检索结果-南通市图书馆

2007中国科协年会

作者： Liu Muxing~1 Wang Jingai~(2,4) Liu Lianyou~(2,3) Yan Ping~(2,3) 1.college of City and Environment,Huazhong normal university,Wuhan 430079,china 2.Key Laboratory of Environmental Change and Natural Disaster of Ministry of Education,beijing normal university,beijing 100875,china 3.college of resources science & technology,beijing normal university,beijing 100875,china 4.college of Geography and Remote Sensing sciences,beijing normal university,beijing 100875,china

Ridge-furrow tillage is a kind of conservation tillage widely used for soil and water conservation in agriculture,with crop planted in ridge or *** previous researches mostly focus on the effects of ridge-furrow tillage with crop planted in ridges on crop growth and soil water content,Influence of ridge-forrow tillage with crop planted in furrows are not well documented,despite it is helpful to crop growth in arid and semiarid *** purpose of this study was evaluating the effect of ridge-furrow tillage with different surface configurations and crop planted in furrow,on the efficiency for rainwater harvesting and crop production,to determine the optimal surface configuration of ridge-furrow *** parameters of ridge heights (H) and ridge-furrow ratios (R,ratio between H and furrow width,W) were defined to determine the configuration of ridge-furrow *** field experiments,seasonal dynamic variation of volumetric soil water content, aboveground biomass and yields of oilseed rape (Brassica napus L.) were *** treatments included four kinds of ridge-furrow tillage with oilseed rape planted in furrow and one kind of conventional field tillage (CT) for *** results indicate that relative to CT,ridge-furrow tillage increased volumetric soil water content of the plow layer (0-30 cm) by 4.2%-12.1%,decreased its fluctuation in the growing season of oilseed *** the soil profile under ridge-furrow tillage,soil layer with the highest soil water content appeared in the depth of 0-30 cm,which helped oilseed rape absorb water by *** aboveground biomass,pods per plant and 1000-seed weigh under ridge-furrow tillage were larger than that under *** field comparison of oilseed rape yields under four forrow planting practices with 15,25 cm H and 1/6,1/12,1/24 R,we found the practice with 25 cm H and 1/24 R increased the efficiency of water harvesting,the growth and yield of the oilseed rape more ***,we recommend furr

关键词： ridge-furrow tillage furrow planting volumetric soil water content aboveground biomass theoretical yield rainfed agriculture

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Scenario simulation and forecast of land use/cover in northern china

引用

Chinese science Bulletin 2008年第9期53卷 1401-1412页

作者： LI YueChen 1,2,3 & HE ChunYang 3 1 college of Geographical science, Chongqing normal university, Chongqing 400047, china 2 college of resources and Environmental science, Chongqing university, Chongqing 400044, china 3.college of resources science & technology, beijing normal university, beijing 100875, china college of Geographical science Chongqing Normal University Chongqing 400047 China college of resources and Environmental science Chongqing University Chongqing 400044 China college of resources science & technology Beijing Normal University Beijing 100875 China

Modeling land use/cover scenario changes and its potential impacts on structure and functions of ecosystem in typical regions are helpful to understanding the interactive mechanism between land use/cover system and ecosystem. Based on the analysis of the existing land use/cover simulation and forecast models, a land use/cover scenario dynamics model by the integration of System Dynamics (SD) model, Back Propagation Neural Network (BPNN) and Cellular Automata (CA) model is developed with land use/cover scenario changes in northern china in the next 30 years and simulated in this paper. The model is to simulate the land use/cover scenario demands by using a SD model at first, and then allocating the land use scenario patterns at the local scale with the considerations of land use/cover suitability, inheritance ability and neighborhood effect by using BPNN-CA model to satisfy the balance between land use/cover scenario demands and supplies. It integrates the advantages of SD, BPNN and CA. Macro-driving factors and the micro-spatial pattern are also fully taken into account. The BPNN simplifies the identification of the factors’ weights used in CA model and improves the reliability of the simulation results. The simulation accuracy of the model developed in this paper was found to be about 74%. It suggests that the model has the ability to reflect the complexity of land use/cover system at different scales to some extent and it is a useful tool for assessing the potential impacts of land use system on ecosystem. The simulated results also indicate that the urban land, water area and forest will increase significantly, and farmland and unable land will decrease gradually. Obvious land use/cover changes will take place in the farming-pastoral zone and the southeast area of northern china.

