辽西城子山遗址夏家店下层文化期农业活动特征及环境效应

以辽西城子山文化遗存剖面为研究对象，运用花粉、炭屑、炭化种子和果壳等指标，重建城子山地区夏家店下层文化期农业活动特征及环境效应。研究显示城子山原生植被主要为松属针叶林，先民采用“刀耕火种”农业模式毁林开荒，导致原生植被消失以及次生榛属灌丛和杂草增加。城子山剖面中禾本科花粉含量峰值与炭屑浓度峰值相对应，表明先民高强度或频度用火主要与农业活动有关。长期耕作活动造成土壤肥力下降，先民弃耕是后期农业活动衰弱的主要原因。城子山剖面记录的夏家店下层文化期农业活动可能经历了毁林开荒期、定居耕作期、弃耕期和原生植被恢复期４个阶段

Jumping Design and Dynamics Analysis on a Hopping Frog Robot

当前,弹跳机器人有着广泛的应用前景,提高其弹跳性能是一个值得探讨的课题。设计并分析了一种仿青蛙跳跃的弹跳腿。将其简化为双质量弹簧模型,得出了其跳起的必要条件及在空中运动状态的动力学方程。仿真结果表明,该弹跳腿的设计是可行的。Now,hopping robot will be used more and more and how to improve its capability of jumping is a valuable research.In virtue of analyzing frog's jumping,this paper designs a hopping leg,then abstracts the leg and find a system model composed by two mass bodies and a spring,finds the qualification and the equation of jumping.The result shows that the designed leg is feasible

Jumping Machine Design and Dynamics Analysis of Hopping Robots

为了阐明弹跳机器人弹跳运动,包括弹跳的必要条件、弹跳高度等,基于仿生学原理、通过模仿青蛙的跳跃,本文设计并制作了一种结构简单、新颖的弹跳机构.通过将其简化成双质量弹簧模型,得出其能实现跳跃时弹簧所需储存的最小能量.在此基础上进一步推导出双质量弹簧系统在空中阶段质心和底座重心运动的规律.仿真结果表明,弹跳腿所能储存的能量超过其跳起的必要条件,从而进一步说明该设计是可行的.In order to describe the robot′s jump movement,including the necessary jumping conditions and the height of jump,this article describes a design of a hopping machine based on the principles of bionics which can jump like a frog.Its structure is simple and novel.By the geminate mass spring model from the hopping machine,the least energy for the hopping machine to jump can be calculated.Based on this result,the moving rules of the model′s jump in sky are acquired,such as the rules of centroids of the geminate mass spring model and its pedestal.The result of emulational experiment illustrates that the energy contained by the hopping legs surpasses the necessary needed,so this means the design is feasible

MIS 3阶段以来沙漠/黄土过渡区植被演替及其对气候变化的响应

选择沙漠／黄土过渡带姬塬、和林格尔两个地点的黄土－古土壤剖面开展较高分辨率花粉记录研究，重建ＭＩＳ３以来植被演替及其对气候变化的响应。黄土高原北部ＭＩＳ３阶段以来植被经历了４个主要阶段：ＭＩＳ３阶段早－中期气候较温湿，植被为疏林草原类型；ＭＩＳ３晚期－末次盛冰期为荒漠草原植被类型；末次冰消期为干草原植被类型；全新世高温期为草甸草原植被类型。沙漠／黄土过渡区ＭＩＳ３阶段以来植被演替显示，增温阶段和高温期有助于草原植被发育和植被盖度的增加，同时，全新世高温期有利于植物多样性增加