检索结果-南通市图书馆

Multiple Time-scale Characteristics of Runoff Variations in Middle Reaches of Huolin River and Their Effects

Chinese Geographical Science 2007年第2期17卷 143-150页

作者： LU Xiaoning DENG wei ZHANG Shuqing Northeast Institute of Geography and Agroecology Chinese Academy of Sciences Changchun 130012 China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Chengdu University of Information Technology Chengdu 620225 China

The Huolin River is one of the most important water sources for Xianghai wetland, Horqin wetland, and Chaganhu wetland in the western Songnen Plain of Northeast China. The annual runoff series of 46 years at Baiyunhushuo Hydrologic Station, which is located in the middle reaches of the Huolin River, were analyzed by using wavelet analysis. Main objective was to discuss the periodic characteristics of the runoff, and examine the temporal patterns of the Huolin River recharging to the floodplain wetlands in the lower reaches of the river, and the corresponding effects of recharging variation on the environmental evolution of the wetlands. The results show that the annual runoff varied mainly at three time scales. The intensities of periodical signals at different time scales were strongly characterized by local distribution in its time frequency domain. The interdecadal variation at a scale of more than 30yr played a leading role in the temporal pattern ofrnnoffvariation, and at this scale, the runoffat Baiyunhushuo Hydrologic Station varied in turn of flood, draught and flood. Accordingly, the landscape of the floodplain wetlands presented periodic features, especially prominent before the 1990s. Compared with intense human activities, the runoff periodic pattern at middle （10-20yr） and small （1-10yr） scales, which has relatively low energy, exerted unobvious effects on the environmental evolution of the floodplain wetlands, especially after the 1990s.

关键词： floodplain wetland runoff multiple time-scale wavelet analysis Huolin River

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

Synthesis and Acid-Catalyzed Cyclization of 2-Alkenylstilbenes： a New Approach to the Substituted Indenes

引用

Chinese Journal of Chemistry 2015年第11期33卷 1276-1286页

作者： wei Ding Xiaoxin Shi Xia Lu Department of Pharmaceutical Engineering School of Pharmacy East China University of Science and Technology Shanghai 200237 China

A base-catalyzed ring-opening of 1-benzylisochromans 1 firstly produced 2-alkenylstilbenes 2, which then underwent a mild acid-catalyzed intramolecular cyclization to furnish 1,2-disubstituted indenes 3 in high yields. Subsequently, a base-catalyzed isomerization of the 1,2-disubstituted indenes 3 afforded the more stable 2,3-disubstituted indenes 4 in almost quantitative yields.

关键词： isochroman stilbene indene cyclization ring-opening synthetic methodology

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 case study of the consistency problem in the inverse estimation

引用

Acta Oceanologica Sinica 2017年第9期36卷 45-51页

作者： wei Yanzhou KANG Xianbiao PEI Yuhua State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administration Hangzhou 310012 China Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China University of Chinese Academy of Sciences Beijing 100049 China College of Air Traffic Management Civil Aviation Flight University of China Guanghan 618307 China

Inverse technique is a widely used method in oceanography, but it has a problem that the retrieved solutions often violate model prior assumptions. To tune the model has consistent solutions, an iteration approach, which successively utilizes the posterior statistics for next round inverse estimation, is introduced and tested from a real case study. It is found that the consistency may become elusive as the determinants of solution and noise covariance matrices become zero in the iteration process. However, after several steps of such operation, the difference between posterior statistics and the model prior ones can be gradually reduced.

关键词： regularization consistency inverse problems box inverse model L-curve method

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

Comparative Study of Tensile and Charpy Impact Properties of X70 and X80 Linepipe Steels After Ultra Fast Cooling Processing

引用

Journal of Wuhan University of Technology(Materials Science) 2017年第3期32卷 654-660页

作者：李壮田勇 SHAO Zhenyao wei Zhanshan College of Materials Science and Engineering Shenyang Aerospace University State Key Lab of Rolling and Automation Northeastern University

