Performance and observation summary of Changchun Satellite Laser Ranging Station

This note introduces the performance and observation summary of the SLR system at Changcun Observatory, the Chinese Academy of Sciences. The performance of the SLR system has been greatly improved since August 1997. The single shot precision is improved from 5–7 cm to 1–2 cm and the normal point precision reaches 4–7 mm. The long-term stability is better than 1 cm. The amount of observation has been increased from 1000 to over 3000 passes. The whole performance of Changcun SLR system has reached the advanced level among the worldwide SLR stations.     

Petrological implication of wagnerite-Ma5bc in the quartzofeldspathic gneiss, Larsemann Hills, East Antarctica

Mg dominantmineralsofwagnerite triplite group,i.e.(Mg,Fe,Mn)2(PO4)(F,OH),arerelativelyrare,buthavebeenfoundinawidevariety ofgeologicenvironments,includingmetamorphic rocksofallgrades[1]suchasquartz carbonateveinsof hydrothermalorigin,pegmatites,kyanite quartzite,micaschist,sillimanitegneiss,andmagnetiteores.Uptonow,wagneriteispresentmainlyasthe Ma2bcpolytype,anaccessorymineralincalcium poorrocks[2,5]inwhichapatite,ifpresent,oftenoc cursasretrograderimaroundwagnerite.Henriques[6]reportedasma…     

用于AVS—M标准的差错复原编码方案

基于无线移动网络的视频通信业务越来越受到重视。无线网络属于易于发生差错的信道，基于无线移动网络的视频通信业务必然要受到信道差错的影响。为了对抗信道差错，必须采取适当的技术措施。目前，差错复原技术已成为易发生差错信道下视频编码的重要组成部分。AVS—M标准是我国自主制定的视频压缩编码标准，对AVS—M标准的差错复原技术进行研究具有重要的意义。提出了两套用于AVS-M标准的差错复原编码方案，并对其差错复原性能进行了实验研究。实验结果表明，这两套方案具有良好的差错复原性能，重建图像的主客观质量均得到了明显的改善。     

Na(THF)2(μ2-η5-Cp)(η5,η5,η1-Cp3Yb)(THF)]n: The synthesis and X-ray structure of an anionic organolanthanidepolymer formed via self-assembly

Cp2Yb·2THF reacts with CpNa in 1：1 molar ratio in THF at 40℃ for 2 h, and the in situ generated anionic divalent complex NaYbCp3（THF）n reacts further with an excess of CpH at 40℃ for 48h, after work-up, affording the trivalent anionic ytterbium complex[Na（THF）2（μ2-η^5-Cp） （η^5, η^5,η^1-Cp3Yb）（THF）]n：（1） by oxidation reaction of Cp2Yb with CpH. Crystal structure determination reveals that complex 1 has one-dimension polymeric chains of distinct Na（THF）2（μ2-η^5-Cp） （η^5, η^5,η^1-Cp3Yb）（THF） units, which were formed by the coordination of the bridging Cp ligand with Cp3Yb＇THF and Na（THF）2 in η^5,η^5 mode via self-assembly.     

Original component of grain size index in core sediment from southwestern slope of the South China Sea and its paleoenvironmental implication

Traditional grain size analysis was basically used to discriminate sediment type based on its particle dimension for sedimentary naming[1,2] and to analyze the dynamic feature of transport medium, including water current and wind strength[3―5]. Recently, some patency advances havebeen made by using different methods to separate different grain sizes in various original composition from sediments for searching a new way of paleoenvironmental study[6―8]. Grain size analysis is even playing an …     

Simulation of a compartment fire using a zone model

This paper presents the zone modeling analysis of a single compartment flashover fire. Two criteria are applied in the model to judge the onset of ignition for different combustibles. By calculating the total received energy through radiation or the surface temperature of the combustible, the fire growth can be quantitatively determined. The improved zone fire model shows the influence of different combustibles upon the fire growth. This model is better than the traditional zone model because the common criteria of flashover, i.e. an upper layer temperature of 600℃ and the heat radiation intensity received by the floor of 20 kW/m^2, have not been applied in it.     

太原市古树名木现状及保护对策刍议

百年以上树龄的树木，稀有、珍贵树木，具有历史价值和重要纪念意义的树木等古树名木，是我国林木资源中的瑰宝，是自然界和前人留下的珍贵遗产，古树名木是历史的见证，活的文物，也是风景旅游资源的重要组成部分，具有极高的科研、生态、观赏和科普价值。做好古树名木的保护工作是全社会长期的、重要的工作。     

基于嵌入式系统的音频点播系统

介绍一种基于嵌入式系统的C／S结构音频点播系统，它将MP3音频文件集中存储在网络服务器上，利用自主开发的MP3播放终端进行网络点播，并重点介绍基于uClinux的嵌入式MP3播放终端的设计。这种音频点播系统可以广泛应用在卡拉OK厅、语音教室和公共广播等许多场所。     

PLC的SFC图在编写顺序控制梯形图中的应用

为了解决应用可编程控制器(PLC)的基本逻辑指令编写顺序控制梯形图时所存在的编程复杂、不易理解等问题,采用PLC的顺序功能图来编写顺序控制梯形图是一种非常有效的方法,该方法具有编程简单而且直观等特点.以送料小车的控制为例,采用顺序功能图的方法编写其控制梯形图,从编程结果可以看出,与应用PLC的基本逻辑指令方法相比具有简单、直观、逻辑性强等特点,提高编程的效率.     

浅谈期刊文献的开发与利用

简要分析了期刊的特点,提出图书馆要利用自身的优势,加强期刊管理,保证期刊质量,实现资源共享。