Effect of Dimension Parameters on the Torsion Property of A C/SiC Pipe

Through finite element numerical simulation and based on laminated plate theory, the effect of dimension on the torsion properties of uniform C/SiC composites pipe was studied to provide a theoretical guidance for preparing the C/SiC pipe with different dimensions. The results show that, with increasing length of pipe, the anti-torsion section coefficient of pipe increases whereas the torsion angle per unit length decreases. Increasing the length can improve the torsion property. Anti-torsion section coefficient rises with increasing internal radius, while the torsion angle per unit length decreases to a constant. With increasing thickness, the anti-torsion section coefficient increases whereas the amplitude decreases gradually, and the torsion angle per unit length is a constant. Increment of internal radius and thickness improves the torsion property finitely.

An Improved Parameter Dimensionality Reduction Approach Based on a Fast Marching Method for Automatic History Matching

History matching is a critical step in reservoir numerical simulation algorithms.It is typically hindered by difficulties associated with the high-dimensionality of the problem and the gradient calculation approach.Here,a multi-step solving method is proposed by which,first,a Fast marching method(FMM)is used to calculate the pressure propagation time and determine the single-well sensitive area.Second,a mathematical model for history matching is implemented using a Bayesian framework.Third,an effective decomposition strategy is adopted for parameter dimensionality reduction.Finally,a localization matrix is constructed based on the single-well sensitive area data to modify the gradient of the objective function.This method has been verified through a water drive conceptual example and a real field case.The results have shown that the proposed method can generate more accurate gradient information and predictions compared to the traditional analytical gradient methods and other gradient-free algorithms.

Effect of growth on wood traits in seed-raised plantations of Dalbergia sissoo Roxb.

We studied the effect of growth on wood anatomical dimensions and specific gravity of seed-raised plantation wood of Dalbergia sissoo with twelve trees of different diameters and similar ages. Fiber length ranged from 925 to1,287 lm, fiber-diameter was 19–23 lm, wall thickness was4.2–5.4 lm, vessel-element-length was 152–188 lm, vesselelement-diameter was 152–200 lm, and specific gravity was0.59–0.72. Growth parameters including tree height, diameter at breast height, net primary productivity and net ecosystem productivity were significantly and positively correlated.Growth parameters showed non-significant positive relationships with fiber-length, fiber diameter, wall thickness, vessel element length, and vessel element diameter. The trend of wood traits increased with growth. Specific gravity showed non-significant negative relationships with growth parameters. Although the growth rate had varied relationships with wood properties, as reported by various workers, the wood element dimensions showed no significant relationship with growth parameters and there was little effect of growth rate on wood traits in seed-raised plantation of D. sissoo.