网络环境下学生学习能力的培养

目前,小学阶段的研究性学习正如火如荼地开展,与综合实践活动相适应的基本学习方法是探究学习。学生的学习方式正发生着根本性的转变,书本知识的学习不再是学生获得知识的唯一途径,在综合实践活动实施的过程中积极运用网络技术等信息手段,以拓展活动的时空范围,信息技术课作为进行信息交流必不可少的学习工具,在综合实践课扮演着重要的角色。因此,电脑课强化学生网上学习意识,培养学生的信息处理能力,是当前我们信息技术老师的首要任务。

Future Changes of Drought and Flood Events in China under a Global Warming Scenario

This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under the SRES(Special Report on Emissions Scenarios) A1B scenario.The standardized precipitation index(SPI),which has well performance in monitoring the drought/flood characteristics(in terms of their intensity,duration,and spatial extent) in China,is used in this study.The projected results of 22 coupled models and the RegCM3 simulation are consistent.These models project a decrease in the frequency of droughts in most parts of northern China and a slight increase in the frequency in some parts of southern China.Considering China as a whole,the spatial extents of droughts are projected to be significantly reduced.In contrast,future flood events over most parts of China are projected to occur more frequently with stronger intensity and longer duration than those prevalent currently.Additionally,the spatial extents of flood events are projected to significantly increase.

A New Upsurge in Global Seismicity

This paper studies the temporal and spatial distribution of great global earthquakes （Mw i〉 8.0） since 1900. We compare the two periods of upsurges of great earthquakes occurring in the middle of last century and beginning of this century. The former period took place between 1950 and 1965 during which 13 great earthquakes （Mw I〉 8.0） occurred, including three events with moment magnitude greater than 9. 0. The largest magnitude in this period reached 9.6. The latter period starts from the beginning of this century. In less than 12 years, 15 great earthquakes have attacked the world with the largest magnitude being Mw 9. 1. On the basis of comparison between these two upsurges of global earthquake activity, we infer that the ongoing high level of earthquake activity may continue for another five years or so. Numerous great earthquakes （Mw I〉8. 0） and many large earthquakes （Mw6.0 ~ 7. 0） will occur globally in these five years. In addition, this paper also discusses the relationships between earthquake activity along the Sumatra segment of the Indian-Australia plate boundary and that in the Bayankala block in the middle of Qinghai-Tibetan plateau as well as in the blocks of the southern plateau. The results indicate that the Qinghai-Tibetan plateau, in particular its middle and southern parts, is a likely place for future earthquakes of magnitude over 7.0.

Thermodynamics of DBI Black Holes in Anti-de Sitter Spacetime

Through the gauge field theory, we obtain the solution of the DBI-AdS black hole, In the meantime, according to the relations between the action and the grand partition function, we obtain the grand partition function in the DBI-AdS black hole. The temperature and the potential of the DBI-AdS black hole are gained from differential of the grand partition function. With the thermodynamic relations, other thermodynamics are also obtained. The solution and the thermodynamics of the DBI-AdS black hole are turned out that they can reduce to the case of a charged black hole in four-dimensional spacetimes.

A new look at the Lagrange method for continuous-time stochastic optimization

We formulate a Lagrange method for continuous-time stochastic optimization in an appropriate normed space by using a proper stochastic process as the Lagrange multiplier.The obtained optimality conditions are applied to different types of problems.Some examples selected from control theory and economic theory are studied to test and illustrate the potential applications of the method.

Interacting Theory of Chiral Bosons and Gauge Fields on Noncommutative Extended Minkowski Spacetime

Several interacting models of chiral bosons and gauge fields are investigated on the noncommutative extended Minkowski spacetime which was recently proposed from a new point of view of disposing noncommutativity.The models include the bosonized chiral Schwinger model,the generalized chiral Schwinger model (GCSM) and its gauge invariant formulation.We establish the Lagrangian theories of the models,and then derive the Hamilton's equations in accordance with the Dirac's method and solve the equations of motion,and further analyze the self-duality of the Lagrangian theories in terms of the parent action approach.

On the Uniqueness of Ghost-Free Special Gravity

Special gravity refers to interacting theories of massless gravitons in Minkowski space-time which are invariant under the abelian gauge invariance hab → hab ＋ δ（axb） only. In this article we determine the most general form of special gravity free of Ostrogradski ghosts, meaning its equation of motion is of at most second order. Together with the recent works, this result could be helpful in formulating proofs of General Relativity as the unique physical theory of self-interacting massless gravitons. We also study how to construct gauge invariant couplings to matter fields.