Ecological distribution and reproductive period of the hermit crab Loxopagurus loxochelis (Anomura,Diogenidae) on the northern coast of São Paulo State,Brazil

The present study aimed to determine the ecological distribution of Loxopagurus loxochelis as a function of selected environmental factors, as well as its reproductive period based on the combined analysis of the presence of ovigerous females and the development of the gonad. The collections were carried out monthly from January to December 2000 in the region of Ubatuba (SP), using a fishing boat equipped with two double rig nets, in isobaths of 5, 10, 15, 20, 25, 30, 35 and 40?m, at which depths samples of sediment and water were collected. The cephalothoracic shield length and sex of the animals were determined; the abdomen was dissected to verify gonad development stages. A total of 334 individuals was obtained (196 males, 48 ovigerous females and 90 non-ovigerous females) with sizes varying from 3.0 to 8.6?mm (5.7±1.0?mm). A greater abundance of L. loxochelis (95.2%) was observed at depths of 20 and 25?m. These sites mainly revealed a substratum stable with a very fine sand fraction, which facilitates the habit of embedding shown by this hermit. With regard to gonadal analysis, it was possible to classify four gonad development stages for each sex: immature, rudimentary, developing and developed. It was observed that in the winter months about 71% of the females had gonads either developing or developed and 67% were ovigerous. Therefore, the winter period can be considered the peak of reproduction for this species, characterizing a typical seasonal-continuous reproduction.     

概率多项式及其应用

本引入概率多项式的概念，利用组合数学计数理论中“贡献法原理”给出概率空间任一事件的概率由若干事件交的概率表达公式。     

Weibull分布可靠性指标区间估计的两种新方法

文本利用刀切U—统计量极限分布的定理,提出了两种对于双参数Weibull分布的参数和各种可靠性指标进行点估计和区间估计的新方法。     

地区配电网络路径选择的一种方法

地区网络按最小费用原则通常以带权图来描述。文章针对这些图分别用Ｋｒｕｓｋａｌ算法，Ｄｉｊｋｓｔｒａ算法及Ｆｏｒｄ＆Ｆｕｌｋｓｏｎ算法进行了优化设计。结果表明，Ｋｒｕｓｋａｌ算法偏重于网络的整体结构布局，而Ｄｉｊｋｓｔｒａ及Ｆｏｒｄ＆Ｆｕｌｋｓｏｎ算法更适合于单电源分支线路的优化路径选择。     

基于Flexsim的配送中心仿真建模研究

本文首先对物流仿真软件Flexsim介绍进行了简要的概述,然后介绍了Flexsim的运作流程,最后利用Flexsim对一个简单的配送中心进行了仿真,通过仿真结果可知Flexsim对提高物流配送中心的效率,降低成本具有积极的作用。     

有限元概率算法

本文提出了一种求解椭圆型有限元方程的新方法——有限元概率算法,应用这种方法可以在不分解总刚矩阵的情况下,求出一个或少数几个网格点上的函数值。     

神经网络理论研究的一些进展

本文阐述了最近几年神经网络理论的进展情况,给出了一些主要的理论模型,并指出了存在的一些问題以及可能解决的途径。     

模q原根中LehmerDH数的一种分布

设奇数ｑ≥３存在原根，本文利用Ｋｌｏｏｓｔｅｒｍａｎ和估计研究了模ｑ原根中ＬｅｈｍｒＤＨ数的一种分布性质，并给出了珍肯趣的分布式公。。     

概率统计的发现法教学

对概率统计教学中如何运用联想类比法、归纳法、对称法和几何直观法等发现法，使学生自己发现新公式、新定理进行了探讨．     

框架分析方法选择—─兼谈结构分析课程内容的优化

通过对框架分析的各种手算和电算方法的综合分析和比较，根据手算和电算对分析方法的不同要求提出选择计算方法的的原则和方案。同时对土木工程各专业的结构分析课程提出一些内容更新和优化的建议。