Modeling and Analysis of Transitional Tube with Constant Sectional Area along Derivative Central Route

Firstly, sample square-circular transition tube along straight central route was modeled on CATIA software. The parameters are as follows： let the tube length is L, and the constant cross section area is S, and S = πR^2 = a2, in which R stands for the circle radius on one end, and a the square side length on the other end; set up the coordinate system with OX axis on the central route in which the origin O is on centroid of the square end and assume the cross section size at x as the square shaped with all four comers filleted in radius r which is proportional to x, that is, the linear slope of r is R/L, thus, both values r and square side length ax can be attained on the constant cross section area assumption. Secondly, some sample polygonal-circular transition tubes along straight, circular and helical central route were implemented similarly. Thirdly, numerical analysis of stress and displacement of these tubes were carried out on MSC/PATRAN software which are important to the distribution of turbulent flow and the layout of these transitional tube structures.

广东省双线盗毒蛾风险性分析

双线盗毒蛾(Porthesia scintillans)是我国华南地区的重要害虫,主要危害桉树、红椎、山乌桕、大花紫薇等多种植物。广东省气候条件和地理位置适宜其生存,且易于爆发成灾。参照国际通用有害生物分析的方法,从适生分布、传播扩散和定殖可能性、潜在危害性、受害对象重要性、危险性治理难度等5方面对广东省双线盗毒蛾风险性进行了定性、定量分析和综合评估,结果为双线盗毒蛾在广东省的风险综合评估R值为1.31,属于低度危险林业有害生物。该结果对制定科学防治双线盗毒蛾的对策具有指导意义。

动物使用工具行为研究进展

使用工具曾被认为是人类独有的能力,然而,在过去的50年中,学界逐渐认识到工具的使用普遍存在于整个动物界。其中,使用工具最多的类群是哺乳类、鸟类和昆虫。动物使用工具有一定目标性,然而大多数动物仅考虑当前的目标,而非长远目标。动物使用工具的行为受到环境因素和动物自身认知能力、生理特点与进化历史的影响,并可能表现出一定的个体差异。有些动物使用工具的行为是与生俱来的,然而大部分高等动物通过试错学习获得使用工具的能力。通过模仿学习,一些使用工具的行为可以传播和演化,从而在种群中广泛分布。工具的使用是动物认知领域的核心概念之一,开展动物使用工具的研究,能够加深对动物认知能力和行为进化的理解。