Approximation properties of the generalized Szasz operators by multiple Appell polynomials via power summability method

In this paper some properties of the generalized Szasz operators by multiple Appell polynomials are given, using into consideration the power summability method. In the first section are given some direct estimation related to the generalized Szasz operators by multiple Appell polynomials, including Korovkin type theorem. In the second section, we give some results related to the weighted spaces of continuous functions and Voronovskaya type theorem. In the third section, we have proved some results related to the statistical convergence of the generalized Szasz operators by multiple Appell polynomials, using into consideration the A− transformation. At the end of the paper are given some illustrative computational examples which make such summability methods (for example, power series method) more useful and fruitful for applications of functional analysis in approximation theory.     

On the classical limit of Bohmian mechanics for Hagedorn wave packets

We consider the classical limit of quantum mechanics in terms of Bohmian trajectories. For wave packets as defined by Hagedorn we show that the Bohmian trajectories converge to Newtonian trajectories in probability.     

两类统计收敛的表示定理

本文证明了Banach空间X中的序列Δ(Δ~m)-统计收敛表示,以及Banach空间X中的双序列(双序列双-Lacunary)统计收敛的表示.     

A minimum distance estimator in an imprecise probability model - Computational aspects and applications

The article considers estimating a parameter θ in an imprecise probability model which consists of coherent upper previsions . After the definition of a minimum distance estimator in this setup and a summarization of its main properties, the focus lies on applications. It is shown that approximate minimum distances on the discretized sample space can be calculated by linear programming. After a discussion of some computational aspects, the estimator is applied in a simulation study consisting of two different models. Finally, the estimator is applied on a real data set in a linear regression model.     

磁流体特性对磁流变火炮后坐阻尼器性能的影响

针对火炮后坐磁流变阻尼器的特点,以某单管25 mm火炮实验用磁流变阻尼器为研究对象,基于Herschel-Bulkley本构模型,建立了该炮磁流变后坐阻尼器的轴对称一维层流模型,获得了不同磁场作用下阻尼力随活塞速度的变化规律。运用火炮的后坐运动方程,计算了不同磁流体特性指数下,火炮的后坐位移和后坐速度。计算结果表明,磁流体特性指数的变化对磁流变后坐阻尼器的性能影响显著。     

土中爆炸地冲击能量分布研究

利用数值模拟方法研究了土中装药不同埋设深度爆炸能量分布问题,通过试验得到了耦合系数数据。给出了自由场条件下,封闭爆炸最小比例埋深为2.0 m/kg1/3,这与美军设计规范TM5-855-1中的数据0.56 m/kg1/3相差较大,分析了产生差异的可能原因。并指出本文中给出的冲量型耦合系数与TM5-855-1中的应力型耦合系数是有所区别的,应该注意其使用范围和对象。     

一种碳纤维织物增强复合材料应变率相关的各向异性强度准则

为了获得一种碳纤维二维正交平纹机织布增强树脂基复合材料在一维应变状态下的强度准则,在已完成的准静态和动态压缩实验的基础上,拟合出了单轴压缩下三个主方向上的计及应变率的应力-应变关系式,进而得到初始屈服应力和压缩破坏强度与应变率相关性表达式。依据该表达式,得到了该复合材料在一维应变下考虑应变率效应的Tsai-Hill屈服强度和破坏强度准则方程。通过计算,考察了Tsai-Hill屈服强度和破坏强度准则随应变率的变化规律。结果表明,本文中研究的复合材料的强度性能,不但存在应变率效应,而且这种效应是各向异性的。     

石英光纤探针在非金属材料冲击实验中的应用

使用石英光纤探针成功测量了Teflon样品中的冲击波速度和电炮加载的厚度为75 m的Mylar膜飞片的平均速度和到达时间一致性。实验证明,石英光纤探针技术为非金属材料的冲击实验提供了一种直接的、不受电磁干扰的、精确的测量手段。     

爆炸成型弹丸对Al2O3装甲陶瓷材料的侵彻实验研究

用爆炸成型弹丸(explosively formed projectile, EFP)对Al2O3装甲陶瓷材料进行了侵彻（depth of penetration, DOP）实验,得到了99Al2O3装甲陶瓷对模拟EFP的质量防护因数和差分防护因数及他们随陶瓷块厚度的变化规律,初步评估了99Al2O3装甲陶瓷对EFP的抗侵彻性能,解释了装甲陶瓷对EFP的抗侵彻过程和机理。研究结果表明,增加约束可以提高陶瓷的抗侵彻性能。     

高应变率大变形下的聚丙烯/尼龙共混高聚物损伤型本构特性

对两种采用不同相容剂的聚丙烯（PP）和尼龙（PA）共混高聚物材料在大变形下的粘弹性力学行为进行研究,着重考察应变率效应和损伤的演化,从而分析不同的界面分子设计对共混体系材料宏观性能的作用。在准静态及冲击实验研究的基础上,基于ZWT非线性粘弹性模型,并结合了遗传算法,分别得到了能有效描述两种共混高聚物大变形阶段计及损伤的非线性粘弹性本构关系。两种材料在不同加载条件下表现出明显不一致的性能,原因在于其损伤演化的率相关性,且两种材料的大变形机制存在一定的差别,能用ZWT方程进行描述的范围也不一样。