2,274 research outputs found

    Ductile Fracture Simulation of Full-scale Circumferential Cracked Pipes: (II) Stainless Steel

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    AbstractThis paper reports ductile fracture simulation of full-scale circumferentially cracked pipes using finite element (FE) damage analysis. In the structural integrity, without experimental investigations or with few ones, it is not an easy task to properly evaluate the crack initiation and crack propagation of large-scale components with a crack-like defect. Unfortunately, from an economic perspective, performing experiments of large-scale components would be consequently unfavorable. For these reasons, ductile fracture simulation using FE damage analysis to predict crack behavior is one efficient way to replace the test procedures. In order to simulate ductile tearing of large-scale cracked pipes, element-size-dependent critical damage model based on the stress-modified fracture strain model is proposed. To evaluate fracture behavior of full-scale cracked pipes, tensile and C(T) specimens are calibrated by FE analysis technique. Tensile properties and fracture toughness of stainless steel at 288oC are taken from Battelle Pipe Fracture Encyclopedia. After calibrations, simulated results of the full-scale pipes with a circumferential crack are compared with test data to validate the proposed method

    Evaluation of Genetic Stability and Effects of Plant Growth Regulators for in vitro Propagation of Underutilized Vitis amurensis ‘Cheongsan’

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    Vitis amurensis ‘Cheongsan’ is a plant with high economic value in both medical and agricultural applications. However, its utilization has been restricted owing to difficulties encountered when applying traditional mass propagation methods, requiring instead application of in vitro propagation methods for their mass scale production. Hence, this study was conducted to find the optimal plant growth regulators for shoot multiplication and root induction during in vitro propagation. Among the three cytokinins used at multiple concentrations for culture initiation and shoot multiplication, the most positive response was found with MS medium containing 5.0 μM 6-benzyladenine (BA), compared to more modest responses from other types of cytokinin, such as kinetin (KIN) and thidiazuron (TDZ). For root induction, medium supplemented with α-naphthaleneacetic acid (NAA) produced a callus and inhibited shoot growth in explants, whereas indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA) did not create any significant problems, but did display differences in root induction efficiencies. Generally, root induction responses with IBA were better that those with IAA. The maximum rooting rates were observed without callus formation and no shoot growth inhibition from explants grown on media supplemented with 0.67 μM IBA. Further, inter-simple sequence repeat (ISSR) analyses revealed that micropropagated plantlets generated in medium supplemented with 5.0 μM BA and 0.67 μM IBA did not lead to genetic variation. Therefore, the application of the in vitro propagation method developed in this study could be used on a commercial scale and will offer opportunities to strengthen the industrial use of V. amurensis ‘Cheongsan’

    In vitro embryo rescue for the production of hypotetraploids after cross between hypotetraploid and tetraploid grape cultivars

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    Consumer demand for seedless grape with high quality and large berry has been increasing. Breeding of hypotetraploid grape was suggested as one of promising methods to satisfy it, but low frequency of hypotetraploid occurrence and low seed germination by abortive embryo were indicated as the major problem to hamper the development of hypotetraploid grape. Hence, this study was carried out to evaluate the basic efficiency of in ovulo embryo culture after the cross between hypotetraploid (‘Hanareum’) and tetraploid (‘Honey Black’ and ‘Kyoho’) grape cultivars on the establishment of hypotetraploid grapes. Embryos and plantlets were hardly obtained in ovules cultured at six after the cross pollination (WAP), but ovules inoculated at 10 WAP produced more embryos as well as plantlets regardless of cross combination. Furthermore, we found that embryo formation was not affected by the basal media in ovules cultured at six WAP, but utilization of specific medium can be more beneficial for embryo formation when ovules were cultured at 10 WAP. A total of 17 plants were obtained from ovules cultured at 10 WAP, and above 50% of plants were identified as hypotetraploid grapes. These results indicate that in vitro embryo rescue after cross pollination between hypotetraploid and tetraploid grape can enhance the efficiency for the breeding of hypotetraploid grapes

    Development of Pd Alloy Hydrogen Separation Membranes with Dense/Porous Hybrid Structure for High Hydrogen Perm-Selectivity

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    For the commercial applications of hydrogen separation membranes, both high hydrogen selectivity and permeability (i.e., perm-selectivity) are required. However, it has been difficult to fabricate thin, dense Pd alloy composite membranes on porous metal support that have a pore-free surface and an open structure at the interface between the Pd alloy films and the metal support in order to obtain the required properties simultaneously. In this study, we fabricated Pd alloy hydrogen separation membranes with dense/porous hybrid structure for high hydrogen perm-selectivity. The hydrogen selectivity of this membrane increased owing to the dense and pore-free microstructure of the membrane surface. The hydrogen permeation flux also was remarkably improved by the formation of an open microstructure with numerous open voids at the interface and by an effective reduction in the membrane thickness as a result of the porous structure formed within the Pd alloy films
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