Topology optimization based on level set for a flexible multibody system modeled via ANCF

A topology optimization methodology is proposed for the flexible multibody system undergoing both large overall motion and large deformation. The system of concern is modeled via the absolute nodal coordinate formulation. The equivalent static load method is employed to transform the topology optimization of the nonlinear dynamic response of the system into a static one, and evaluated to adapt to the absolute nodal coordinate formulation by splitting the elastic deformations of the flexible components from the overall motions of those components. During the static topology optimization, the material interface is implicitly described as the zero level set of a higher-dimensional scalar function. Then, the semi-implicit level set method with the additive operator splitting algorithm is employed to solve the corresponding Hamilton-Jacobi partial differential equation. In addition, the expert evaluation method of weights based on the grey theory is utilized to define the objective function, and a modified augmented Lagrange multiplier method is proposed to treat the inequality volume constraint so as to avoid the oscillation and drift of the volume. Finally, two numerical examples are provided to validate the proposed methodology.     

有限差分法和隐式龙格库塔法求解Burgers方程

提出一个新的方法求解一维Burgers方程,组合使用有限差分法和隐式龙格库塔法求解Burgers方程。首先使用二阶有限差分法进行空间离散,得到一个常微分方程组,然后使用高阶A稳定的隐式龙格库塔法求解常微分方程组,最后比较数值解和精确解,数值结果证实该方法有很高的精度和稳定性。     

Fe_2O_3基陶瓷的气湿敏特性

论述了由不同制备工艺获得的Ｆｅ２Ｏ３陶瓷及各种添加剂下表面羟基和吸附氧的形成和性质，分析了表面羟基和吸附氧的酸碱性对气湿特性的影响。     

关于丢番图方程x^3±1=2Dy^2

给出了当Ｄ含６ｋ＋１型素因子时，方程ｘ＾３±１＝２Ｄｙ＾２无正整数解的充分性条件。     

关于丢番图方程 x~3 ± 512 = Dy~2

用初等方法研究了丢番图方程ｘ３±５１２＝Ｄｙ２，并给出了无非平凡整数解的充分性条件．     

高压射流的理论分析

本文研究了高压射流装置喷咀部分液流的动态特性,建立了数学模型,讨论了一种拟线性偏微分方程组的哥西问题,并利用特征线将此问题转化为非线性积分方程组,给出了它解的存在唯一条件和解的逐次迭代公式。     

Simulation of X-ray pulsar signals with multiphysical properties

In view of the few and discontinuous X-ray pulsar data, based on the physical properties of the X-ray pulsar real data from the Rossi X-ray Timing Explorer (RXTE) spacecraft, this paper adopts the fast iterative method and the 10 μs time transformation model, simulates the X-ray pulsar signals which have the periodic property, spectral property, and the background noise property as well as a variety of delay effects. We design and implement simulation software which can simulate the X-ray pulsar signals with multi-physical properties. The results of comparing the real data and simulation data in the same situation show that the simulation noises and the actual noises have the same distribution, that the period stability of the simulated X-ray pulsar data agrees with the real data, with the error of only 0.43％, in different energy levels, that the simulated data's integrated profile and the real data's standard profile are highly correlated with the Pearson correlation coefficient of 0.99, and that under the 10μs time transformation model, the time conversion accuracy of the simulation data can reach 10^-7s, the error between the simulation and the real data being just only 10^-7s, which meets the time transformation accuracy. Therefore, the proposed method can realize the high-fidelity simulations and generate the continuous pulsar signal with many physical properties.     

军用自动测试系统通用性技术研究与应用

自动测试系统软、硬件平台的通用性技术是目前测试领域研究的热点之一。本文在自动测试系统发展历程的基础上,介绍了通用平台的概念和系统结构,详细讨论了如何从硬件平台和软件平台两方面实现通用性的关键技术,并通过某机载综合检测设备的应用实例描述了关键技术的使用方法。工程实用表明,该综合检测设备具有很强的通用性、易扩展性和维护性。     

石墨镶嵌Co纳米晶的形成及其特性

用直流碳弧法在阳极石墨棒中加入金属Ｃｏ产生石墨镶嵌Ｃｏ纳米晶,研究在复合石墨棒中加入不同的Ｃｏ含量对石墨镶嵌Ｃｏ纳米晶的形貌、结构特性及晶粒尺寸分布的影响,探讨石墨镶嵌Ｃｏ纳米晶的形成原因及碳弧法中氦气压力和Ｃｏ含量对掺Ｃｏ阳极石墨棒所产生的碳灰的Ｃ６０／７０产率的影响。结果表明,复合阳极棒中的Ｃｏ含量决定了石墨镶嵌Ｃｏ纳米晶的数量和晶凿直径分布,碳弧法中的Ｈｅ气压力仍是影响掺Ｃｏ阳极棒所产生的碳     

大直径PPS/PA6共混单丝的结构与性能研究

采用PPS/PA6共混的方法来改进大直径PPS单丝的力学性能.探讨了共混体系的结构对共混单丝力学性能的影响,并与相关聚合物单丝进行了对比分析,同时研究了共混单丝的耐酸碱性能.结果表明:PA6的加入能有效地改善PPS单丝的力学性能,提高了单丝的拉伸强度和勾结强度,增加了PPS单丝的韧性.同时,PPS/PA6共混单丝能保持...