基于二分法迭代的频谱感知节能优化策略

针对认知无线电(CR)系统中频谱感知技术能量效率低的问题,提出了一种基于二分法迭代寻优的联合优化算法。该算法通过联合传输功率与感知时隙进行优化,最大化地提高了CR系统的能量效率,并且在针对优化参数ξ的寻优过程中,使用了二分法与迭代算法结合的寻优方法。通过理论分析,与其他类似算法相比,该算法的寻优速度更快,算法复杂度更低,函数收敛速度更快,实际应用的可扩展性更强。数值仿真分析结果表明,在保证检测性能的前提下,提出的算法能够很好地解决能效的最优化问题,在恒定检测概率Pd=0.9和Pd=0.7条件下,所提出算法的能耗开销均低于其他算法,在系统吞吐量中所提出算法均优于其他算法,为CR系统的发展提供了理论支撑,更加符合未来CR系统的节能发展方向。     

Multiple paths to aquatic specialisation in four species of Central American Anolis lizards

Aquatic anoles present an interesting ecomorphological puzzle. On the one hand, the link between habitat use and morphology is well established as convergent within the Caribbean anole radiation. On the other hand, aquatic anoles do not appear to form an ecomorphological group – rather, it appears that there may be several ways to adapt to aquatic habitats. We explore this issue by examining the ecology, morphology and performance of four species of Central American aquatic anoles belonging to two different lineages. Overall, we find that aquatic anoles overlap in multiple ecological and morphological dimensions. However, we do find some differences in substrate use, claw and limb morphology, and bite force that distinguish Anolis aquaticus from the other three species (A. lionotus, A. oxylophus and A. poecilopus). Our results suggest that A. aquaticus is adapted to climb on boulders, whereas the other species utilise vegetation in streamside habitats.     

生态环境哲学:哲学当代创新之域

生态环境哲学缘起于人类对自身当代生存状况与未来命运的忧虑和关注，人类生命中自然意识的觉醒以及人类文明范式的当代转型的科学基础与文化背景中。对于人与自然生态系统及人与自然生态系统中生物、非生物的关系思考和研究，生态环境哲学可在吸收与转换现代生态科学与环境科学的知识与原理的基础上而进行哲学当代创新。这种创新意味着哲学范式的一种根本性转变。     

Late Pleistocene glaciation of the Changbai Mountains in northeastern China

The Changbai Mountains （2749 m a.s.l.） in northeastern China are one of the typical mountain regions with glaciation since late Pleistocene as evidenced by well-preserved erosive and accumulative landforms at elevations above 2000 m a.s.l, formed by glaciers around the crater lake, Tianchi Lake. Cirque glaciers developed on both the inner and outer sides of the volcanic cone. Well-preserved cirques, glacial trough valleys, glacial threholds, polished surfaces of the glacial erratics and the moraine ridges indicate that several glaciation processes took place during the last glacial period in this region. Resuits of optically stimulated luminescence （OSL） dating on the moraine sediments, and the K/Ar, thermal ionization mass spectrometry （TIMS）, electronic spinning resonance （ESR） dating on the volcanic rocks suggest two periods of glacier advances. One is named the Black Wind Mouth glacier advance taking place on the west and north slopes of the volcanic cone at an elevation of 2000-2100 m a.s.l., which is dated to about 20 ka, being the result of the Last Glacial Maximum （LGM）. The other is named the Meteorological Station glacier advance at the elevation of 2400-2600 m a.s.l., dated to 11 ka during the late glacial period, and is tentatively correlated to the Younger Dryas stage. The scope of the former glacier advance is larger than that of the latter. Regional comparisons showed that the glacial sequences in the Changbai Mountains are similar to other glaciated areas in eastern Asia during the later part of the last glacial cycle.     

朝鲜崖柏生境及高生长规律分析

采用标准地调查法测定朝鲜崖柏的土壤特征、林下植被和高生长规律.结果表明:朝鲜崖柏生长于土层较薄且呈弱酸性的山地暗棕壤,不同标准地林下植被差异明显;不同标准地朝鲜崖柏树高的年生长量均呈逐年下降趋势.     

高校参与上海市14项重点工业项目会战的现状分析及完善措施的研究（续）

高校参与上海市１４项重点工业项目会战的现状分析及完善措施的研究（续）穆义生，孟宝棣，邵传芳，陶爱珠（高教研究所）３面临的几个问题在上海市１４项攻关会战中，高校科技人员发挥了聪明才智与拼搏精神，取得了令人瞩目的成果．但是由于种种原因，在攻关过程中还存在...     

稀土元素对粉末渗硼渗层深度的影响

本文研究了不同稀土含量对粉末渗硼层深的影响。试验结果表明,粉末渗硼剂中加入稀土元素均有催渗作用,并存在一个起明显催渗作用的最佳值。本章分析了稀土含量对渗硼过程动力学及表层硬度的影响,对稀土催渗机理进行了探讨。     

外沿生产函数的DEA估计新方法

本文提出了一种更符合生产函数定义的Ｃ－Ｄ生产函数的ＤＥＡ估计方法，利用这种方法估计出的生产函数是由各决策周期内不同投入组分所带来的最大产出点构成的，同时，本文给出实际生产过程向外沿生产过程转化的方向和程度。     

高师地理学科教学改革若干问题的思考

文章论述了近年来由于高考制度改革 ,高师地理学科部分新增专业 (土地、环境、旅游及GIS等 )给高师院校地理系带来了新的生存空间 ,指出由于人才、技术和师资队伍建设等因素制约产生的一些问题 ,并对此进行了分析和讨论 ,并提出推行政府主导战略 ,扶持新专业 ,采用科研与教学相结合等若干对策和建议 .