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A revised rotation curve of the Milky Way with maser astrometry

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Research in Astronomy and Astrophysics 2013年第7期13卷 849-861页

作者： Xiao-Sheng Xin xing-wu zheng School of Astronomy and Space Science Nanjing University

We reconstruct the rotation curve of the Milky Way using the new trigono-metric parallax and proper motion data for masers in 43 high-mass star-forming re-gions obtained by VLBI, as well as the existing data from the literature, based on a new set of galactic constants （R0, -0） = （8.4 kpc, 254 km s^-1） measured by Reid et al. The revised rotation curve of the Milky Way is almost fiat or slightly rising in the region from about 6 to 15 kpc. The rotation velocities within 5 kpc of the Galactic center, as determined by VLBI, differ from those obtained by measurement of the HI-and CO-line tangent velocities. We fitted the revised rotation curve arising from three mass components： the bulge, disk and dark matter halo. The total mass of the Milky Way is found to be 2.3× 10^11 M⊙ （20 kpc）. This is about 10% larger than that from Sofue et al, and is comparable with the mass of M31, 3.4× 10^11 M⊙ （35 kpc）, given by Carignan et al. The limited accurate observational data, especially the VLBI data, do not permit a fully satisfactory fit to the rotation curve. The extensive par-allax and proper motion data that will be produced by the Bar and Spiral Structure Legacy Survey project in the next few years should lead to considerable progress in understanding the rotation curve and dark matter halo of the Milky Way.

关键词： Galaxy: structure - Galaxy: bulge - Galaxy: disk - Galaxy: halo-dark matter - masers

12 GHz methanol maser outflow from the massive star-forming region: G35.20-0.74

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Research in Astronomy and Astrophysics 2013年第7期13卷 815-826页

作者： Qing-Zeng Yan Bo Zhang zheng-Hong Tang xing-wu zheng Shanghai Astronomical Observatory Chinese Academy of Sciences Max-Plank-Institut für Radioastronomie Auf dem Hügel 6953121 BonnGermany School of Astronomy and Space Science Nanjing University

We report the internal proper motions of 12 GHz methanol masers in mas-sive star-forming region G35.20-0.74 observed with the Very Long Baseline Array （VLBA） at four epochs spanning about 1.5 yr. Two groups of maser features were de-tected, groups A and B, and the latter that had a V-shaped spatial distribution is likely tracing the north outflow in G35.20-0.74. We present a three-dimensional model for the kinematics of these masers, by assuming the interstellar medium was blown by the stellar wind from the driving source （G35.2N） of the outflow. Adopting a position angle of ～ 81° for the main axis of the outflow from previous studies, we estimate an inclination of 35 ° ± 5.5°, a velocity of 8.1 ± 0.7 km s^-1 for the stellar wind along the main axis and an expansion speed gradient of 0.05 ± 0.016 km s^-1 AU^-1. From the model, we derive the age of the north outflow in G35.20-0.74 to be ～ 1.6 × 10^4 yr.

关键词： masers - ISM: molecules - stars: kinematics - stars: individual(G35.20-0.74) - stars: winds outflows

Research and application of reanalysis data for radio astronomical site testing

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Research in Astronomy and Astrophysics 2020年第12期20卷 279-286页

作者： Ming-Shuai Li Rui Li Na Wang xing-wu zheng Xinjiang Astronomical Observatory Chinese Academy of Sciences830011 UrumqiChina Key Laboratory of Radio Astronomy Chinese Academy of Sciences210034 NanjingChina School of Astronomy&Space Science Nanjing UniversityNanjing 210093China

Selecting a good site for ground-based astronomy is very important. Based on the ERA-Interim global reanalysis data, this paper studied the atmospheric conditions of the Qitai Telescope(QTT) site from the aspects of absolute humidity, mixing ratio and precipitable water vapor(PWV). Error estimations of meteorological parameters are also analyzed. These primary results show that the QTT site has obvious advantages in terms of conditions with much less atmospheric water vapor than two well-known existing sites with 100-meter-aperture radio telescopes in the world. In addition, due to the influence of atmospheric water vapor on radio observations, the atmospheric transmittance for each frequency band of the site are simulated, and the atmospheric opacity is also calculated as well as Planck radiation brightness. Based on these results, the effective observational time of different bands is further estimated.