Ultra fast cooling（UFC） processing after hot deformation was conducted on X70 and X80 linepipe steels. Tensile and charpy impact properties of both steels have been investigated in this work. The results have shown that the mechanical properties satisfy all the standard requirements of the X70 and X80 steels. UFC results in a presence of microstructure containing quasi polygonal（QF）, acicular ferrite（AF） and granular bainite（GB）. The alloying elements and UFC enhance the strengthening contribution caused by solid solution, dispersion, dislocation and precipitation strengthening. The size and distribution of precipitates in the linepipe steels are fine and dispersed. MA is also homogeneously dispersed due to UFC. Average grain size in the X80 steel is finer than that in the X70 steel. The volume fractions of secondary phases in the X80 steel are greater than those in the X70 steel. The X80 steel remains finer and more dispersed precipitates compared to the X70 steel. As a result, the tensile properties of X80 steel are higher than those of X70 steel. The Charpy absorbed energies of X70 and X80 steels at-10 ℃ reached 436 and 460 J, respectively. They reached 433 and 461 J at-15 ℃, respectively. This is mainly attributed to the presence of larger amounts of AFs in the X80 steel. A microstructure of AF for the X80 steel results in combining high strength and high toughness.

关键词： linepipe steel ultra fast cooling(UFC) Charpy impact properties acicular ferrite(AF)

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

Linking a farmer crop selection model(FCS) with an agronomic model(EPIC) to simulate cropping pattern in Northeast China

引用

Journal of Integrative Agriculture 2016年第10期15卷 2417-2425页

作者： HE Ying-bin CAI wei-min Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Management School Tianjin Polytechnic University

In this paper, authors established a farmer crop selection model（FCS） for the three provinces of Liaoning, Jilin and Heilongjiang of the Northeast China. With linking to the environmental policy integrated climate model（EPIC）, the simulated results of FCS model for maize, rice and soybean were spatialized with 1 km×1 km grids to obtain cropping pattern. The reference map of spatial distribution for the three staple crops acquired by remote sensing imageries was applied to validate the simulated cropping pattern. The results showed that（1） the total simulation accuracy for the study area was 78.62%, which proved simulation method was applicable and feasible;（2） simulation accuracy for Jilin Province was the highest among the three provinces with a rate of 82.45% since its simple cropping system and not complex topography;（3） simulation accuracy for maize was the best among the three staple crops with a ratio of 81.14% because the study area is very suitable for maize growth. We hope this study could provide the reference for cropping pattern forecasting and decision-making.

关键词： cropping pattern staple crops EPIC model FCS model simulation

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 novel gain design method to improve the consensus performance of output-feedback multi-agent systems

引用

Control Theory and Technology 2016年第4期14卷 335-346页

作者： wei ZHENG Qiang LING Hai LIN Department of Automation University of Science and Technology of China Hefei Anhui 230027 China Department of Electrical Engineering University of Notre Dame Notre Dame IN 46556 U.S.A.

This paper considers the consensus problem of a group of homogeneous agents. These agents are governed by a general linear system and can only directly measure the output, instead of the state. In order to achieve the consensus goal, each agent estimates its state through a Luenberger observer, exchanges its estimated state with neighbors, and constructs the control input with the estimated states of its own and neighbors. Due to the existence of observation and process noises, only practical consensus, instead of asymptotical consensus, can be achieved in such multi-agent systems. The performance of the achieved practical consensus can be measured by the ultimate mean square deviation of the states of agents. That performance is closely related to the observation gains of the state observers and the control gains of agents. This paper proposes a method to optimize such performance with respect to the concerned observation and control gains. That method starts with a set of feasible observation and control gains and formulates a group of linear matrix inequalities （LMIs）. Solving these LMIs gives some intermediate matrix variables. By perturbing observation and control gains, and the intermediate matrix variables, the original LMIs yield another group of LMIs, which can be solved to provide a descent direction of observation and control gains. Moving along that descent direction, observation and control gains can be improved to yield better performance and work as the starting point of the next iteration. By iteratively repeating this procedure, we can hopefully improve the consensus performance of the concerned multi-agent system. Simulations are done to demonstrate the effectiveness of the proposed method.

