检索结果-南通市图书馆

Strong Spatial Aggregation of Martian Surface Temperature Shaped by Spatial and Seasonal Variations in Meteorological and Environmental Factors

引用

Research in Astronomy and Astrophysics 2022年第1期22卷 156-173页

作者： Yao-Wen Luo Fei Li jian-guo yan Jean-Pierre Barriot Chinese Antarctic Center of Surveying and Mapping Wuhan UniversityWuhan430070China State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan430070China Observatoire Geodesique de Tahiti University of French PolynesiaBP 6570F-98702 Faa'aTahitiFrench Polynesia

Spatio-temporal variation in the Martian surface temperature(MST)is an indicator of ground level thermal processes and hence a building block for climate ***,the distribution of MST exhibits different levels of spatial aggregation or heterogeneity,and varies in space and ***,the effect of regional differences in meteorological or environmental factors on the MST is not well ***,we investigated the degree of spatial autocorrelation of MST across the surface of Mars globally by Moran’s I,and identified the hot spots by GetisOrd G;*.We also estimated the regional differences in the influence of seasonally dominant factors including thermal inertia(TI),albedo,surface pressure,latitude,dust and slope on MST by a geographically weighted regression *** results indicate(1)that MST is spatially aggregated and hot and cold spots varied over time and space.(2)Hemispheric differences in topography,surface TI and albedo were primarily responsible for the hemispheric asymmetry of hot spots.(3)The dominant factors varied by geographical locations and *** example,the seasonal Hadley circulation dominates at the low-latitudes and CO;circulation at the high-latitudes.(4)Regions with extreme variations in topography and low TI were sensitive to meteorological and environmental factors such as dust and CO_(2)*** conclude that the spatial autocorrelation of MST and the spatial and seasonal heterogeneity of influencing factors must be considered when simulating Martian climate *** work provides a reference for further exploration of Martian climatic processes.

关键词： methods:analytical planets and satellites:surfaces methods:statistical planets and satellites:fundamental parameters

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

Application of the Bayes’ theory to the failure rate evaluation of electrical apparatus

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第3期8卷 501-505页

作者： JIN Shao-hua LU jian-guo WAN yan-ping SUN Shu-guang Department of Mathematics Hebei University of Technology Tianjin 300130 China

The Weibull distribution has been widely used in reliability fields. A mixed Weibull distribution represents a popu- lation that consists of several Weibull subpopulations. In this paper, a new approach which combines the least-squares method with Bayes’ theorem, takes advantage of the parameter estimation for single Weibull distribution is developed to estimate the pa- rameters of each subpopulation. The estimates given by this paper also satisfy the maximum likelihood equation. The estimates of the failure rate of the mixed Weibull population are given. An actual test data is computed by using the proposed method. The Kolmogorov-Smirnov goodness-of-fit test turns out that the proposed method yields more accurate result.

关键词： Bayesian estimation Failure rate Least-squares method Maximum likelihood principle Mixed-Weibull distribution

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

Hydrothermal Synthesis,Crystal Structure and Thermal Analysis of a Dinuclear Complex Cd_2(3,5-Dinitrobenzoate)_4(pyridine)_4

引用

Chinese Journal of Structural Chemistry 2006年第11期25卷 1297-1302页

作者： guo Jin-Yu ZHANG Tong-Lai ZHANG jian-guo LIU yan-Hong QIAO Xiao-Jing yanG Li State Key Laboratory of Explosion Science and Technology Beij＇ing Institute of Technology Beij＇ing 100081 China

A dinuclear complex Cd2（dnba）4（pyridine）4 （dnba = 3,5-dinitrobenzoate） has been synthesized by hydrothermal method and characterized by X-ray single-crystal diffraction, elemental analysis, FT-IR spectroscopy, DSC and TG-DTG techniques. The complex with empirical formula C48H32Cd2NI2024 （Mr = 692.83） crystallizes in monoclinic, space group P21/n with a - 12.0344（14）, b = 10.5752（13）, c = 21.578（3） A, β = 104.150（2）°, V = 2662.8（6） A^3, Z = 2, D, = 1.728 g/cm^3,μ（MoKa） = 0.897 mm^-1, F（000） = 1384, S = 1.016 and （△/σ）max = 0.001. R = 0.0638 and wR = 0.0737 for all data; the final R = 0.0337 and wR = 0.0644. In this complex, four carboxylates are bidentate-or chelate-coordinated with the Cd（Ⅱ） centers to give the dinuclear structure. The other coordination positions of Cd（Ⅱ） are occupied by the lone pair electrons from N of four pyridines. Thermal analyses DSC and TG-DTG have been used to determine the thermal decomposition mechanism of the title complex.

