异面腔四频差动激光陀螺的智能选模

针对异面腔四频差动激光陀螺(DILAG)工作模式不确定性和跳模对其性能的负面影响,提出了根据开机时腔体温度快速选择最优初始模的智能选模方法。分析了纵模阶数对DILAG的零偏和比例因子的影响以及跳模的危害,指出选择最优初始模是在现有基础上进一步提高DILAG性能的重要方法。通过温度实验做出了最优模相应的压电换能器(PZT)驱动电压随温度的变化曲线,为建立选模模型提供了基本依据。实验表明,智能选模使腔长控制系统加电后能快速稳定在最优初始模,减小了跳模几率,提高了腔长控制电路的鲁棒性和自适应性,对改善DILAG的性能、可靠性具有实用价值。     

Laser-induced Alignment and Coulomb Explosion of CO2

实验研究了CO₂分子在飞秒强激光脉冲作用下的动力学过程,包括分子取向,隧穿电离和库仑爆炸,激光强度从1×10¹³W/cm²变化到6×10¹⁴W/cm². 当激光强度小于分子的电离阈值时,CO₂分子的非绝热转动激发形成一个相干转动波包,波包演化导致分子沿激光电场方向取向. 激光脉冲结束后,分子取向可以周期性地再现,利用另一束激光可以对取向结构进一步进行修饰. 当激光强度大于分子     

Discotic molecules in cylindrical nanopores: A Monte Carlo study

We report Monte Carlo simulations of a model discotic molecule embedded in cylindrical pores. We consider a planar anchoring of the molecules on the surface for two different cylinder radii: R ^* = 5 and R ^* = 10 , in units of the molecular diameter. For both radii, we note that the system is progressively structured in concentric shells when decreasing the temperature. With the small radius, we observe continuous transitions from an isotropic to a nematic phase and then to a crystal one. The radius of the pores is sufficiently small to force the crystal to grow along their main axis. However some orientational discrepancies are observed: some samples present a zigzag configuration. With the big radius, the situation is more complex and it is likely that different scenarios are available. The crystals can be built along the main axis of the cylinders, as for the small radius, but also in any other direction. Thus we observe samples with different orientational domains. In the case of crystals oriented along the nanopore axis, we note that only the first 5 shells close to the wall are sensitive to it.     

正支共焦非稳腔的自动准直调整实验研究

谐振腔的自动准直调整技术是实现高能激光器系统自动化的关键技术之一。在对正支共焦非稳腔自动准直调整方法的研究基础上,应用基于系统性能评价函数无模型最优化的随机并行梯度下降（SPGD）控制算法实现腔的自动准直调整。实验结果表明该方法可实现腔镜的闭环控制准直调整,其调腔共轴精度在一定程度上高于传统的人工调腔精度。     

光斑缺碎情形下光学天线光轴对准实验研究

针对同时存在方位偏移及俯仰误差的情况,提出了一种适用于捕获、对准与跟踪系统的光斑检测方法.分析了破碎光斑与高斯完整光斑的位置误差;解决了当光束存在漂移、入射光束与天线视轴不平行同时存在而四象限探测器无法分别探测的问题.最后实验验证了本文方法的有效性,提高了检测的准确度.     

Generalized magneto-thermoelastic half-space with diffusion under initial stress using three-phase-lag model

The present paper is aimed at studying the effect of initial stress and the magnetic field on thermoelastic interactions in an isotropic, thermally and electrically conducting half-space whose surface is subjected to mechanical and thermal loads. The formulation is applied under the thermoelasticity theory with three-phase-lag, proposed by Choudhuri (2007 Choudhuri, S. K. R. (2007). On a thermoelastic three-phase-lag model. Journal of Thermal Stresses 30:231–238. doi:10.1080/01495730601130919[Taylor & Francis Online], [Web of Science ®] [Google Scholar]). The normal mode analysis is used to obtain the expressions for the variables considered. Numerical and computations are performed for a specific material and the results obtained are represented graphically. Comparisons are made with the results predicted by different theories Lord–Shulman theory (L–S), the theory of thermoelasticity type III (G-N III) and the three-phase-lag model (3PHL) in the absence and presence of the initial stress and magnetic field.     

