检索结果-南通市图书馆

SELECTING AN ADAPTIVE SEQUENCE FOR COMPUTING RECURSIVE M-ESTIMATORS IN MULTIVARIATE LINEAR REGRESSION MODELS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2013年第4期26卷 583-594页

作者： MIAO Baiqi tong qian WU Yuehua JIN Baisuo Department of Statistics and Finance University of Science and Technology of China Department of Mathematics and Statistics York UniversityTorontoOntarioM3J1P3Canada

In this paper, the authors consider an adaptive recursive algorithm by selecting an adaptive sequence for computing M-estimators in multivariate linear regression models. Its asymptotic property is investigated. The recursive algorithm given by Miao and Wu （1996） is modified accordingly. Simu- lation studies of the Mgorithm is also provided. In addition, the Newton-Raphson iterative algorithm is considered for the purpose of comparison.

关键词： Adaptive sequence M-estimation multivariate linear model recursive algorithm scatter parameters.

LEGENDRE-GAUSS-RADAU SPECTRAL COLLOCATION METHOD FOR NONLINEAR SECOND-ORDER INITIAL VALUE PROBLEMS WITH APPLICATIONS TO WAVE EQUATIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2024年第1期42卷 217-247页

作者： Lina Wang qian tong Lijun Yi Mingzhu Zhang Department of Mathematics Shanghai Normal UniversityShanghai 200234China School of Science Henan University of EngineeringZhengzhou 451191China

We propose and analyze a single-interval Legendre-Gauss-Radau(LGR)spectral collocation method for nonlinear second-order initial value problems of ordinary differential *** design an efficient iterative algorithm and prove spectral convergence for the single-interval LGR collocation *** more effective implementation,we propose a multi-interval LGR spectral collocation scheme,which provides us great flexibility with respect to the local time steps and local approximation ***,we combine the multi-interval LGR collocation method in time with the Legendre-Gauss-Lobatto collocation method in space to obtain a space-time spectral collocation approximation for nonlinear second-order evolution *** results show that the proposed methods have high accuracy and excellent long-time *** comparison between our methods and several commonly used methods are also provided.

关键词： Legendre-Gauss-Radau collocation method Second-order initial value problem Spectral convergence Wave equation

Effects of Si and Cr on Complete Decarburization Behavior of High Carbon Steels in Atmosphere of 2 vol.%O2

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

Journal of Iron and Steel Research International 2016年第12期23卷 1316-1322页

作者： Yang-bo LIU Wei ZHANG qian tong Qi-song SUN Shougang Research Institute of Technology Beijing 100048China Beijing Key Laboratory of Green Recyclable Process for Iron&Steel Production Technology Beijing 100048China

The effects of chemical compositions, especially silicon and chromium contents, on the complete decarburization behaviors of steels in atmosphere of 2 vol. %O2 and 98 vol. % N2 were investigated by using a simuhaneous thermal analyzer. Complete decarburization was observed at both 750 and 800 ℃ for 60Si2MnA steel, while 750℃ only for 92A steel. For GCr15 steel, no decarburization was found at 750 or 800 ℃, and only partial decarburization was observed at 850 ℃. It indicates that silicon promotes while chromium prevents the complete decarburization of steels in atmosphere with 2 vol. % O2. The main reason is that silicon increases while chromium reduces the equilib rium concentration of ferrite at the interface of ferrite and austenite, which results in the complete decarburization.

关键词： complete deearburization silicon chromium low oxygen concentration oxide scale

Multi-parametric Sensitivity Analysis of Improved Transformer Thermal Models Considering Nonlinear Effect of Oil Time Constant

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2023年第5期9卷 1950-1958页

作者： tong qian qianlong Wei Zeyuan Yu Wenhu Tang Qing-Hua Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