关键词：土地利用中国北方细胞自动机系统动力学

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

Developing land use scenario dynamics model by the integration of system dynamics model and cellular automata model

引用

science china Earth sciences 2005年第11期48卷 1979-1989页

作者： HE Chunyang, SHI Peijun, CHEN Jin, Li Xiaobing, PAN Yaozhong, LI Jing, LI Yuechen & LI Jinggang Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education of china, beijing normal university college of resources science & technology, beijing normal university, beijing 100875, china 1. Key Laboratory of Environmental Change and Natural Disaster Ministry of Education of China Beijing Normal University China 2. college of resources science & technology Beijing Normal University 100875 Beijing China

Modeling land use scenario changes and its potential impacts on the structure and function of the ecosystem in the typical regions are helpful to understanding the interactive mechanism between land use system and ecological system. A Land Use Scenario Dynamics (LUSD) model by the integration of System Dynamics (SD) model and Cellular Automata (CA) model is developed with land use scenario changes in northern china in the next 20 years simulated in this paper. The basic idea of LUSD model is to simulate the land use scenario de-mands by using SD model at first, then allocate the land use scenario patterns at the local scale with the considerations of land use suitability, inheritance ability and neighborhood effect by using CA model to satisfy the balance between land use scenario demands and supply. The application of LUSD model in northern china suggests that the model has the ability to reflect the complex behavior of land use system at different scales to some extent and is a useful tool for assessing the potential impacts of land use system on ecological system. In addition, the simulated results also indicate that obvious land use changes will take place in the farming-pastoral zone of northern china in the next 20 years with cultivated land and urban land being the most active land use types.

关键词： system dynamics, cellular automata, scenario, land use, model

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

Development and application of ergodicity model with FRCM and FLAR for hydrological process

引用

science china(Technological sciences) 2009年第2期52卷 379-386页

作者： WANG HongRui1, FENG QiLei2, LIN Xin3 & ZENG WenYi4 1 college of Water science, Key Laboratory for Water and Sediment sciences of the Ministry of Education, beijing normal university, beijing 100875, china 2 School of science, beijing Institute of Education, beijing 100011, china 3 School of Mathematical sciences, beijing normal university, beijing 100875, china 4 college of Information science and technology, beijing normal university, beijing 100875, china 1. college of Water science Key Laboratory for Water and Sediment Sciences of the Ministry of Education Beijing Normal University Beijing 100875 China 2. School of science Beijing Institute of Education Beijing 100011 China 3. School of Mathematical sciences Beijing Normal University Beijing 100875 China 4. college of Information science and technology Beijing Normal University Beijing 100875 China

In this paper, a new ergodic property analysis model of hydrological process is proposed based on fuzzy-rough c-means clustering (FRCM), autocorrelogram, and fuzzy least absolute regression (FLAR). A precipitation time series (1951―2004) from Shanghai Hydrology Station is then analyzed with the model. The results show that the precipitation time series of April, May, June, and September has er-godic property. We conclude that in the long run, the precipitation of April, May, June, and September will not keep decreasing; it will converge to its mean value in some period.

关键词： hydrological process ergodic autocorrelogram fuzzy-rough c-means clustering fuzzy least absolute regression

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

ENERGY FLOWS IN COMPLEX ECOLOGICAL SYSTEMS:A REVIEW

引用

Journal of Systems science & Complexity 2009年第3期22卷 345-359页

作者： Jiang ZHANG Department of Systems science,School of Management,beijing normal university,beijing 100875,china. Department of Systems science School of Management Beijing Normal University Beijing 100875 China

Energy flow drives the complex systems to *** allometric scaling as the universalenergy flow pattern has been found in different scales of ecological *** reflects the generalpower law relationship between flow and *** underlying mechanisms of energy flow patterns areexplained as the branching transportation networks which can be regarded as the result of systematicoptimization of a biological target under *** flows in the ecological system may bemodelled by the food web model and population dynamics on the *** paper reviews thelatest progress on the energy flow patterns,explanatory models for the allometric scaling and modellingapproach of flow and network evolution dynamics in ***,the possibility of generalizingthese flow patterns,modelling approaches to other complex systems is discussed.

关键词： Allometric scaling energy flow flows in complex systems food web.

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

Functional central limit theorem for super α-stable processes

引用

science china Mathematics 2004年第6期47卷 874-881页

作者： HONG WenmingDepartment of Mathematics, beijing normal university, beijing 100875, china 1. Department of Mathematics Beijing Normal University 100875 Beijing China

A functional central limit theorem is proved for the centered occupation time process of the super α-stable processes in the finite dimensional distribution sense. For the intermediate dimensions α < d < 2α (0 < α ≤ 2), the limiting process is a Gaussian process, whose covariance is specified; for the critical dimension d= 2α and higher dimensions d < 2α, the limiting process is Brownian motion.

