检索结果-南通市图书馆

Velocity Space of Galactic O-B Stars

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and Astrophysics 2006年第3期6卷 363-371页

作者： Zi Zhu Department of Astronomy Nanjing University Nanjing 210093

Based on the Hipparcos proper motions and available radial velocity data of O-B stars, we have re-examined the local kinematical structure of the young disk population of 1500 O-B stars not including the Gould-belt stars. A systematic warping motion of the stars about the direction to the Galactic center has been reconfirmed. A negative K-term implying a systematic contraction of stars in the solar vicinity has been detected. Two different distance scales are used in order to find out their impact on the kinematical parameters, and we conclude that the adopted distance scale plays an important role in characterizing the kinematical parameters at the present level of the measurement uncertainty.

关键词： astrometry - Galaxy: kinematics and dynamics - stars: early-type - Galaxy:solar neighborhood

A MODIFIED CONJUGATE DIRECTION METHOD FOR COMPUTING THE PSEUDOINVERSF

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1994年第2期12卷 185-194页

作者： Zhao Jin-xi (Dept. of Math., nanjing University, nanjing,China) 南京大学数学系江苏南京

In this paper we are concerned with the modified conjugate direction method for computing the pseudoinverse by using an orthogonal basis of the range space of A. Numerical results show that the new method retains some... 详细信息

关键词： A MODIFIED CONJUGATE DIRECTION METHOD FOR COMPUTING THE PSEUDOINVERSF ATA

Effects of free iron oxyhydrates and soil organic matter on copper sorption-desorption behavior by size fractions of aggregates from two paddy soils

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2009年第5期21卷 618-624页

作者： WANG Fang, PAN Genxing, LI Lianqing Institute of Resource, Ecosystem and Environment of Agriculture, nanjing Agricultural University, nanjing 210095, China. [a]Institute of Resource Ecosystem and Environment of Agriculture Nanjing Agricultural University Nanjing 210095 China

Effects of free iron oxyhydrates （Fed） and soil organic matter （SOM） on copper （Cu^2＋） sorption-desorption behavior by size fractions of aggregates from two typical paddy soils （Ferric-Accumulic Stagnic Anthrosol （Soil H） and Gleyic Stagnic Anthrosol （Soil W）） were investigated with and without treatments of dithionite-citrate-bicarbonate and of H2O2. The size fractions of aggregates were obtained from the undisturbed bulk topsoil using a low energy ultrasonic dispersion procedure. Experiments of equilibrium sorption and subsequent desorption were conducted at soil water ratio of 1：20, 25℃. For Soil H, Cu^2＋ sorption capacity of the DCB-treated size fractions was decreased by 5.9% for fine sand fraction, by 40.4% for coarse sand fraction, in comparison to 2.9% for the bnlk sample. However, Cu^2＋ sorption capacities of the H2O2-treated fractions were decreased by over 80% for the coarse sand fraction and by 15% for the clay-sized fraction in comparison to 88% for bulk soil. For Soil W, Cu^2＋ sorption capacity of the DCB-treated size fraction was decreased by 30% for the coarse sand fraction and by over 75% for silt sand fraction in comparison to 44.5% for the bulk sample. Cu^2＋ sorption capacities of the H2O2-treated fractions were decreased by only 2.0% for the coarse sand fraction and by 15% for the fine sand fraction in comparison to by 3.4% for bulk soil. However, Cu^2＋ desorption rates were increased much in H2O2-treated samples by over 80% except the clay-sized fraction （only 9.5%） for Soil H. While removal of SOM with H2O2 tendend to increase the desorption rate, DCB- and H2O2-treatments caused decrease in Cu^2＋ retention capacity of size fractions, Particularly, there hardly remained Cu^2＋ retention capacity by size fractions from Soil H after H2O2 treatment except for clay-sized fraction. These findings supported again the dominance of the coarse sand fraction in sorption of metals and the preference of absorbed metals bound to SOM in differently stabilized

关键词： paddy soils Cn^2+ sorption-desorption soil organic matter free iron oxyhydrates size fraction of aggregates

Landscape structure and land uese on county level in northeastern Yunnan Province of China——a case study of Huize County

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2000年第3期12卷 355-360页

作者： WANG Jin\|liang, NI Shao\|xiang (College of Geographical Science, nanjing Normal University, nanjing 210097, China) 南京师范大学江苏南京 2 1 0 0 97

Taking Huize County as an example, the paper analyzed the landscape structure(landscape element structure, landscape type structure, landscape spatial structure, landscape succession structure) and the relations between landscape structure and land use. It was pointed out that the agriculture should be developed in harmony with the landscape structure in the study area.

关键词： landscape structure land use agriculture Yunnan Province China

Distributed GEP query optimization on grid service

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2010年第3期17卷 118-122,128页

作者： DENG Yong, WANG Ru-chuan College of Computer, nanjing University of Posts and Telecommunications, nanjing 210003, China [a] College of Computer Nanjing University of Posts Telecommunications Nanjing 210003 China

In order to better solve the problem of distributed query optimization, a query optimization algorithm on gene expression programming （GEP）（QO-GEP） is presented. On the basis of QO-GEP, distributed GEP query optimization on grid service （DGEPQO-GS） is proposed which combines grid service. Simulated experiments show that with the increment of the number of query relation, query time which QO-GEP carries out query decreases apparently. Meanwhile, with the increase of the number of grid nodes, the average querying success rate of DGEPQO-GS increases significantly.

