This article discusses the problem of the detection of influential cases in nonlinear reproductive dispersion models (NRDM). A diagnostic based on case\|deletion approach in estimating equations is proposed. The relat...This article discusses the problem of the detection of influential cases in nonlinear reproductive dispersion models (NRDM). A diagnostic based on case\|deletion approach in estimating equations is proposed. The relationships between the generalized leverage defined by Wei et al. in 1998, statistical curvature, and the local influence of the response vector perturbations are investigated in NRDM. Two numerical examples are given to illustrate the results.展开更多
The airborne electromagnetic （AEM） method has a high sampling rate and survey flexibility. However, traditional numerical modeling approaches must use high-resolution physical grids to guarantee modeling accuracy, e...The airborne electromagnetic （AEM） method has a high sampling rate and survey flexibility. However, traditional numerical modeling approaches must use high-resolution physical grids to guarantee modeling accuracy, especially for complex geological structures such as anisotropic earth. This can lead to huge computational costs. To solve this problem, we propose a spectral-element （SE） method for 3D AEM anisotropic modeling, which combines the advantages of spectral and finite-element methods. Thus, the SE method has accuracy as high as that of the spectral method and the ability to model complex geology inherited from the finite-element method. The SE method can improve the modeling accuracy within discrete grids and reduce the dependence of modeling results on the grids. This helps achieve high-accuracy anisotropic AEM modeling. We first introduced a rotating tensor of anisotropic conductivity to Maxwell＇s equations and described the electrical field via SE basis functions based on GLL interpolation polynomials. We used the Galerkin weighted residual method to establish the linear equation system for the SE method, and we took a vertical magnetic dipole as the transmission source for our AEM modeling. We then applied fourth-order SE calculations with coarse physical grids to check the accuracy of our modeling results against a 1D semi-analytical solution for an anisotropic half-space model and verified the high accuracy of the SE. Moreover, we conducted AEM modeling for different anisotropic 3D abnormal bodies using two physical grid scales and three orders of SE to obtain the convergence conditions for different anisotropic abnormal bodies. Finally, we studied the identification of anisotropy for single anisotropic abnormal bodies, anisotropic surrounding rock, and single anisotropic abnormal body embedded in an anisotropic surrounding rock. This approach will play a key role in the inversion and interpretation of AEM data collected in regions with anisotropic geology.展开更多
This paper investigates the problem of the model validation in identifying discrete-time-nonlinear dynamic systems by using neural networks with a single hidden layer.Based on the estimation theory,a synthetic error-i...This paper investigates the problem of the model validation in identifying discrete-time-nonlinear dynamic systems by using neural networks with a single hidden layer.Based on the estimation theory,a synthetic error-index(SEI)criterion for the neural network models has been developed.By using the powerful training algorithm of recursive prediction error (RPE),two simulated non-linear systems are studied,and the results show that the synthetic error-index criterion can be used to verify the dynamic neural network models.Furthermore,the proposed technique is much simple in calculation than that of the effective correlation tests.Finally,some problems required by further study are discussed.展开更多
In this paper, the classical risk process perturbed by diffusion is generalized by allowing for “size fluctuation” and the ruin probability for this new model is discussed.
