基于像素级估计的视频显著性检测

为了减少背景噪声干扰,准确地从复杂视频中提取显著目标,提出一种具有时空一致性的视频显著区域检测算法。将视频帧划分为超像素,以超像素为基本单元提取光流特征,在时空一致性原则指导下动态融合颜色、边界信息和光流特征,获取视频显著图。在此基础上,借助视频帧的细节和区域特征对视频显著图进行细化增强。实验结果表明,算法的准确率[CD*2]召回率曲线在复杂图像数据库中高于传统经典算法,具有足够高的鲁棒性,能够减少相机运动和背景运动以及突变情况对跟踪检测的影响。所提方法能够在各种运动模式下和外观复杂场景中较为完整地提取显著目标,可作为预处理技术,改善目标跟踪、行为检测、视频压缩等的性能。     

中部地区承接加工贸易梯度转移探讨

我国加工贸易存在的地区发展不平衡问题,日益成为阻碍中国经济协调发展的重要因素。如何顺应国内、国际经济发展趋势,使加工贸易在地区分布上进行科学合理地调整,形成地区协调梯级发展的态势,是目前亟待研究和解决的问题。     

城市群空间层级的定量分析--一种方法的引入及在长江三角洲城市群中的应用

文章首先介绍了城市群的基本概念和功能,然后指出城市群空间层级对城市存在重大影响;接着引入了一种新的研究方法,从城市地理空间、城市规模、城市功能及城市开放度四个方面来综合考察城市群的空间层级结构,并应用该方法对长三角城市群的空间层级进行了研究分析,在此基础上对     

雄安新区对京津冀城市群低碳协同发展促进作用预评估

以低碳经济联系强度模型和多中心源辐射效应叠加模型开发为基础,以分维值测算和GIS空间分析及比较为量化评估工具,采用反现实的研究方法(假设雄安新区没有建立是一种情景),通过比较京津冀城市群在2018-2030年有雄安新区和没有雄安新区两种不同情景下的低碳经济辐射情况,预评估雄安新区的建立对京津冀城市群低碳协同发展的促进作用。结果显示:①如果不建立雄安新区,京津冀城市群的梯度断档问题有加重之趋势;②雄安新区的建立,可以有效促进中间层级城市的快速成长,解决城市群的梯度断档问题,从而改善京津冀城市群西南部和东北部低碳经济联系强度的空间分布;③雄安新区的建立能够有效促进京津冀城市群低碳经济联系强度分维值的提高,而且这种促进作用在2025年之后随着时间的推移会越来越显著,有利于城市群整体的低碳协同发展。     

Error Calculus and Path Sensitivity in Financial Models

In the framework of risk management, for the study of the sensitivity of pricing and hedging in stochastic financial models to changes of parameters and to perturbations of the stock prices, we propose an error calculus that is an extension of the Malliavin calculus based on Dirichlet forms. Although useful also in physics, this error calculus is well adapted to stochastic analysis and seems to be the best practicable in finance. This tool is explained here intuitively and with some simple examples.     

Small‐sample testing inference in symmetric and log‐symmetric linear regression models

This paper deals with the issue of testing hypotheses in symmetric and log‐symmetric linear regression models in small and moderate‐sized samples. We focus on four tests, namely, the Wald, likelihood ratio, score, and gradient tests. These tests rely on asymptotic results and are unreliable when the sample size is not large enough to guarantee a good agreement between the exact distribution of the test statistic and the corresponding chi‐squared asymptotic distribution. Bartlett and Bartlett‐type corrections typically attenuate the size distortion of the tests. These corrections are available in the literature for the likelihood ratio and score tests in symmetric linear regression models. Here, we derive a Bartlett‐type correction for the gradient test. We show that the corrections are also valid for the log‐symmetric linear regression models. We numerically compare the various tests and bootstrapped tests, through simulations. Our results suggest that the corrected and bootstrapped tests exhibit type I probability error closer to the chosen nominal level with virtually no power loss. The analytically corrected tests as well as the bootstrapped tests, including the Bartlett‐corrected gradient test derived in this paper, perform with the advantage of not requiring computationally intensive calculations. We present a real data application to illustrate the usefulness of the modified tests.     

Flash软件的应用

阐述了对Flash软件的应用,及在做《共轭凸轮开口机构》的Flash动画中所应用的工具和其具体步骤。     

一种修正的自适应算法

本文首先对基于累积误差准则与共轭梯度的2种自适应算法进行了讨论和比较，在此基础上提出了一种改进的自适应算法，其收敛性能优于文献（2）中算法，且不出现不稳定现象。     

新诗教学在文学史教材中的渐变研究——以唐搜、黄修己及钱理群编著教材为中心

“十七年”以及“新时期”之初的新文学史教材中，新诗章节最大的缺陷是对非左翼诗人的叙述和评价采取了一种或者遮蔽，或者贬低，从而不符合新诗史本来面目的一种写作模式。“新时期”以来从唐瞍、黄修己直至钱理群所著的新文学史，其新诗章节通过对具有代表性的非左翼诗人胡适、徐志摩、周作人、李金发、戴望舒、卞之琳等的诗歌，以及其所代表的诗歌流派的价值逐步重估，并给予合理评价，渐渐恢复了他们在新诗史上地位．某种程度上也恢复了新诗史的本来面目。     

Early Tracking and the Misfortune of Being Young

Recent research suggests that the relative age of a student within a grade has a causal effect on educational achievement, and that this effect fades with the duration of schooling. In this study, we estimate the causal relative‐age effect on track choice in Austria, a country where students are first tracked in grade 5 (at the age of 10 years), and again in grade 9. We find a strong positive relative‐age effect on track choice in grades 5–8. The age effect persists beyond grade 8 for students from less‐favorable socioeconomic backgrounds and students in urban areas.