关键词： gene expression programming distributed query grid service query relation

Karst conduit flow and its hydrodynamic characteristics——Houzhai River drainage basin in Fueling,Guizhou,China as an example

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第S1期46卷 45-51页

作者： WANG Lachun & ZHANG YongzhanDepartment, of Urban & Resource Sciences, nanjing University, nanjing 210093, China Key Laboratory of Coast & Island Development of Ministry of Education of China, nanjing University, nanjing 210093, China 1. Department of Urban & Resource Sciences Nanjing University 210093 Nanjing China 2. Key Laboratory of Coast & Island Development of Ministry of Education of China Nanjing University 210093 Nanjing China

Conduit flow is a special geomorphologic and hydrological phenomenon in karst area. Houzhai River drainage basin in Puding, Guizhou Province is a large-scale test field in the main and broad karst area in the southern part of China, where conduit flow is a general reserve and drainage system for groundwater. Based on the great deal of field investigation and indoor research work during the 1970s-1980s, pulse tests were done four times there during 1988-1991 in wet and dry seasons. It shows that water level at each observation site changes from 10 to 1800 mm, with the larger variation in upper stream and at karst windows than in lower reaches and at each exit along subterraneous rivers. The average flow velocity in conduit system is determined within 200-800 m/h, with the less change from flood to dry seasons, and it is higher in principal conduits and in upper stream area. Also, the reliable divided discharge ratio among each hydrological conduit of sunken system has been got. Thus, combined with

关键词： conduit flow karst pulse test Houzhai River.

Recent progress of solar physics research in China

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2011年第12期11卷 1377-1402页

作者： Cheng Fang 1 School of Astronomy and Space Science,nanjing University,nanjing 210093,China 2 Key Laboratory of Modern Astronomy and Astrophysics(nanjing University),Ministry of Education,China School of Astronomy and Space Science Nanjing University Nanjing 210093 China Key Laboratory of Modern Astronomy and Astrophysics (nanjing University) Ministry of Education China

Owing to the largely improved facilities and working conditions, solar physics research in China has recently shown marked development. This paper reports on the recent progress of solar physics research in China's Mainland, mainly focusing on several hot issues, including instrumentations, magnetic field observations and research, solar flares, filaments and their eruptions, coronal mass ejections and related processes, as well as active regions and the corona, small-scale phenomena, solar activity and its predictions. A vision of the future is also described.

关键词： Sun: general -- Sun: coronal mass ejections (CMEs) -- solar physics:recent progress

Multi-dimensional scattering properties diagnosis system of scale aircraft model in an anechoic chamber

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2014年第4期25卷 588-595页

作者： Chufeng Hu Zhou Zhou nanjing Li Kun Zhang National Key Laboratory of Science and Technology on UAV Northwestern Polytechnical University Electronic Information Department Northwestern Polytechnical University

Aiming at the concept of ＂diagnosis＂, a simple and effective broadband radar cross section （RCS） measurement system is constructed, and some multi-dimensional scattering properties diagnosis techniques are presented based on the system. Firstly, a stepped-frequency signal is employed to achieve high range resolution, combining with a variety of signal processing tech- niques. Secondly, cross-range resolution is gained with a rotating table, and the high-resolution two-dimensional （2-D） imaging of the scale model is obtained by the microwave imaging theory. Finally, two receiving antennas with a small distance in altitude are used, and the three-dimensional （3-D） height distribution of scattering points on the scale model is extracted from the phase of images. Some typical bodies and a scale aircraft model are diagnosed in an anechoic chamber. The experimental results show that, after scaling with a metal sphere, the accurate one- dimensional （l-D） RCS pattern of the model is obtained, and it has a large dynamic range. When the bandwidth of the transmitting signal is 4 GHz, the resolution of the 2-D image can reach to 0.037 5 m. The 3-D height distribution of scattering points is given by interferometric measurement. This paper provides a feasible way to obtain high-precision scattering properties parameters of the scale aircraft model in a conventional rectangular anechoic chamber.

关键词： diagnosis stepped-frequency multi-dimension anechoic chamber.

Existence and stability of solutions to inverse variational inequality problems

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2017年第5期38卷 749-764页

作者： Yu HAN nanjing HUANG Jue LU Yibin XIAO Department of Mathematics Sichuan University School of Mathematical Sciences University of Electronic Science and Technology of China

In this paper, two new existence and quasi-variational inequality problems are theorems of solutions to inverse variational proved using the Fan-Knaster-Kuratowski- Mazurkiewicz （KKM） theorem and the Kakutani-Fan-Glicksberg fixed point theorem. Upper semicontinuity and lower semicontinuity of the solution mapping and the approximate solution mapping to the parametric inverse variational inequality problem are also discussed under some suitable conditions. An application to a road pricing problem is given.

关键词： inverse variational inequality Fan-Knaster-Kuratowski-Mazurkiewicz (KKM)theorem Kakutani-Fan-Glicksberg fixed point theorem upper semicontinuity lower semicontinuity