全经验视角下小学数学教育教学

儿童具有具体性和直观形象性思维,需要在大量的感性材料的基础上,通过感知、体验、比较、抽象、概括,最终形成对数学的理性认识.全经验是指儿童经验领域对客观世界的全覆盖.全经验视角下开展的数学教育教学主要包括全经验数学拓展课、全经验数学课外活动、数学阅读与创作三部分,三者相辅相成、互为补充,对提升儿童数学核心素养,乃至综合素养,建构儿童完整的数学生活世界具有重要意义和作用.

“小学生全经验课程”的设计与实施

从孩子身边的生活世界出发,以覆盖儿童经验领域的60件事为载体,完整建构关键经验的＂全经验课程＂,为孩子创设了真实情境下的活动化学习机会,帮助他们丰富了经验领域的学习,从而促进学生综合素质的提高,培养学生的实践能力和创新精神。

全原子经验赝势法模拟InAs/InAsSbⅡ类超晶格

为了研究InAs/InAs1-xSbxⅡ类超晶格结构的物理特性,首次采用全原子的经验赝势方法对InAs/InAs1-xSbx结构进行模拟,并对体系的近带边能级、单粒子波函数和带边跃迁矩阵元进行了计算。结果表明,量子限制效应造成超晶格带隙的宽化;超晶格中基态电子主要局域在InAs层,基态空穴主要局域在合金层,与相关体材料及I型超晶格所做的对比结果表明,电子、空穴的物理分离效应是造成体系载流子寿命较长的重要原因;将带边跃迁矩阵元作为衡量载流子寿命的重要元素,针对固定波段的超晶格系统进行优化,最终得到带边跃迁矩阵元更小的体系(163?) InAs/(82?) InAs0. 72Sb0. 28结构,其跃迁矩阵元是0. 010 684 3 a.u.。

基于生活体验,提升小学生语言表达力

当下,提升小学生语言表达力已经引起了广大教师的高度重视。一般来说,通过精妙、有深度的阅读教学提升学生口语表达能力;利用方法、内容等方面的指导,让习作教学提升学生的书面表达能力。本文结合我校的全经验课程,谈谈怎样利用真实的生活体验提升小学生语言表达力。

Assessing quality of crash modification factors estimated by empirical Bayes before-after methods

Before-after study with the empirical Bayes(EB)method is the state-of-the-art approach for estimating crash modification factors(CMFs).The EB method not only addresses the regression-to-the-mean bias,but also improves accuracy.However,the performance of the CMFs derived from the EB method has never been fully investigated.This study aims to examine the accuracy of CMFs estimated with the EB method.Artificial realistic data(ARD)and real crash data are used to evaluate the CMFs.The results indicate that:1)The CMFs derived from the EB before-after method are nearly the same as the true values.2)The estimated CMF standard errors do not reflect the true values.The estimation remains at the same level regardless of the pre-assumed CMF standard error.The EB before-after study is not sensitive to the variation of CMF among sites.3)The analyses with real-world traffic and crash data with a dummy treatment indicate that the EB method tends to underestimate the standard error of the CMF.Safety researchers should recognize that the CMF variance may be biased when evaluating safety effectiveness by the EB method.It is necessary to revisit the algorithm for estimating CMF variance with the EB method.

Safety and success of precut biliary sphincterotomy: Is it linked to experience or expertise?

AIM： To determine the rates of success and complications of precut biliary sphincterotomy （PBS） based on prior experience and to compare the complication rates between PBS and standard endoscopic sphincterotomy （ES）. METHODS： A retrospective evaluation of prospectively collected non-randomized data at an academic tertiary referral center, The study included all patients in an eight-year period who underwent PBS and ES by a single endoscopist who had no formal training in PBS. The main outcorne measures of the study were success and complications of PBS with a comparison to complications of ES.RESULTS： A total of 2939 endoscopic retrograde chola ngiopancreatographies （ERCPs） were performed during the study period, including 818 （28%） ES and 150 （5%） PBS procedures. Selective biliary cannulation via PBS was successful at the first attempt in 75% of the patients. Cannulation was achieved in an additional 13% of the patients at a subsequent attempt （total 87%）. Complication rate from PBS was 45% higher than ES, but did not differ significantly [7% （10/50） vs 5% （38/818）, P = 0.29]. None of the complications from PBS was severe. A significant trend towards increasing success existed with regard to the endoscopist＇s first attempt at precut （P = 0.0393, Cochran-Armitage exact test for trend, Z = -1.7588）. CONCLUSION： Despite the lack of specific training in this technique, PBS was performed with a high success rate and a complication rate similar to or less than reports from other experienced centers. These results suggest that endoscopic experience and perhaps innate endoscopic skill may play an important role in the outcome of this procedure.

A comparative study on three EOF analysis techniques using decades of Arctic sea-ice concentration data

Change in Arctic sea ice extent is one of the indicators of global climate changes. Spatio-temporal change and change patterns can be identified using various methods to facilitate human understanding global climate changes. Three empirical orthogonal function(EOF) techniques are discussed and applied to decades of sea-ice concentration(SIC) dataset in Arctic area for identifying independent patterns. It was found that: 1) discrepancies exist in magnitude and scope for each EOF pattern, however, the first two leading EOFs of variability possess high similarities in structure and shape; 2) Even though there are somewhat differences in amplitude of each PC mode, the first two leading PC modes maintain consistent in overall trend and periodicity; 3) There are significant discrepancies and inconsistencies in the third and fourth leading EOF and PC modes. The accuracies of three techniques are further validated in representing the physical phenomena of SIC anomaly patterns.

