论数学教育中的数学观念体系

本文从培养数学观念的角度，就数学教育如何培养人们的科学思维方式和形成良好的思维习惯作一论述。     

洋桔梗叶盘高频率不定芽诱导的初步研究

采用正交设计法研究了细胞分裂素ZT,生长素NAA,培养基pH值和光照强度对洋桔梗叶盘不定芽诱导的影响.结果表明,实验的4个因子对洋桔梗叶盘不定芽都具有极显著的诱导作用,最佳培养基和培养条件为:MS ZT 0.5 mg/L NAA 0.01 mg/L,培养基pH值为6.3,光照强度为3000 lx.该处理中每叶盘再生不定芽数平均达9.41个.     

Reconsidering the Evolution of Nonlinguistic Communication: The Case of Laughter

Nonlinguistic communication is typically proposed to convey representational messages, implying that particular signals are associated with specific signaler emotions, intentions, or external referents. However, common signals produced by both nonhuman primates and humans may not exhibit such specificity, with human laughter for example showing significant diversity in both acoustic form and production context. We therefore outline an alternative to the representational approach, arguing that laughter and other nonlinguistic vocalizations are used to influence the affective states of listeners, thereby also affecting their behavior. In the case of laughter, we propose a primary function of accentuating or inducing positive affect in the perceiver in order to promote a more favorable stance toward the laugher. Two simple strategies are identified, namely producing laughter with acoustic features that have an immediate impact on listener arousal, and pairing these sounds with positive affect in the listener to create learned affective responses. Both depend on factors like the listener's current emotional state and past interactions with the vocalizer, with laughers predicted to adjust their sounds accordingly. This approach is used to explain findings from two experimental studies that examined the use of laughter in same-sex and different-sex dyads composed of either friends or strangers, and may be applicable to other forms of nonlinguistic communication.     

环境规制对农户清洁取暖采纳行为的影响——兼论政府信任的调节作用

基于“目标群体回应行动评价政策及执行有效性”的思路,利用汾渭平原微观农户调查数据,以农户的清洁取暖采纳行动来评估“双替代”政策及环境规制执行效能。鉴于清洁取暖双重政策目标,将农户清洁取暖采纳分为采纳决策和采纳效果两个阶段。采用Heckman模型,从约束型规制和激励型规制两个维度分析不同环境规制手段对农户清洁取暖采纳的影响效应。结果表明:约束型规制对农户清洁取暖采纳决策具有显著正向影响,而对农户清洁取暖采纳效果具有显著负向影响;激励型规制对农户清洁取暖采纳决策和采纳效果均有正向影响。控制内生性的IV Heckman模型和PSM反事实估计结果支持了上述研究结论。运用同时克服环境规制内生性和样本选择偏差问题的IV Heckman模型,从中央政府信任和地方政府信任两个层级拓展研究不同政府信任在环境规制对农户清洁取暖采纳影响中的调节作用。结果表明:中央政府信任在约束型规制对农户清洁取暖采纳中发挥增强性调节作用,地方政府在约束型规制和激励型规制对农户清洁取暖采纳中均发挥增强性调节作用。最后,提出环境规制政策执行应兼顾农户资本禀赋差异、提升地方政府信任度等对策建议。     

对RC4算法的错误引入攻击研究

错误引入攻击假设攻击者可以向密码设备(智能卡)引入错误,使其出现错误的加密结果。攻击者同时利用正确的和错误的加密结果来发现隐藏在密码设备中的秘密信息(密钥)。该文给出了一种对RC4算法的错误引入攻击方法。模拟实验表明,一轮攻击有可能找出RC4初始状态中3个位置的值,连续使用该算法能以较高(大于1/2)的概率恢复RC4的整个初始状态。恢复整个初始状态所需的密钥字个数约为O(216),引入的错误数量约为O(216)。     

现代建筑中的通感艺术

本文就建筑设计中的“通感”艺术手法结合实例进行了分析 ,以便扩大审美视野 ,打开创作繁荣的一条通道     

Indoor Climate and Thermal Comfort from a Long-Term Perspective

ABSTRACT

This article discusses how a Swedish wooden burgher house, the mid-1660s Burmeister House, was adapted over the course of 250 years to satisfy ever-changing expectations of thermal comfort. The investigation is based on the climatic conditions of the Nordic Region, where the issue of thermal comfort is crucial when attempting to understand the development of indoor environments. The article explores how spatiality, heating, and interior decor and furnishing operated and affected the inhabitants' experiences of indoor climate and thermal comfort. The results show that Burmeister House followed a general pattern of improvement, especially with regard to innovations in heating. Burmeister House ceased to be a private residence when it was restored and turned into a historic house museum. Rather than revealing its history, restorations carried out in the twentieth century worked to conceal or remove most of the building's more recent history. As a consequence, the house has become more difficult to use since it can no longer be efficiently heated.     

The foundations of econometrics-are there any

The conclusions of alogically consistent economic theory which strictly adheres to Aristotle's axioms of logic are factually true if its sufficient conditions are all factually true. Alternatively, if a conclusion of such a theory is false, then at- least one of its assumptions is false. Unfortunately, the factual truth of sufficient conditions cannot be established because the problem of induction i s impossible t o solve. It is algo true that the falsity of a conclusion cannot be established in the presence of uncertainty. While the philosophy of instrumentalism applied to sufficient and logically consistent explanations may provide useful solutions to immediate practical problems, the principles of simplicity, parsimony and profligacy--all of them requiring conditional deductive arguments--are useless as criteria for model choice.     

三相异步电动机缺相起动及运行的探讨

三相异步电动机缺相时无法正常起动,运行中缺相时转速变慢,缺相是造成电动机损坏的主要原因。为保证安全、可靠运行,三相异步电动机应设置电源缺相保护。