关键词： site testing opacity radiative transfer

An Approach of Tropospheric Correction for VLBI Phase-Referencing using GPS Data

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Chinese Journal of Astronomy and Astrophysics 2008年第1期8卷 127-132页

作者： Bo Zhang xing-wu zheng Jin-Ling Li Ye Xu Department of Astronomy Nanjing University Nanjing 210093 Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008

The dominant source of error in VLBI phase-referencing is the troposphere at observing frequencies above 5 GHz. We compare the tropospheric zenith delays derived from VLBI and GPS data at VLBA stations collocated with GPS antennas. The systematic biases and standard deviations both are at the level of sub-centimeter. Based on this agreement, we suggest a new method of tropospheric correction in phase-referencing using combined VLBI and GPS data.

关键词： techniques VLBI - techniques GPS - atmospheric effects - methods data analysis- astrometry

Measurements for the Performance of the Digital Autocorrelation Spectrometer

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Chinese Journal of Astronomy and Astrophysics 2007年第2期7卷 297-303页

作者： Fa-Chun Lu Jarken Esimbek Jian-Jun Zhou xing-wu zheng National Astronomical Observatories/Urumqi Observatory Chinese Academy of Sciences Urumqi830011 Graduate University of Chinese Academy of Sciences Beijing 100049 Department of Astronomy Nanjing University Nanjing 210093

Injecting phase calibration （PCAL） signals to the feed horn of the observation system and analyzing the output response signals of the spectrometer, we measured the working performance of a 4096-channel digital autocalibration spectrometer. The results demonstrate that the spectrometer has a fine working performance：（1） the channels are distributed uniformly in the spectrometer; （2） line drift produces little effect on the observation results; （3） spectral resolution shows little changes with observation time. The distribution of the frequency resolution in an 80 MHz bandwidth was measured. A trial observation on the two molecular spectral lines of H2CO and H110α taken with this spectrometer is described.

关键词： instrumentation spectrometer- ISM: molecules - radio lines ISM

Simplified geometric reliability assessment of foundation piles under specific buildings based on limited test data

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Yantu Lixue/Rock and Soil Mechanics 2020年 41卷 482-490页

作者： wu, xing-zheng Wang, Rui-Kai Xin, Jun-Xia College of Civil Engineering and Architecture Hebei University Baoding 071002 China Beijing Building Construction Research Institute Beijing 100039 China Beijing Construction Engineering Quality First Testing Institute Co. Ltd. Beijing 100039 China

According to current detection technical specifications, the detection number of static load for piles under particular buildings is extremely limited (i.e., usually only 3 or more). Due to the influence of spatial variability of soil around the pile, the load-displacement curves of these tests are difference. If each test curve can be regressed by a power law function of two parameters, the discretization between curves under a specific building is cited as being revealed by the uncertainty of regression parameters. In this paper, an assessment technique for evaluating the loading capacity of such piles is presented using a geometric reliability algorithm. In the calculation of geometric reliability index, considering the limitation of data, the marginal distribution of regression parameters is assumed to be normal distribution. Furthermore, its statistical characteristics are expressed by the mean, standard deviation and correlation coefficient between regression parameters. In order to validate the algorithm, the testing data of concrete pipe piles, augered cast-in-situ piles and cement fly-ash gravel(CFG) piles are used to calculate the geometric reliability index of these foundation piles under a specific building. The reliability indexes based on the proposed method are consistent with the results calculated by the conventional reliability method(FORM). This evaluation technique can be directly applied in the reliability analysis of foundation piles under a specific building. Finally, a software developed using a visual programming language is presented to better promote this algorithm. © 2020, Science Press. All right reserved.

