西方自然主义教育家视野中主体性教育路径观的当代价值

西方自然主义教育家建构了具有"自然主义"特色的路径观,它对我们如何实施主体性教育有重要的启示价值:激发儿童的求知热情和兴趣;倡导发现教学;倡导自主学习;在经验的改造中彰显儿童的主体性。

公民教育:内涵、观念与研究路径

公民教育是21世纪教育的时代诉求,是我国未来学校教育发展的重要内容。为此,有必要对公民教育领域的文献进行系统的研究。本文首先阐述了对公民教育内涵的研究,在此基础上,梳理了国内外关于公民教育观的研究,并提出了公民教育研究＂三大路径＂,希翼对我国公民教育研究的繁荣与发展提供必要的参考和借鉴。

Wintertime Cyclone Activity and Its Relation to Precipitation over China

The authors examined the variability in wintertime cyclone activity and storm tracks and their relation to precipitation over China for the period 1951-2006 using the observational data.Two apparent modes of variability were assumed for the cyclone activity and storm tracks.The first mode describes the oscillation in the strength of the storm tracks in East Asia,which significantly increased since the mid-1980s,whereas the second mode describes a seesaw oscillation in the storm track strength between the Central-Southeast China and northem East Asia.The storm tracks over the Central-Southeast China have increased since the late 1960s.The possible causes for the variation of the cyclone activity and storm tracks are also explored.It is shown that wintertime precipitation,which has increased since the mid-1980s,concentrates in Central-Southeast China.The enhancement may be caused by the first mode of variability of storm tracks,whereas the interannual variability of precipitation may be linked to the second mode of the storm track variability.

Thermo-Calc and T-f_S-C_L coupling based method to determine solidification paths of alloys solidified under condition of Biot≤0.1

A binary continuum model for dendritic solidification transport phenomena and corresponding numerical algorithm for the strong nonlinear coupling of T-fS-CL were extended to multicomponent alloys solidified under condition of Biot≤0.1. Based on the extended model/algorithm, a method considering heat transfer was proposed to predict the solidification paths and microsegregation of alloys solidified under the same condition. The new algorithm and method were closely coupled with the commercial Thermo-Calc package via its TQ6-interface codes for instantaneous determination of the related thermodynamic data at each calculation time step. The sample simulation performed on an Al-2Si-3Mg alloy system indicates the availability and reliability of the model/algorithm and the proposed method for predicting solidification paths and microsegregation. Computional and experimental investigations on an Al-5.17Cu-2.63Si ternary alloy were conducted, and a reasonable agreement between the computation and experiment was obtained.

Effect of element Gd on phase constituent and mechanical property of Mg-5Sn-1Ca alloy

The Mg-5Sn-1Ca-xGd (x=0, 1) alloys were chosen to investigate the change in solidification paths, phase formation and mechanical properties. The microstructure of as-cast Mg-5Sn-1Ca alloy is composed of α-Mg, Mg2Sn and CaMgSn phases. With the addition of Gd, the formation of the Mg2Sn phase is impeded and the CaMgSn phase is refined, whereas the ultimate tensile strength and elongation decrease. The possible reasons for the variation in microstructure and mechanical properties were discussed.

Entropy Production along Dominant Pathway of Nonequilibrium Phase Transition in Mesoscopic Chemical System

We consider a bistable mesoscopic chemical reaction system and calculate entropy produc- tion along the dominant pathway during nonequilibrium phase transition. Using probability generating function method and eikonal approximation, we first convert the chemical master equation into the classical Hamilton-Jacobi equation, and then find the dominant pathways between two steady states in the phase space by calculating zero-energy trajectories. We find that entropy productions are related to the actions of the forward and backward dominant pathways. At the coexistence point where the stabilities of the two steady states are equiv alent, both the system entropy change and the medium entropy change are zero; whereas at non-coexistence point both of them are nonzero.

Sliding-mode control of path following for underactuated ships based on high gain observer

A nonlinear robust control strategy is proposed to force an underactuated surface ship to follow a predefined path with uncertain environmental disturbance and parameters.In the controller design,a high-gain observer is used to estimate velocities,thus only position and yaw angle measurements are required.The control problem of underactuated system is transformed into a control of fully actuated system through adopting an improved line-of-sight(LOS) guidance law.A sliding-mode controller is designed to eliminate the yaw angle error,and provide the control system robustness.The control law is proved semi-globally exponentially stable(SGES) by applying Lyapunov stability theory,and numerical simulation using real data of a monohull ship illustrates the effectiveness and robustness of the proposed methodology.

在深入“走转改”中践行马克思主义新闻观

通过阐释当前践行马克思主义新闻观的意义,以及"走转改"与践行马克思主义新闻观的关系,重点论述了在深入"走转改"过程中践行马克思主义新闻观的路径和方法。并提出要真正从思想和行动上用马克思主义新闻观武装头脑,指导实践,这样才能提高认识,坚定信念,明确方向,谨言慎行,增强服务人民、服务社会、服务国家的自觉性,做一个真正让人民满意的新闻工作者。