共查询到20条相似文献，搜索用时 156 毫秒
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梁伍七 《安徽广播电视大学学报》2012,(3):117-120,128
为解决对象模型和关系模型之间的不匹配,引入对象关系映射框架来解决。Hibernate是目前主流的ORM映射框架。分析了Web应用程序的体系结构和Hibernate体系结构。以在线购物系统为例,给出了对象关联关系映射策略,通过映射文件实现了该映射策略。实验结果表明,映射文件成功实现了该映射策略。通过Hibernate的数据持久层解决方案,提高了数据存取的速度,降低了系统的耦合性,保证了系统的扩展性。 相似文献
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文章通过对国内外xML数据存储管理模式的研究,分析了XML存储方式的现状,针对XML数据的特性,提出了基于对象关系数据库的x20RDB模型.该模型把关系数据库存储方法与面向对象存储方法结合起来,利用关系数据库的技术和面向对象的特性.根据XMI应用模式的特点将关系映射中的对象一关系映射方法进行改进,生成一种新的基于模式的映射机制. 相似文献
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使用对象关系映射技术将面向对象技术和关系数据库相结合,以解决对象和关系模型之间的＂阻抗不匹配＂问题。本文分析了对象关系映射技术,并以毕业生论文（设计）管理系统为例,给出了Django的数据持久化解决方案,降低了系统的耦合度,保证了系统的可扩展性。 相似文献
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为了解决大型数据库结构复杂而引起的应用程序存取数据上的不便,本文详细讲解了将数据库关系模型映射成为对象的基本方法,对反射技术、OR映射等相关概念做了概述。并详述了如何利用反射技术将主键、外键等约束映射到对象模型上。 相似文献
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充分利用XML的可扩展性和自描述性等特性,建立异构数据库数据转换冲突的解决方法,并在此基础上建立XML与关系模型和对象模型的映射规则,实现了数据从关系模型数据库到对象模型数据库的转换,并通过实例验证了方法的正确性． 相似文献
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在非标准模型下,首先介绍了超结构的超幂模型及其有关结论.其次给出了M-映射和e-映射的定义以及这两个映射的性质,得出了*-映射是由M-映射和e-映射合成的,即得出了*-映射的本质构造.最后给出了*-映射的性质. 相似文献
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为了提高灰色GM(1,1)模型在城市用水量预测中的精度,结合BP神经网络的优点,给出了两种灰色-神经网络组合模型GM-BP1和GM-BP2.模型1利用神经网络对GM(1,1)模型的误差序列进行回归训练,将得到的预测值作为原始误差的修正来减小误差;而模型2由部分数据建立了GM(1,1)模型组,通过神经网络训练得到部分数据GM(1,1)模型组与真实值之间的非线性映射关系,利用这种精准的映射关系来提高预测精度.最后实际算例表明了所给方法是有效的,该组合模型可用于城市用水量的中长期预测. 相似文献
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徐小青 《扬州职业大学学报》2008,12(4)
以扫描器外壳为例,利用BP神经网络、遗传算法和优选训练样本方法,建立了成型质量到工艺参数之间的非线性映射关系的反求模型。试验和反求结果表明,该模型反求精度控制在5％之内,验证了其可靠性。 相似文献
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Most electronics products use PCB to carry electronic circuits. This paper classifies information contained in PCB-based electronic circuits into several models: geometry model, physics model, performance model and function model. Based on this classification, a multi-information model of product is established. A composite model of product is also created based on object-orientation and characteristics of the product. The model includes a 3D geometry model, a physics model with integrated information that can be divided into microscopic and macroscopic information, a generalized performance model and a function model that are from top to bottom. Finally, a multi-unit analysis is briefly discussed. 相似文献
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This article examines Bayesian model averaging as a means of addressing predictive performance in Bayesian structural equation models. The current approach to addressing the problem of model uncertainty lies in the method of Bayesian model averaging. We expand the work of Madigan and his colleagues by considering a structural equation model as a special case of a directed acyclic graph. We then provide an algorithm that searches the model space for submodels and obtains a weighted average of the submodels using posterior model probabilities as weights. Our simulation study provides a frequentist evaluation of our Bayesian model averaging approach and indicates that when the true model is known, Bayesian model averaging does not yield necessarily better predictive performance compared to nonaveraged models. However, our case study using data from an international large-scale assessment reveals that the model-averaged submodels provide better posterior predictive performance compared to the initially specified model. 相似文献
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教学模式构建引入伦理思考源于对教育属性和伦理规范的分析及对教学模式构建的伦理反思.为确保教学模式构建的合伦理性,需要秉持公平、效率、人道的伦理精神,彰显教学模式构建的关怀意蕴,生成教学模式构建的实践智慧,培育教学模式构建的伦理文化. 相似文献
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虚拟道德示范是道德示范的新方式。虚拟道德示范不是虚假道德的示范,也不是虚拟的道德示范。现代社会中,虚拟榜样的传播、虚拟空间的生成以及虚拟实践的发展促进了虚拟道德示范从可能走向现实。新时期,深入研究虚拟道德示范有助于增强道德示范教育的接受性与实效性。 相似文献
