超宽谱钛宝石飞秒激光器的研究进展

超宽谱钛宝石飞秒激光器的出现是近年来飞秒激光技术的重要进展之一.文章对近年来国际上出现的几种主要的钛宝石超宽谱飞秒激光器的原理、结构及优缺点进行了介绍,给出了其发展趋势.     

定义在屏幕上显示汉字形文件形的函数

在工程图样中技术要求、标题拦与明细表等用汉字来说明。用户使用非汉化的ＡｕｔｏＣＡＤ（英）２．１８版～１０．０版编辑图形，有时需要加汉字文本到图上。本文将介绍应用定义在屏幕上显示一个汉字形文件中各个形的函数，在输出的汉字表上可以准确检索出汉字的形名，便于汉字调用。     

同步辐射貌相术在研究单晶CuZnAl形状记忆合金马氏体相变中的应用

采用同步辐射貌相术跟踪单晶ＣｕＺｎＡｌ形状记忆合金随温度循环而演变的马氏体相变全过程。研究结果表明，该合金的马氏体转变为热弹性的。     

软件无线电的关键技术与发展动态

软件无线电是利用软件来实现无线通信系统中的各种功能的一种通信技术，近年来获得了较大的发展。本文分别介绍软件无线电的关键技术、评价标准和发展过程，并对软件无线电的技术前景做了展望。     

Highlights of the Brazilian Solar Spectroscope

The digital, decimetric (950–2500 MHz) Brazilian Solar Spectroscope (BSS, Sawant, H.S., Subramanian, K.R., Faria, C., et al. Brazilian Solar Spectroscope (BSS). Solar Phys. 200, 167–176, 2001) with high time (10–1000 ms) and frequency (1–10 MHz) resolution is in regular operation since April, 1998, at the National Space Research Institute (INPE) at São José dos Campos, Brazil. The BSS has now been upgraded with a new digital data acquisition and data processing system. The new version of the BSS has improved the observational possibilities with the capability to record up to 200 frequency channels available in the selectable frequency range 950–2500 MHz. The GPS receiver permits the acquisition of data with time accuracy in the order of 0.1 ms. The software system of the BSS is composed by two distinct modules: the first, data acquisition system provides a flexible Graphical User Interface (GUI) that allows one to choose the observational parameters. The second module is the real time visualization system that permits real time visualization of the observed dynamic spectrum and additionally allows procedures for visualization and preliminary analysis of the recorded solar spectra. Using the new visualization system, we have realized two new types of dm-radio fine structures: narrow band type III bursts with positive as well as negative group frequency drift and dots emissions arranged in zebra-like and fiber-like chains. Furthermore, we have found flare generated fast wave trains according to their tadpole signature in wavelet power spectra for a decimetric type IV radio event (June 6, 2000 flare).     

The Swift Supergiant Fast X-ray Transients Project: A review,new results and future perspectives

We present a review of the Supergiant Fast X-ray Transients (SFXT) Project, a systematic investigation of the properties of SFXTs with a strategy that combines Swift monitoring programs with outburst follow-up observations. This strategy has quickly tripled the available sets of broad-band data of SFXT outbursts, and gathered a wealth of out-of-outburst data, which have led us to a broad-band spectral characterization, an assessment of the fraction of the time these sources spend in each phase, and their duty cycle of inactivity. We present some new observational results obtained through our outburst follow-ups, as fitting examples of the exceptional capabilities of Swift in catching bright flares and monitor them panchromatically.     

Tropopause analysis over the Iranian region using GPS radio occultation data

Near-tropopause phenomena like upper level fronts and cyclones, penetrative cumulus convection and mesoscale mechanisms of exchange make important contributions to the mixing processes in the atmosphere. Spatio-temporal monitoring of the tropopause height, temperature and pressure is an appropriate tool to show the running processes in the atmosphere. In this study, GPS radio occultation data is used to investigate the tropopause height fluctuations and the relation between the stratosphere–troposphere exchange and the aforementioned phenomena over the Iranian region. The paper shows how the position of the sub-tropical jet has changed with time, using GPS radio occultation observations. The tropopause height changes latitudinally, and three different bimodal probability distribution functions are observed. The results also show that the mixing region in the south of Iran is associated with the subtropical jet in winter. However, this region shifts north of Iran due to changes in the position of the subtropical jet during the summer. Consistency of the mixing region from the radio occultation data and the total ozone of TOMS over the Iranian region is also observed.     

Various methods of calibration of the STEREO/WAVES antennas

On October 25th, 2006, NASA’s two STEREO spacecraft were launched which are designed to increase our knowledge of the physics of the solar system. On board they carry a sophisticated radio experiment, called S/WAVES. The key technology, used by S/WAVES is the direction finding capability in addition to the use of two spacecraft which makes it possible to triangulate radio sources. Direction finding requires the reception properties of the antennas to be known very accurately. We applied several different methods to calibrate the S/WAVES antennas. In this paper the methods are described and compared and the results are presented and discussed with respect to advantages and disadvantages of the different methods.