疏影横斜水清浅 暗香浮动月黄昏——简评蒋冰的书法创作     

范进军 《娄底师专学报》2013,(5):65-67

蒋冰是近年来崛起的一位卓有成就的青年书法家。他的书法创作呈现出一种神清骨秀、高洁端庄、幽独超绝的气质风韵,具有极强的艺术审美价值。这与其深厚的文化底蕴、自然的创作理念、强烈的情感流露和执着的艺术追求密切相关。他的作品给当下书坛带来了一种不同凡响的清新气息。  相似文献   

基于MAX125的多通道同步采样数据采集系统   总被引：2，自引：0，他引：2  

涂水林 《常熟理工学院学报》2004,18(2):56-58

介绍了一种基于MAX125的多通道同步采样数据采集系统.该系统由89C51单片机作为控制核心完成控制功能.文中较详细地介绍了本系统的硬件电路设计和软件设计方法.  相似文献   

Universal bound on sampling bosons in linear optics and its computational implications     

Man-Hong Yung  Xun Gao  Joonsuk Huh 《国家科学评论(英文版)》2019,6(4):719

  相似文献   

意愿调查法中的偏好不确定性研究综述     

苏红岩  王华 《资源科学》2019,41(12):2327-2341

对非市场物品和服务,如环境改善和资源保护,进行经济价值评估是学术界面临的一大难题。意愿调查法（Contingent Valuation Method, CVM）作为非市场物品经济价值评估的一种重要方法,其方法论在不断地接受检验并得到改进,近年来一个重要进展是其分析框架由确定偏好假设向不确定偏好假设转变。为系统认识国际上对CVM中受访者偏好不确定性的研究进展、推动国内相关研究,本文在简单介绍产生不确定结果的原因和不确定偏好假设下标准CVM不足的基础上,系统梳理了不确定偏好的测度方法和不确定偏好下价值计算方法,分析了各种方法的优劣以及考虑不确定性对价值估计值大小和估计效率的影响。总体来看,不确定偏好假设已基本形成共识,个人支付意愿应为随机变量也得到广泛支持。多数学者认为借助一定的测度技术获取的不确定性信息是有价值的,而如何更准确地测度和利用偏好不确定程度以提高资源环境等非市场物品价值估计效率应是今后研究的重点。最后,针对既有研究存在的问题,从加强个人偏好及不确定性的异质性研究、改进问卷设计等方面提出对未来研究工作的建议。  相似文献   

2001-2017年尼泊尔中部地区滑坡变化及其影响因素     

孙国庆  陈方  于博  王宁 《中国科学院大学学报》2020,37(3):308-316

滑坡是造成尼泊尔巨大经济损失和人员伤亡的主要地质灾害。目前，遥感方法对滑坡信息的识别、提取和监测具有巨大的潜力。基于随机森林模型的平均不纯度减少算法，选用NDBI、MNDWI、NDVI和红波段4个参数对Landsat遥感数据进行滑坡信息的初提取，同时借助目视解译得到滑坡的精提取结果。采用数据格网的方法将研究区划分为0.05°×0.05°的滑坡格网，并在不同土地覆盖类型中，对滑坡与降雨和温度进行偏相关分析。研究表明：1）尼泊尔中部地区的滑坡主要分布在海拔1 000~2 500 m，坡度20°~40°的范围内；2）相比其他土地覆盖类型，林地中滑坡数目与降雨的偏相关系数为0.671 5，而在草地中滑坡数目与温度的偏相关性最强，其偏相关系数为0.436 1；3）研究区片麻岩、页岩分布广泛，加之地震、断裂带、人类活动的影响，破坏边坡的稳定性，极易造成滑坡灾害。  相似文献   

The effect of toxicity on COVID-19 news network formation in political subcommunities on Reddit: An affiliation network approach     