[Objective] The study aimed to assess the health state of rivers by using fuzzy matter-element model.[Method] Based on fuzzy matter-element analysis theory,the assessment model of river health was established,then a m...[Objective] The study aimed to assess the health state of rivers by using fuzzy matter-element model.[Method] Based on fuzzy matter-element analysis theory,the assessment model of river health was established,then a modified method to calculate the superior subordinate degree was put forward according to Hamming distance.Afterwards,a multi-level evaluation model,which contained the assessment indicators about hydrological features,ecological characteristics,environmental traits and service function,was set up based on this method above.Finally,the model was applied in the health assessment of Qinhuai River.[Result] The health state of Qinhuai River was at medium level.This assessment result was consistent with that of comprehensive index method,and it showed that the multi-level fuzzy matter-element model was effective in the assessment of river health.[Conclusion] The research provided an effective method to evaluate the state of river health.展开更多
在教育实践特别是开放远程和在线学习(Open Distance and e-Learning,ODe L)实践中,学习活动日益受到重视,但是由于对学习活动概念、分类的认识不一而引发的学习活动设计方面的问题频出,直接影响了学习交互行为的发生,进而影响了教学效...在教育实践特别是开放远程和在线学习(Open Distance and e-Learning,ODe L)实践中,学习活动日益受到重视,但是由于对学习活动概念、分类的认识不一而引发的学习活动设计方面的问题频出,直接影响了学习交互行为的发生,进而影响了教学效果。在大规模在线开放课程(MOOCs)、数字教材等新型数字化学习资源的设计与开发过程中,也不可避免遇到上述问题。本研究通过文献研究和对教材、网络课程等建设实践的观察,进一步明确了交互式数字教材学习活动设计所面临的两个主要问题,即学习活动内涵和学习活动设计如何有效纳入教学设计过程的方法。针对问题,本研究首先基于活动理论和活动系统的应用方式厘清了学习活动的内涵和所包含的要素,通过对学习活动分类相关观点的比较分析,明确了适合数字教材学习活动的任务形式和任务内容;其次拓展了学习活动的分析工具属性,将其纳入教学设计过程的不同阶段,作为课程战略决策分析工具、用户研究分析工具、学习动机分析工具和设计实践分析工具,基于此开发了数字教材的实例,并在不同课程的数字教材开发中进行运用。在对建设完成的交互式数字教材进行小范围试用中,多数学习者对此持积极态度。下一步将扩大适用范围,对基于交互式数字教材的学习模式、学习活动设计及交互功能开展更深层次的研究。展开更多
Difficulty in generalizing and lack of adapt ability are important factors that hamper a computer aided process planning (CAP P) system from being popular and practical. New manufacturing philosophies such as Concur...Difficulty in generalizing and lack of adapt ability are important factors that hamper a computer aided process planning (CAP P) system from being popular and practical. New manufacturing philosophies such as Concurrent Engineering require special characteristic of a CAPP system. Propose d in this paper is a CAPP framework system for Concurrent Engineering (CAPPFS C E) which can meet the requirements of Concurrent Engineering and whose informati on models, function models and decision logic can be customized by users to form various CAPP application systems. Its function requirements are discussed broadly. An architecture for CAPPFS CE is presented. It is based on abstract in formati on models (AIMs) and abstract function models (AFMs). The kernel is formed by cu stomization interpretation, internal process control and decision engine. A new information modeling and system development method, information element method ( IEM), is introduced to build up AIMs, decision engine, and AFMs and then realize a CAPPFS CE. THCAPP SHELL, a CAPPFS CE developed by IEM, is demonstrated. A CAPP system produced by customizing THCAPP SHELL for complex structural parts i n a concurrent engineering environment is shown.展开更多
文摘This article discusses the problem of the detection of influential cases in nonlinear reproductive dispersion models (NRDM). A diagnostic based on case\|deletion approach in estimating equations is proposed. The relationships between the generalized leverage defined by Wei et al. in 1998, statistical curvature, and the local influence of the response vector perturbations are investigated in NRDM. Two numerical examples are given to illustrate the results.
基金financially supported by the Key Program of National Natural Science Foundation of China(No.41530320)China Natural Science Foundation for Young Scientists(No.41404093)+1 种基金Key National Research Project of China(Nos2016YFC0303100 and 2017YFC0601900)China Natural Science Foundation(No.41774125)
文摘The airborne electromagnetic （AEM） method has a high sampling rate and survey flexibility. However, traditional numerical modeling approaches must use high-resolution physical grids to guarantee modeling accuracy, especially for complex geological structures such as anisotropic earth. This can lead to huge computational costs. To solve this problem, we propose a spectral-element （SE） method for 3D AEM anisotropic modeling, which combines the advantages of spectral and finite-element methods. Thus, the SE method has accuracy as high as that of the spectral method and the ability to model complex geology inherited from the finite-element method. The SE method can improve the modeling accuracy within discrete grids and reduce the dependence of modeling results on the grids. This helps achieve high-accuracy anisotropic AEM modeling. We first introduced a rotating tensor of anisotropic conductivity to Maxwell＇s equations and described the electrical field via SE basis functions based on GLL interpolation polynomials. We used the Galerkin weighted residual method to establish the linear equation system for the SE method, and we took a vertical magnetic dipole as the transmission source for our AEM modeling. We then applied fourth-order SE calculations with coarse physical grids to check the accuracy of our modeling results against a 1D semi-analytical solution for an anisotropic half-space model and verified the high accuracy of the SE. Moreover, we conducted AEM modeling for different anisotropic 3D abnormal bodies using two physical grid scales and three orders of SE to obtain the convergence conditions for different anisotropic abnormal bodies. Finally, we studied the identification of anisotropy for single anisotropic abnormal bodies, anisotropic surrounding rock, and single anisotropic abnormal body embedded in an anisotropic surrounding rock. This approach will play a key role in the inversion and interpretation of AEM data collected in regions with anisotropic geology.
