在高数中利用数学哲理性知识进行思维教学及人文教学

数学哲理性知识是蕴涵在数学学科的知识体系之中,具有哲学思想和哲学意义的数学知识。其在培养人们数学素养和数学能力方面具有不可或缺、极其重要的地位和价值。若在高数课程的教学过程中加深对数学哲理性知识的挖掘及体验、点拨,将提高学生的辩证逻辑思维能力,使其体验数学文化的魅力。     

行政价值：概念、体系及其实现

行政价值,从本质上讲是指行政活动满足公众需要的效用性;而在实践中它一方面表现为公众对于行政的希望、期待和要求,另一方面也表现为行政组织、行政人员在行政活动中应该奉行和实际奉行的尺度和规范。行政价值体系是指行政价值的判断、观念和规范的体系。行政价值的实现,则是行政价值由潜在走向现实,行政价值的理念和规范落实在行政行为中,社会公众充分感受和分享行政行为效用的过程。这既是全面正确认识行政价值的过程,也是创造和践行行政价值的过程。     

Effects of Sn addition on microstructure and mechanical properties of Mg- Zn-Al alloys

The effects of Sn addition(0, 0.5, 1.0, 2.0 and 3 wt%) on microstructure of Mg-4Zn-1.5Al alloy in cast and extruded states were investigated, and the mechanical properties of as-extruded Mg-4Zn-1.5Al-xSn studied. The experimental results showed that the as-cast Mg-4Zn-1.5Al alloy was composed of two phases α-Mg and Mg_(32)(Al, Zn)_(49), while Sn-containing alloys consisted of α-Mg, Mg_(32)(Al, Zn)_(49) and Mg_2Sn phases, and Mg_(32)(Al, Zn)_(49) was not detected after extruding due to that the most of them dissolved into the matrix during the homogenized treatment. The addition of Sn refined the grains of as-cast and as-extruded Mg-Zn-Al alloys obviously. It was noted that the basal texture intensity reduced with increasing Sn content significantly in as-extruded Mg-Zn-Al alloys. The tensile tests results indicated that Sn addition improve the tensile strength of the extruded alloys,while it had a harmful effect on the ductility. When the addition of Sn was 2 wt%, the ultimate tensile strength(UTS), yield strength(YS) and elongation(ε_f) of the alloy were 280 MPa, 147 MPa and 17.4%, respectively.     

Synergistic effect of Al and Gd on enhancement of mechanical properties of magnesium alloys

The effect of Gd/Al ratio on the properties of as-cast Mg-Gd-Al-Zn alloys was investigated by changing the chemical composition from that of AZ61 to GZ61. At the ratio of 1, the Al2Gd phase becomes predominant and Mg17Al12 is hardly seen in the microstructure. As a potent inoculant, the Al2Gd phase resulted in intense grain refinement and enhancement of strength, ductility and toughness. For instance, the tensile strength and elongation to failure of Mg-3Gd-3Al-1Zn alloy were enhanced by ~4% and 180% compared with those of AZ61 alloy, respectively. However, at high Gd/Al ratios, the Al2Gd phase was replaced by (Mg,Al)3Gd and Mg5Gd phases and very large grain sizes were achieved, which led to poor tensile properties and the appearance of cleavage facets on the fracture surfaces. Therefore, it can be deduced that the presence of Gd and Al, in appropriate amounts to reach Gd/Al ratio of ~ 1, is required for the achievement of grain refinement, good ductility, high strength, and the appearance of ductile fracture surfaces in the Mg-Gd-Al-Zn system. Conclusively, the Mg-Gd-Al-Zn alloys can be considered as a new class of structural magnesium alloy and it is superior to both AZ (Mg-Al-Zn) and GZ (Mg-Gd-Zn) series of alloys.     

基于改进LLE算法的机械故障特征压缩与诊断

局部线性嵌入法(locally linear embedding,LLE)是一种典型的流形学习算法。在分析LLE算法的基本计算思路的基础上,提出了一种基于最佳分类效果的k和d综合参数选择方法。此方法综合考虑了故障类内和类间的离散度,并以此作为LLE算法特征压缩效果的评价依据。根据LLE算法的局部线性特征保持的基本特点,提出了一种增量式LLE算法用于柴油机机械故障特征压缩与诊断中。以平均子带能量法构造特征向量空间,子带数目的确定以同种故障类型特征参数间方差最小为准则。实验中,分别使用基于最佳参数选择的LLE算法、传统的主成分分析(principal component analysis,PCA)、增量式LLE算法对柴油机特征向量进行压缩,并对这三种算法的特征压缩结果运用K近邻算法(K-nearest neighborm,KNN)进行故障诊断与分类。结果表明基于最佳参数选择的LLE算法的诊断分类效果要优于传统的PCA方法,增量式LLE算法也取得良好的分类效果。实验表明,对LLE算法进行有关改进可以很好地应用到机械故障特征压缩与诊断中。     

Investigation of the microcrack evolution in a Ti-based bulk metallic glass matrix composite

The initiation and evolution behavior of the shear-bands and microcracks in a Ti-based metallic-glass–matrix composite(MGMC) were investigated by using an in-situ tensile test under transmission electron microscopy(TEM). It was found that the plastic deformation of the Ti-based MGMC related with the generation of the plastic deformation zone in crystalline and shear deformation zone in glass phase near the crack tip. The dendrites can suppress the propagation of the shear band effectively. Before the rapid propagation of cracks, the extending of plastic deformation zone and shear deformation zone ahead of crack tip is the main pattern in the composite.     

论《了凡四训》的“立命”观及其现实意义

《了凡四训》是明代影响很大的一部劝善书，该书的《立命篇》阐述了“命由我作，福自己求”的“立命之学”思想。这一“立命”观的思想基础是传统儒家思想和佛教思想。它强调因果报应、端庄态度、清净本心，教导人们通过自己的努力，通过一系列的方法积善成德、改变命运。在当今社会，这一“立命”观对当前良好社会风尚的形成和个人道德的培养具有重要意义。     

库恩后期哲学中抛弃了“范式”吗

20世纪80年代库恩哲学中原本的核心概念“范式”消失了。这似乎成为库恩哲学转向的标志，甚至成为历史主义科学哲学转向的标志。事实上“范式”观念以“类词”的名称依然存在于库恩哲学中，我们完全可以追溯这一演变的历程，从而揭示演变发生的原因。     

方志敏关于“死”的理念的哲学解

在方志敏关于"死"的理念中,"死"是一种辩证的否定。它既是生命的终结,也是生命的升华,产生的是一种激励后人更加努力奋斗的精神。方志敏的关于死的意义、死的价值、死的期望及对死的态度的表述,蕴含着非常深刻的马克思主义哲学道理。方志敏关于"死"的理念渊源于孔子的"杀身成仁"和孟子的"舍生取义"的哲学命题,但它具有时代特征,有自己独特的哲学之道。     

蒙古族传统哲学思维方式研究

通过天与人、人与神以及人与英雄等范式的哲学研究,揭示了蒙古族哲学的思维路径,历史地展示了蒙古族在形而上等问题上的哲学智慧以及道德思考的民族性。