关键词： Reliability analysis

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中国与荷兰洪水风险分析方法的比较研究

自然灾害学报 2005年第4期14卷 19-24页

作者：王艳艳吴兴征中国水利水电科学研究院防洪减灾研究所北京100038

基于洪水风险的定义,从洪灾发生概率、洪灾后果评估、风险评价指标和防洪标准经济优化决策原则等方面阐述了中荷两国在洪水风险分析研究方面的异同,初步分析了存在差别的原因以及两种方法的特点。在分别应用中国和荷兰现有风险评估方法... 详细信息

基于洪水风险的定义,从洪灾发生概率、洪灾后果评估、风险评价指标和防洪标准经济优化决策原则等方面阐述了中荷两国在洪水风险分析研究方面的异同,初步分析了存在差别的原因以及两种方法的特点。在分别应用中国和荷兰现有风险评估方法分析安庆市堤防圈的洪水风险的基础上,探讨了将两国的风险分析方法进行整合的思路。算例表明,将堤防的工程风险与洪水本身出现的水文风险相结合,并考虑在不同洪水位下损失的差异的方法是与洪灾发生机理相符,综合考虑了各种不确定因素的、切合我国洪灾特点的一种值得进一步深入研究的新方法。

关键词：洪水风险概率洪灾损失后果经济优化

Resting-state brain network remodeling after different nerve reconstruction surgeries:a functional magnetic resonance imaging study in brachial plexus injury rats

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Neural Regeneration Research 2025年第5期20卷 1495-1504页

作者： Yunting Xiang Xiangxin xing Xuyun Hua Yuwen Zhang Xin Xue Jiajia wu Mouxiong zheng He Wang Jianguang Xu School of Rehabilitation Science Shanghai University of Traditional Chinese MedicineShanghaiChina Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation Ministry of EducationShanghaiChina Department of Rehabilitation Medicine Yueyang Hospital of Integrated Traditional Chinese and Western MedicineShanghai University of Traditional Chinese MedicineShanghaiChina Department of Traumatology and Orthopedics Yueyang Hospital of Integrated Traditional Chinese and Western MedicineShanghai University of Traditional Chinese MedicineShanghaiChina Institute of Science and Technology for Brain-Inspired Intelligence Fudan UniversityShanghaiChina Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence(Fudan University) Ministry of EducationShanghaiChina Human Phenome Institute Fudan UniversityShanghaiChina

Distinct brain remodeling has been found after different nerve reconstruction strategies,including motor representation of the affected ***,differences among reconstruction strategies at the brain network level have not been *** study aimed to explore intranetwork changes related to altered peripheral neural pathways after different nerve reconstruction surgeries,including nerve repair,endto-end nerve transfer,and end-to-side nerve ***–Dawley rats underwent complete left brachial plexus transection and were divided into four equal groups of eight:no nerve repair,grafted nerve repair,phrenic nerve end-to-end transfer,and end-to-side transfer with a graft sutured to the anterior upper ***-state brain functional magnetic resonance imaging was obtained 7 months after *** independent component analysis algorithm was utilized to identify group-level network components of interest and extract resting-state functional connectivity values of each voxel within the *** in intra-network resting-state functional connectivity were compared among the *** muscle reinnervation was assessed by behavioral observation(elbow flexion)and *** results showed that alterations in the sensorimotor and interoception networks were mostly related to changes in the peripheral neural *** repair was related to enhanced connectivity within the sensorimotor network,while end-to-side nerve transfer might be more beneficial for restoring control over the affected limb by the original motor *** thalamic-cortical pathway was enhanced within the interoception network after nerve repair and end-to-end nerve *** areas related to cognition and emotion were enhanced after end-to-side nerve *** study revealed important brain networks related to different nerve *** networks may be potential targets for enhancing motor recovery.

关键词： brain functional networks end-to-end nerve transfer end-to-side nerve transfer independent component analysis nerve repair peripheral plexus injury resting-state functional connectivity

A Search for High-velocity Gas Associated H_2O Masers and Ultracompact HII Regions

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Chinese Journal of Astronomy and Astrophysics 2001年第1期1卷 60-65页

作者： YeXu Dong－RongJiang 等 ShanghaiAstronomicalObservatory ChineseAcademyofSciencesShanghai200030 NationalAstronomicalObservato

With the objective of studying the relationships between high-velocity gas and water maser emissions the results of a search from 95 IRAS sources for high-velocity gas associated with star forming molecular clouds are... 详细信息

关键词： HII regions - ISM: jets and outflows - stars: formation - masers