检索结果-南通市图书馆

The ALMA-QUARKS Survey. Ⅱ. The ACA 1.3 mm Continuum Source Catalog and the Assembly of Dense Gas in Massive Star-Forming Clumps

引用

Research in Astronomy and Astrophysics 2024年第6期 121-141页

作者：许峰玮 Ke Wang Tie liu Lei Zhu Guido Garay Xunchuan liu Paul Goldsmith Qizhou Zhang Patricio Sanhueza Shengli Qin Jinhua He Mika Juvela Anandmayee Tej Hongli liu Shanghuo li Kaho Morii Siju Zhang Jianwen Zhou Amelia Stutz Neal J.Evans Kee-Tae Kim Shengyuan liu Diego Mardones guangxing li Leonardo Bronfman Ken'ichi Tatematsu Chang Won Lee Xing Lu Xiaofeng Mai Sihan Jiao James O.Chibueze Keyun Su Viktor L.Tóth School of Physics and Astronomy Yunnan University Yunnan Observatories Chinese Academy of Sciences Department of Physics University of Helsinki Indian Institute of Space Science and Technology Max Planck Institute for Astronomy Department of Astronomy Graduate School of Science The University of Tokyo Max-Planck-Institut für Radioastronomie Departamento de Astronom'?a Universidad de Concepcion Department of Astronomy The University of Texas at Austin Korea Astronomy and Space Science Institute Kavli Institute for Astronomy and Astrophysics Peking University Institute of Astronomy and Astrophysics Academia Sinica South-Western Institute for Astronomy Research Yunnan University University of Science and Technology National Astronomical Observatories Chinese Academy of Sciences Department of Mathematical Sciences University of South Africa Centre for Space Research Physics Department North-West University Department of Physics and Astronomy Faculty of Physical Sciences University of Nigeria Institute of Physics and Astronomy E?tv?s Lorànd University University of Debrecen Faculty of Science and Technology Department of Astronomy School of Physics Peking University Shanghai Astronomical Observatory Chinese Academy of Sciences Chinese Academy of Sciences South America Center for Astronomy National Astronomical Observatories Chinese Academy of Sciences Departamento de Astronomía Universidad de Chile Jet Propulsion Laboratory California Institute of Technology Center for Astrophysics | Harvard & Smithsonian National Astronomical Observatory of Japan National Institutes of Natural Sciences Astronomical Science Program The Graduate University for Advanced Studies

Leveraging the high resolution, sensitivity, and wide frequency coverage of the Atacama Large Millimeter/submillimeter Array（ALMA）, the QUARKS survey, standing for “Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures”, is observing 139 massive starforming clumps at ALMA Band 6（λ～1.3 mm）. This paper introduces the Atacama Compact Array（ACA） 7 m data of the QUARKS survey, describing the ACA observations and data reduction. Combining multiwavelength data, we provide the first edition of QUARKS atlas, offering insights into the multiscale and multiphase interstellar medium in high-mass star formation. The ACA 1.3 mm catalog includes 207 continuum sources that are called ACA sources. Their gas kinetic temperatures are estimated using three formaldehyde transitions with a non-LTE radiation transfer model, and the mass and density are derived from a dust emission model. The ACA sources are massive（16–84 percentile values of 6–160 M⊙）, gravity-dominated(M ∝ R1.1)fragments within massive clumps, with supersonic turbulence（M >1） and embedded star-forming protoclusters. We find a linear correlation between the masses of the fragments and the massive clumps,with a ratio of 6% between the two. When considering fragments as representative of dense gas, the ratio indicates a dense gas fraction（DGF） of 6%, although with a wide scatter ranging from 1% to 10%. If we consider the QUARKS massive clumps to be what is observed at various scales, then the size-independent DGF indicates a self-similar fragmentation or collapsing mode in protocluster formation. With the ACA data over four orders of magnitude of luminosity-to-mass ratio（L/M）, we find that the DGF increases significantly with L/M, which indicates clump evolutionary stage. We observed a limited fragmentation at the subclump scale,which can be explained by a dynamic global collapse process.

