Cause–effect analysis: improvement of a first year engineering students’ calculus teaching model

This study focuses on the mathematics department at a South African university and in particular on teaching of calculus to first year engineering students. The paper reports on a cause–effect analysis, often used for business improvement. The cause–effect analysis indicates that there are many factors that impact on secondary school teaching of mathematics, factors that the tertiary sector has no control over. The analysis also indicates the undesirable issues that are at the root of impeding success in the calculus module. Most important is that students are not encouraged to become independent thinkers from an early age. This triggers problems in follow-up courses where students are expected to have learned to deal with the work load and understanding of certain concepts. A new model was designed to lessen the impact of these undesirable issues.     

Exploring inequality violations by classical hidden variables numerically

There are increasingly suggestions for computer simulations of quantum statistics which try to violate Bell type inequalities via classical, common cause correlations. The Clauser–Horne–Shimony–Holt (CHSH) inequality is very robust. However, we argue that with the Einstein–Podolsky–Rosen setup, the CHSH is inferior to the Bell inequality, although and because the latter must assume anti-correlation of entangled photon singlet states. We simulate how often quantum behavior violates both inequalities, depending on the number of photons. Violating Bell 99% of the time is argued to be an ideal benchmark. We present hidden variables that violate the Bell and CHSH inequalities with 50% probability, and ones which violate Bell 85% of the time when missing 13% anti-correlation. We discuss how to present the quantum correlations to a wide audience and conclude that, when defending against claims of hidden classicality, one should demand numerical simulations and insist on anti-correlation and the full amount of Bell violation.     

Tabu Search When Noise is Present: An Illustration in the Context of Cause and Effect Analysis

In the field of combinatorial optimization, it may be possible to more accurately represent reality through stochastic models rather than deterministic ones. When randomness is present in a problem, algorithm designers face new difficulties which complicate their task significantly. Finding a proper mathematical formulation and a fast evaluation of the objective function are two major issues. In this paper we propose a new tabu search algorithm based on sampling and statistical tests. The algorithm is shown to perform well in a stochastic environment where the quality of feasible solutions cannot be computed easily. This new search principle is illustrated in the field of cause and effect analysis where the true cause of an undesirable effect needs to be eliminated. A set of n potential causes is identified and each of them is assumed to be the true cause with a given probability. The time to investigate a cause is a random variable with a known probability distribution. Associated with each cause is the reward obtained if the cause is really the true cause. The decision problem is to sequence the n potential causes so as to maximize the expected reward realized before a specified time horizon.     

两相同部件温贮备可修的人机系统解的性质分析

本文首先用强连续算子半群理论证明了两相同部件温贮备可修的人机系统动态非负解的存在唯一性 ,然后证明了 0是系统主算子的本征值 ,并得到 0本征值对应的本征向量是正的 ,从而系统存在稳态正解 .     

The Limits of Common Cause Approach to EPR Correlation

It is often argued that no local common cause models of EPR correlation exist. However, Szabó and Rédei pointed out that such arguments have the tacit assumption that plural correlations have the same common causes. Furthermore, Szabó showed that for EPR correlation a local common cause model in his sense exists. One of his requirements is that common cause events are statistically independent of apparatus settings on each side. However, as Szabó knows, to meet this requirement does not entail that different combinations of common cause events (e.g. meet and join in lattice-theoretic terminology) are statistically independent of measurement settings. This further condition is formulated in two ways. First, the apparatus settings are completely independent of such combinations. Second, the apparatus settings on each side are independent of such combinations. Does a common cause model which meets the former and the latter respectively exist? This problem is considered. In particular, the latter version is Szabó’s and Rédei’s open problem. Negative answers are given to both versions.     

Local Primitive Causality and the Common Cause Principle in Quantum Field Theory

If (V) is a net of local von Neumann algebras satisfying standard axioms of algebraic relativistic quantum field theory and V ₁ and V ₂ are spacelike separated spacetime regions, then the system ( (V ₁ ), (V ₂ ), ) is said to satisfy the Weak Reichenbach's Common Cause Principle iff for every pair of projections A (V ₁ ), B (V ₂ ) correlated in the normal state there exists a projection C belonging to a von Neumann algebra associated with a spacetime region V contained in the union of the backward light cones of V ₁ and V ₂ and disjoint from both V ₁ and V ₂ , a projection having the properties of a Reichenbachian common cause of the correlation between A and B. It is shown that if the net has the local primitive causality property then every local system ( (V ₁ ), (V ₂ ), ) with a locally normal and locally faithful state and suitable bounded V ₁ and V ₂ satisfies the Weak Reichenbach's Common Cause Principle.     

以8807号台风为例分析杭州台风、暴雨的特点、原因及对策

本文分析了1988年8月8日杭州遭到的7号强台风暴雨(简称8807号台风暴雨)给杭州市造成的灾害特点及原因,在此基础上对杭州市的防灾抗灾提出对策和建议,为城市的总体规划、基础设施、市政建设、防灾抗灾提供科学依据,也为东南沿海其它城市的防灾抗灾对策研究提供参考依据.     

柔性多体系统产生动力刚化原因的研究

传统的柔性多体系统建模理论由于对柔性体的变形及其与大范围运动产生惯性力之间的耦合处理得过于简单,所以在分析存在高速大范围运动柔性多体系统的动力学性态时会得到完全错误的结论。本文将通过对作大范围运动弹性薄板的讨论来揭示产生这种错误的及探讨对传统性多体系统建模理论作出改进的对策     

基于超图的多冲击共因失效模型

复杂冗余系统的共因失效一直是工程中亟待解决的问题.针对传统共因失效模型的缺点,利用超图概念和矩阵相似度的原理,在充分考虑了不同共同原因冲击耦合问题的基础上,提出了一种新的共因失效模型.该模型从实际统计数据出发,不需要专家分析,可以精确计算出不同共同原因冲击对系统的影响,且在实际应用中更加简单.     

Reichenbach’s Common Cause in an Atomless and Complete Orthomodular Lattice

Hofer-Szabo, Redei and Szabo (Int. J. Theor. Phys. 39:913–919, 2000) defined Reichenbach’s common cause of two correlated events in an orthomodular lattice. In the present paper it is shown that if logical independent elements in an atomless and complete orthomodular lattice correlate, a common cause of the correlated elements always exists.