解斜三角形

本单元的重点：理解和掌握正弦定理和余弦定理；熟记两定理的各种表达形式．     

Diffusion behavior of helium in titanium and the effect of grain boundaries revealed by molecular dynamics simulation

The microstructures of titanium(Ti), an attractive tritium(T) storage material, will affect the evolution process of the retained helium(He). Understanding the diffusion behavior of He at the atomic scale is crucial for the mechanism of material degradation. The novel diffusion behavior of He has been reported by molecular dynamics(MD) simulation for the bulk hcp-Ti system and the system with grain boundary(GB). It is observed that the diffusion of He in the bulk hcp-Ti is significantly anisotropic(the diffusion coefficient of the [0001] direction is higher than that of the basal plane),as represented by the different migration energies. Different from convention, the GB accelerates the diffusion of He in one direction but not in the other. It is observed that a twin boundary(TB) can serve as an effective trapped region for He.The TB accelerates diffusion of He in the direction perpendicular to the twinning direction(TD), while it decelerates the diffusion in the TD. This finding is attributable to the change of diffusion path caused by the distortion of the local favorable site for He and the change of its number in the TB region.     

黄渤海沉积物有机碳光谱分析在不同仪器间的差异

光谱仪作为可见-近红外光谱分析核心工具,对于光谱分析的影响还有待深入研究。这里,以黄渤海沉积物为研究对象,利用安捷伦Cary 5000、 ASD FieldSpec 4、海洋光学QEPro三种光谱仪,研究有机碳含量的反射光谱及其光谱分析在不同光谱仪间的差异。其中,Cary 5000为室内台式光谱仪,FieldSpec 4和QEPro是便携式光谱仪;QEPro只能采集200～1 000 nm的反射率,而且反射率在三种光谱仪中最高;Cary 5000和FieldSpec 4能够采集完整的可见-近红外反射率(350～2 500 nm),光谱曲线几乎完全一致,尤其是近红外部分,但Cary 5000采集的反射率高于FieldSpec 4。三种光谱仪的光谱分析能力也存在显著差异,其中,Cary 5000的光谱分析能力最强,其光谱模型具有很强的预测能力,建模集r²高达0.99,验证集r²高达0.86,均方根误差(RMSE)在建模集和验证集分别为0.04、 0.11,相对分析偏差(RPD)高达2.6,显示了对黄渤海沉积物有机碳强大的预测能力。FieldSpe...     

激光3D投影高精度校准建模方法

为了提高激光3D投影校准系统的校准可靠性、获得最佳校准参数,根据校准系统的基本原理,提出了一种将激光3D投影观测值求解模型与校准参数求解模型结合的方式,来建立激光3D投影校准模型的方法.该方法采用两个步骤进行激光3D投影校准系统的校准参数的求解.第一步是通过等距法建立激光3D投影观测值求解模型,引入模型初值的求解,这种初值的设计结果避免了该求解模型运用的牛顿迭代法呈现的弊端.第二步通过四元数法建立校准参数求解模型.仿真结果显示,在H、V上施加服从正态分布的均值为0、标准差σ=0.5″的误差后,该激光3D投影校准系统求解模型误差RMS在0.3mm以内,同时,采用激光跟踪仪作为对比基准验证了本方法的可靠性及校准精度,在3m至5m的定位空间范围内,最大误差在0.4mm以内,满足激光3D投影系统的投影定位精度.即该校准模型可实现对激光3D投影校准系统校准参数的求解,且校准精度高,校准方法收敛速度快,提高了系统校准工作速率,为激光投影系统的研制提供了新的算法思路.     

虚拟机在舰艇编队一体化防御系统中的应用

面对信息化、远程精确打击的空袭作战,必须构建网络化、一体化的防空作战体系;主要针对舰艇编队一体化防御系统中无线网络的不可靠性,设计了基于嵌入式虚拟机的架构,提出了任务的动态分配和移植算法;首先根据作战环境中网络的拓扑条件,虚拟机动态的将控制任务分配到可靠的无线节点中,并实时监测网络状态,当网络结构发生变化时,将底层不可靠无线节点中的控制任务移植到可靠的无线节点中;通过这种方法可以解决作战环境恶劣和无线网络本身的不可靠引起的控制的不稳定性问题,确保防御任务的顺利进行;仿真结果表明,当编队一体化防御系统的链路发生故障时,此方法能够在不改变原有控制算法的基础上,迅速重建控制构架,不仅适用于舰艇编队一体化防御系统这种对时间要求和安全性要求高的系统,而且对基于无线网络的控制系统也有一定的借鉴意义。     

