Difflugia mulanensis nov spec., a freshwater testate amoeba from Lake Mulan, China

Testate amoebae are an important and abundant component of aquatic ecosystems. Our knowledge of their distribution and the species inventory in Asia is still limited. This paper describes a new planktonic Difflugia from Lake Mulan, province of Hubei, China. These findings are of taxonomic, as well as biogeographic significance because Difflugia mulanensis nov. spec. is a rare and perhaps the only locally distributed member of the well-known urceolate division within this most species-rich genus of lobose testate amoebae. We have studied its morphology and biometry with light and scanning electron microscopical methods. D. mulanensis differs from related species by its very large wide funnel-shaped apertural collar which normally exceeds the width of the test, a relatively long neck, its rounded apical end and the presence of only one nucleus. All shell parameters are normally distributed with low variability. Only the collar height is more variable. This shows that D. mulanensis is a size-monomorphic species. (c) 2005 Elsevier GrnbH. All rights reserved.

Morphology, biometry and distribution of Difflugia biwae Kawamura, 1918 (Protozoa : Rhizopoda)

The freshwater testate amoeba Difflugia biwae Kawamura, 1918, isolated from Mulan Lake, Hubei Province, China is investigated using light microscopy and scanning electron microscopy. The morphology, biometry and distribution of this little known species are supplied. After careful comparison with three other similar species, including D. delicatula Gauthier-Livre et Thomas, D. elegans Penard and D. oblonga caudata Stepanek, we believe that the characteristics of smooth fusiform shell, conspicuous great collar flare (always larger than body-width) around the aperture, constriction behind the aperture and a somewhat curved aboral horn set D. biwae apart from all other Difflugia species. This species shows a great diversity in total length, collar height and aboral horn length which have high variability (CV between 11.76 and 24.52). However, body width, collar diameter, neck width, body length and aperture diameter are fairly constant with low variability (CV between 5.34 and 8.79) which shows a remarkable uniformity of D. biwae. Also, the size frequency distributions of both body width and body length yield bell-shaped (normally distributed) curves and indicate that D. biwae is a size-monomorphic species, characterized by a main-size class and a small size range. D. biwae is probably endemic to East Asia (China and Japan) because it has such a large size (165-306 mu m) that it would have been easily found in Europe and North America, if it were there. Consequently, D. biwae must have a restricted geographical distribution, disproving the old hypothesis that microscopic organisms are cosmopolitan.

Redescription of Difflugia tuberspinifera Hu, Shen, Gu et Gong, 1997 (Protozoa : Rhizopoda : Arcellinida : Difflugiidae) from China

The freshwater testate amoeba Difflugia tuberspinifera Hu et al. 1997 collected from pond and lake in China, is investigated by light and scanning electron microscopy. This little known taxon is redescribed and its morphology, biometry and ecology are supplied. After carefully comparison with other six similar species including Difflugia bartosi Stepanek, D. corona Wallich, D. corona cashi Deflandre, D. corona tuberculata Vucetich, D. muriformis Gauthier-Lievre et Thomas and Netzelia tuberculata (Wallich) Netzal we believe that the sub-spherical to spherical shell, the mulberry-shaped appearance, the 7-10 apertural tooth-like structures, the short collar and the conical spines numbering from 4 to 8 at the upper equatorial region in D. tuberspinifera set it apart from other species. Besides, statistical analysis indicates that D. tuberspinifera is a size-monomorphic species characterized by a main-size class and a small size range and the shell height is significant correlated with other morphometric characters at p < 0.05 excepting the number of aperture tooth-like structures and the number of spines. Moreover, D. tuberspinifera inhabits not only lotic but also lentic environment.

一种可变形移动机器人协同构形变换方法

提出了一种可变形移动机器人AMOEBA-I的协同构形变换方法,建立了机器人系统的数学模型,对各个模块之间的协同变换及运动特性进行了分析.研究了机器人3个模块在协同变换过程中的电流变化情况,实现了3种特殊构形之间的变换.通过理论分析和实验比较了协同构形变换方法的特点,实验验证了在多种地面条件下机器人协同构形变换方法的有效性.

基于网络的自重构机器人重构路径研究

文中针对自重构机器人的重构问题提出了一种基于网络的分析方法.自重构模块机器人"AMOEBA-I"的9种不同构形组成了一个构形网络.机器人的每种构形被看成带有权值的有向构形网络中的一个节点.一种构形向另一种构形的转换可描述为一条非负值的有向路径.将图论应用于构形变化的分析,根据构形的拓扑信息相应定义了重构路径、可重构矩阵和路径矩阵.在此基础上,将图论中的算法应用于重构路径的计数和最佳重构路径的选择.数值分析与仿真实验结果验证了该方法的可行性.同时,该方法还可以用于其他自重构机器人的构形控制与自重构规划.

可变形机器人协同转向运动研究

可变形机器人AMOEBA-I具有多种构形和多种转向方式.为实现机器人转向性能的优化,提出了可变形机器人的协同转向方法,并建立了相应的数学模型,对不同构形下的协同转向方式进行了理论分析.设定了机器人三个模块在协同转向过程中的运动关系,在此基础上给出了可变形机器人协同转向性能的评价指标.通过理论和实验比较了不同构形下的协同转向方式,实验验证了协同转向方法的有效性.

可变形机器人协同越障方法及控制策略研究

在复杂环境中工作的机器人对越障能力的要求越来越高。为了充分发挥可变形机器人AMOEBA-Ⅰ的越障能力,增强机器人在非结构环境中的适应性,提出了可变形机器人的协同越障方法。建立了数学模型,对机器人越障高度与其重心位置的关系进行了理论分析。从理论上比较了常规越障方法与协同越障方法所能翻越障碍的最大高度。同时提出了自主越障过程的控制策略,采用了根据情感状态的变化对机器人控制策略进行微调,并建立了相应地情感模型。实验验证了协同越障方法及自主越障控制策略的有效性。

可变形机器人自适应路径规划研究

可变形机器人AMOEBA-Ⅰ具有多种构形方式,通过构形的改变可以增强机器人在狭窄空间中的通过能力.本文提出了将可变形机器人的变形能力融入到势场法中进行自适应路径规划的方法,以充分发挥可变形机器人特有的通过性能.研究了改进势场法,有效地解决了局部极小问题。引入了可见度概念,研究了减小计算量提高实时性品质指标的方法。通过实验结果证明机器人能够根据环境变化改变自身构形,表现自适应路径规划.同时有效地缩短了路径。

一种可重构模块机器人中心构形的选择方法

可重构模块机器人具有多种构形以适应不同环境和任务的要求,构形的多变增加了构形研究的难度.在可重构模块机器人的众多构形中,中心构形作为可重构模块机器人的首选构形或基准构形,对系统的实际应用有重要参考价值.文中提出了一种在所有构形中选择一个中心构形的方法.根据构形之间可以相互转化的拓扑特征,利用网络图中的基本思想和原理对可重构模块机器人的构形进行建模;相应定义了构形转换耗值矩阵和构形中心因子,根据最大构形中心因子可以对中心构形进行选择.以中国科学院沈阳自动化研究所研制的三模块可重构机器人AMOEBA-I为例,利用仿真计算的结果对机器人9种构形的中心因子进行计算和比较,验证了该方法的可行性.最后根据构形邻接数,给出了中心构形选择方法的应用举例.此方法还可以适用于其他可重构模块机器人系统中心构形的选择.