1,721,106 research outputs found
Inverse Method in Sheet Metal Forming for Auto-body Design
No full textThis paper is concerned with inverse analysis in sheet metal forming for auto-body design that includes the feasibility of forming of sheet metal parts and the crashworthiness assessment of formed parts as auto-body structures. The inverse analysis is an efficient and convenient method to evaluate the plastic strain distribution in formed sheet metal parts without preparation of tooling prior to process design as well as the crashworthiness of formed parts considering the fabrication history. The method also provides information on the optimum process parameters for sheet metal forming and remedy for forming of complicated and infeasible sheet metal parts.
The inverse method incorporates with the plastic deformation theory, minimization of plastic work with constraints, and a pertinent initial guess in order to obtain the plastic strain distribution and the initial blank shape from a desired final shape. The method needs to deal with the corresponding sliding constraint surfaces for minimization iteration and the convergence among intermediate shapes for multi-stage forming processes. Although the present method requires many numerical schemes mentioned above, it needs only short computing time for the sake of its inherence.
The numerical example demonstrates the versatility and efficiency of the present method. One of them is a multi-stage deep-drawing process of a rectangular cup with the large aspect ratio, which is hardly realized without the aid of the present method. Another is the prediction of the plastic strain distribution in formed sheet metal members of which an auto-body structure consists. With the strain distribution predicted, the crashworthiness assessment of auto-body structures can be carried out accurately at the initial stage of auto-body design
Application of multiplex PCR using species specific primers within the 16S rRNA gene for rapid identification of Nocardioides strains
No full textFor the rapid identification of Nocardioides strains, multiplex PCR, using 16S rDNA as target gene, was used and its value was evaluated. Forward primers specific for Nocardioides albus, Nocardioides jensenii, Nocardioides plantarum and Nocardioides simplex, among the five validly described Nocardioides species, were designed from the alignment of 16S rDNA sequences. Nocardioides luteus has been shown to be a member of the same species as N. albus by recent molecular systematic studies and preliminary DNA-DNA relatedness tests, Therefore, Ri. albus and N. luteus were considered as members of the same species in this study. Each primer was found to be species-specific by specificity testing. N. albus NSP01(T), Ri. jensenii NSP19(T), Ri. plantarum NSP21(T) and Ri. simplex NSP22(T) could be clearly differentiated by PCR products characteristic for each species in the multiplex PCR assay. N. luteus gave an identical result to Ri. albus NSP01(T). The additional 17 strains of Ri. albus and the additional four strains of RI. simplex gave PCR products identical to those of N. albus NSP01(T) and N. simplex NSP22(T), respectively. Multiplex PCR was found to be rapid, species-specific and reproducible. The technique evaluated in this study proved to be effective for rapidly identifying Nocardioides strains to species level
Inter- and intraspecific phylogenetic analysis of the genus Nocardioides and related taxa based on 16S rDNA sequences
No full textThe 16S rDNAs from 38 strains of the genus Nocardioides, two Aeromicrobium species and Terrabacter tumescens were directly sequenced and then analysed, The mean nucleotide similarity value between the type strains of validly described Nocardioides species was 96.1+/-3.0%. The mean nucleotide similarity value between the type strains of validly described Nocardioides species and the two Aeromicrobium species was 93.7+/-1.4%. T. tumescens was distantly related to the genera Nocardioides and Aeromicrobium. The mean intraspecific nucleotide similarity value of 16S rDNA sequences from Nocardioides albus was 99.5+/-0.5%. The mean intraspecific nucleotide similarity of 16S rDNA sequences from Nocardioides simplex was 100%, except for N. simplex strains ATCC 13260, ATCC 19565 and ATCC 19566, which were shown not to be members of the genus Nocardioides. 'Nocardioides flavus' strains IFO 14396(T) and IFO 14397, and 'Nocardioides fulvus' JCM 3335(T) showed a 16S rDNA similarity value of 100% with Nocardioides luteus KCTC 9575(T) and Nocardioides albus JCM 5854. 'N. fulvus' IFO 14399 shared its highest 16S rDNA similarity with Nocardioides sp, ATCC 39419 at 99%, 'N. fulvus' IFO 14399 and Nocardioides sp, ATCC 39419 formed a phylogenetic lineage distinct from the genera Nocardioides and Aeromicrobium, 'Nocardioides thermolilacinus' strains IFO 14335(T) and IFO 14336 displayed a close relationship to the genus Streptomyces. From 16S rDNA sequence analyses, it is considered that some strains that have been attributed to the genus Nocardioides should be taxonomically re-evaluated
Finite element analysis of polycrystalline deformation with the rate-dependent crystal plasticity
