Types of reasoning required in university exams in mathematics

Empirical research shows that students often use reasoning founded on copying algorithms or recalling facts (imitative reasoning) when solving mathematical tasks. Research also indicate that a focus on this type of reasoning might weaken the students’ understanding of the underlying mathematical concepts. It is therefore important to study the types of reasoning students have to perform in order to solve exam tasks and pass exams. The purpose of this study is to examine what types of reasoning students taking introductory calculus courses are required to perform. Tasks from 16 exams produced at four different Swedish universities were analyzed and sorted into task classes. The analysis resulted in several examples of tasks demanding different types of mathematical reasoning. The results also show that about 70% of the tasks were solvable by imitative reasoning and that 15 of the exams could be passed using only imitative reasoning.     

GPU-accelerated real-time IR smoke screen simulation and assessment of its obscuration

With the growing demand for the Battlefield Environment Simulation (BES), IR smoke screen, which is computationally expensive and absolutely indispensable, should be modeled true to life and correct in its thermal radiation characteristics. This paper analyzes the features of an IR smoke screen, and represents an IR smoke screen model based on light extinction, particle dispersion and temperature attenuation, which is calculated by GPU and rendered to screen in real time. Thus a method considering both the real-life in profile and the real-time in efficiency is presented. Additionally, the comparison between the simulated results and the measured data is made to verify the correctness of the smoke screen’s obscuration, which illustrates the effect of its interference feature in an infrared scene.     

Reliability of pitch discrimination of vowel and piano tones

This study evaluated the reliability of pitch judgments as a basic step toward increasing interrater and intrarater reliability of multidimensional perceptual judgments of the speaking voice. Forty-five undergraduate university students studying speech/language pathology made piano-to-piano tone pitch matches and vowel-to-piano pitch matches using a computer software program. The mean percentage correct of piano-to-piano tone matches was 91.3% and of vowel-to-piano matches was 75.6%. Subjects who scored 100% correct were significantly faster at the pitch matching task. Further research of perceptual judgments of pitch and its contribution to multidimensional rating tasks is warranted.     

建筑场地地震液化危害评价及地基处理

本文分析了地基失稳，计算震陷值及差异震陷等地基失效形式和液化土层的隔震作用，研究了液化指数、地基失效、液化土层隔震与多层房屋震害的关系，根据液化土的双重作用原理划分了液化危害等级，并提出了建筑场地地震液化危害评价方法和按“小震不坏，中震可修，大震不倒”的抗液化处理原则。     

Students’ geometric thinking with cube representations: Assessment framework and empirical evidence

While representations of 3D shapes are used in the teaching of geometry in lower secondary school, it is known that such representations can provide difficulties for students. In order to assess students’ thinking about 3D shapes, we constructed an assessment framework based on existing research studies and data from G7-9 students (aged 12–15). We then applied our framework to assess students’ geometric thinking in lessons. We report two cases of qualitative findings from a classroom experiment in which Grade 7 students (aged 12–13) tackled a problem in 3D geometry that was, for them, quite challenging. We found that students who failed to answer given problems did not mentally manipulate representations effectively, while others could mentally manipulate representations and reason about them in order to reach correct solutions. We conclude with the proposition that this finding shows the framework can be used by teachers in instruction to assess their students’ 3D geometric thinking.     

基于模糊理论的软件寿命周期费用评价模型

软件寿命周期费用评价模型涉及到软件开发、使用和维护过程中各种资源最有效利用的权衡分析。由于软件开发不是一门严谨的精确科学,往往存在大量具有不确定性的需求以及许多未知和不确定因素,所有这些都给软件寿命周期费用评价带来模糊效用。本文将模糊理论应用于软件寿命周期费用的评价,给出了从评价属性模糊值的确定、模糊评价模型的建立,到模型求解和最优方案选择的模糊评价方法,并通过对一个算例的分析,证明了该模型的可行性。     

New Developments in Environmental Exposure Assessment in the EU Pesticide Regulatory Process

The paper discusses key aspects of the European Union (EU) regulatory policy for environmental exposure assessment of agricultural pesticide active substances (a.s.) in soil and water, which is examined in the context of the EU Authorisations Directive (91/414/EEC). For agricultural pesticide regulation within EU Member States (MS), the Authorisations Directive will gradually replace existing national systems. Discussion is concentrated on this directive, looking in particular at the Uniform Principles therein and the possible ways that these decision-making guidelines are being developed into a workable regulatory framework. The aim in this process of negotiated development involving the Member States, the Agrochemical Industry and the European Commission (EC), is to identify any questions or data requirements that will be needed for agricultural pesticides.     

Uses and limitations of quantitative structure-activity relationships (QSARs) to categorize substances on the Canadian domestic substance list as persistent and/or bioaccumulative,and inherently toxic to non-human organisms

Under sections 73 and 74 of the revised Canadian Environmental Protection Act (CEPA 1999) , Environment Canada and Health Canada must "categorize" and "screen" about 23,000 substances on the Domestic Substances List (DSL) for persistence (P), bioaccumulation (B), and inherently toxic (iT) properties. Since experimental data for P, B and iT are only available for a few DSL substances, a workshop was held to address issues associated with the use of Quantitative Structure-Activity Relationships (QSARs) to categorize these substances. This paper describes the results of an 11-12 November 1999 International Workshop sponsored by Environment Canada to discuss potential uses and limitations of QSARs to categorize DSL substances as either persistent or bioaccumulative and iT to non-human organisms and to recommend future research needed to develop methods for predicting the P, B and iT of difficult-to-model substances.     

基于组合权重和模糊随机方法的台风灾害风险评估

利用2000~2016年登陆华南地区的24个台风样本的灾情与致灾源数据,建立台风灾害风险评估模型。首先,运用层次分析法和熵权法构建一种新的组合权重;然后,利用组合权重构建灾情指数序列和致灾源指数序列,计算每个台风灾害风险值,并将风险值从小到大划分为五个区间;最后,采用模糊随机方法建立华南地区台风灾害模糊风险评估模型,计算得到五个风险等级区间的模糊可能性,以此来表示各等级台风灾害发生的可能性大小。结果表明,基于组合权重构造的灾情指数序列与致灾源指数序列相关性较强;华南地区发生第二风险等级台风灾害的可能性最大,发生第五风险等级台风灾害的可能性最小,与实际情况较为吻合。