The application of the MOOCs postgraduate education in the army

MOOCs as a new kind ofordine teaching mode worldwide at breakneck speed. This paper analyzes the development and advantages of MOOCs, to draw lessons fi＇om the successful experience of the MOOCs, build conform to the demand of our colleges and universities graduate education MOOCs platforrr~ promote excellent education experts in the army,high-quality teaching resource sharing, to promote the teaching idea transformation,teaching content update and the teaching method reform, improve the quality of military high-level talent cultivation.

Verifying Ricardo＇s Model--Whether TPP is Right or Wrong？

Through his attempt to clarify justifiable economic circumstances where a policy of globalization and/or a policy of national isolation is proven valid, the author reveals in this thesis that there are two such economic phases： an economy where the theory of comparative advantage, proposed by David Ricardo, is applicable, and an economy where the theory is not applicable. The author applied his original approach to prove the validity of Ricardo＇s comparative advantage theory, and found that the theory can be justified only when a macro economy is in the thetical economic phase, where a policy of globalization is effective. It is a necessary and sufficient condition for the theory to be valid. In other words, Ricardo＇s theory of comparative advantage is not applicable when a macro economy is in the antithetical economic phase, where a policy of national isolation, instead of that of globalization, is valid. The thetical economic phase and the antithetical economic phase of a macro economy, referred to in this thesis by the author, are a version of an expression quite common in OR （operations research）.

Global features and trends of the tropopause derived from GPS/CHAMP RO data

The global characteristics and trends of the tropopause physical parameters,height and temperature,obtained from the GPS/CHAMP radio occultation(RO) data in the period from Jul.2001 to Oct.2008,were modeled and analyzed in this work.The global distribution and variation of these parameters with latitude were estimated and analyzed using the Empirical Orthogonal Function(EOF),which was introduced to reveal the possible relationship between the tropopause variations and global climate change.The tropopause height and temperature varied with latitude.The results obtained by using the Empirical Orthogonal Function analysis suggested a recent rise in tropopause height and decrease in tropopause temperature;and also partly supported the argument that the global rise in the tropopause is consistent with global climate change.These results also revealed that the tropopause height increased mainly in the Polar regions,particularly in the South Polar region,as well as the regions where human activity is relatively significant,and decreased in the areas that are sparsely populated or have less human activity,such as the tropic region and south hemisphere.This paper also confirms that the GPS/LEO RO data are more reliable and can be effectively used to analyze the tropopause physical parameters.

A global empirical model for estimating zenith tropospheric delay

Tropospheric delay acts as a systematic error source in the Global Navigation Satellite Systems(GNSS) positioning. Empirical models UNB3, UNB3 m, UNB4 and EGNOS have been developed for use in Satellite-Based Augmentation Systems(SBAS). Model performance, however, is limited due to the low spatial resolution of the look-up tables for meteorological parameters. A new design has been established in this study for improving performance of the tropospheric delay model by more effectively eliminating the error produced by tropospheric delay. The spatiotemporal characteristics of the Zenith Tropospheric Delay(ZTD) were analyzed with findings that ZTD exhibits different annual variations at different locations and decreases exponentially with height increasing. Spherical harmonics are utilized based on the findings to fit the annual mean and amplitude of the ZTD on a global scale and the exponential function is utilized for height corrections, yielding the ZTrop model. On a global scale, the ZTrop features an average deviation of ?1.0 cm and Root Mean Square(RMS) of 4.7 cm compared with the International GNSS Service(IGS) ZTD products, an average deviation of 0.0 cm and RMS of 4.5 cm compared with the Global Geodetic Observing System(GGOS) ZTD data, and an average deviation of ?1.3 cm and RMS of 5.2 cm compared with the ZTD data from the Constellation Observing System of Meteorology, Ionosphere, and Climate(COSMIC). The RMS of the ZTrop model is 14.5% smaller than that of UNB3, 6.0% smaller than that of UNB3 m, 16% smaller than that of UNB4, 14.5% smaller than that of EGNOS and equivalent to the sophisticated GPT2+Saas model in comparison with the IGS ZTD products. The ZTrop, UNB3 m and GPT2+Saas models are finally evaluated in GPS-based Precise Point Positioning(PPP), as the models act to aid in obtaining PPP position error less than 1.5 cm in north and east components and relative large error(>5 cm) in up component with respect to the random walk approach.

Thermography analyses of rock fracture due to excavation and overloading for tunnel in 30° inclined strata

Large-scale physical model test of 30°inclined strata was conducted to investigate the damage mechanisms during the excavation and overloading using infrared detection.The experiment results were presented with thermal images which were divided into three stages including a full face excavation stage,a staged excavation stage,and an overloading stage.The obtained results were compared with the previously reported results from horizontal,45?,60?,and vertical strata models.Infrared temperature(IRT)for 30°inclined strata model descended with multiple fluctuations during the full-face excavation.For the staged excavation,the excavation damage zone(EDZ)showed enhanced faulting-like strips as compared in the 45?,60?,and vertical models,indicating the intensified stress redistribution occurred in the adjacent rock mass.In contrast,EDZ for the horizontal strata existed in a plastic-formed manner.During the overloading,abnormal features in the thermal images were observed preceding the coalescence of the propagating cracks.The ultimate failure of the model was due primarily to the floor heave and the roof fall.