关键词： Consensus output-feedback multi-agent systems least mean square deviation perturbation method

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

Rounded Data Analysis Based on Multi-Layer Ranked Set Sampling

引用

Acta Mathematica Sinica,English Series 2011年第12期27卷 2507-2518页

作者： wei Ming LI Zhi Dong BAI KLMIB and School of Mathematics and Systems Science Beijing University of Aeronautics and Astronautics Beijing 100191 P. R. China Key Laboratory for Applied Statistics of MOE and School of Mathematics and Statistics Northeast Normal University Changchun 130024 P. R. China

Observations of sampling are often subject to rounding, but are modeled as though they were unrounded. This paper examines the impact of rounding errors on parameter estimation with multi-layer ranked set sampling. It shows that the rounding errors seriously distort the behavior of covariance matrix estimate, and lead to inconsistent estimation. Taking this into account, we present a new approach to implement the estimation for this model, and further establish the strong consistency and asymptotic normality of the proposed estimators. Simulation experiments show that our estimates based on rounded multi-layer ranked set sampling are always more efficient than those based on rounded simple random sampling.

关键词： Rounding error multi-layer ranked set sampling work likelihood method

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

Splitting Method for Support Vector Machine in Reproducing Kernel Banach Space with a Lower Semi-continuous Loss Function

引用

Chinese Annals of Mathematics,Series B 2024年第6期45卷 823-854页

作者： Mingyu MO Yimin wei Qi YE Academy for Advanced Interdisciplinary Studies Peking University School of Mathematical Science South China Normal University School of Mathematical Science Key Laboratory of Mathematics for Nonlinear Sciences Fudan University Corresponding author.School of Mathematical Science South China Normal University

In this paper, the authors employ the splitting method to address support vector machine within a reproducing kernel Banach space framework, where a lower semicontinuous loss function is utilized. They translate support vector machine in reproducing kernel Banach space with such a loss function to a finite-dimensional tensor optimization problem and propose a splitting method based on the alternating direction method of multipliers. Leveraging Kurdyka-Lojasiewicz property of the augmented Lagrangian function,the authors demonstrate that the sequence derived from this splitting method is globally convergent to a stationary point if the loss function is lower semi-continuous and subanalytic. Through several numerical examples, they illustrate the effectiveness of the proposed splitting algorithm.

关键词： 46E22 68P01 68Q32 68T05 Lower semi-continuous loss function Reproducing kernel Banach space Splitting method Support vector machine Tensor optimization problem

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

Signature of symmetry of laterally coupled quantum dots in far-infrared spectrum

引用

Chinese Physics B 2012年第2期21卷 477-482页

作者： Gu Li-Ying Li Yan-Fang Chu wei-Dong wei Ying-Hui College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China Institute of Applied Physics and Computational Mathematics Beijing 100088China

We study the effect of structure asymmetry on the energy spectrum and the far-infrared spectrum （FIR） of a lateral coupled quantum dot. The calculated spectrum shows that the parity break of coupled quantum dot results in more coherent superpositions in the low-lying states and exhibits unique anti-crossing in the two-electron FIR spectrum modulated by a magnetic field. We also find that the Coulomb correlation effect can make the FIR spectrum of coupled quantum dot without strict parity deviate greatly from Kohn theorem, which is just contrary to the symmetric case. Our results therefore suggest that FIR spectrum may be used to determine the symmetry of coupled quantum dot and to evaluate the degree of Coulomb interaction.

关键词： structure symmetry far-infrared spectrum coupled quantum dot Coulomb interaction

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

Gregory Solid Construction for Polyhedral Volume Parameterization by Sparse Optimization

引用

Applied Mathematics(A Journal of Chinese Universities) 2019年第3期34卷 340-355页

作者： HU Chuan-feng LIN Hong-wei School of Mathematics Zhejiang UniversityHangzhou 310027China State Key Lab of CAD&CG Zhejiang UniversityHangzhou 310027China

In isogeometric analysis,it is frequently required to handle the geometric models enclosed by four-sided or non-four-sided boundary patches,such as trimmed *** this paper,we develop a Gregory solid based method to parameterize those ***,we extend the Gregory patch representation to the trivariate Gregory solid ***,the trivariate Gregory solid representation is employed to interpolate the boundary patches of a geometric model,thus generating the polyhedral volume *** improve the regularity of the polyhedral volume parametrization,we formulate the construction of the trivariate Gregory solid as a sparse optimization problem,where the optimization objective function is a linear combination of some terms,including a sparse term aiming to reduce the negative Jacobian area of the Gregory ***,the alternating direction method of multipliers(ADMM)is used to solve the sparse optimization *** of experimental examples illustrated in this paper demonstrate the effectiveness and efficiency of the developed method.

关键词： Gregory solid Polyhedral volume parametrization Sparse optimization Regularity Isogeometric 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

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：