关键词： hydrothermal synthesis dinuclear complex crystal structure thermal analysis

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

Influence of the layered Moon and Earth’s orientation on lunar rotation

引用

Research in Astronomy and Astrophysics 2020年第2期20卷 45-52页

作者： Yong-Zhang yang Jin-Song Ping jian-guo yan Jin-Ling Li State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430070China Instituto de Astronomia y Ciencias Flanetarias de Atacama Universidad de AtacamaCopayapu 485Chile National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China University of Chinese Academy of Sciences Beijing 100049China

One of the most efficient ways to probe the lunar inner structure at present is through the study of its *** and range rate(Doppler) data between the Chang’E-3 lander and station on the Earth were collected from the beginning of the Chang’E-3 lunar mission in *** observation data,taken together with the existing lunar laser ranging data,provide a new approach to extend research on the Earth-Moon *** high precision of current observation data imposes exacting demands,making it necessary to include previously neglected *** this paper,motivated by progress of the Chinese lunar exploration project and to use its data in the near future,two lunar models:a one-layer model and a two-layer model with a fluid core,were applied to the rotational equations based on our implemented algorithm of the Moon’s *** was a difference of about 0.5′′in φ and ψ,but 0.2′′in θ between the two *** result confirms that stratification of the inner structure of the Moon can be inferred from rotation *** also added precise Earth rotation parameters in our model;the results show that this factor is negligible at present,due to the limited precision of the existing *** results will help us understand the rotational process clearly and build a more realistic Earth-Moon model when we combine Lunar Laser Ranging data with high precision radio data to fit lunar motion in the near future.

关键词： Moon rotation model numerical integration Earth orientation parameters

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

Method for differential phase delay resolution of phase referencing VLBI technique and its experimental verification

引用

Research in Astronomy and Astrophysics 2021年第11期21卷 267-272页

作者： Huan Zhou jian-guo yan De-Zhen Xu Yong Huang Hai-Tao Li State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430070China Beijing Institute of Tracking and Telecommunications Technology Beijing 100094China Shanghai Astronomical Observatory Chinese Academy of ScienceShanghai 200030China

The phase referencing Very Long Baseline Interferometry(VLBI)technique is a newly developed tool to measure the angular position of a deep space exploration probe in the *** alternating observations between the probe and a nearby reference radio source,their accurate relative angular separation can be obtained from the radio images generated by this *** meet the requirements of the current orbit determination software,differential delay should be firstly derived from those radio images.A method to resolve the differential phase delay from the phase referencing VLBI technique is proposed in this paper,and as well the mathematical model for differential phase ambiguity resolution is *** method is verified with practical measurement data from the Chang’E-3 *** differential phase delay between the Chang’E-3 lander and rover was derived from the phase referencing VLBI measurements,and was then imported into the Shanghai astronomical observatory Orbit Determination Program(SODP)to calculate the position of the rover relative to the lander on the lunar *** results are consistent with those acquired directly from radio images,indicating that the differential phase ambiguity has been correctly *** proposed method can be used to promote applications of the phase referencing VLBI technique in future lunar or deep space explorations,and more accurate orbit determination becomes promising.

关键词： Phase referencing VLBI technique differential phase delay radio interferometry Chang’E-3 mission

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

Green and controllable metal-free nitrification and nitration of arylboronic acids

引用

Chinese Chemical Letters 2012年第6期23卷 643-646页

作者： Shuai Wang Chun Chun Shu Tao Wang jian Yu guo Bing yan Department of Chemistry Lishui University Lishui 32300 China

A novel and green nitrating reagent has been developed for the nitrification and nitration of arylboronic acids, which can be controlled by the reaction conditions. The process provides an attractive alternative to th... 详细信息

关键词： Nitrification Nitration Arylboronic acids

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

FeBr_3-catalyzed dibromination of alkenes and alkynes

引用

Chinese Chemical Letters 2011年第10期22卷 1195-1198页

作者： Yun Fa Zheng jian Yu guo Bing yan Xu Li Song Luo Department of Chemistry Lishui University Lishui 323000 China

The dibromination of alkenes and alkynes with bromosuccinimide and sodium bromide catalyzed by FeBr_3 under mild conditions has been *** trans-dibromo compounds were exclusively obtained with excellent yields.

