概率积分的几种计算方法

文章给出计算概率积分∫-∞^∞e^x^dx的几种简便方法。     

Non-linear 2-DOF model and centre manifold theory to study limit cycle oscillations caused by drum-brake judder

This paper presents the research on the laws of systematic-parameter dependent variation in the vibration amplitude of drum-brake limit cycle oscillations (LCO). We established a two-degree non-linear dynamic model to describe the low-frequency vibration of the drum brake, applied the centre manifold theory to simplify the system, and obtained the LCO amplitude by calculating the normal form of the simplified system at the Hopf bifurcation point. It is indicated that when the friction coefficient is smaller than the friction coefficient at the bifurcation point, the amplitude decreases; whereas with a friction coefficient larger than the friction coefficient of bifurcation point, LCO occurs. The results suggest that it is applicable to suppress the LCO amplitude by changing systematic parameters, and thus improve the safety and ride comfort when applying brake. These findings can be applied to guiding the design of drum brakes.     

关于粘性导数的几个性质的探讨

M .G .Crandall等人在文 [1]中给出了函数的粘性导数的概念。在这个概念的基础上我们讨论了函数的粘性导数的上 (下 )导集的几个性质 :在函数可微点处的性质、闭凸性质、与C1类函数的和的性质、与C2 类函数的差在严格局部极大 (小 )值点的性质。     

实现计算机与PLC自由口模式串行通信的研究

PLC作为一种稳定可靠的控制器得到广泛的运用,但它也有自身的一些缺点:数据的计算处理和管理能力较弱,不能给用户提供良好的界面等。而计算机恰好能弥补PLC的不足,它不但有很好的数据计算处理和管理能力,而且能给用户提供非常美观而又易于操作的界面。将PLC与计算机通信网络连接起来,并实现串行通信,可以有效地提高控制系统的整体自动化程度。     

几个重要积分不等式

从简单的代数不等式ab~≤a+b/2出发,通过变形,观察,猜想,用极限思想得出并证明了一些新的积分不等式。     

Implicit knowledge of general upper secondary school in a bridge-building project

Bridge-building activities are practiced widely in the education systems of Europe. They are meant to bridge transitions between lower and upper secondary school and form a mandatory part of the youth guidance system in Denmark. By giving pupils the opportunity to experience the different educational context of upper secondary school, bridge-building activities are meant to facilitate their decision-making on educational paths, but also to attract more and new groups of pupils. However, the premises of the inherent differences of educational contexts and of pupils’ lacking knowledge of upper secondary education can be questioned. In this ethnographic case study of a bridge-building project in a rural area in Denmark, we analyse the implicit knowledge of the general upper secondary school, as it is practiced in a bridge-building project, and how it is experienced by the pupils on the background of their prior knowledge. The analysis is theoretically informed by especially the code concepts of Basil Bernstein.     

双向偏压的实用简化计算

将双向偏压构件中的四边形、三角形等多边形砼受压区简化为等效矩形，采用多排配筋且沿截面周边均匀对称配置来简化双向偏压的实用计算。     

Modeling of Normal Perforation of Reinforced Concrete Slabs by a Rigid Projectile

An analytical model on the normal perforation of reinforced concrete slabs is constructed. The effect of reinforcing bars is further hybridized in a general three-stage model consisting of initial cratering, tunnelling and shear plugging. Besides three dimensionless numbers, i. e. , the impact function /, the geometry function of projectile N and the dimensionless thickness of concrete target X, which are employed to predict the ballistic performance of perforation of concrete slabs, the reinforcement ratioρs of concrete and the tensile strength fs of reinforcing bars are considered as the other main factors influencing the perforation process. Simpler solutions of ballistic performances of normal perforation of reinforced concrete slabs are formulated. Theoretical predictions agree well with individual published experimental data.     

在显示器上描绘直线的要求和几种直线生成算法之比较

在显示器上描绘直线的基本要求和几种算法。     

浅析赵翼论六言诗兼谈六言诗的发展

赵翼在《陔馀丛考》中有关六言诗的评价可谓触及六言诗发展的实质问题。本文通过解读赵翼关于六言诗的一些观点。例如,赵翼认为六言诗的起源不始于谷永,偏爱王维的六言绝句,并认为六言诗没能兴盛是因为“其虽工但非天地自然之音节”,结合赵翼的诗学理论,客观分析上述观点。与此同时。试对六言诗的发展和最终没能繁荣的原因做一个粗浅探究。