随钻用光纤陀螺惯导系统振动误差建模与辨识

随钻振动工作环境下,针对惯导系统传统的线性器件误差模型不能适用于线振动工作环境的问题,提出了适用于振动条件下的高阶器件误差模型。通过分析二次项误差在静止与振动状态下的误差传播特性,得出加速度计二次项误差为线振动中主要误差项,建立包含加速度计二次项误差的36阶Kalman滤波器。与传统33阶误差模型相比,36阶误差模型可以有效分离和辨识器件误差。最后,在线振动状态下进行导航验证。结果表明,补偿了二次项误差之后的导航误差得到了大幅优化,速度误差由50m/s减小至2.2m/s,位置误差由90000m减小至2000m,姿态误差由0.7°减小至0.01°。     

改进的Neumann-LU混合法在失谐整体叶盘随机分析中的应用

为了降低失谐整体叶盘的随机分析矩阵求逆的计算成本,提出一种基于Neumann级数和LU分解的改进Neumann-LU混合法。一方面,在非共振频率附近的大区域采用Neumann级数频域展开式以提高计算效率;另一方面,在共振频率附近小区域采用LU分解法以提高计算计算精度;根据Neumann级数展开项数来选定自适应阀值,实现两种矩阵求逆方法的自动转换而不用消耗额外的计算资源。选取具有失谐特征的整体叶盘为研究对象,分别运用改进的Neumann-LU混合法和单一LU分解法求解叶片在阶次激励下的频域响应,并从计算效率和计算精度方面进行比较。研究结果表明,在保证计算精度误差不大于0.1%的前提下,改进的Neumann-LU混合法可以提高失谐整体叶盘随机分析大约55%的计算效率。     

Detection of aerosol pollution sources during sandstorms in Northwestern China using remote sensed and model simulated data

The present paper has used a comprehensive approach to study atmosphere pollution sources including the study of vertical distribution characteristics, the epicenters of occurrence and transport of atmospheric aerosol in North-West China under intensive dust storm registered in all cities of the region in April 2014. To achieve this goal, the remote sensing data using Moderate Resolution Imaging Spectroradiometer satellite (MODIS) as well as model-simulated data, were used, which facilitate tracking the sources, routes, and spatial extent of dust storms. The results of the study have shown strong territory pollution with aerosol during sandstorm. According to ground-based air quality monitoring stations data, concentrations of PM₁₀ and PM_2.5 exceeded 400?μg/m³ and 150?μg/m³, respectively, the ratio PM_2.5/PM₁₀ being within the range of 0.123–0.661. According to MODIS/Terra Collection 6 Level-2 aerosol products data and the Deep Blue algorithm data, the aerosol optical depth (AOD) at 550?nm in the pollution epicenter was within 0.75–1. The vertical distribution of aerosols indicates that the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) 532?nm total attenuates backscatter coefficient ranges from 0.01 to 0.0001?km^?1?×?sr^?1 with the distribution of the main types of aerosols in the troposphere of the region within 0–12.5?km, where the most severe aerosol contamination is observed in the lower troposphere (at 3–6?km). According to satellite sounding and model-simulated data, the sources of pollution are the deserted regions of Northern and Northwestern China.     

Validation on MERSI/FY-3A precipitable water vapor product

The precipitable water vapor is one of the most active gases in the atmosphere which strongly affects the climate. China's second-generation polar orbit meteorological satellite FY-3A equipped with a Medium Resolution Spectral Imager (MERSI) is able to detect atmospheric water vapor. In this paper, water vapor data from AERONET, radiosonde and MODIS were used to validate the accuracy of the MERSI water vapor product in the different seasons and climatic regions of East Asia. The results show that the values of MERSI water vapor product are relatively lower than that of the other instruments and its accuracy is generally lower. The mean bias (MB) was ?0.8 to ?12.7?mm, the root mean square error (RMSE) was 2.2–17.0?mm, and the mean absolute percentage error (MAPE) varied from 31.8% to 44.1%. On the spatial variation, the accuracy of MERSI water vapor product in a descending order was from North China, West China, Japan -Korea, East China, to South China, while the seasonal variation of accuracy was the best for winter, followed by spring, then in autumn and the lowest in summer. It was found that the errors of MERSI water vapor product was mainly due to the low accuracy of radiation calibration of the MERSI absorption channel, along with the inaccurate look-up table of apparent reflectance and water vapor within the water vapor retrieved algorithm. In addition, the surface reflectance, the mixed pixels of image cloud, the humidity and temperature of atmospheric vertical profile and the haze were also found to have affected the accuracy of MERSI water vapor product.     