This paper aims to develop an approach to investigating the effect of a particular parameter on the output accuracy of transformer thermal models,*** analysis,which can not only reveal the most sensitive parameter of a thermal model but also improve model output *** the first time,the nonlinear time constant(NTC)of transformer oil is proposed to reshape three practical top-oil temperature models based on an expression of nonlinear thermal conductance:the modified IEEE clause 7 model,Swift’s model,and Susa’s ***,the multi-parametric sensitivity analysis(MPSA)is undertaken to reveal the effect of each parameter on the model output *** onsite data validation,the results show that the accuracy performance of the proposed NTC thermal models are improved significantly by considering the nonlinear effect of oil time ***,the derived sensitivity performances can clearly reveal the most dominant parameter of the model,so as to simplify the model parameter identification process by reducing the number of insensitive ***,the heat-run test data is used as a reference to validate parameters optimized through a genetic algorithm(GA),which demonstrates that the proposed NTC IEEE model has not only one sensitive parameter but also superior accuracy performance.

关键词： Constant genetic algorithm multi-parametric sensitivity analysis nonlinear oil time transformer thermal model

The influence of four dual-cure resin cements and surface treatment selection to bond strength of fiber post

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

International Journal of Oral Science 2014年第1期6卷 56-60页

作者： Chang Liu Hong Liu Yue-tong qian Song Zhu Su-qian Zhao College and Hospital of Stomatology Jilin University Clinical Medical College Jilin University

In this study, we evaluate the influence of post surface pre-treatments on the bond strength of four different cements to glass fiber posts. Eighty extracted human maxillary central incisors and canines were endodontically treated and standardized post spaces were prepared. Four post pre-treatments were tested：（i） no pre-treatment （NS, control）, （ii） sandblasting （SA）, （iii） silanization （SI） and （iv） sandblasting followed by silanization （SS）. Per pre-treatment, four dual-cure resin cements were used for luting posts： DMG LUXACORE Smartmix Dual, Multilink Automix, RelyX Unicem and Panavia F2.0. All the specimens were subjected to micro push-out test. Two-way analysis of variance and Tukey post hoc tests were performed （α=0.05） to analyze the data. Bond strength was significantly affected by the type of resin cement, and bond strengths of RelyX Unicem and Panavia F2.0 to the fiber posts were significantly higher than the other cement groups. Sandblasting significantly increased the bond strength of DMG group to the fiber posts.

关键词： air abrasion field emission scanning electron microscope micro push-out bond strength silane surface pre-treatment

An improved positioning model of deep-seafloor datum point at large incidence angle

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2024年第1期42卷 90-100页

作者： qianqian LI Shoulian CAO Fanlin YANG Yu LUO qian tong College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150000China College of Geodesy and Geomatics Shandong University of Science and TechnologyQingdao 266590China Key Laboratory of Ocean Geomatics Ministry of Natural ResourcesQingdao 266590China

The inhomogeneous sound speed in seawater causes refraction of sound waves,and the elimination of the refraction effect is essential to the accuracy of underwater acoustic *** raytracing method is an indispensable tool for effectively handling ***,this method has a conflict between localization accuracy and computational *** equivalent sound speed profile(ESSP)method uses a simple sound speed profile(SSP)instead of the actual complex SSP,which can improve positioning precision but with residual *** residual error is especially non-negligible in deep water and at large beam incidence *** analyzing the residual error of the ESSP method through a simulation,an empirical formula of error is *** data collected in the sailing circle mode(large incidence angle)of the South China Sea are used for *** experiments show that compared to the ESSP method,the improved algorithm has higher positioning precision and is more efficient than the ray-tracing method.

关键词： underwater acoustic positioning seafloor datum points large incident angle equivalent sound speed profile(ESSP) deep water

Changes in soil free-living diazotrophic community and co-occurrence patterns along desert wetland degradation gradient in the Mu Us Desert,northern China

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2023年第4期33卷 638-648页

作者： Kun WANG Hongyan FEI qian tong Chuanyu WAN Ruopeng PAN Fengpeng HAN State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau College of Natural Resources and EnvironmentNorthwest A&F UniversityShaanxi 712100(China) Research Center on Soil&Water Conservation Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water ResourcesShaanxi 712100(China)

