检索结果-南通市图书馆

Soil erosion and sediment transport in the gullied Loess Plateau:Scale effects and their mechanisms

Science china(Technological Sciences) 2009年第5期52卷 1283-1292页

作者： LI TieJian1,WANG GuangQian1,XUE Hai2,3 & WANG Kai4 1 state key laboratory of hydroscience and engineering,tsinghua university,beijing 100084,china 2 Yellow River engineering Consulting Co.,Ltd.,Zhengzhou 450003,china 3 North china Institute of Water Conservancy and Hydropower,Zhengzhou 450008,china 4 china Institute of Water Resources and Hydropower Research,beijing 100038,china 1. state key laboratory of hydroscience and engineering Tsinghua University Beijing 100084 China 2. Yellow River engineering Consulting Co. Ltd. Zhengzhou 450003 China 3. North china Institute of Water Conservancy and Hydropower Zhengzhou 450008 China 4. china Institute of Water Resources and Hydropower Research Beijing 100038 China

Scale effects exist in the whole process of rainfall-3-runoff-3-soil erosion-3-sediment transport in river basins. The differences of hydrographs and sediment graphs in different positions in a river basin are treated as basic scale effects, which are more complex in the gullied Loess Plateau, a region notorious for high intensity soil erosion and hyper-concentrated sediment-laden flow. The up-scaling method of direct extrapolation that maintains dynamical mechanism effective in large scale application was chosen as the methodology of this paper. Firstly, scale effects of hydrographs and sediment graphs were analyzed by using field data, and key sub-processes and their mechanisms contributing to scale effects were clearly defined. Then, the Digital Yellow River Model that integrates sub-models for the subprocesses was used with high resolution to simulate rainfall-3-runoff-3-soil erosion-3-sediment transport response in Chabagou watershed, and the distributed results representing scale effects were obtained. Finally, analysis on the simulation results was carried out. It was shown that gravitational erosion and hyper-concentrated flow contribute most to the spatial variation of hydrographs and sediment graphs in the spatial scale. Different spatial scale distributions and superposition of different sub-processes are the mechanisms of scale effects.

关键词： scale effect soil erosion hyper-concentrated sediment-laden flow the Loess Plateau

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

Quantum threshold group signature

引用

Science china(Physics,Mechanics & Astronomy) 2008年第10期51卷 1505-1514页

作者： YANG YuGuang1,2,3 & WEN QiaoYan4 1 College of Computer Science and Technology, beijing university of Technology, beijing 100124, china 2 state key laboratory of Integrated Services Network, Xidian university, Xi’an 710071, china 3 state key laboratory of Information Security (Graduate university of Chinese Academy of Sciences), beijing 100049, china 4 state key laboratory of Networking and Switching Technology, beijing university of Posts and Tele-communications, beijing 100876, china College of Computer Science and Technology Beijing University of Technology Beijing 100124 China state key laboratory of Integrated Services Network Xidian University Xi’an 710071 China state key laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing 100049 China state key laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

In most situations, the signer is generally a single person. However, when the message is written on behalf of an organization, a valid message may require the approval or consent of several persons. Threshold signature is a solution to this problem. Generally speaking, as an authority which can be trusted by all members does not exist, a threshold signature scheme without a trusted party appears more attractive. Following some ideas of the classical Shamir’s threshold signature scheme, a quantum threshold group signature one is proposed. In the proposed scheme, only t or more of n persons in the group can generate the group signature and any t-1 or fewer ones cannot do that. In the verification phase, any t or more of n signature receivers can verify the message and any t-1 or fewer receivers cannot verify the validity of the signature.

关键词： threshold quantum signature trusted party quantum cryptography

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 ALGORITHM FOR PURX O-1 LINEAR PROGRAMS WITH INEQUALITY CONSTRAINTS

引用

Systems Science and Mathematical Sciences 1996年第1期9卷 50-54页

作者： CHEN Jianfei(Biochemical engineering state key laboratory,beijing 100080,china)XIA Shaowei(Department of Automation, tsinghua university, beijing 100084,china)

ＡＮＥＷＡＬＧＯＲＩＴＨＭＦＯＲＰＵＲＸＯ－１ＬＩＮＥＡＲＰＲＯＧＲＡＭＳＷＩＴＨＩＮＥＱＵＡＬＩＴＹＣＯＮＳＴＲＡＩＮＴＳ￥ＣＨＥＮＪｉａｎｆｅｉ（ＢｉｏｃｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇＳｔａｔｅＫｅｙＬａｂ... 详细信息

ＡＮＥＷＡＬＧＯＲＩＴＨＭＦＯＲＰＵＲＸＯ－１ＬＩＮＥＡＲＰＲＯＧＲＡＭＳＷＩＴＨＩＮＥＱＵＡＬＩＴＹＣＯＮＳＴＲＡＩＮＴＳ￥ＣＨＥＮＪｉａｎｆｅｉ（ＢｉｏｃｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙ，Ｂｅｉｊｉｎｇ１０...

