14C measurement of forest soils in Dinghushan Biosphere Reserve

Organic carbon in forest soils of Qingyunsi and Wukesong profiles can be divided into fast and slow components. Δ 14C values of these profiles decrease with increasing of depth. The Δ 14C values in 30-40 cm depth interval of Wukesong profile are decreasing sharply until a very low value, showing that a strong geological environment change occurred about 1 560 years ago. The 14C apparent ages of Wukesong profile show that the coniferous and broad-leaf mixed forests around Wukesong profile have been developing since 425 a BP, which is consistent with historical documents. The penetrating depths of "bomb 14C" in Qingyunsi and Wukesong profiles are 10 and 20 cm, respectively.     

一种改进的遗传算法用于二自由度PID调节器设计

提出了一种改进的遗传算法，成功地应用二自由度ＰＩＤ调节器设计，并突破了常规调节器参数的限制（０＜α，β，γ＜１）。仿真结果表明了改进算法的有效性及实用性。