Timing in EPR correlations

Detecting the instants of absorption of two paired EPR particles, and varying independently the distances of the detectors to the source, will experimentally display the V-shaped causal link between the two correlated occurrences.     

A PRELIMINARY STUDY ON THE IMPACT OF MESOSCALE IRRIGATION OVER ARID LAND ON MESOSCALE CLIMATE

The present study investigated the modification of mesoscale inhomogeneous distribu-tion of soil wetness, resulting from mesoscale irrigation over arid or semiarid lands in mid-latitude in the later summer or early autumn, on mesoscale climate under conditions withand without synoptic flow influence, using an interactive model between soil and atmo-sphere. The simulations indicated that after a mesoscale irrgation, a wet soil breeze circu-lation was thermally forced, which was, in many features, similar to that of the sea breezecirculation. The influence of synoptic flows on the structure of thermally--induced wet soilbreeze circulation was also discussed.     

Indestructibility and level by level equivalence and inequivalence

If κ < λ are such that κ is indestructibly supercompact and λ is 2^λ supercompact, it is known from [4] that

• {δ < κ | δ is a measurable cardinal which is not a limit of measurable cardinals and δ violates level by level equivalence between strong compactness and supercompactness}

must be unbounded in κ. On the other hand, using a variant of the argument used to establish this fact, it is possible to prove that if κ < λ are such that κ is indestructibly supercompact and λ is measurable, then

• {δ < κ | δ is a measurable cardinal which is not a limit of measurable cardinals and δ satisfies level by level equivalence between strong compactness and supercompactness}

must be unbounded in κ. The two aforementioned phenomena, however, need not occur in a universe with an indestructibly supercompact cardinal and sufficiently few large cardinals. In particular, we show how to construct a model with an indestructibly supercompact cardinal κ in which if δ < κ is a measurable cardinal which is not a limit of measurable cardinals, then δ must satisfy level by level equivalence between strong compactness and supercompactness. We also, however, show how to construct a model with an indestructibly supercompact cardinal κ in which if δ < κ is a measurable cardinal which is not a limit of measurable cardinals, then δ must violate level by level equivalence between strong compactness and supercompactness. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Combinatorial and accessible weak model categories

In a previous work, we have introduced a weakening of Quillen model categories called weak model categories. They still allow all the usual constructions of model category theory, but are easier to construct and are in some sense better behaved. In this paper we continue to develop their general theory by introducing combinatorial and accessible weak model categories. We give simple necessary and sufficient conditions under which such a weak model category can be extended into a left and/or right semi-model category. As an application, we recover Cisinski-Olschok theory and generalize it to weak and semi-model categories. We also provide general existence theorems for both left and right Bousfield localization of combinatorial and accessible weak model structures, which combined with the results above gives existence results for left and right Bousfield localization of combinatorial and accessible left and right semi-model categories, generalizing previous results of Barwick. Surprisingly, we show that any left or right Bousfield localization of an accessible or combinatorial Quillen model category always exists, without properness assumptions, and is simultaneously both a left and a right semi-model category, without necessarily being a Quillen model category itself.     

Learning about multiplication by comparing algorithms: “One times one,but actually they are ten times ten”

Multiplication algorithms in primary school are still frequently introduced with little attention to meaning. We present a case study focusing on a third grade class that engaged in comparing two algorithms and discussing “why they both work”. The objectives of the didactical intervention were to foster students' development of mathematical meanings concerning multiplication algorithms, and their development of an attitude to judge and compare the value and efficiency of different algorithms. Underlying hypotheses were that it is possible to promote the simultaneous unfolding of the semiotic potential of two algorithms, considered as cultural artifacts, with respect to the objectives of the didactical intervention, and to establish a fruitful synergy between the two algorithms. As results, this study sheds light onto the new theoretical construct of “bridging sign”, illuminating students’ meaning-making processes involving more than one artifact; and it provides important insight into the actual unfolding of the hypothesized potential of the algorithms.     

可变形多孔介质渗透系数的测定方法

在Ｂｉｏｔ理论基础上给出可变形多孔介质耦合渗流基本方程；求出小试件一维定常耦合渗流问题的解答；表明在一维流固耦合情况下试件内部压力梯度有明显的非均匀性。因此通过实验确定可变形多孔介质渗透系数在数学上可归结为微分方程的反问题，传统的测试渗透系数的方法需要改进。介绍了可变形多孔介质渗透系数的测试原理和测试方法。对粒状多孔材料实验的结果表明，传统实验方法得到的渗透系数误差较大。     

时域边界元法分析撞水响应

基于势流理论，考虑流场的可压缩性，首先利用积分变换导得了势流问题的一个动力学倒易定理，在此基础上，进而求得问题对应的时空边界积分方程，然后通过对边界和时间轴同时离散，建立了一组有递推形式的时间边界元方程最后结合液面条件和物体运动方程耦全求解得到了刚体的撞水响应。     

圆形刚性夹杂双周期分布的反平面问题

研究含双周期分布的圆形刚性夹杂在无穷远受纵向剪切的弹性平面问题，遵循复合材料中各夹杂相互影响的重要条件。采用复变函数方法。构造相应模型的复应力函数。通过坐标变换，同时满足夹杂边界位移条件，再利用围线积分将求争方程组化为线性代数方程组。导出了圆形刚性夹杂双周期分布的界面应力解析表达式。算例给出了界面应力最大值与夹杂间距的变化规律。求出了刚性夹杂的合理间距问题，本文发展的分析方法为研究夹杂材料的细观机理探索了一条有效的分析途径。     

Near-Boundary Stress Wave Field in Anisotropic Plates under Impulsive Load

The stress wave field and the behavior of waves near the free boundary in an orthotropic plate and at the interface between two anisotropic media are studied. The results presented were obtained using the dynamic photoelastic method and optically sensitive fibrous models. Experimental data for impulsively loaded plates with various boundary conditions are analyzed     

基于土拱效应的抗滑桩与护壁桩的桩间距分析

抗滑桩与护壁桩分别在滑坡治理和基坑支护中发挥着巨大的作用 ,其实施正是利用了土中的成拱效应 ,然而传统桩的设计虽考虑土拱效应的存在 ,但桩间距确定理论与方法并未建立起来。本文首先基于土体的极限平衡条件对滑坡推力作用下的土体中的成拱作用进行研究 ,得出了抗滑桩的最大桩间距公式 ,并以某一具体工程为例 ,对该最大桩间距的物理意义和可用性进行了讨论。在此基础上 ,给出了在考虑土拱效应的情况下合理桩间距的确定方法 ,并以此为据 ,对边坡加固设计提出一些建议.