leaves were green when the genotype was RLRB ; leaves were silvery white when the genotype was RBRB. The aggregafive pattern of each locus formed different leaf vein types. The gene control modes of leaf vein variations were the basis for the breeding of excellent varieties of Cyclamen Hederifolium.

Biomimic Vein-Like Transparent Conducting Electrodes with Low Sheet Resistance and Metal Consumption

In this contribution,inspired by the excellent resource management and material transport function of leaf veins,the electrical transport function of metallized leaf veins is mimicked from the material transport function of the vein networks.By electroless copper plating on real leaf vein networks with copper thickness of only several hundred nanometre up to several micrometre,certain leaf veins can be converted to transparent conductive electrodes with an ultralow sheet resistance 100 times lower than that of state-of-the-art indium tin oxide thin films,combined with a broadband optical transmission of above 80%in the UV–VIS–IR range.Additionally,the resource efficiency of the vein-like electrode is characterized by the small amount of material needed to build up the networks and the low copper consumption during metallization.In particular,the high current density transport capability of the electrode of>6000 A cm^−2 was demonstrated.These superior properties of the vein-like structures inspire the design of high-performance transparent conductive electrodes without using critical materials and may significantly reduce the Ag consumption down to<10%of the current level for mass production of solar cells and will contribute greatly to the electrode for high power density concentrator solar cells,high power density Li-ion batteries,and supercapacitors.

Plant vs. Animal Prototype for Designing Bio-inspired PEMFC Flow Fields: Corn Veins or Murray’s Law?

Designing bio-inspired flow fields holds great potential in improving the performance of Proton Exchange Membrane Fuel Cell(PEMFC).Two kinds of biological prototypes are widely used:plant prototype and animal prototype.It remains a question which one of these prototypes is more appropriate for the scenario of PEMFC.Here,a comparative study was conducted to compare bionic flow fields based on animal and plant prototypes.First,a Corn Leaf Vein Mathematical Model(CLMM)was established by extracting structural parameters from corn leaves of two growth stages.Then the obtained CLMM and well-known Murray’s law were employed to design bionic flow fields corresponding to the plant and animal prototypes,respectively,which have been subsequently compared by numerical investigations.The results demonstrate that the flow field guided by Murray’s law outperforms the counterpart based on the structural parameters of CLMM in terms of PEMFC net output power,mass transport,water management and pressure drop,suggesting that animal circulation system is more suitable to the bionic flow field design of PEMFC than plant leaf veins.The work may also offer valuable insights into the design of other flow fields related to electrochemical energy conversion.

Polarity, Continuity, and Alignment in Plant Vascular Strands

Plant vascular cells are joined end to end along uninterrupted lines to connect shoot organs with roots;vascular strands are thus polar, continuous, and internally aligned. What controls the formation of vascular strands with these properties？ The “auxin canalization hypothesis”-based on positive feedback between auxin flow through a cell and the cell’s capacity for auxin transport-predicts the selection of continuous files of cells that transport auxin polarly, thus accounting for the polarity and continuity of vascular strands. By contrast, polar, continuous auxin transport-though required-is insufficient to promote internal alignment of vascular strands, implicating additional factors. The auxin canalization hypothesis was derived from the response of mature tissue to auxin application but is consistent with molecular and cellular events in embryo axis formation and shoot organ development. Objections to the hypothesis have been raised based on vascular organizations in callus tissue and shoot organs but seem unsupported by available evidence. Other objections call instead for further research; yet the inductive and orienting influence of auxin on continuous vascular differentiation remains unique.