基于效用价值驱动的旅客出行动力学研究与建模

为了探究交通体系中旅客出行行为的特征与机理,以某机场离港旅客的陆侧出行数据为研究对象,对旅客出行模式进行了统计。分析发现,旅客聚集行为具有强烈的阵发性,不同出行维度旅客群体的聚集时间间隔分布具有幂律特征,且幂指数和阵发性强度呈正相关关系。同时,研究认为旅客出行换乘决策是综合时间、费用、便捷舒适度、突发情况等多因素的期望实现,是一种基于效用价值驱动的人类行为。基于此构建了效用价值驱动模式下的旅客出行行为动力学模型,可输出幂指数为参数可调的幂律分布,且仿真输出和实证数据分析结果相吻合。      

一种X频段50 kW高功放的设计

针对未来深空测控及其他航天器测控通信业务不断拓展的需求,设计了一种基于速调管方案的X频段连续波高功放。该方案采用了高效率低电源纹波的模块化高压开关电源、集中式液体冷却设备、串联与并联相结合的高功率谐波和收阻滤波器,以及高速可靠的控保措施,实现了在深空X频段连续波高功率输出的技术能力。测试结果表明：在规定的带宽内,输出连续波功率达到了50 kW,最高可达60 kW以上,第2、3、4次谐波及接收频段内信号的抑制能力等主要指标都达到了预期目标,整机散热效果理想;经长时间连续加电考机表明：设备考核指标和工作状态都稳定可靠。这将为我国深空探测技术的进一步发展、探测能力的进一步提高奠定坚实基础。     

AZ31镁合金板热成形中的屈服和损伤:本构实现与数值分析

为了准确预测各向异性镁合金板的成形质量,将改进的GTN损伤模型与各向异性拉压不对称的CPB06屈服本构耦合,并考虑了屈服面形状随塑性应变累积的变化,得到了考虑本构参数随塑性应变演化的各向异性屈服CPB06-GTN损伤模型。基于该模型,在ABAQUS/Explict中编译得到了相应的VUMAT子程序,采用单个单元进行了单轴拉伸和压缩模拟,并通过与实验一致性对比验证了子程序的正确性。使用子程序不仅能够模拟镁合金的各向异性屈服及其不规则的硬化,同时也能够模拟镁合金的损伤破坏。此外,采用编写的子程序进行了热拉深成形的数值模拟,模拟预测与实验结果对比表明,采用各向异性损伤模型的计算结果能够准确预测镁合金的变形及其损伤破坏,模拟结果与实验数据吻合;采用合适的压边力和成形的温度条件及非等温成形方法能够提高镁合金的成形性。     

一种新型弱撞击对接机构运动学分析

目前各国在轨应用的对接机构属于硬碰撞式对接机构,在此构型下两航天器在空间进行碰撞接触时撞击能量较大,并且此结构下目标飞行器的对接范围较窄。随着空间探测任务的深入,需要对对接机构提出更高层次的设计要求,因此弱撞击对接机构也将成为空间探测任务中一项重要的研究方向。本文对弱撞击对接机构运动学的正解和反解进行了研究分析,得到了相应的推导公式,并通过MATLAB软件对其进行了算例校验。求解出了对接环运动速度和执行推杆伸出速度的关系,这对弱撞击对接机构的工程研制有很大的应用价值。