基于Allan方差解耦自适应滤波的旋转SINS精对准方法

对旋转式SINS精对准方法进行了研究,由于转位机构转动干扰以及惯性器件误差不确定性带来的影响,旋转式SINS状态方程和量测方程噪声方差参数难以确定,进而导致初始对准精度降低,针对这个问题引入自适应Kalman滤波技术。Sage-Husa是一种常用的自适应滤波算法,但是存在噪声参数强耦合缺陷。通过研究Allan方差与量测噪声方差之间的关系,利用Allan方差滤波器具有带通滤波的特点,独立计算量测噪声协方差阵R_k,该方法能够有效克服Sage-Husa滤波耦合问题,相比其它改进方法具有简单易实现等特点。对该研究进行了仿真实验与实际系统验证实验,结果表明:对于中等精度光纤陀螺单轴旋转SINS,自适应Kalman滤波算法航向角对准精度比标准Kalman滤波算法精度要高0.6’左右,且在误差估计过程中,自适应Kalman滤波器能够更好地抑制外界干扰误差的影响,是一种较好的精对准方法。     

Photothermal waves for two temperature with a semiconducting medium under using a dual-phase-lag model and hydrostatic initial stress

The dual-phase-lag (DPL) model with two different time translations and Lord–Shulman (LS) theory with one relaxation time are applied to study the effect of hydrostatic initial stress on medium under the influence of two temperature parameter(a new model will be introduced using two temperature theory) and photothermal theory. We solved the thermal loading at the free surface in the semi-infinite semiconducting medium-coupled plasma waves with the effect of mechanical force during a photothermal process. The exact expressions of the considered variables are obtained using normal mode analysis also the two temperature coefficient ratios were obtained analytically. Numerical results for the field quantities are given in the physical domain and illustrated graphically under the effects of several parameters. Comparisons are made between the results of the two different models with and without two temperature parameter, and for two different values of the hydrostatic initial stress. A comparison is carried out between the considered variables as calculated from the generalized thermoelasticity based on the DPL model and the LS theory in the absence and presence of the thermoelastic and thermoelectric coupling parameters.     

恒速偏频激光陀螺系统静基座初始对准中等效东向陀螺漂移估计

以单轴恒速偏频激光陀螺系统为研究对象,在分析IMU传感器误差的基础上,建立了合理有效的静基座初始对准滤波器模型。针对系统连续旋转运行的特性,提出了简洁适用的滤波器估计误差检验方法,利用自主设计的原理样机验证了恒速偏频技术的实际可行性,对滤波算法进行了实验测试。实验结果表明,初始对准滤波算法能够稳定有效地估计IMU传感器误差,且等效东陀螺漂移估计精度优于0.0004(°)/h,该系统具有很高的工程应用潜力。     

侧斜与负载对螺旋桨无空化和空化水动力性能的影响

为了定量分析空化初始航速的影响因素,首先分析侧斜和负载对螺旋桨无空化和有空化时性能的影响。以NSRDC4381无侧斜桨和4383100％侧斜桨为对象,采用改进Sauer空化模型和修正SST湍流模型,对空化崩溃性能、空化初生性能和无空化时正车、倒车以及紧急倒车敞水性能进行了计算与比较。结果表明,预报两个桨的敞水性能曲线和多空化数下的空化崩溃性能曲线均与实验值吻合较好。在中度负载区间（J=0．5-0．9）内,侧斜对正车和紧急倒车时敞水性能以及空化时推力和力矩崩溃性能均无明显影响,但会使倒车敞水性能显著下降。在重载和轻载条件下,侧斜均能明显改善空化初生性能。侧斜一定时,负载会直接影响尾流湍流速度脉动量和涡核集中区分布,影响轴面速度流管收缩程度,进而影响无空化和有空化条件下的推进性能。