水下舷侧多层防护隔舱接触爆炸毁伤载荷特性分析

为探讨水下多层防护隔舱结构设计,以典型三舱式结构为对象,利用Dytran软件分析了水下接触爆炸下舷侧多层防护隔舱中膨胀空舱内的毁伤载荷特性,得到了载荷的简化模型,并拟合出膨胀舱压力载荷脉动平稳阶段准静态气压值的计算公式。结果表明,膨胀空舱内的毁伤载荷特性在时间尺度上可分为气团膨胀扩散阶段和脉动平稳两个阶段;在空间分布上,主要分为正反射区和马赫反射区,正反射区作用载荷由初始瞬态脉冲载荷和后续逐渐衰减的准静态气压载荷叠加而成,马赫反射区作用载荷则以准静态气压为主。     

液滴对爆炸冲击波的衰减作用

为分析液滴对舰船舱内爆炸冲击波的耗散与衰减作用,通过有限元分析方法,建立冲击波作用于不同尺寸单个液滴和多排液滴的模型,分析冲击波与单个及多个液滴的作用过程及液滴形态变化,对冲击波衰减规律进行分析总结。得到结论如下:单个液滴模型中,小液滴破碎更迅速,破碎的规律性强;大液滴抛撒现象发生较早,抛撒出的小液滴数目多,但整体变化规律性偏差;不同尺寸单个液滴对冲击波有一定的衰减作用,衰减率随液滴尺寸增大而增大,线性规律较明显;成排液滴对冲击波有明显的衰减作用,相同液滴密度下衰减率随着液滴数量的增多而增大,呈现明显的线性特性。     

基于紫外-可见光光谱的水质分析方法研究进展与应用

相对于传统水质分析方法,紫外-可见光(ultraviolet-visible,UV-Vis)光谱法具有检测速度快、维护成本低、无二次污染等优点,目前已被广泛应用于水质在线监测各个领域。介绍了UV-Vis光谱法的检测原理,论述了基于UV-Vis光谱的常规水质分析方法研究现状,以及UV-Vis光谱法与其他水质检测方法相融合以提高水质检测性能方面的研究进展,探讨了UV-Vis光谱分析在水质多参数在线监测、水质分类、水质报警等方面的应用现状及其发展趋势。     

Crystal Structure of β-La2Mo2O9 from First Principles Calculation

Arrangements of O ions in β-La2Mo2O9 are studied by first principles calculation with two different calculation schemes. All final structure configurations consist of MoO4-tetrahedra, MoO5-hexahedra, LaO8 and LaO7 polyhedra. Molybdenum polyhedra are isolated from each other, lanthanum polyhedra are connected together by sharing O ions. The occupancies of three crystallographic distinct O sites O（1）, O（2） and O（3） are 100%, 91.7% and 25%, respectively, consistent with experiments. All configurations are related to each other by one of 12 symmetry operations of P213 space group, suggesting that the structure observed experimentally may be interpreted as a time and spatial average of these local or inherent structures.     

Geant4模拟δ电子对单粒子翻转的影响

利用Geant4蒙特卡洛程序包, 基于RPP (Rectangular ParallelePiped Volume)模型构建SRAM器件单元的灵敏体积, 编写了重离子在器件材料中的输运程序和单粒子翻转截面计算方法, 得到了简化器件结构的单粒子翻转截面σ与线性能量转移LET的关系曲线, 计算得到的翻转LET阈值和饱和截面与实验结果基本一致。模拟获得了LET值为99.69 MeV/(cm-2·mg)的Bi离子及LET值为69 MeV/(cm-2·mg)的Bi离子和Xe离子在器件材料中产生的δ电子分布图像,讨论了δ电子分布对翻转截面的影响。 计算了灵敏体积中能量沉积与δ电子分布的关系,认为δ电子分布对单粒子效应的影响随着器件的特征尺寸减小将更加严重。In this paper, the sensitive volume of SRAMs was constructed based on RPP(Rectangular ParallelePiped Volume) model using the Monte-Carlo code Geant4. The interactions of heavy ion with materials and the SEU(Single Event Upset) cross section calculation method were presented in the program. The SEU cross section curves with the linear energy deposition ware obtained. The SEU threshold value and saturation cross section were consistent with the testing data with heavy ions beam. The δ electrons distribution were different in the device material, which were generated by Bi ion with LETs of 99.67 MeV/(cm2·mg) and Bi ion, Xe ion with LETs of 69 MeV/(cm-2·mg). These results indicate δ electrons distribution impacts on the SEU cross section. According to the relation of energy deposition in the sensitive volume, the δ electrons distribution have more and more important effect on the Single Event Effect with reducing the feature size of semiconductor devices.