No full textConstitutive models for the crystal plasticity have the common objective which relates the behavior of microscopic single crystals in the crystallographic texture to the macroscopic continuum response. This paper presents the texture analysis of polycrystalline materials using the rate-dependent single crystal plasticity to develop a multi-scale description of the mechanism at the grain and aggregate levels. The texture analysis requires a numerical algorithm for integrating the constitutive equations. The implicit deformation gradient approach is employed to update the stresses and texture orientations as an integration algorithm. It considers elastic or plastic deformation gradient as the primary unknown variables and constructs the residual of the elastic and plastic velocity gradients as the governing equations. This algorithm is shown to be an efficient and robust algorithm in rather large time steps. The texture analysis of the asymmetric rolling process is also presented to show investigation of the effect of texture evolution based on the finite element analysis as a numerical example. The analysis result for texture evolution is investigated by comparing the pole figure before and after the asymmetric rolling process
Genetic analyses of the genus Nocardioides and related taxa based on 16S-23S rDNA internally transcribed spacer sequences
No full textThe 16S-23S internally transcribed spacer (ITS) sequences were analysed to clarify inter- and intraspecific relationships among strains of the genus Nocardioides and the relationship between two Aeromicrobium species. The 16S-23S ITS regions from 33 Nocardioides strains, two Aeromicrobium species and Terrabacter tumescens were sequenced directly after polymerase chain reaction (PCR) amplification and lambda exonuclease treatment. The genomes of some Nocardioides strains included two types of 16S-23S ITS sequences. The sizes of the 16S-23S ITS sequences of Nocardioides strains ranged from 328 to 539 bp, The 16S-23S ITS sequences of Aeromicrobium erythreum NSP37(T), Aeromicrobium fastidiosum NSP38(T) and T. tumescens NSP39(T) were 349, 355 and 386 bp long, respectively. Nucleotide similarity among 16S-23S ITS sequences of Nocardioides albus strains and of Nocardioides simplex strains was 84.1-100% and 97.7-100%, respectively. The 16S-23S ITS sequence of Nocardioides luteus was identical to that of 'Nocardioides fulvus' NSP32(T) and was only 1 bp different from that of 'Nocardioides flavus' strains. However, the 16S-23S ITS sequences of 'N. fulvus' NSP33 showed only a low degree of similarity to 'N. fulvus' NSP32(T) (54.8%). The degree of 16S-23S ITS similarity between N. luteus NSP20(T) and N. albus strains ranged from 85 to 93%. The mean nucleotide similarity values between the type strains of validly described Nocardioides species were highly divergent at 68.1 +/- 16.8%. The two Aeromicrobium species showed a level of 16S-23S ITS similarity of 71.2%. In this study, 16S-23S ITS sequences of the members of the genera Nocardioides and Aeromicrobium were useful for inferring the relationships between closely related strains and species. However, they were not found to be appropriate for elucidating the phylogenetic relationships between distantly related organisms at the genus level
Rigid-Plastic Finite Element Analysis of Aluminum Extrusion Processes based on Rate-Independent Crystal Plasticity
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Simultaneous degradation of p-nitrophenol and phenol by a newly isolated Nocardioides sp.
No full textA p-nitrophenol (PNP)- and phenol-mineralizing bacterium (strain NSP41) was isolated from an industrial wastewater and identified as a member of the genus Nocardioides, PNP was degraded via a hydroquinone pathway, and phenol was degraded through a catechol pathway in strain NSP41, Both enzyme systems for the degradation of PNP and phenol were induced simultaneously in the presence of both compounds. Although both enzyme systems were induced at the same time, PNP and phenol were degraded by the hydroquinone and catechol pathway, respectively. However, during the simultaneous degradation in the low phenol concentration, after the exhaustion of phenol, some PNP was transformed by the catechol pathway and 4-nitrocatechol was transiently accumulated. Kinetically, the addition of phenol greatly enhanced the apparent PNP degradation rate, which may be due to the increased cell mass by the assimilation of phenol
DNA-DNA relatedness between Saccharomonospora species: Saccharomonospora caesia' as a synonym of Saccharomonospora azurea
No full textSaccharomonospora species were subjected to DNA-DNA relatedness determination to investigate their genetic relationships based on genomic DNA, The levels of DNA-DNA relatedness among the type strains of the four validly described Saccharomonospora species ranged from 18 to 46%. Saccharomonospora viridis KCTC 9156, which was described as 'Saccharomonospora internatus' but later reclassified as a member of S. viridis, showed a similarity level of 90% to S. viridis KCTC 9115(T). Saccharomonospora sp, strain K180 exhibited levels of DNA-DNA relatedness that are indicative of a new species. Saccharomonospora azurea exhibited levels of DNA-DNA homology of 84-95% to 'Saccharomonospora caesia' strains including the type strain. Therefore, on the basis of DNA-DNA relatedness data and taxonomic data described previously, it is proposed that 'S. caesia' should be considered as a synonym of S. azurea
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