关键词： Neural network pure 0-1 linear program near-optimal solution simplex algorithm.

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

Threshold quantum secret sharing between multi-party and multi-party

引用

Science china(Physics,Mechanics & Astronomy) 2008年第9期51卷 1308-1315页

作者： YANG YuGuang1,2,3 & WEN QiaoYan4 1 College of Computer Science and Technology,beijing university of Technology,beijing 100124,china 2 state key laboratory of Integrated Services Network,Xidian university,Xi’an 710071,china 3 state key laboratory of Information Security (Graduate university of Chinese Academy of Sciences),beijing 100049,china 4 state key laboratory of Networking and Switching Technology,beijing university of Posts and Tele-communications,beijing 100876,china College of Computer Science and Technology Beijing University of Technology Beijing 100124 China state key laboratory of Integrated Services Network Xidian University Xi’an 710071 China state key laboratory of Information Security (Graduate university of Chinese Academy of Sciences) Beijing 100049 China state key laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

A threshold quantum secret sharing (TQSS) scheme between multi-party and multi-party was proposed using a sequence of single photons,which is useful and efficient when the parties of communication are not all present. We described the process of this TQSS scheme and discussed its security. It was shown that entan-glement is not necessary for quantum secret sharing. Moreover,the theoretic effi-ciency was improved to approach 100% as almost all the instances can be used for generating the private key,and each photon can carry one bit of information. This protocol is feasible with the present-day technique.

关键词： threshold quantum secret sharing quantum cryptography single photon multi-party and multi-party

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

Threshold proxy quantum signature scheme with threshold shared verification

引用

Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 1079-1088页

作者： YANG YuGuang1,3,4 & WEN QiaoYan2 1 College of Computer Science and Technology,beijing university of Technology,beijing 100124,china 2 state key laboratory of Networking and Switching Technology,beijing university of Posts and Tele-communications,beijing 100876,china 3 state key laboratory of Integrated Services Network,Xidian university,Xi’an 710071,china 4 state key laboratory of Information Security(Graduate university of Chinese Academy of Sciences) ,beijing 100049,china 1. College of Computer Science and Technology Beijing University of Technology Beijing 100124 China 3. state key laboratory of Integrated Services Network Xidian University Xi’an 710071 China 4. state key laboratory of Information Security (Graduate university of Chinese Academy of Sciences) Beijing 100049 China 2. state key laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

A threshold proxy quantum signature scheme with threshold shared verification is proposed. An original signer could authorize a group as its proxy signers. Then only t or more of n persons in the proxy group can generate the proxy signature on behalf of the original signer and any t-1 or fewer ones cannot do that. When the proxy signature needs to be verified,any t or more of n persons belonging to the verification group can verify the message and any t-1 or fewer ones cannot verify the validity of the proxy signature.

关键词： quantum signature threshold proxy quantum group signature threshold shared verification

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

Fuzzy tolerance quotient spaces and fuzzy subsets

引用

Science china(Information Sciences) 2010年第4期53卷 704-714页

作者： ZHANG Ling1 & ZHANG Bo2,3,4* 1Computer Science & Technology College, Anhui university, Anhui 230039, china 2state key laboratory of Intelligent Technology and Systems, beijing 100084, china 3tsinghua National laboratory of Information Science & Technology, beijing 100084, china 4Information Science & Technology College, Computer Science & Technology Department, tsinghua university, beijing 100084, china 1. Computer Science & Technology College Anhui University Anhui 230039 China2. State Key Laboratory of Intelligent Technology and Systems Beijing 100084 China3. Tsinghua National Laboratory of Information Science & Technology Beijing 100084 China4. Information Science & Technology College Computer Science & Technology Department Tsinghua University Beijing 100084 China

The structure and characteristic of fuzzy subsets are discussed by using the concepts of granulation and hierarchy in quotient space theory. First, the equivalence relation based quotient space theory is extended to the fuzzy tolerance relation. Second, the isomorphism and its discriminant of fuzzy tolerance relations are discussed. Finally, by using the fuzzy tolerance relation to define the fuzzy subset, its properties are addressed. The main results are given below: (1) several equivalent statements of fuzzy tolerance relations; (2) the definition of isomorphism of fuzzy tolerance relations; (3) the isomorphic discriminant of fuzzy tolerance relations; (4) the definition and properties of fuzzy subsets based on the fuzzy tolerance relations; and (5) the necessary and sufficient condition of the isomorphism of fuzzy subsets. These results will help us further comprehend the concepts of fuzzy tolerance relations and fuzzy subsets.