关键词：

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Galactic interstellar scintillation observed from four globular cluster pulsars by FAST

引用

中国科学:物理学、力学、天文学英文版 2023年第9期66卷 119-127页

作者： Dandan Zhang Zhenzhao Tao Mao Yuan Jumei Yao Pei Wang Qijun Zhi Weiwei Zhu Xun Shi Michael Kramer Di li Lei Zhang guangxing li School of Mathematical Sciences School of Physics and Electronic SciencesGuizhou Normal UniversityGuiyang 550001China National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guiyang 550001China Department of Astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China South-Western Institute for Astronomy Research(SWIFAR) Yunnan UniversityKunming 650000China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Max-Planck Institut fr Radioastronomie Bonn D-53121Germany Key Laboratory of Radio Astronomy and Technology Chinese Academy of SciencesBeijing 100101China Computational Astronomy Platform Zhejiang LabHangzhou 311121China

We report detections of scintillation arcs for pulsars in globular clusters M5,M13 and M15 for the first time using the Fivehundred-meter Aperture Spherical radio Telescope(FAST).From observations of these arcs at multiple epochs,we infer that screen-like scattering medium exists at distances 4.1_(-0.3)^(+0.2),6.7_(-0.2)^(+0.2)and 1.3_(-1.0)^(+0.7) kpc from Earth in the directions of M5,M13 and M15,respectively.This means M5's and M13's scattering screens are located at 3.0_(-0.2)^(+0.1) and 4.4_(-0.1)^(+0.1) kpc above the galactic plane,whereas,M15's is at 0.6_(-0.5)^(+0.3) kpc below the plane.We estimate the scintillation timescale and decorrelation bandwidth for each pulsar at each epoch using the one-dimensional auto-correlation in frequency and time of the dynamic spectra.We found that the boundary of the Local Bubble may have caused the scattering of M15,and detected the most distant off-plane scattering screens to date through pulsar scintillation,which provides evidence for understanding the medium circulation in the Milky Way.

关键词： pulsars scintillation globular clusters

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Preparation of hierarchical mesoporous Zn/HZSM-5 catalyst and its application in MTG reaction

引用

Journal of Natural Gas Chemistry 2011年第3期20卷 237-242页

作者： Youming Ni Aiming Sun XiaolingWu Guoliang Hai Jianglin Hu Tao li guangxing li School of Chemistry ＆ Chemical Engineering Huazhong University of Science ＆ Technology Wuhan 430074 Hubei China Hubei Key Laboratory of Materials Chemistry ＆ Service Failure Huazhong University of Science ＆ Technology Wuhan 430074 Hubei China

The hierarchical mesoporous Zn/ZSM-5 zeolite catalyst was prepared by NaOH treatment and Zn impregnation, and its application in the conversion of methanol to gasoline （MTG） was studied. N2 adsorption-desorption results showed that the mesopores with sizes of 2-20 nm in HZ5/0.3AT was formed by 0.3 M NaOH alkali treatment. The zeolite samples after modification were also characterized by XRF, AAS, XRD, SEM and NH3-TPD methods. Zn impregnated catalyst Zn/HZ5/0.3AT exhibited dramatic improvements in catalytic lifetime and liquid hydrocarbons yield. The selectivity of aromatic hydrocarbons was also improved after Zn impregnation. It is suggested that the mesopores of Zn/HZ5/0.3AT enhanced the synergetic effect of Zn species and acid sites and the capability to coke tolerance, which were confirmed by the results of catalytic test and TGA analysis, respectively.

关键词： hierarchical mesoporous ZSM-5 alkali treatment zinc impregnation methanol-to-gasoline

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

AB062. Cortical state contribution to neuronal response variability

引用

Annals of Eye Science 2018年第1期 468-468页

作者： Shangge Jiang guangxing li Curtis L.Baker McGill Vision Research Department of OphthalmologyMcGill UniversityMontréalQCCanada

