High precision subsurface structural mapping of the Trompsburg complex (South Africa) from gravity and magnetic data

Trompsburg Complex, South Africa, is obscured by the Karoo sediments, and it is not observed on the surface. Knowledge of the boundaries of the subsurface geological bodies in the region is of main interest in many applications of the Earth Sciences. There are many methods developed to delineate boundaries of subsurface geological sources such as the curvature-based method and parabola-based methods. In this study, we applied an improved approach based on parabolic curve fitting to the gradient amplitudes of gravity and magnetic data for extracting geological structures of the Trompsburg Complex. The results showed ring structures with a diameter of about 50 km, that include granitic rocks in the central part of the Trompsburg Complex. The results also demonstrated the existence of boundaries of the other structures in the south-eastern region of the Complex, which were not determined in previous studies. The result provides new information for a better understanding of the structural and tectonic features of the Trompsburg Complex. The success of this study suggests that the improved technique based on parabolic curve, is helpful in outlining the edge locations of subsurface geologic structures.     

Error modeling and compensating of a novel 6-DOF aeroengine rotor docking equipment

In the docking process of aeroengine rotor parts, docking accuracy that indicates the gaps between the end faces is strictly required. A key issue is improving docking accuracy using automated docking equipment. In this paper, a systematic study is carried out on the error modeling and compensation of a novel six-degrees-of-freedom(6-DOF) docking equipment for aeroengine rotors. First, a new model for indicating the main indexes of docking accuracy is proposed. Then, the error model of a special...     

基于空基平台的激光通信技术研究和展望

深低温阀门多为常温设计，低温服役。宽温域引起的结构变形将诱发阀门导向卡滞、密封泄漏等安全问题。采用有限元分析方法获取阀门导向副配合部位变形量，提出迭代镜像补偿方法解决深低温服役的阀门导向副变形超差问题。经分析，在深低温工况下阀门配合间隙均超出设计允许值，导向行程最大时配合间隙减小17.95%至16.41 μm；补偿后导向副配合间隙变形量控制在1 μm内，满足深低温工况下阀门形状设计要求，验证了迭代镜像补偿方法的有效性。     

用于光纤F-P声压传感器的直流补偿解调技术研究

提出了一种改进的双腔直流补偿技术，用于解调非本征法布里-珀罗干涉(EFPI)光纤传感器，以消除腔长差与入射光波长相匹配的要求。通过消除直流分量和校准信号相位，可以从具有任意相位差的原始信号中获 得两路正交信号。通过理论仿真，制作了具有不同腔长差的EFPI光纤传感器，对所提出的方法进行了试验验证。 结果表明，该方法在解调双 F P腔 EFPI传感器时，不需要保证初始相位差恒定，且对腔长漂移不敏感，具有良好的 稳定性和实用价值。     

基于被动相位噪声补偿的自由空间光学频率传递

针对自由空间光信号传输更易受到环境影响的特点，提出了一种被动相位噪声补偿技术。该方法利用探测往返传输的光信号与发射端参考信号拍频获得链路引入的相位噪声，在发射端通过声光移频器（acousto-optic modulator, AOM）对待传递信号移频取共轭即可在接收端获得相位稳定的光学频率信号。该方法避免了使用复杂的鉴相和伺服控制电路，使系统具有更快的补偿速度且没有鉴相范围的限制。实验结果表明，150 m的室外自由空间链路的平均时间1 s的附加频率不稳定度约为1.9×10-16，平均时间1 000 s的附加频率不稳定度约为4.6×10-19。该相位噪声补偿技术为高精度的自由空间光学频率传递提供了一个简单可靠的方案。     

星载高精度反射面模具型面补偿设计方法

为满足高通量卫星对反射面高精度型面和低成本要求，从碳纤维蜂窝夹层结构反射面在固化成型过程中的固化收缩变形角度出发，根据模具型面补偿原理，提出了反射面模具型面补偿设计方法，并基于六面体单元有限元模型和三维正交各项异性材料属性及三点边界约束方法进行了试验验证。试验结果表明，通过型面补偿后的铸铁模具加工得到的两米口径反射面型面精度达到0.096mm均方根（root mean square,RMS），为模具型面补偿和高精度反射面提供了参考。     

Novel orbit-attitude combination mode for solar power satellites to reduce mass and fuel

Solar power satellite receives great attention because it can release the energy crisis and environmental problems in the future. However, the launch and maintenance costs are tremendous due to the large system mass and large fuel consumption to counteract space perturbations. To reduce mass and fuel, a novel quasi-Sun-pointing attitude in Sun-frozen orbit is proposed. The Sun-frozen orbit has a nonzero eccentricity vector that always points towards the Sun. The quasi-Sun-pointing attitude is a periodic solution of the Sun-pointing attitude angle. Although about 3 % electricity must be given up because of the variation of Sun-pointing attitude angle, little control action is required to deal with the solar radiation pressure and gravity-gradient torque. The algorithm to obtain initial conditions is proposed. The influences of system parameters and structural flexibilities are studied. Simulation results reveal that the quasi-Sun-pointing attitude in Sun-frozen orbit dramatically reduce fuel consumption, the dry mass, and complexity of the control system. In addition, structural vibration is hardly induced by the gravity-gradient torque. Thus, the bending stiffness as well as the mass of the supporting structure can be reduced.     

光纤环非互易相位误差尾纤补偿方法研究CSCD

针对光纤环的热致非互易误差的补偿方法进行研究,并通过仿真分析与实验验证,证明了某种光纤环尾纤长度与光纤环热致非互易误差之间的关系。根据等效介质理论和Mohr理论,建立了光纤环热致非互易相位误差仿真分析模型,并利用该模型计算了不同温度环境条件下,某类型光纤环顺逆时针方向光纤长度发生变化时,陀螺仪输出的全温零位漂移的变化量。仿真及实验结果表明,在1℃/min温变速率条件下,总长约800m的光纤环圈顺逆时针方向光纤长度相差约0.5m时,光纤环全温零位漂移量缩小了0.4(°)/h。研究结果得出了针对此类型的光纤环,当光纤环尾纤每减少0.5m,其热致非互易相位误差减小0.4(°)/h的规律。该项研究成果为后续优化光纤环的全温精度奠定了基础。     

一种复杂结构天线罩相位误差补偿算法

在某些雷达应用领域，天线罩的气动外形严重影响其电磁特性，从而对雷达系统测向性能造成恶劣影响。针对一种复杂结构天线罩，分析其透波率和额外引入的相位误差对雷达测向系统造成的恶劣影响;采用动态查表法实现目标角度粗搜索，并基于均匀圆阵提出长短基线结合聚类寻优的改进干涉仪测向算法，从而实现天线罩补偿后相位数据的精确测向。该算法操作简便，具有较高的运行效率，且能在宽频段、大角度范围内实现对天线罩的相位误差高精度补偿。实验结果表明:该方法能有效地解决非均匀天线罩引起的测向失败问题，具有较强的工程指导意义。