Prevalent irregular rainfall, flooding for weed control, and unleveled fields in the middle and lower reaches of the Yangtze River all contribute to flooding stress on germination and growth of direct-seeded rice (Oryza sativa L.). Herein, some experiments were conducted so as to assess the effects of seed priming with selenium (Se) on the germination and growth of rice under hypoxia. The experiment was arranged in a completely randomized factorial design with two factors and five replicates. Factors included Se concentration (0, 30, and 60 μmol/L) and duration of flooding stress (0, 2, 4, and 8 days). The experimental results showed that Se accelerated seed germination and increased emergence index and final emergence percentage. Additionally, Se increased shoot and root lengths and dry weights, but high Se concentration (60 μmol/L) reduced 18-day-old seedling dry weight under long-term flooding (8 days). Furthermore, Se reduced malondialdehyde content and increased starch hydrolysis efficiency in seeds, superoxide dismutase, peroxidase, catalase, and glutathione peroxidase activities and seedling soluble protein and total chlorophyll contents. Se improved seedling total Se and organic Se contents while increasing total dry weight and yield. Notably, the highest yield was obtained after a 4-day flooding period. Although Se priming favored rice seedling emergence and growth under flooding conditions, Se concentrations equal or above 60 μmol/L increased the risk of seedling death during long-term flooding (≥8 days).

The forming process simulation and springback prediction of an automobile body panel is implemented by using JSTAMP/LS-DYNA. Yoshida-Uemori model is selected to characterize the anisotropic material behavior of sheet metal during forming. Simulation predictions on spingback are compared with experiment measurements along with numerical results from other material models to demonstrate the effectiveness and accuracy of the Yoshida-Uemori model.

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This paper put forward the importance of stress concentration factors (SCF) of positive large eccentricity CHS N-joints under compression in vertical brace although the static behavior of the N-joints has been researched. The four positive large eccentricity CHS N-joints were first tested for the verification and calibration of finite element (FE) models. As eccentricity increased, the experimental results and FE analysis showed that the position of maximum SCF moved from the crown heel point to the saddle point at the chord and vertical brace intersection. At the inclined brace and chord intersection, the position of maximum SCF moved from the saddle point to the crown toe point with the decrease of eccentricity. A set of parametric formulae was proposed to predict the SCFs of positive large eccentricity CHS N-joints based on 256 FE models. For positive large eccentricity CHS N-joints, SCF increased as τ increased. As β and 2γ increased, SCF distribution was complex. SCF linearly increased with the increase of eccentricity to chord diameter ratio (ε) at the chord and vertical brace intersection welding seam. SCF of N-joint around inclined brace and chord intersection increased when the value of θ increased. The assessment of the proposed formulae and CIDECT formulae were based on the database of FE analysis results. Simple method for predicting SCFs of positive large eccentricity CHS N-joints given in CIDECT was unreliable. The new formulae of SCFs were proposed for positive large eccentricity CHS N-joints under axial loading, which were verified to be accurate and reliable.

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