Background:Visual cortex neurons often respond to stimuli very differently on repeated trials.This trial-by-trial variability is known to be correlated among nearby neurons.Our long-term goal is to quantitatively estimate neuronal response variability,using multi-channel local field potential(LFP)data from single trials.Methods:Acute experiments were performed with anesthetized(Remifentanil,Propofol,nitrous oxide)and paralyzed(Gallamine Triethiodide)cats.Computer-controlled visual stimuli were displayed on a gamma-corrected CRT monitor.For the principal experiment,two kinds of visual stimuli were used:drifting sine-wave gratings,and a uniform mean-luminance gray screen.These two stimuli were each delivered monocularly for 100 sec in a random order,for 10 trials.Multi-unit activity(MUA)and LFP signals were extracted from broadband raw data acquired from Area 17 and 18 using A1X32 linear arrays(NeuroNexus)and the OpenEphys recording system.LFP signal processing was performed using Chronux,an open-source MATLAB toolbox.Current source density(CSD)analysis was performed on responses to briefly flashed full-field stimuli using the MATLAB toolbox,CSDplotter.The common response variability(global noise)of MUA was estimated using the model proposed by Scholvinck et al.[2015].Results:On different trials,a given neuron responded with different firing to the same visual stimuli.Within one trial,a neuron’s firing rate also fluctuated across successive cycles of a drifting grating.When the animal was given extra anesthesia,neurons fired in a desynchronized pattern;with lighter levels of anesthesia,neuronal firing because more synchronized.By examining the cross-correlations of LFP signals recorded from different cortical layers,we found LFP signals could be divided to two groups:those recorded in layer IV and above,and those from layers V and VI.Within each group,LFP signals recorded by different channels are highly correlated.These two groups were observed in lighter and deeper anesthetized animals,also in sine-wave and unifo

关键词： Cortical state response variability local field potential(LFP) multi-unit activity(MUA) visual cortex

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A Novel Catalyst CuCl/1,10-Phenanthroline/N-Methylimidazole for the Oxidative Carbonylation of Ethanol to Diethyl Carbonate

引用

催化学报 2003年第1期24卷 3-4页

作者： MO Wanling, li guangxing, ZHU Yongqiang, XIONG Hui, MEI Fuming (Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China) DepartmentofChemistry HuazhongUniversityofScienceandTechnology 湖北 430074

Diethyl carbonate(DEC)is one of the important green chemicals widely used for organic synthesis because of its various functional groups.DEC is the molecule than methyl tert-butyl ether(MTBE),40.6% VERSUS 18.2%,which reduces emissions from gasoline and diesel engine.For these reasons many studies on the production of DEC have been extensively carried out

关键词：碳酸二乙酯催化体系液相氧化羰基化 CuCl/1,10-菲罗啉/N-甲基咪唑氯化亚铜合成

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

从不同版本LATBSDC规范修订看美国性能化设计思路变化

引用

建筑结构 2023年第S1期53卷 863-868页

作者：王一功李光星广州城建开发设计院有限公司广州510620

LATBSDC规范是洛杉矶高层建筑设计委员会推出的一本基于性能化设计原则的高层设计规范。LATBSDC规范推出后经历了多个版本的修编,反映了美国性能化设计思路的变化。对比了不同版本LATBSDC规范对性能目标、材料强度与刚度取值、地震输入... 详细信息

LATBSDC规范是洛杉矶高层建筑设计委员会推出的一本基于性能化设计原则的高层设计规范。LATBSDC规范推出后经历了多个版本的修编,反映了美国性能化设计思路的变化。对比了不同版本LATBSDC规范对性能目标、材料强度与刚度取值、地震输入、阻尼比、最小底部剪力、偶然偏心和扭转位移比、位移限值等方面规定的修订以及与我国规范的异同,以供今后在性能化设计和规范修订中参考。通过对比分析发现我国规范三水准两阶段设计方法具有一定的合理性;在充分采用大震弹塑性动力分析手段验证结构大震性能的情况下,可适当减弱小震弹性分析中的整体性指标的控制;建议我国对于弹塑性动力分析中材料强度取值、初始刚度取值、是否考虑偶然偏心、是否区分峰值弹塑性层间位移角和残余弹塑性层间位移角作出更明确规定;建议更广泛采用地震安全性评估方法确定不同重现期地震输入;建议重新评估高层建筑阻尼比的合理取值方式;建议适当放松正常使用极限状态下的弹性层间位移角限值。

关键词：洛杉矶高层抗震方法替代规程性能化设计多遇地震罕遇地震阻尼比结构变形

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Parameter analysis of composite pile foundation in bridge foundation

引用

Global Geology 2012年第1期15卷 42-47页

作者： li guangxing WANG Rusheng WANG Lei WANG Jinsong College of Construction Engineering Jilin University Changchun 130061 China Key Laboratory of Earth Information Detection Equipment Ministry of Education Changchun 130061 China

In the current theory of bridge foundation design,all of the loads above the cap are loaded by the pile,and the bearing capacity of the soil among piles is not taken into account.In order to analyze the bearing capacity of the soil among piles in bridge pile foundation,a model of pile foundation is established based on a bridge foundation which is under construction,and by the finite element analysis software ANSYS.According to the results of finite element analysis(FEA)and current bridge foundation design theory,a feasible composite pile foundation which can be applied in the design of bridge foundation,is recommended.Additionally,a number of modifications are made to the original design.It was confirmed that these modifications derived from numerical simulations can improve the performance of the foundation.