Climate change and human activity have led to the degradation of desert ***-living diazotrophs are vital for soil nitrogen ***,a comprehensive understanding of how soil free-living diazotrophic communities and their co-occurrence patterns respond to desert wetland degradation is ***,quantitative polymerase chain reaction(qPCR),amplicon sequencing targeting nitrogenase gene(nifH),and network analysis were used to investigate the abundance,diversity,community composition,and co-occurrence patterns of soil free-living diazotrophs along the wetland degradation gradient,i.e.,non-degraded(ND),lightly degraded(LD),moderately degraded(MD),and severely degraded(SD),in the southeastern Mu Us Desert,northern *** abundance and Shannon,Simpson,Chao 1,and ACE indexes decreased(P0.05)was observed between ND and LD *** relative abundance of Proteobacteria generally decreased(by 53.5%–19.7%)across the different degradation levels,while the relative abundance of Cyanobacteria increased(by 6.2%–40.1%)from ND to MD *** abundance,diversity,and community composition of diazotrophs were most strongly related to soil organic carbon,followed by total nitrogen,moisture,and *** least number of network nodes and edges and the lowest density were observed for MD and SD wetlands,indicating that the complexity of free-living diazotrophic networks was reduced by continued ***,severe desert wetland degradation affected the abundance,diversity,and network complexity of soil free-living diazotrophs more negatively than light *** degradation promoted the growth of autotrophic diazotrophs and inhibited the growth of heterotrophic *** changes were mostly related to the loss of soil organic carbon.

关键词： amplicon sequencing biological nitrogen fixation co-occurrence network analysis nifH gene quantitative polymerase chain reaction soil organic carbon

An improved algorithm based on equivalent sound velocity profile method at large incident angle

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2024年第2期43卷 161-167页

作者： qianqian Li qian tong Fanlin Yang Qi Li Zhihao Juan Yu Luo College of Geodesy and Geomatics Shandong University of Science and TechnologyQingdao 266590China College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150001China

With the development of ultra-wide coverage technology,multibeam echo-sounder(MBES)system has put forward higher requirements for localization accuracy and computational efficiency of ray tracing *** classical equivalent sound speed profile(ESSP)method replaces the measured sound velocity profile(SVP)with a simple constant gradient SVP,reducing the computational workload of beam ***,in deep-sea environment,the depth measurement error of this method rapidly increases from the central beam to the edge *** analyzing the positioning error of the ESSP method at edge beam,it is discovered that the positioning error increases monotonically with the incident angle,and the relationship between them could be expressed by polynomial ***,an error correction algorithm based on polynomial fitting is *** simulation experiment conducted on an inclined seafloor shows that the proposed algorithm exhibits comparable efficiency to the original ESSP method,while significantly improving bathymetry accuracy by nearly eight times in the edge beam.

关键词： equivalent sound speed profile ray tracing method large incident angle edge beam deep sea error correction multibeam echo-sounder system

Network Embedding Algorithm for Vulnerability Assessment of Power Transmission Lines Using Integrated Structure and Attribute Information

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第1期10卷 351-360页

作者： Xianglong Lian tong qian Zepeng Li Xingyu Chen Wenhu Tang Q.H.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

In power systems,failures of vulnerable lines can trigger large-scale cascading failures,and vulnerability assessment is dedicated to locating these lines and reducing the risks of such *** on a structure and attribute network embedding(SANE)algorithm,a novel quantitative vulnerability analysis method is proposed to identify vulnerable lines in this ***,a two-layered random walk network with topological and electrical properties of transmission lines is ***,based on the weighted degree of nodes in the two-layered network,the inter-layer and intra-layer walking transition probabilities are developed to obtain walk ***,a Word2Vec algorithm is applied to obtain lowdimension vectors representing transmission lines,according to obtained walk sequences for calculating the vulnerability index of transmissions ***,the proposed method is compared with three widely used methods in two test *** show the network embedding based method is superior to those comparison methods and can provide guidance for identifying vulnerable lines.

关键词： Network embedding random walk transmission lines vulnerability assessment