亮红外星系NGC 1614中多谱线示踪的致密分子气体

利用高空间分辨率的¹²CO(1-0)、¹³CO(1-0)、¹²CO(3-2)、¹²CO(6-5)、HCN(3-2)、\lk HCN(4-3)、 HCO⁺(3-2)和HCO⁺(4-3)分子谱线的ALMA (Atacama Large Millimeter/ submillimeter Array)归档数据, 来研究近邻亮红外星系NGC 1614的分子气体性质, 尤其是致密分子气体的性质. 在高分辨率分子气体谱线的积分强度图中, 在星系中心区域($<$ 1kpc)可以看到环状结构, 分子气体主要分布于星系中心区域, 核区分子气体含量较少. ¹²CO(1-0)显示出向南部、 北部以及东南部的延展结构, 高阶的CO ($J \ge$ 3, J为转振能级量子数)分子谱线和致密分子HCN、HCO⁺谱线显示, 较致密的分子气体主要集中于星系中心区域. HCN(4-3)/¹²CO(1-0)和HCN⁺(4-3)/¹²CO(1-0)积分强度比值图显示, 致密分子气体主要集中于中心区域的环状结构上. HCN/HCO⁺强度比值的分布变化表明星暴环的不同区域可能具有不同的激发条件. HCN/HCO⁺(4-3)强度比值分布在环的东、西部(sim0.44 pm 0.04)高于环的南、北部(sim0.35 pm 0.03). HCN/HCO⁺(3-2)强度比值较高的区域(sim0.38 pm 0.04)分布在HCN(3-2)峰值位置, 而环的西北、东南部强度比值相对较低(sim0.3 pm 0.03). 对于中心不同区域 HCN/HCO⁺比值变化的原因进行了讨论.     

山基GPS掩星观测实验及其反演原理

分别在湖北省药姑山和九宫山的山头上开展GPS掩星观测实验,成功获取山基掩星观测数据,对掩星事件进行了分析和统计.给出利用山基掩星观测数据反演大气折射指数剖面和电波弯曲角的原理和算法.利用山基GPS掩星观测模拟数据,对反演方法进行试算和检验,结果表明反演方法准确可行.将该反演方法应用于观测数据的反演,获得了观测点高度以下的大气折射率剖面,以及电波弯曲角.实验结果和原理研究表明,山基掩星观测技术是一种潜在的低层大气环境监测新技术.     

无线电波透视在煤矿中的应用现状和研究方向

自70年代以来,无线电波透视技术在探查矿井地质小构造中先后解决了仪器防爆、探测距离、井下金属导体干扰、数据采集及资料处理、通讯联络等技术问题;今后必须对仪器性能、探测方法、资料处理、基础理论、实验室等方面加强研究,提高其探测精度,扩展其应用范围,使该技术在煤矿安全生产和矿井通讯等领域发挥更重要的作用。      

分米波毫秒级太阳射电爆发的几个形态

介绍使用１０ｍ天线上２１ｃｍ波段ｍｓ级连续快速记录系统,观测到分米波太阳射电快速活动的几种形态、特征、尖峰辐射及其共生现象。     

The development of radio astronomy

Following the detection of extraterrestrial radio waves in 1932 by Karl Jansky, radio astronomy developed quickly after World War II. It established itself soon as a new branch of astronomy with today's outstanding record in the detection of new phenomena in space. These have been honoured by a number of Nobel prizes. Radio astronomy largely depends on technical developments in receiver technology, antenna systems, electronics and computing power. Ever shorter wavelengths down to the submm‐wavelength range became accessible, resulting in new exciting discoveries. However, now and in future care must be taken, in particular for the lower frequency range, of harmful man‐made interferences, which might mask the weak signals from space. New international facilities with orders‐of‐magnitude higher sensitivity like ALMA and SKA are planned or under construction. Space‐borne observatories like PLANCK will detect weak fluctuations of the cosmic microwave background, which will constrain cosmological models with an unprecedented accuracy.     

Introduction to Volume 323 (6) – Proceedings of the Special Colloquium “European Astronomy in the 20th Century” at the Joint European and National Astronomical Meeting (JENAM) for 2001

This issue of AN contains the proceedings of the Special Colloquium “European Astronomy in the 20th Century”, which formed part of the JENAM (2001) conference in Munich, Germany. Subjects covered are the history of γ‐ray and radio astronomy, extragalactic research and compact objects, new media, southern observatories and ESO, as well as some archaeoastronomical questions. Some biographic sketches of individual European astronomers are also given.     