关键词：桥梁基础基础桩复合地基有限元分析软件桥梁桩基础设计理论 ANSYS 承载能力

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

城市综合体灭火救援技战术的特点及应用

引用

今日消防 2022年第3期7卷 27-29页

作者：李光星青岛市消防救援支队山东青岛266000

当前大型城市综合体建筑普遍存在消防隐患多、大空间立体燃烧的问题,这不仅加剧了城市建筑火灾风险,也增加了火灾发生时人员逃生疏散工作和被困人员救援工作的难度,再加上此类建筑排烟散热性能较差,这导致火灾损失更加严重。为了降低大... 详细信息

当前大型城市综合体建筑普遍存在消防隐患多、大空间立体燃烧的问题,这不仅加剧了城市建筑火灾风险,也增加了火灾发生时人员逃生疏散工作和被困人员救援工作的难度,再加上此类建筑排烟散热性能较差,这导致火灾损失更加严重。为了降低大型城市综合体火灾损失,文章将从如何开展大型城市综合体火灾扑救工作出发,深入研究火灾扑救战术。

关键词：城市综合体灭火救援技战术特点应用

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

不同氮源溶剂热合成N-TiO_2纳米颗粒及其光催化降解气相苯(英文)

引用

催化学报 2013年第12期34卷 2263-2270页

作者：何霏马芳李涛李光兴华中科技大学化学与化工学院湖北武汉430074 华中科技大学大型电池关键材料与系统教育部重点实验室湖北武汉430074

采用三种不同的氮源溶剂热合成了锐钛矿-板钛矿混晶的N-TiO2催化剂.采用X射线衍射、N2吸附-脱附、X射线光电子能谱和透射电子显微镜等手段对催化剂进行了表征.重点研究了不同氮源对催化剂的相组成、晶粒尺寸、微观结构以及比表面积的影... 详细信息

采用三种不同的氮源溶剂热合成了锐钛矿-板钛矿混晶的N-TiO2催化剂.采用X射线衍射、N2吸附-脱附、X射线光电子能谱和透射电子显微镜等手段对催化剂进行了表征.重点研究了不同氮源对催化剂的相组成、晶粒尺寸、微观结构以及比表面积的影响.采用紫外光降解气相苯测试了合成材料的催化活性.结果表明,以水合肼为氮源合成的N-TiO2表现出最优的光催化活性,其活性明显高于P25,且能够循环使用15次以上.采用气相色谱-质谱技术分析了光降解过程的中间产物,基于此提出了相应的降解机理.

关键词：氮掺杂二氧化钛溶剂热合成光催化降解气相苯光催化机理

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

DEliBERATlON TO THE DEFINITION OF TOOTH THICKNESS FOR INVOLUTE HEliCAL GEAR IN INTERNATIONAL STANDARD ISO1122／1

引用

Chinese Journal of Mechanical Engineering 1995年第3期8卷 187-202页

作者： Yang Guoling Chen Minli Xianming Hu guangxing Feng Shenghua li Baosong(Shenyang Institute of Gold Technology)( Shenyang Centre of Robot)

The definitions of the normal chordal tooth thichness and the constant chord in interna-tional standard ISO 1122/1-1983(E) are analyzed according to the basic principle of involute cy-lindrical gear geometry. It is pointed out that in the case of spur gears, the two definitions arerespectively identical with generally recognized traditional formulas, but in the case of helical gears,they are respectively contradictory with their traditional formulas. The general principle of themethod of the two-point measuring for the tooth thickness of gears is analysized, and the calcula-tion formulas of the two-point measuring for the tooth thickness of the involute helical gear ispresented. It is proved theoretically that a constant chord can be measured with the method of thetwo-point measuring (with the tooth thickness caliper) while normal chordal tooth thickness cannot be measured with the tooth thickness caliper (the method of the two-point measuring). The is-sues of the two definitions of the tooth thickness in the international standard are analysed outagain in measurng.

关键词： International standard Normal chordal tooth thickness Constant chordMeasurement of tooth thickness

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：