韩国小学数学教材估算内容的编排特点及启示

随着时代的发展和科技的进步,估算作为一种重要的数学思想和数学能力,正逐渐受到重视。加强估算、鼓励算法多样化已经成为当前各国计算教学改革的重要理念之一。文章通过对韩国的《小学数学教科书》估算内容的编排方式进行分析,总结出其基本特点,这些特点不仅反映了韩国教育改革的理念和趋势,同时对我国的教材编写也有一定的借鉴作用。     

平方损失函数下Pareto分布参数的Bayes估计

对Pareto分布主要作了以下的工作:在平方损失函数下,给出了Pareto分布参数的Bayes估计,并且证明了这一估计是_口J容许.     

矩阵最小奇异值的估计

讨论了矩阵最小奇异值的估计.给出了矩阵最小奇异值的两个新的估计和数值算例验证所得结果的优越性.     

SVM for density estimation and application to medical image segmentation

A method of medical image segmentation based on support vector machine （SVM） for density estimation is presented. We used this estimator to construct a prior model of the image intensity and curvature profile of the structure from training images. When segmenting a novel image similar to the training images, the technique of narrow level set method is used. The higher dimensional surface evolution metric is defined by the prior model instead of by energy minimization function. This method offers several advantages. First, SVM for density estimation is consistent and its solution is sparse. Second, compared to the traditional level set methods, this method incorporates shape information on the object to be segmented into the segmentation process. Segmentation results are demonstrated on synthetic images, MR images and ultrasonic images.     

非齐次等式约束线性回归模型的条件岭估计的效率

利用文[7]提出的相对效率定义,研究文[8]、[9]非齐次等式约束线性回归模型回归系数的狭义条件岭估计和广义条件岭估计的效率,证明在一定条件下,狭义条件岭估计和广义条件岭估计的效率比约束最小二乘估计的效率高,并且广义条件岭估计的效率比狭义条件岭估计的效率高,从而进一步证明了在病态的模型中,有偏估计优于无偏估计。     

Climate change by the numbers: Leveraging mathematical skills for science learning online

The purpose of this preregistered study was to test an online intervention that presents participants with novel numbers about climate change after they estimate those numbers. An experimental study design was used to investigate the impact of the intervention on undergraduate students’ climate change understanding and perceptions that human caused climate change is plausible. Findings revealed that posttest climate change knowledge and plausibility perceptions were higher among those randomly assigned to use the intervention compared with those assigned to a control condition, and that supplementing this experience with numeracy instruction was linked with the use of more explicit estimation strategies and greater learning gains for people with adaptive epistemic dispositions. Findings from this study replicate and extend prior research, support the idea that novel data can support knowledge revision, identify estimation strategies used in this context, and offer an open-source online intervention for sharing surprising data with students and teachers.     

图像序列中快速全局运动估计和运动目标提取算法

提出了一种基于边界灰度投影匹配的全局运动估计和运动目标提取算法．算法将边界灰度水平投影和垂直投影值作为匹配特征,较好地估计了全局运动参数．由于只需计算一维特征向量所以降低了全局运动估计的计算量．经过全局运动补偿后,可以运用传统的帧间差法得到运动目标、为了减少噪声的影响,准确地提取到目标,采用了高阶统计量的方法（HOS）来区分背景和运动目标．试验结果证明所提出的方法在估计全局运动参数和提取运动目标方面有较好的鲁棒性．     

约束线性回归模型回归系数的广义条件岭估计

对齐次等式约束线性回归模型回归系数的岭估计进行推广,得出广义条件岭估计．证明了在一定的条件下,在均方误差矩阵、均方误差及广义均方误差意义下广义条件岭估计都优于约束最小二乘估计,并且证明了广义条件岭估计是回归系数的可容许估计．     

《国家学生体质健康标准》与《学生体质健康标准(试行方案)》比较

通过对3604名大学生进行《学生体质健康标准(试行方案)》与《国家学生体质健康标准》的比较研究,分析了《新标准》在测试项目、权重系数、评分标准和评价等级等方面的实用性和科学性.研究表明,《新标准》在测试项目上仍然存在分类不清,选测项目相关度不高的问题.《新标准》调整了权重系数和评分标准,对大学生提出了更高的要求,可以更好地调动学生锻炼的积极性,达到增强体质的目的.另外,《新标准》中肺活量体重指数、立定跳远的提高幅度较大,学生在短期内无法达到要求,需要做进一步的调整.     

A Technical Note on IRT Simulation Studies: Dealing With Truth,Estimates, Observed Data,and Residuals

Simulation studies are extremely common in the item response theory (IRT) research literature. This article presents a didactic discussion of “truth” and “error” in IRT‐based simulation studies. We ultimately recommend that future research focus less on the simple recovery of parameters from a convenient generating IRT model, and more on practical comparative estimation studies when the data are intentionally generated to incorporate nuisance dimensionality and other sources of nuanced contamination encountered with real data. A new framework is also presented for conceptualizing and comparing various residuals in IRT studies. The new framework allows even very different calibration and scoring IRT models to be compared on a common, convenient, and highly interpretable number‐correct metric. Some illustrative examples are included.