DEFPOS and Its First Results

A spectrometer was built to examine the interstellar medium (ISM) using the hydrogen Balmer a line. It is called Dual Etalon Fabry-Perot Optical Spectrometer (DEFPOS). DEFPOS will be coupled to coude exit of the 150 cm telescope (RTT150) installed at TUBITAK National Observatory (TUG). DEFPOS was ready for observations about two years ago, but work was still continuing on the RTT150 coude exit alignment. So we have started observing HII regions with DEFPOS without the RTT150. We present here some characteristics of the instrument and some of the results obtained.     

TRAFICOS – an Échelle Zeeman spectrograph

We describe the TRAnsportable Flbre COupled échelle Spectrograph (TRAFICOS) equipped with a Zeeman analyzer and manufactured mainly for the observation of stellar magnetic fields. The spectrograph, designed at the Astrophysikalisches Institut Potsdam and constructed at the Thüringer Landessternwarte Tautenburg, is laid out in a quasi-Littrow configuration. The part attached to the Nasmyth focus of the 2 m telescope contains the telescope adapter for the fibre input and output of the star and calibration light, the cases for the flatfield and the wavelength calibration, and the Zeeman analyzer. The optical scheme and the reduction software are mentioned in some details and the first results of the determination of the magnetic field and radial velocity of several stars are given showing the performance of the device in comparison with existing data.     

VLBI标准接口的发展

VLBI标准接口是近年来在VLBI技术中诞生的一个新概念,它旨在解决多年来各VLBI数据传输系统不兼容的问题．该文阐述了VLBI数据传输系统的发展历史,包括传统的记录／回放系统和新兴的网络数据传输两方面的内容;说明了VLBI标准接口的作用和意义;并分别介绍了VLBI标准接口规范3方面的内容:VLBI标准接口件规范(VSI-H)、VLBI标准接口软件规范(VSI-S)和VLBI标准接口网络规范(VSI-E)．     

昆明VLBI观测站终端控制软件的设计

针对昆明VLBI观测站终端设备(S3数据采集系统)的特殊性,设计在标准的终端控制计算机(Field System)上能够控制相应硬件设备的软件.S3数据采集系统包括SX接收机、中频分配器、视频转换器、时延计数器、噪声控制开关和气象数据自动采集仪.设计过程中,考虑到软件的可读性和可维护性,各种设备分别用相应的子函数来完成具体功能,各子函数由主程序调用.在完成程序安装后,经测试能与S3数据采集系统进行良好的通讯,达到控制各硬件设备的目的及满足实际测控工作的需要.     

Determining the optimum scan map strategy for Herschel-SPIRE using the SPIRE photometer simulator

The forthcoming Herschel space mission will provide an unprecedented view of the far-infrared/submillimetre Universe, with the SPIRE instrument covering the 200–670 μm wavelength range. To obtain the best quality of astronomical data from such an expensive mission the observing modes must be optimized as far as possible. This paper presents the possible scanning strategies that can be utilized by the SPIRE photometer, within the limitations imposed by the Herschel spacecraft. Each strategy is investigated for effectiveness by performing simulated observations, using the SPIRE photometer simulator. By quantifying the data quality using a simple metric, we have been able to select the optimum scanning strategy for SPIRE when it begins taking science data within the next couple of years.
Additionally, this work has led to the development of a specific SPIRE mapmaking algorithm, based on the CMB code MADmap, to be provided as part of the SPIRE data pipeline processing suite. This will allow every SPIRE user to take full advantage of the optimized scan map strategy, which requires the use of maximum likelihood mapmakers such as MADmap.     

Radial thresholding to mitigate laser guide star aberrations on centre-of-gravity-based Shack–Hartmann wavefront sensors

Sodium laser guide stars (LGSs) are elongated sources due to the thickness and the finite distance of the sodium layer. The fluctuations of the sodium layer altitude and atom density profile induce errors on centroid measurements of elongated spots, and generate spurious optical aberrations in closed-loop adaptive optics (AO) systems. According to an analytical model and experimental results obtained with the University of Victoria LGS bench demonstrator, one of the main origins of these aberrations, referred to as LGS aberrations, is not the centre-of-gravity (CoG) algorithm itself, but the thresholding applied on the pixels of the image prior to computing the spot centroids. A new thresholding method, termed 'radial thresholding', is presented here, cancelling out most of the LGS aberrations without altering the centroid measurement accuracy.     

潮汐性旅游流研究：概念框架与研究思路

旅游流是一种重要的旅游现象,是旅游地理学研究的核心问题之一,目前整体呈现出尺度多元、案例话题多样、大数据与精细化并重的研究态势,但这些研究大多是基于技术方法层面或是基于案例话题层面的创新,误将旅游流视作了最终的科学问题与研究目标,旅游流基础理论研究亟待重新认识、强化和丰富。“黄金周”假日旅游流是一种受时间、空间、信息等多项条件制约的、特殊的短时高强度旅游流,休假时间的集中化促使部分景区客流量达到一定程度时必然引发过度旅游,旅游企业管理如何正确应对和有效缓解“黄金周”带来的井喷效应、推进假日旅游的持续健康规范发展,仍需进一步深入探讨。论文以拥有品牌知名度且以资源禀赋优势为核心竞争力的强吸引力旅游景区的假日旅游流潮汐涨落与进退现象为立论依据,对比自然界海洋潮汐现象,推演旅游流的潮汐运动理论,并从流动特性、空间过程、系统动力、尺度效应、能量特征、数字模拟等角度构建了潮汐性旅游流研究的系统体系结构。通过将复杂的假日旅游流流动现象提炼为精简的理论解释,研究突破了传统的旅游季节性研究瓶颈,有益于丰富和充实中国旅游流研究的基础理论,并为旅游景区的“黄金周”假日旅游流管理实践提供现实指导。