关键词： super α-stable processes occupation time central limit theorem evolution equation

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

On asymptotics of t-type regression estimation in multiple linear model

引用

science china Mathematics 2004年第4期47卷 628-639页

作者： GUI HengjianDepartment of Mathematics, beijing normal university, beijing 100875, china 1. Department of Mathematics Beijing Normal University 100875 Beijing China

We consider a robust estimator (t-type regression estimator) of multiple linear regression model by maximizing marginal likelihood of a scaled t-type error *** marginal likelihood can also be applied to the de-correlated response when the withinsubject correlation can be consistently estimated from an initial estimate of the model based on the independent working assumption. This paper shows that such a t-type estimator is consistent.

关键词： t-type regression estimator, M-estimator, one-step estimate, consistency, asymptotic normality.

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 secure multi-party computation solution to intersection problems of sets and rectangles

引用

Progress in Natural science:Materials International 2006年第5期16卷 538-545页

作者： LI Shundong, DAI Yiqi, WANG Daoshun and LUO Ping (Department of Computer science and technology, beijing normal university, beijing 100875, china Department of Computer science and technology, Tsinghua university, beijing 100084, china) [a]Department of computer science and technology Beijing Normal University Beijing China [b]Department of Computer science and technology Tsinghua University Beijing China

Secure multi-party computation (SMC) is a research focus in international cryptographic community. At present, there is no SMC solution to the intersection problem of sets. In this paper, we first propose a SMC solution to this problem. Applying Cantor encoding method to computational geometry problems, and based on the solution to set-intersection problem, we further propose solutions to points inclusion problem and intersection problem of rectangles and further prove their privacy-preserving property with widely accepted simulation paradigm. Compared with the known solutions, these new solutions are of less computational complexity and less communication complexity, and have obvious superiority in computational and communication complexity.

关键词： Cantor encoding secure multi-party computation set-intersection rectangle-intersection computational complexity.

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

Research progress in studies on the coalbed gas geochemistry

引用

Progress in Natural science:Materials International 2006年第3期16卷 215-220页

作者： TAO Mingxin (college of resources sciences & technology, beijing normal university, beijing 100875, china Key Laboratory of Gas Geochemistry, Institute of Geology and Geophysics, Chinese Academy of sciences, Lanzhou 730000, china) [a]college of resources sciences & technology Beijing Normal University Beijing China [b]Key Laboratory of Gas Geochemistry Institute of Geology and Geophysics Lanzhou China

The current situation of geochemical studies on coalbed gas is reviewed in this paper. Generally, coalbed gas is composi-tionally dominated by methane with δ13C1 values ranging approximately from - 80‰ to - 10‰. However, few isotopic studies have been carried out on other components of coalbed gas except for hydrogen and carbon dioxide, whose δDCH4 values available for utilization vary from - 333‰ to - 117‰, and δ13CCO2 values from - 29. 4‰ to + 18. 6‰. Two major types of coalbed gas, thermogenic gas and secondary biogenic gas, have been identified, and there are also some other classification criteria. Compared with conventional natural gases, coalbed gas has a wide distribution range of δ13C1 and δ13CCO2 values, especially possessing some extremely heavy values. Current problems that remain unsolved in the coalbed gas geochemistry include the variation mechanism, controlling factors and application of carbon and hydrogen isotopes of methane, the relation between the values of δ13C1 and Ro, the systematic classification scheme and criterion of genetic types, and the application of the coalbed gas geochemistry in evaluating target districts of the coalbed gas exploration.

关键词： coalbed gas geochemistry isotopic composition genetic type novel resource.

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

Entropy number and non-linear approximations on multivariate Besov space by manifolds of finite pseudo-dimension

引用

Progress in Natural science:Materials International 2006年第3期16卷 260-265页

作者： LONG Jingfan and FANG Gensun (School of Mathematical sciences, beijing normal university, beijing 100875, china Department of Computer science, Information technology Institute, beijing 100101, china) [a]School of Mathematical sciences Beijing Normal University Beijing China [b]Department of Computer science Information Technology Institute Beijing China

We determine the asymptotic order of entropy number and optimal non -linear approximations of anisotropic periodic Besov class of Bpθr(Td') (1≤p≤∞,1≤0≤∞) by manifolds of finite pseudo-dimension in the metric Lq... 详细信息

关键词： Pseudo-dimension anisotropic Besov class of functions entropy number nonlinear width.

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

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：