关键词： Dibromination Alkenes and alkynes Iron catalyst

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

A new method for resolving phase ambiguity in radio interferometry using Earth rotation synthesis

引用

Research in Astronomy and Astrophysics 2021年第7期21卷 115-122页

作者： Huan Zhou De-Zhen Xu jian-guo yan Shao-Wu Chen Hai-Tao Li State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430070China Beijing Institute of Tracking and Telecommunications Technology Beijing 100094China

As a key technique in deep space navigation, radio interferometry can be used to determine the accurate location of a spacecraft in the plane-of-sky by measuring its signal propagation time delay between two remote stations. To improve the measurement accuracy, differential phase delay without phase ambiguity is usually desired. Aiming at the difficulties of resolving phase ambiguity with few stations and narrowband downlink signals, a new method is proposed in this work by taking advantage of the Earth rotation. The high accurate differential phase delay between the spacecraft and a calibrator can be achieved not only in the in-beam observation mode but also in the out-of-beam observation mode. In this paper we firstly built the model of phase ambiguity resolution. Then, main measurement errors of the model are analyzed, which is followed by tests and validations of the model and method using the tracking data of the Cassini mission and Chang'E-3 mission. The results show that the phase ambiguities can be correctly resolved to generate a 10-picosecond level accuracy differential phase delay. Angular measurement accuracy of the Cassini reaches the milli-arc-second level, and the relative position accuracy between the Chang'E-3 rover and lander reaches the meter level.

关键词： radio interferometry Earth rotation synthesis phase ambiguity differential phase delay Cassini mission Chang'E-3 mission

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

A new method to determine the gravity field of small bodies from line-of-sight acceleration data

引用

Research in Astronomy and Astrophysics 2019年第3期19卷 155-164页

作者： Nian-Chuan jian jian-guo yan Jin-Song Ping Jean-Pierre Barriot J.Alexis P.Rodriguez Shanghai Astronomical Observatory Chinese Academy of Science State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Instituto de Astronomia y Ciencias Planetarias de Atacama Universidad de Atacama National Astronomical Observatory of China Chinese Academy of Science University of French Polynesia Geodesy Observatory of Tahiti Laboratoire GEPASUD Planetary Science Institute

We present a new method to derive line-of-sight acceleration observables from spacecraft radio tracking data. The observables can be used to estimate the mass and gravity of a natural satellite as a spacecraft flyby. The corresponding observation model adapts to one-way and two/three-way tracking modes. As a test case for method validation and application, we estimated the mass and degree two gravity field for the Martian moon Phobos using simulated tracking data when the spacecraft Mars Express flew by Phobos on 2013 December 29. We have a few real tracking data during flyby and they will be used to confirm raw data simulation. The main purpose of this paper is to demonstrate the method of line-of-sight acceleration reduction from raw tracking data and the feasibility to estimate mass and gravity of a natural satellite using this type of observable. This novel method is potentially applicable to planet and asteroid gravity field studies combined with Doppler tracking data.

关键词： line of sight acceleration-Doppler-celestial mechanics

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

Processing of a low-costγ-γ'NiPtAl coating with improved oxidation resistance

引用

Rare Metals 2024年第6期43卷 2832-2841页

作者： yan jiang Liang-Liang Wei jian He Hong-Bo guo School of Materials Science and Engineering Beihang UniversityBeijing 100191China Key Laboratory of High-Temperature Structural Materials and Protective Coatings Ministry of Industry and Information TechnologyBeihang UniversityBeijing 100191China

A novelγ-γ'(Ni solid solution—Ni_(3)Al)NiPtAl coating was produced on advanced single-crystal(SC)superalloy N5 by electroplating of a thin Pt coating with~3μm in thickness followed by heat treatment at 1000℃in *** comparison,a traditionalγ-γ'NiPtAl coating was also produced by electroplating of a thick Pt coating with~6μm in thickness followed by heat treatment at 1100℃in *** novel coating has a mass gain of~0.5 mg·cm^(-2)after 100 h 1-h cyclic oxidation at 1150℃,showing better oxidation resistance than the traditional *** oxide scale mostly consisting ofα-Al_(2)O_(3)grew on the novel coating because the element Cr from the SC alloy substrate contributes to the formation ofα-Al_(2)O_(3).Pt content in the novel coating has significant effect on the oxidation *** optimized Pt content in the coating is about 16 at%,which is helpful to reduce the diffusion of harmful elements from the substrate into the coating but also to reduce the cost of the coating.

关键词： γ-γ'NiPtAl coating Platinum Oxidation Al_(2)O_(3) Superalloy

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：