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Inferences and conclusions drawn from model fitting analyses are commonly based on a single “best fitting” model. If model selection and inference are carried out using the same data model selection, uncertainty is ignored. We illustrate the Type I error inflation that can result from using the same data for model selection and inference, and we then propose a simple bootstrap-based approach to quantify model selection uncertainty in terms of model selection rates. A selection rate can be interpreted as an estimate of the replication probability of a fitted model. The benefits of bootstrapping model selection uncertainty are demonstrated in growth mixture analyses of data from the National Longitudinal Study of Youth, and a 2-group measurement invariance analysis of the Holzinger–Swineford data. 相似文献
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WANG Rui-min CAO Guang-yi ZHU Xin-jian 《浙江大学学报(A卷英文版)》2007,8(5):741-747
Model and simulation are good tools for design optimization of fuel cell systems. This paper proposes a new hybrid model of proton exchange membrane fuel cell (PEMFC). The hybrid model includes physical component and black-box com-ponent. The physical component represents the well-known part of PEMFC, while artificial neural network (ANN) component estimates the poorly known part of PEMFC. The ANN model can compensate the performance of the physical model. This hybrid model is implemented on Matlab/Simulink software. The hybrid model shows better accuracy than that of the physical model and ANN model. Simulation results suggest that the hybrid model can be used as a suitable and accurate model for PEMFC. 相似文献
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张维亚 《金陵科技学院学报(社会科学版)》2008,22(1):58-62
将WebGIS和公众参与理论相结合应用到文化遗产旅游地管理中是新兴的课题。通过构建PPWGIS模型对文化遗产旅游地管理进行新的模式探讨。PPWGIS文化遗产旅游地管理模式主要包括公众参与信息输入模块、公众参与信息处理模块和公众参与信息输出模块。PPWGIS文化遗产旅游地管理模式的核心是处于We-bGIS系统中的公众。 相似文献
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Purya Baghaei 《European Journal of Psychology of Education - EJPE》2013,28(3):1087-1103
This study aims to develop and validate a multidimensional scale of willingness to communicate in a foreign language. Multidimensional random coefficient multinomial logit model was employed to analyze the scale. Likelihood deviance test and information criteria showed that a three-dimensional model fits significantly better than a two-dimensional model and the two-dimensional model fits significantly better than a unidimensional model. A four-dimensional model, however, did not improve model fit. Low and moderate correlations among the three dimensions supported the multidimensionality of the scale. Further evidence for the validity of the scale was derived from correlation with an English proficiency test used as an external criterion. 相似文献
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以1978年至2008年的某省职工年平均工资作为样本数据、2009年至2010年的数据作为模型检验数据,建立了基于时间序列分析的ARMA模型,使用Eviews软件对时间序列进行分析,根据Box-Jenkins模型识别方法,得出模型的参数,进而得到模型,误差分析表明模型的预测结果非常理想。 相似文献
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This study evaluates latent differential equation models on binary and ordinal data. Binary and ordinal data are widely used in psychology research and many statistical models have been developed, such as the probit model and the logit model. We combine the latent differential equation model with the probit model through a threshold approach, and then compare the threshold model with a naive model, which blindly treats binary and ordinal data as continuous. Simulation results suggest that the naive model leads to bias on binary data and on ordinal data with fewer than 5 levels, whereas the threshold model is unbiased and efficient for binary and ordinal data. Two example analyses on empirical binary data and ordinal data show that the threshold model also has better external validity. The R code for the threshold model is provided. 相似文献