基于课堂观察的教与学言语行为量化分析——以“水的组成”教学为例

选取全国初中化学优质课教师C的课堂教学视频作为研究对象,根据改进的言语互动分类工具进行课堂观察,采用信息熵理论模型对课堂中教师与学生语言及活动行为的丰富度进行定量分析,再进一步以学生-教师（S-T）分析法分析课堂教学类型。为教师优化课堂教学行为与学生学习行为提供支持,从而促进教师专业发展和学生学习方法的改进。     

电极扩散层内物质浓度及分布研究方法进展

评述了测试电极扩散层内物质浓度及分布的各种方法,分别从方法原理、实验装置、影响因素及其应用等方面加以论述,评价了各种方法的特点,并对发展方向进行了展望。共引用文献５２篇。     

A Nonparametric Estimation Problem From Indirect Observations

This paper deals with a nonparametric estimation problem of an integral-type functional from indirect observations where the observation Y (t) is a sum of a known function of an unobservable process X (t) and a Gaussian white noise, and X (t) is a sum of an unknown function a(t) and a Gaussian process. The minimax lower bound on the quality of nonparametric estimation is derived and an asymptotically efficient estimator is proposed. The paper concludes with some examples including one about reduction to parameter estimation.     

软产道血肿的观察和护理体会

为探讨软产道血肿发生的原因,预防和减少阴道分娩的并发症,对12例软产道血肿发生的情况及相关因素进行了分析。结果表明,软产道血肿的形成与有无妊娠合并症、产程长短、助产技术密切相关。提示做好围产期保健工作,提高助产技术,加强产后的观察与护理,是防止软产道血肿的关键。     

Cavitation field from a horn—A new model

The cavitation field from a horn-type transducer is experimentally probed by the optical method.Based on these observations,we propose a model of the field which hypothesizes that most violent caviation bubbles originate from the vibrating surface and there-from fast drift to the near liquid region.These bubbles are chiefly responsible for the practical applications of cavitation for a large power input to the transducer.During migration they become weakened.Cavitation bubbles are also produced in the liqui...     

Dark energy: A brief review

The problem of dark energy is briefly reviewed in both theoretical and observational aspects. In the theoretical aspect, dark energy scenarios are classified into symmetry, anthropie principle, tuning mechanism, modified gravity, quantum cosmology, holographic principle, back-reaction and phenomenologieal types. In the observational aspect, we introduce cosmic probes, dark energy related projects, observational constraints on theoretical models and model independent reconstructions.     

基于PI调节占空比的自适应MPPT方法

最大功率点跟踪(MPPT)技术是提高光伏发电效率的重要途径之一。扰动观测法是MPPT控制中最常用的方法,针对其无法兼顾跟踪速度与最大功率点跟踪过程的震荡问题,提出了一种基于PI调节占空比的自适应MPPT方法,该方法针对占空比采用基于PI调节的自适应策略。通过Simulink建模仿真,与其他方法进行对比分析,结果显示了该方法可显著地提高了最大功率点跟踪的速度与精度。     

高精度千赫兹流动激光测距系统中国西部地区实测结果分析

为了解决人造卫星激光测距观测站在我国东西部地区分布不均衡的现状,中国地震局地震研究所采用方便运输的载车结构和皮秒级千赫兹半导体激光器,结合自行研制的皮秒级事件计数器和纳秒级距离门,研制了新一代的大口径流动卫星激光测距系统TROS1000.TROS1000具备千赫兹流动激光测距的能力,并且具有机动灵活、架设周期短等特点.2019年9月,TROS1000抵达中国科学院新疆天文台南山观测站,在我国西部地区首次获取千赫兹激光观测数据.经过数据预处理,中低轨卫星的单次精度优于14 mm,高轨卫星的单次精度优于19 mm,与上一代流动激光测距系统相比,其单次精度更高,有效回波信号更多,目标探测能力更强.     

Exponential family non-linear models for categorical data with errors of observation

We present a general framework for treating categorical data with errors of observation. We show how both latent class models and models for doubly sampled data can be treated as exponential family nonlinear models. These are extended generalized linear models with the link function substituted by an observationwise defined non-linear function of the model parameters. The models are formulated in terms of structural probabilities and conditional error probabilities, thus allowing natural constraints when modelling errors of observation. We use an iteratively reweighted least squares procedure for obtaining maximum likelihood estimates. This is faster than the traditionally used EM algorithm and the computations can be made in GLIM.¹ As examples we analyse three sets of categorical data with errors of observation which have been analysed before by Ashford and Sowden,² Goodman³ and Chen,⁴ respectively.