赖草属5个种的核型与进化

报道了国产赖草属5 个种的核型, 即大赖草, 2n = 4x = 28= 24m (2SA T ) + 4sm(2SA T) ; 粗穗赖草, 2n= 4x= 28= 22m (2SA T ) + 4sm + 2st (2SA T ) ; 若羌赖草, 2n= 4x= 28=20m (4SA T) + 6sm + 2st (2SA T ) ; 羊草, 2n= 4x= 28= 22m (4SA T ) + 2sm + 4st (4SA T ) ; 窄颖赖草, 2n= 4x= 28= 22m (2SA T) + 4sm (2SA T ) + 2st (2SA T )。同时, 根据Stebbins的核型进化理论和分支系统学的编序赋值方法, 对核型4个重要性状进行了分析, 总结出了5个种的进化指数, 并同外部形态演化分析相印证, 揭示了宏观分类中3个组的系统发育水平。

状态受限的非完整链式系统的实际镇定及其在移动机器人中的应用

本文考虑了状态受限的非完整单链式系统的实际镇定问题.利用链式系统的特殊结构设计了两步控制算法,该方法能够使闭环系统的状态最终收敛到原点的任意小邻域中,且若系统初值小于任意正数(1+ε<,1>)M,那么除了一个收敛到零的状态变量外,其余状态变量在整个实际镇定过程中均小于正数,其中ε<,1>可事先任意小.最后对平面移动机器人进行了仿真,验证了所给方法的有效性.

Methanol steam reforming in a compact plate-fin reformer for fuel-cell systems

A compact plate-fin reformer (PFR) consisting of closely spaced plate-fins, in which endothermic and exothermic reactions take place in alternate chambers, has been studied. In the PFR, which was based on a plate-fin heat exchanger, catalytic combustion of the reforming gas, as a simulation of the fuel cell anode off gas (AOG), supplied the necessary heat for the reforming reaction. One reforming chamber, which was for hydrogen production, was integrated with two vaporization chambers and two combustion chambers to constitute a single unit of PFR. The PFR is very compact, easy to be placed and scaled up. The effect of the ratio of H2O/CH3OH on the performance of the PFR has been investigated, and temperature distributions in different chambers were studied. Besides, the stationary behavior of the PFR was also investigated. Heat transfer of the reformer was enhanced by internal plate-fins as well as by external catalytic combustion, which offer both high methanol conversion ratio and low CO concentration. In addition, the fully integrated reformer exhibited good test stability. Based on the PFR, a scale-up reformer was designed and operated continuously for 1000 h, with high methanol conversion ratio and low CO concentration. (c) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.