关键词： Fuzzy tolerance relation quotient space isomorphism fuzzy subset

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

The Construction of Numerical Scheme forHyperbolic Equation and Exact Considerationof Numerical Diffusion and Dispersion

引用

Communications in Nonlinear Science and Numerical Simulation 1999年第2期4卷 156-162页

作者： Qingdong CAI(state key laboratory for Turbulence Research, Peking university, beijing 100871, china) state key laboratory for Turbulence Research Peking University Beijing 100871 China

A new technique in the formulation of numerical scheme for hyperbolicequation is developed. It is different from the classical FD and FE methods. We begin withthe algebraic equations with some undefined parameters, and get the difference equationthrough Taylor-series expansion. When the parameters in the partial difference equationare defined, the equation is what the scheme will simulate. The numerical example ofthe viscous Burgers equation shows the validity of the scheme. This method deals withthe numerical viscosity and dispersion exactly, giving a preliminary explanation to someproblems that the CFD face now.

关键词： modified equation Taylor expansion consistency truncation error

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

A 2-D HYDRODYNAMIC MODEL FOR THE RIVER,LAKE AND NETWORK SYSTEM IN THE JINGJIANG REACH ON THE UNSTRUCTURED QUADRANGLES

引用

Journal of Hydrodynamics 2010年第3期22卷 419-429页

作者： ZHANG Xi-bing HU De-chao WANG Min state key laboratory of Water Resources and Hydropower engineering Science Wuhan University Wuhan430072 China Yangtze River Scientific Research Institute Wuhan 430010 China state key laboratory of hydroscience and engineering Tsinghua University Beijing 100084 China

The main river, the Dongting Lake and river networks in the Jingjiang reach of the Yangtze River constitute a complex water system, for which a full 2-D hydrodynamic model is established instead of the traditional 1-D or compound models for simulation of such complex systems, based on the latest developments of computer technologies and numerical methods. To better handle irregular boundaries and keep the computation cost well in a reasonable limit, unstructured grids of moderate scale are used. In addition, a dynamic boundary tracking method is proposed to simulate variable flow domains at different floods, especially, when the moderate scale gird can not describe flows in narrow river-network channels at low water levels. The t9 semi-implicit method and the Eulerian-Lagrangian Method （ELM） are adopted, which make the model unconditionally stable with respect to the gravity wave speed and Courant number restrictions. Properties and efficiency of the model are discussed, and it is concluded that the new model is robust and efficient enough for the simulation of a big, complex water system. Validation tests show that the simulation results agree well with field data. It takes about 0.96 h to complete the computation of a 76 d flood, which indicates that the model is efficient enough for engineering applications.

关键词： 2-D numerical model river network unstructured grid semi-implicit Eulerian-Lagrangian Method (ELM) boundarytracking

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

PREDISPERSED SOLVENT EXTRACTION──THE state-OF-THE-ART REVIEW

引用

化工学报 2000年第S1期51卷 299-302页

作者： Wang Yundong, Huang Yingyi and Dai Youyuan (state key laboratory of Chemical engineering---Solvent Extraction laboratory, Department of Chemica engineering, tsinghua university, beijing 100084)

Predispersed solvent extraction (PDSE) is a new extraction technique in which one of the two phases (usually the oil phase) is predispersed into minute droplets. The essential part of this novel technique is the use of colloidal liquid aphrons (CLA) together with colloidal gas aphrons (CGA). The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interfacial mass transfer etc. In this paper, PDSE process, CLA and CGA are systematically reviewed and the potential applications of CLA, CGA and PDSE for the various areas of separation as well as the latest development in this area are discussed.

关键词： Predispersed solvent extraction colloidal liquid aphrons colloidal gas aphrons

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

Semi-Supervised Classification based on Gaussian Mixture Model for remote imagery

引用

Science china(Technological Sciences) 2010年第S1期53卷 85-90页

作者： XIONG Biao1,ZHANG XiaoJun1 & JIANG WanShou1,2 1 state key laboratory of Information engineering in Surveying,Mapping and Remote Sensing,Wuhan university,Wuhan 430079,china 2 state key laboratory of Remote Sensing Science,beijing,china 1. state key laboratory of Information engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan 430079 China2. State Key Laboratory of Remote Sensing Science Beijing China

Semi-Supervised Classification (SSC),which makes use of both labeled and unlabeled data to determine classification borders in feature space,has great advantages in extracting classification information from mass *** this paper,a novel SSC method based on Gaussian Mixture Model (GMM) is proposed,in which each class’s feature space is described by one *** show the proposed method can achieve high classification accuracy with small amount of labeled ***,for the same accuracy,supervised classification methods such as Support Vector Machine,Object Oriented Classification,*** be provided with much more labeled data.

关键词： remote sensing image classification Semi-Supervised Classification Gaussian Mixture Model EM algorithms

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：