《International Journal of Information Management》2021

Political polarization remains perhaps the “greatest barrier” to effective COVID-19 pandemic mitigation measures in the United States. Social media has been implicated in fueling this polarization. In this paper, we uncover the network of COVID-19 related news sources shared to 30 politically biased and 2 neutral subcommunities on Reddit. We find, using exponential random graph modeling, that news sources associated with highly toxic – “rude, disrespectful” – content are more likely to be shared across political subreddits. We also find homophily according to toxicity levels in the network of online news sources. Our findings suggest that news sources associated with high toxicity are rewarded with prominent positions in the resultant network. The toxicity in COVID-19 discussions may fuel political polarization by denigrating ideological opponents and politicizing responses to the COVID-19 pandemic, all to the detriment of mitigation measures. Public health practitioners should monitor toxicity in public online discussions to familiarize themselves with emerging political arguments that threaten adherence to public health crises management. We also recommend, based on our findings, that social media platforms algorithmically promote neutral and scientific news sources to reduce toxic discussion in subcommunities and encourage compliance with public health recommendations in the fight against COVID-19.  相似文献   

基于反向随机投影的神经网络改进算法          下载免费PDF全文

许邓艳卢民荣 《福建工程学院学报》2020,(4):358-364

提出基于反向随机局部投影的神经网络效率改进算法，通过降低深度学习中的网络规模，重点解决了从“局部连接”到“全连接”和随机节点抽取时输入端节点信息丢失的问题，从而提升网络的效率。在算法中设置缩减参数，提升了算法的可伸展性，以适用于不同数据集的学习。通过数据集ISO-LET进行实验，结果表明，基于反向随机局部投影的神经网络效率改进算法的准确率、效率分别平均提升了3.48%和105.21%?在迭代20次的实验中进行了缩减参数调节实验，当参数设置为1.4时其准确率则优于传统全连接网络2.61%，效率提升了272.78%，具有明显的优势。  相似文献   

Measuring Textbook Content Coverage: Efficient Content Analysis with Lesson Sampling     

Jiahui Zhang  Leland S. Cogan  William H. Schmidt 《Educational Measurement》2020,39(2):74-84

This study addresses measurement issues around a standards-based content analysis of mathematics textbooks’ coverage of standards for use in large-scale monitoring of standards implementation as proposed in a 2013 report by the National Research Council. An earlier study produced an exhaustive content analysis of textbooks using the 2012 Common Core State Standards for Mathematics. This yielded an accurate and reliable portrait of a textbook's coverage of standards. However, such an in-depth analysis is not feasible for large-scale standards-implementation monitoring in which a large number of textbooks may need to be analyzed. To provide such a portrait with sufficient accuracy while also substantially reducing the associated resources needed to produce such a portrait, a simulation study was conducted with the exhaustively coded database to compare different sampling schemes. Results indicated that sampling 1 day from each week and coding the corresponding lessons led to sufficiently accurate representations of the overall content of the textbook. The results provide empirical evidence for large-scale standards-based content analyses of mathematics textbooks for monitoring standards implementation which could be adapted for other subject areas.  相似文献   

Sample, Random and Variation: The Vocabulary of Statistical Literacy     

Jane M. Watson  Ben A. Kelly 《International Journal of Science and Mathematics Education》2008,6(4):741-767

This paper considers the development of school students’ ability to define three terms that are fundamental to statistical literacy: sample, random, and variation. A total of 738 students in grades 3, 5, 7, and 9 were asked in a survey to define and give an example for the word “sample.” Of these, 379 students in grades 7 and 9 were also asked about the words “random” and “variation.” Responses were used to describe developmental levels overall and to document differences across grades on the understanding of these terms. Changes in performance were also monitored after lessons on chance and data, emphasizing variation for 335 students. After 2 years, 132 of these students and a further 209 students who were surveyed originally but did not take part in specialized lessons, were surveyed again. The difference after 2 years between the performance of students who experienced the specialized lessons and those who did not was considered, revealing no differences in performance longitudinally. For students in grades 7 and 9, the association of performance on the three terms was explored. Implications for mathematics and literacy educators are discussed.  相似文献   

带右删失数据的非线性随机效应模型参数估计     

费绍金  宗序平  卞金萍 《洛阳师范学院学报》2008,27(5)

本文讨论了带右删失数据的非线性随机效应模型的参数估计,给出Gauss-Newton迭代法和改进后的Gauss-Newton迭代法,根据参数估计和算法给出数值模拟,验证了参数估计和算法的可行性.  相似文献