入园适应相关因素解析     

纪红霞 《金华职业技术学院学报》2005,5(2):103-105

上学是孩子成长中的重要事件，现代教育与心理学研究的成果显示，入因适应的问题，涉及家庭、学校、社区的诸多因素。本文重点从幼儿因工作的角度来分析幼儿入因适应的问题，主要包括家庭的人际交往特征、家因合作的运行起点与水平、幼儿因管理者的保教观念与硬件设施、教师在工作中显现的自身特征等几个方面。  相似文献   

How sequencing and fading affects the relationship between intrinsic and germane cognitive loads     

Christopher Lange 《Distance Education》2019,40(2):243-261

Scaffolding techniques, such as sequencing and fading, used in online video lectures may help mitigate the negative relationship between complex contents represented by intrinsic load and content understanding represented by germane load. This study analyzed survey responses from university students (n = 2365) who participated in online classes in South Korea, and looked at the relationships between sequencing and fading and germane load, intrinsic load and germane load, and the moderating effect of sequencing and fading on the relationship between intrinsic load and germane load. Results showed a positive relationship between sequencing and fading and germane load and a negative relationship between intrinsic load and germane load. Furthermore, sequencing and fading moderated the negative relationship between intrinsic load and germane load. This article examines conflicting evidence on the topic and provides explanations as to why sequencing and fading reduces the negative impact of complex contents found in the current study.  相似文献   

广义分布式天线系统容量解析界     

孙欢  王新宇  尤肖虎 《东南大学学报》2007,23(4):479-483

首先对广义分布式天线系统的复合信道模型,如瑞利对数正态衰落信道模型,进行了分析.通过与传统多输入多输出系统的比较,对广义分布式天线系统容量进行了分析,并得出广义分布式天线系统历经容量完整的解析表达式是不可能存在的.为了有效地对广义分布式天线系统历经容量的性能进行评估,利用多元统计理论和矩阵不等式理论推导了在瑞利对数正态衰落信道模型及在发射端采用等功率分配方案下广义分布式天线系统历经容量的解析下界和解析上界.最后,通过数值仿真证明了系统的历经容量可以很好地用其解析界来表述.  相似文献   

国外政府数据开放研究的主题关联结构与演化态势          下载免费PDF全文

朱晓峰  葛锐  蒋勋 《情报科学》2022,39(1):109-120

【目的/意义】数字时代“开放政府数据”热潮产出了丰硕成果,对其研究主题结构和演化脉络进行全面、精 准的可视化揭示,有助于进一步丰富和完善该领域研究,科学地指导我国实践开展。【方法/过程】以 2000-2019 年 WOS数据库中“开放政府数据”主题文献为基础,借助新型SLM算法探测主题社区,梳理研究主题分布;同时嵌入 SNA方法,引入“传导率”指标定量评估主题社区成熟度和内外部关联,并利用Cortext平台构建时序演进过程。【结 果/结论】国外开放政府数据研究已形成四类主题社区：健康社区、开放数据社区、管理社区以及安全社区,目前仍 存在“主题遍布粒度不够细化、新兴主题社区亟需成长、演化脉络断续明显”等问题。【创新/局限】嵌入新型算法 SLM 划分主题社区,结合 LDA 模型对国外 OGD 研究主题关联与演化进行了完整阐释。但本文仅选取 WOS核心 库的相关主题文献作为数据源,存在进一步扩充的空间。  相似文献   

桑椹红—双氧水褪色光度法测定微量铜     

刘欣  王鑫彤 《唐山师范学院学报》2013,(5):16-18

建立了桑椹红-双氧水褪色光度法测定微量铜的新方法。考察了酸度、桑椹红色素浓度、双氧水浓度、反应温度、反应时间对铜离子催化双氧水桑椹红褪色反应的影响,得到了测定铜的最佳条件。利用此方法测定绿茶及红茶中铜含量分别为1.881μg·mL-1、0.946μg·mL-1,加标回收率为95%~104%,相对标准偏差分别为0.27%、0.49%。  相似文献   

基于强跟踪滤波器的多传感器非线性动态系统状态容错融合估计     

文成林  周东华 《上海海事大学学报》2001,22(3):162-166

将强跟踪滤波理论与多传感器数据融合估计方法相结合,提出基于强跟踪滤波器的多传感器数据融合估计新算法.对拥有相同采样率的分布式多传感器单模型非线性动态系统,应用强跟踪滤波器,得到目标状态基于全局信息融合估计结果,并利用计算机仿真结果对算法的有效性进行了验证.这些工作初步解决了Kalman滤波中由于模型的不确定性而造成估计误差值偏大情况下的状态融合估计问题,从而丰富和发展了多源信息融合理论.  相似文献   

Generating model of a sub-Rayleigh fading     

V. Lyandres   《Journal of The Franklin Institute》2003,340(6-7):407-414

The generating model of a narrow band random process with the envelope probability density function left shifted relative to the Rayleigh law is presented. The model is based on the interpretation of the process as a stationary output of a nonlinear dissipative system, excited by white Gaussian noise. This representation may be considered as an effective tool for simulating a wireless communication channel with essentially severe fading.  相似文献   

数据库中相关子查询的实现初探   总被引：1，自引：0，他引：1  

李春艳  高伟 《唐山师范学院学报》2009,31(2):105-106

在使用关系数据库时,用户需要的数据经常散步在多个表中,可以使用相关子查询获得所需数据。说明了相关子查询的一种执行过程。给带蕴涵语义查询功能的实现和执行提供了一些参考．  相似文献   

Average SNR of maximum ratio transmission with selection combining     

Xian-yi Rui 《浙江大学学报(A卷英文版)》2009,10(12):1683-1687

Two kinds of selection combining schemes including generalized selection combining （GSC） and generalized order selection combining （GOSC） are investigated. In the GSC scheme, L strongest diversity branches from a total of R diversity branches are selected and coherently combined by maximal ratio combining. GOSC means that the Lth strongest diversity branch from R diversity branches is selected for reception. Closed-form expressions for the average signal-to-noise ratios of maximum ratio transmission with GSC and GOSC are derived in Rayleigh fading channels.  相似文献   

Evaluation of Maximal Reliability for Unidimensional Measuring Instruments With Correlated Errors     

Siegfried Gabler 《Structural equation modeling》2017,24(1):104-111

A latent variable modeling method for studying maximal reliability of unidimensional multicomponent measuring instruments with correlated errors is outlined. In the presence of correlation between 2 residual terms, the procedure allows one to point and interval estimate the reliability of the linear combination of the scale components that possesses the highest possible reliability coefficient. The approach is readily applicable with popular latent variable modeling software and also provides an alternative scoring rule to the widely used overall sum score for homogeneous psychometric scales. The discussed method is illustrated with a numerical example.  相似文献