The Effelsberg Bonn H I Survey (EBHIS)

The Effelsberg‐Bonn H I survey (EBHIS) comprises an all‐sky survey north of Dec = –5° of the Milky Way and the local volume out to a red‐shift of z ≃ 0.07. Using state of the art Field Programmable Gate Array (FPGA) spectrometers it is feasible to cover the 100 MHz bandwidth with 16.384 spectral channels. High speed storage of H I spectra allows us to minimize the degradation by Radio Frequency Interference (RFI) signals. Regular EBHIS survey observations started during the winter season 2008/2009 after extensive system evaluation and verification tests. Until today, we surveyed about 8000 square degrees, focusing during the first all‐sky coverage of the Sloan‐Digital Sky Survey (SDSS) area and the northern extension of the Magellanic stream. The first whole sky coverage will be finished in 2011. Already this first coverage will reach the same sensitivity level as the Parkes Milky Way (GASS) and extragalactic surveys (HIPASS). EBHIS data will be calibrated, stray‐radiation corrected and freely accessible for the scientific community via a webinterface. In this paper we demonstrate the scientific data quality and explore the expected harvest of this new all‐sky survey (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于PSP观测的行星际Ⅲ型射电爆发的研究进展

与太阳射电爆发相比,通常认为频率较低的行星际射电爆发产生于远离低日冕的行星际空间.地球电离层的截止导致地基设备无法对其进行观测.美国国家航空航天局(National Aeronautics and Space Administration, NASA)发射的帕克太阳探测器(Parker Solar Probe, PSP)是迄今为止距离太阳最近的空间探测器.其搭载的射电频谱仪能够对10 k Hz–19.17 MHz频段范围内的射电辐射进行观测. PSP能够靠近甚至可能穿越行星际III型射电爆发的辐射源区,因此使用PSP对行星际射电爆发进行观测具有前所未有的优势.简要介绍了目前为止使用PSP的射电观测数据对行星际III型射电爆发的多方面研究,包括爆发的发生率、偏振、散射、截止频率、可能的辐射机制和相关的辐射源区等方面的研究进展,并讨论了其未来的研究前景.     

A regression model-based method for indoor positioning with compound location fingerprints

ABSTRACT

This paper proposed and evaluated an estimation method for indoor positioning. The method combines location fingerprinting and dead reckoning differently from the conventional combinations. It uses compound location fingerprints, which are composed of radio fingerprints at multiple points of time, that is, at multiple positions, and displacements between them estimated by dead reckoning. To avoid errors accumulated from dead reckoning, the method uses short-range dead reckoning. The method was evaluated using 16 Bluetooth beacons installed in a student room with the dimensions of 11 × 5 m with furniture inside. The Received Signal Strength Indicator (RSSI) values of the beacons were collected at 30 measuring points, which were points at the intersections on a 1 × 1 m grid with no obstacles. A compound location fingerprint is composed of RSSI vectors at two points and a displacement vector between them. Random Forests (RF) was used to build regression models to estimate positions from location fingerprints. The root mean square error of position estimation was 0.87 m using 16 Bluetooth beacons. This error is lower than that received with a single-point baseline model, where a feature vector is composed of only RSSI values at one location. The results suggest that the proposed method is effective for indoor positioning.     

联合单站地基GNSS和空基掩星近实时反演电离层电子密度

采用非组合精密单点定位技术估算VTEC,并选取一系列与测站共址的COSMIC掩星电离层产品共同作为约束条件,利用函数模型近实时地探测GNSS测站上空电离层电子密度剖面特性。为了验证新方法的可行性,选取东亚11个IGS跟踪站2016年4个季节中3月、6月、9月和12月最后一周的观测数据及与测站共址的COSMIC掩星ionPrf产品进行实验。将每一个反演结果与同一时刻COSMIC掩星探测的电离层电子密度（作为真值）进行比较。结果表明,新方法实时反演的电子密度剖面与掩星电离层产品相比具有很好的一致性,所获得的f0F2与hmF2参数精度皆优于IRI2016模型。