从航展看中国航空发展

2008年第7届珠海航展亮点不少，但笔者认为真正蕴含未来趋势的现象主要有3个：无人机的兴旺，战略空军概念的火爆，美国公司订购ARJ21支线客机。对前两者的思考有助于理清中国空军的发展方向，后者则事关中国航空产业的前途。     

Analysis of Pulverized Coal by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy （LIBS） has been used to detect atomic species in various enviromnents. The quantitative analysis （C, H, O, N and S） of representative coal samples are being carried out with LIBS, and the effects of particle size are analyzed. A powerful pulse Nd：YAG laser is focused on the coal sample at atmosphere pressure, and the emission spectra from laser-induced plasmas are measured by time-resolved spectroscopy, and the intensity of analyzed spectral lines is obtained through observing the laser plasma with a delay time of 0.4 #s. The experimental results show that the slope of calibration curve is nearly 1 when the concentration of the analyzed element is relatively low, and the slope of curve is nearly 0.5 when the concentration of C is higher than other elements. In addition, using the calibration-free model without self-absorption effect, the results show that the decreasing of particle size leads to an increase of the plasma temperature.     

推介2013世界武器贸易报告

2013年3月,著名的瑞典斯德哥尔摩国际和平研究所（SIPRI）发布了新的世界武器贸易报告。报告提出：2008-2012年,中国取代英国成为军火出口的五强之一。报告引发了国际军贸界的高度关注。军贸统计有多有少军贸是世界上最特殊的贸易之一。有的武器独此一家,别无分号;有的武器给钱也不卖;有的高层互访之后,武器招标结果立刻改变;有的招标结果明显不公,却无法按常规的国际贸易规则提起申诉。另外,世界军费开支极不均衡。     

被动锁模掺铒光纤激光器自相似脉冲的啁啾提取

In this paper, we adopt cloud computing in a specific scientific computing field for its virtualization, distribution and dynamic extendibility as follows : We obtain highenergy parabolic selfsimilar pulses by numerical simulation using our nondistributed passively modelocked Erdoped fiber laser model. For researching characteristics of these wavebreakingfree selfsimilar pulses , chirp of them must be extracted. We propose several timefrequency analysis methods adopted in chirp extraction of ultrashort optical pulses for the first time and discuss the advantages and disadvantages of them in this particular application.     

一次成型大跨度楼地面金刚砂地坪施工技术及质量控制

以杭州某大型物流仓储库房为例，从混凝土配合比、混凝土标高控制、大跨度地坪施工工艺、金刚砂面层磨光及细部处理等方面分析了一次成型大跨度楼地面金刚砂地坪施工中面临的重难点以及质量控制措施，以供参考。