基于SAX和DOM的XML嵌套信息提取

层次关系是一份XML文件的重要信息。根据XML文件的设计规则,当它要描述的数据具有层次关系时,这种层次关系应该反映在相应的标记里面。因此,如果我们对一份XML文件进行分析,对其标记的层次关系进行提取,那么我们就得到了这些标记所描述的数据之间的层次关系。使用SAX和DOM两种机制,分别对XML文件进行了分析并对其标记所反映的层次关系进行了提取。     

时间步长对铜平衡熔点模拟计算结果的影响

采用二分搜索等温等压分子动力学方法和EAM (embeddedatommethod)势,对单质铜的平衡熔点进行计算,研究了不同时间步长对模拟计算结果的影响.结果表明:时间步长越小,熔点计算结果越接近实验值;当时间步长小于0·05fs后,进一步减小时间步长,熔点计算结果在计算精度范围内没有变化.     

PCM/FM遥测信号软件解调算法研究

针对目前航天测控中PCM/FM遥测系统使用的调频非相干解调技术存在解调门限较高的问题,研究一种基于最大似然思想的多符号检测(Multi-Symbol Detection, MSD)解调方法。介绍多符号检测原理,并针对以往同步方法的不足,研究一种将码元判决过程与同步相结合的变步长同步方法。仿真和测试结果表明,基于MSD解调PCM/FM信号是一种非常有效的方法。对下一代遥测信号解调系统的研制具有重要的应用价值。     

Effects of sintering curves on microstructure,physical and mechanical properties and on low temperature degradation of zirconia-toughened alumina

The objective of this work was to study two-step sintering as a means of controlling the microstructure of coarse Al₂O₃ matrix composites containing submicrometric and nanometric inclusions of ZrO₂ ranging from 0–30 wt. % by weight based on commercially available powders and evaluate its hydrothermal degradation as function of a water vapour pressure and its mechanical properties. The results showed that two-step sintering allowed a more efficient microstructural control than single-step sintering, resulting in good mechanical properties. The highest flexural strength was achieved for ZTA samples sintered in two-stage sintering conditions TSS2 with T1 = 1560 °C for 3 h, T2 = 1460 °C for 8 h. The studied composites showed good resistance to hydrothermal degradation compared to composites sintered in single step sintering conditions.     

基于天空光偏振模式的导航姿态最优化解算方法

针对传统导航系统自主性差、抗电磁干扰能力弱的问题,本文提出一种基于天空光偏振模式的仿生导航方案。利用自主研发的偏振光传感器实现导航定向功能,并结合惯性测量单元设计了一种导航姿态最优化解算方法。现有的姿态最优化求解策略一般是采用步长固定的搜索算法,但是其直接影响了运动状态下姿态估计的准确性,为此本文采取动态步长搜索机制。实验结果表明:本文提出的算法能有效抑制陀螺仪漂移误差,而且对高频噪声干扰有明显滤除效果,表现出良好的静态性能;同时,本文提出的方法较常规算法具有更高的动态精度,进一步提高了偏振光导航系统的稳定性与可靠性,为无人机飞行控制提供更准确的参数信息。     

Biomolecular Simulations with the Three-Dimensional Reference Interaction Site Model with the Kovalenko-Hirata Closure Molecular Solvation Theory

The statistical mechanics-based 3-dimensional reference interaction site model with the Kovalenko-Hirata closure (3D-RISM-KH) molecular solvation theory has proven to be an essential part of a multiscale modeling framework, covering a vast region of molecular simulation techniques. The successful application ranges from the small molecule solvation energy to the bulk phase behavior of polymers, macromolecules, etc. The 3D-RISM-KH successfully predicts and explains the molecular mechanisms of self-assembly and aggregation of proteins and peptides related to neurodegeneration, protein-ligand binding, and structure-function related solvation properties. Upon coupling the 3D-RISM-KH theory with a novel multiple time-step molecular dynamic (MD) of the solute biomolecule stabilized by the optimized isokinetic Nosé–Hoover chain thermostat driven by effective solvation forces obtained from 3D-RISM-KH and extrapolated forward by generalized solvation force extrapolation (GSFE), gigantic outer time-steps up to picoseconds to accurately calculate equilibrium properties were obtained in this new quasidynamics protocol. The multiscale OIN/GSFE/3D-RISM-KH algorithm was implemented in the Amber package and well documented for fully flexible model of alanine dipeptide, miniprotein 1L2Y, and protein G in aqueous solution, with a solvent sampling rate ~150 times faster than a standard MD simulation in explicit water. Further acceleration in computation can be achieved by modifying the extent of solvation layers considered in the calculation, as well as by modifying existing closure relations. This enhanced simulation technique has proven applications in protein-ligand binding energy calculations, ligand/solvent binding site prediction, molecular solvation energy calculations, etc. Applications of the RISM-KH theory in molecular simulation are discussed in this work.     

Recovery rheology via rheo-SANS: Application to step strains under out-of-equilibrium conditions

Stress relaxation from a step strain test provides important information about constituent dynamics, but if a material has experienced a complex shear history, the underlying physics is not straightforward to access. We use recovery rheology and rheo-small-angle neutron scattering to probe the nonlinear dynamics of an entangled wormlike micelle solution by applying step strains after complex shear histories enforced by large-amplitude oscillatory shear (LAOS) flow. We show that a universal relaxation modulus can be obtained from step strain tests with complex shear histories, as long as the modulus is defined in terms of the recoverable strain. The shear and normal stresses, as well as the alignment of micellar Kuhn segments, are shown to be positively correlated with the recoverable strain. We identify re-entanglement of polymeric chains after cessation of LAOS and show that this process occurs over the same timescales as linear-regime stress relaxation. This work, therefore, lays the foundation of how to accurately probe out-of-equilibrium rheology in a consistent manner.     

Two–step processing of thermoelectric (Ca0.9Ag0.1)3Co4O9/nano–sized Ag composites with high ZT

A two–step processing method, spark plasma sintering (SPS) combined with a heat–treatment, was used to fabricate (Ca_0.9Ag_0.1)₃Co₄O₉/nano–sized Ag composites. Sliver within the lattice generated hole carriers, and silver along the grain boundaries improved the transport path of the charge carriers. Samples sintered using SPS at different temperatures had very different thermoelectric properties. The results showed that when the sample was sintered at 1233 K, the maximum power factor reached 0.43 mW/(m·K²) along with an electrical resistivity of 8.61 mΩ·cm and a Seebeck coefficient of 196.90 μV/K, and the corresponding lattice thermal conductivity was 1.86 W/(m·K). This study shows how to improve the properties and broaden the application of Ca₃Co₄O₉ thermoelectric ceramics.     

两级载荷作用下疲劳短裂纹扩展与疲劳损伤

通过正火３５钢带孔圆棒试样的旋弯疲劳试验，研究了两级加载下孔边疲劳短裂纹扩展的统计特性，以及应力水平改变对疲劳短裂纹扩展的影响。     

金相研磨抛光机自动控制系统的研究

金相检验是确定材料组织最可靠的方法。金相试样的质量最终是由抛光质量决定。根据制备金相试样的技术要求 ,在现有抛光机的基础上对其自动控制系统进行了技术改造 ,使其具有更高的精度。对显示面板重新设计提高可操作性和界面美观度。为金相试样制备提供一种更友好的操作界面。