大型拼接镜面望远镜子镜装卸装置的研究

自从400 yr前伽利略第1次使用望远镜观测天空以来,人类为了探索更深的宇宙,望远镜的口径越做越大,拼接镜面望远镜成为趋势.本世纪初一批大口径拼接望远镜先后被研制出来,这其中包括我国的大天区面积多目标光纤光谱天文望远镜LAMOST.随着望远镜口径增大,子镜单元增多,子镜单元的装卸问题日益突出.本文试图对这一问题进行探讨,设计了一套用于LAMOST球面主镜的子镜单元装卸装置,希望为大口径望远镜的子镜装卸提供一些思路和借鉴.     

LAMOST子镜镀膜研究进展

对大口径光学/红外天文望远镜而言,为保障其稳定高效运行,镜面镀膜是重要的维护环节之一.镀膜质量的好坏直接影响镜面光学反射率的高低,也严重影响到天文望远镜的成像质量、观测效率.国家重大科技基础设施—大天区面积多目标光纤光谱天文望远镜(Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST,又名郭守敬望远镜)自2009年6月通过国家竣工验收并逐步投入巡天观测,目前已进入第2个5 yr巡天计划阶段,取得近两千万的光谱产出和大批高显示度的科学成果. LAMOST共拥有24块施密特改正镜子镜和37块球面主镜子镜,为了确保在野外恶劣观测环境下镜面反射率维持在较高水平,每年要对大批子镜进行镀膜.主要介绍了镀膜需求、镀膜设备,并基于大量实验和多年的完善探索出一套可行的镀膜工艺流程,确保了LAMOST子镜极高的镀膜质量.镀膜后子镜平均反射率高达90%以上,满足了LAMOST光谱巡天的镜面反射率要求.     

单跨框架教学楼橡胶隔震与BRB减震联合加固技术研究

新版抗震设防烈度区划图实施以来,大量单跨框架结构校舍因抗侧力体系不合理以及抗震承载力不足急需加固改造。针对单跨框架结构不满足刚度及承载力要求的现状,提出并阐述了BRB减震与橡胶隔震联合加固技术原理,并对昆明某实际单跨框架结构进行了动力弹性和弹塑性有限元分析,结果表明:在多遇地震下,防屈曲支撑（BRB）未屈服,结构整体处于弹性;在设防地震作用下,部分BRB屈服耗能,结构层间位移角最大值为1/582,结构主体处于弹性阶段;在罕遇地震作用下,所有BRB屈服耗能,且其滞回曲线饱满,结构弹塑性层间位移角最大值为1/148,大部分梁端部产生塑性铰,少数柱产生塑性铰,且梁较柱先出铰,表现出良好的抗震性能。研究为单跨框架结构的加固提供一条有效的新途径。     

What controls early or late onset of tropical North Atlantic hurricane season?

The occurrence of first hurricane in early summer signifies the onset of an active Atlantic hurricane season. The interannual variation of this hurricane onset date is examined for the period 1979-2013. It is found that the onset date has a marked interannual variation. The standard deviation of the interannual variation of the onset day is 17.5 days, with the climatological mean onset happening on July 23.A diagnosis of tropical cyclone (TC) genesis potential index (GPI) indicates that the major difference between an early and a late onset group lies in the maximum potential intensity (MPI). A further diagnosis of the MPI shows that it is primarily controlled by the local SST anomaly (SSTA). Besides the SSTA, vertical shear and mid-tropospheric relative humidity anomalies also contribute significantly to the GPI difference between the early and late onset groups.It is found that the anomalous warm (cold) SST over the tropical Atlantic, while uncorrelated with the Niño3 index, persists from the preceding winter to concurrent summer in the early (late) onset group. The net surface heat flux anomaly always tends to damp the SSTA, which suggests that ocean dynamics may play a role in maintaining the SSTA in the tropical Atlantic. The SSTA pattern with a maximum center in northeastern tropical Atlantic appears responsible for generating the observed wind and moisture anomalies over the main TC development region. A further study is needed to understand the initiation mechanism of the SSTA in the Atlantic.     

双频激电在普查找矿工作中应注意的几个技术问题

简述了双频道激电法的特点,并讨论了在特殊地质景观条件下,双频道激电法在工作设计、野外工作中所面临的工作频率选择、常见人文干扰、接地电阻、电容耦合及感应耦合等方面的影响,产生的原因和避免的方法技术问题.     

云南天文台1m红外望远镜的主镜热力学分析

云南天文台1m红外太阳望远镜是多功能、多波段的太阳望远镜,望远镜使用过程中主镜的热变形直接关系这系统的光学精度,建立光学系统的光机热结合的分析方法,可以直观的得到热辐射对光学系统的影响结果,使得望远镜的设计阶段就能评估热变形对系统的精度影响,确定光学元件是否满足要求.