S─闭对称拓扑分子格

本文的目的是在对称拓扑分子格的框架下继续对我们于［１３］中引入的Ｓ─闭性进行讨论。值得注意的是，Ｍ．Ｅｒｎｅ＇于［１］中提出的所谓“翻译ｈ”在对称格的情形是寸步难移的。

Variations in wood tratis in micro and macro propagated plantation woods of Populus deltoides Bartr. ex Marsh

The paper presents a comparison between intra-ramet, intra-clonal and inter-clonal variations in girth at breast height (gbh), fiber length, fiber diameter, wall thickness, vessel element length, vessel element diameter and specific gravity in the ramets of L34, G3 and S7C15 clones of Populus deltoides at the age of 6 years old produced from planting material grown by macro- and micro-propagation techniques. Variance ratio (F) test indicated that intra-ramet variations were non-significant for all the characters except specific gravity for height in L34 for macro and specific gravity and vessel element diameter for radial locations for micro, and fiber length for G3 (micro) for height, and specific gravity for radial location and fiber length for height for S7C15 clone for both the techniques. The clone L34 showed the significantly higher girth followed by G3 and S7C15. The variations were significant for girth, vessel element length and specific gravity between the wood produced from planting stocks grown by two techniques. Intra-clonal variations were significant for fiber length, fiber diameter and vessel element length. In general wood element’s dimensions and specific gravity increased from bottom to top and pith to periphery radial locations. G3 clone was different from the L34 and S7C15 clone for the wood traits. The three different clones of Populus deltoides showed variability in wood anatomical properties and specific gravity in the woods grown from macro- and micro-propagated planting stock. So, the plantation raised by two techniques could not produce similar type of wood even from the same clone. G3 clone was the exception as it did not show variation in wood traits for two techniques. Intra-clonal variations in all the three clones of P. deltoides indicated that wood traits were not stable within the population of same clone grown by either method.

基于ANSYS卧式容器支座布置优化

文章针对卧式容器支座定位尺寸A进行了研究。采用有限元方法,计算了不同A值下,双支座支撑的卧式容器各考察截面的轴向应力、切向剪应力和周向应力,并根据计算结果分析了各应力随A值变化趋势,进而总结出在指定范围内调整A值以减小应力值的方法,为卧式容器的支座定位提供了参考依据。

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.

深水动力定位原油转驳船主尺度设计

针对大规模、远距离深海油田原油外输成本高、效率低的问题,通过对现有市场上离岸深水浮式生产储卸油平台FPSO和VLCC油船及穿梭油船应用分析,结合所需新型船舶工作用途、船级社规范要求、总布置要求,利用参考母型船方法,设计出一款将现有常规油船不加改造就能从事深海油田的原油运输作业的全新概念的深水动力定位原油转驳船,充分发挥常规油船数量多、造价低、载重大、运输成本低的优势,实现原油输送装载量大、成本低、作业风险小、适应性强等效果。

UFPP特殊结构应力分析

UFPP是一种结构特殊的夹套容器,由于该设备操作工况所承受的载荷复杂,现有标准计算结果不能准确地反映这些特殊结构的应力。介绍了利用ANSYS软件对这些部位进行应力分析和外压稳定性分析全过程,通过分析计算,明确了不同工况下这些特殊结构部位的应力分布与变形趋势;运用特征值和非线性屈曲分析,得到上端内壳和夹套外压临界压力,为类似产品的设计提供参考借鉴。