文摘This paper investigates the problem of the model validation in identifying discrete-time-nonlinear dynamic systems by using neural networks with a single hidden layer.Based on the estimation theory,a synthetic error-index(SEI)criterion for the neural network models has been developed.By using the powerful training algorithm of recursive prediction error (RPE),two simulated non-linear systems are studied,and the results show that the synthetic error-index criterion can be used to verify the dynamic neural network models.Furthermore,the proposed technique is much simple in calculation than that of the effective correlation tests.Finally,some problems required by further study are discussed.
文摘In this paper, the classical risk process perturbed by diffusion is generalized by allowing for “size fluctuation” and the ruin probability for this new model is discussed.
基金Supported by National Natural Science Foundation of China (50879018)Innovation Project of Jiangsu Province in 2008+1 种基金Special Fee for Scientific Research in Public Welfare Industry of Ministry of Water Resources (201001030)Special Fee of Key National Laboratories (1069-50987112)
文摘[Objective] The study aimed to assess the health state of rivers by using fuzzy matter-element model.[Method] Based on fuzzy matter-element analysis theory,the assessment model of river health was established,then a modified method to calculate the superior subordinate degree was put forward according to Hamming distance.Afterwards,a multi-level evaluation model,which contained the assessment indicators about hydrological features,ecological characteristics,environmental traits and service function,was set up based on this method above.Finally,the model was applied in the health assessment of Qinhuai River.[Result] The health state of Qinhuai River was at medium level.This assessment result was consistent with that of comprehensive index method,and it showed that the multi-level fuzzy matter-element model was effective in the assessment of river health.[Conclusion] The research provided an effective method to evaluate the state of river health.
文摘在教育实践特别是开放远程和在线学习(Open Distance and e-Learning,ODe L)实践中,学习活动日益受到重视,但是由于对学习活动概念、分类的认识不一而引发的学习活动设计方面的问题频出,直接影响了学习交互行为的发生,进而影响了教学效果。在大规模在线开放课程(MOOCs)、数字教材等新型数字化学习资源的设计与开发过程中,也不可避免遇到上述问题。本研究通过文献研究和对教材、网络课程等建设实践的观察,进一步明确了交互式数字教材学习活动设计所面临的两个主要问题,即学习活动内涵和学习活动设计如何有效纳入教学设计过程的方法。针对问题,本研究首先基于活动理论和活动系统的应用方式厘清了学习活动的内涵和所包含的要素,通过对学习活动分类相关观点的比较分析,明确了适合数字教材学习活动的任务形式和任务内容;其次拓展了学习活动的分析工具属性,将其纳入教学设计过程的不同阶段,作为课程战略决策分析工具、用户研究分析工具、学习动机分析工具和设计实践分析工具,基于此开发了数字教材的实例,并在不同课程的数字教材开发中进行运用。在对建设完成的交互式数字教材进行小范围试用中,多数学习者对此持积极态度。下一步将扩大适用范围,对基于交互式数字教材的学习模式、学习活动设计及交互功能开展更深层次的研究。
文摘Difficulty in generalizing and lack of adapt ability are important factors that hamper a computer aided process planning (CAP P) system from being popular and practical. New manufacturing philosophies such as Concurrent Engineering require special characteristic of a CAPP system. Propose d in this paper is a CAPP framework system for Concurrent Engineering (CAPPFS C E) which can meet the requirements of Concurrent Engineering and whose informati on models, function models and decision logic can be customized by users to form various CAPP application systems. Its function requirements are discussed broadly. An architecture for CAPPFS CE is presented. It is based on abstract in formati on models (AIMs) and abstract function models (AFMs). The kernel is formed by cu stomization interpretation, internal process control and decision engine. A new information modeling and system development method, information element method ( IEM), is introduced to build up AIMs, decision engine, and AFMs and then realize a CAPPFS CE. THCAPP SHELL, a CAPPFS CE developed by IEM, is demonstrated. A CAPP system produced by customizing THCAPP SHELL for complex structural parts i n a concurrent engineering environment is shown.
