电控液压助力转向系统的初步匹配计算

电控液压助力转向系统(ECHPS)具有随车速调节的可变助力特性,可改善驾驶员的转向路感.通过对转向器转阀及ECHPS的分析,建立了转向器模型以及分流式ECHPS的模型,采用简化算式对转向器及分流式ECHPS操舵力特性曲线进行了分析.通过改变转阀的预开隙、转阀的坡口半径、转向器扭杆刚度及电磁阀阀芯节流口形状等参数,分析了ECHPS的影响参数.计算结果表明分流式ECHPS操舵力特性主要取决于转向器转阀的结构参数,并且和电磁阀阀芯开口有一定关系.      

改善三元子阵测距精度方法研究

在水声领域,三元子阵测距、目标运动分析(TMA)和匹配场处理(MFP)是被动噪声测距的3种主要技术。文中以三元子阵测距声呐为研究对象,从波束形成、相关系数处理、测向精度改进等方面讨论提高时延估计精度的方法,对工程应用具有一定的参考价值。     

一种加速度干扰下的稳定被动定位跟踪算法

在研究一种具有误差自动解耦的观测域滤波的目标跟踪算法和自适应渐消EKF算法的基础上,提出一种匀速运动模型下,基于观测域的自适应目标跟踪算法。使用实测GPS导航数据进行数字仿真,结果表明：观测域的自适应目标跟踪算法在加速度扰动下,稳定性优于观测域滤波算法。     

基于序优化理论的同步轨道入轨优化

基于序优化理论的多目标遗传(GA)算法,对小推力同步轨道卫星入轨控制方案设计与优化进行了研究.针对直接法中优化参数搜索范围大的缺点,提出了一种基于序优化理论的参数选定算法.给出了远地点变轨轨道控制优化方案,并利用序优化理论确定优化参数初始区间与约束关系.仿真结果表明:采用序优化算法可明显加快收敛速度,提高计算效率.对相同的GA参数设置,用序优化算法有可能得到比原来性能更好的子代,获得更理想的目标函数值.     

Assessing ecohydrological factors variations and their relationships at different spatio-temporal scales in semiarid area,northwestern China

As a typical semiarid farming-pastoral ecotone sensitive to the environmennt, the Plain of West Liaohe Basin (WLBP) is currently experiencing drastic environmental changes. To identify how environmental change affect vegetation in the WLBP, we analysed spatiotemporal variation characteristics of Ecological environment factors based on monthly and annual air temperature (T), precipitation (P) and Normalized Difference Vegetation Index (NDVI) from 1982 to 2015. And the correlations between them were investigated by correlation analysis (Simple correlation, partial correlation and complex correlation) at temporal and spatial scale. The results showed that: (1) the vegetation growth of the WLBP showed ameliorated trend, with a change rate of 0.004/yr.; (2) P was more sensitive to NDVI than T; (3) and the influence of hydrothermal changes on vegetation growth was more significant than that of the change of single climate factors at time scales; (4) the effects of anthropogenic factors on vegetation change were 75.07% (1982–1993) and 98.08% (1994–2015), respectively. At the temp-special scales, P&T and land use type change (LUCC) were the main climatic and anthropogenic factors that affect vegetation changes, respectively.     

发动机叶片流道内辐射换热的数值计算

应用贴体坐标系下辐射传递方程的离散坐标法，数值模拟了三维叶片流道内的辐射换热，计算了进口燃气总温分别为1673K和2193K时，发动机叶片流道内燃气对发动机机匣、轮毂和叶片的入射辐射热流密度。数值模拟表明，当进口燃气总温增加29.9%时，入射辐射热流密度将增加188%～212%。与直角坐标系下有限体积法的计算结果比较，二者非常接近。     

微重力环境模拟作业训练机器人碰撞力反馈控制

针对航天员在地球表面进行微重力环境中操作训练时微重力环境模拟作业训练机器人存在的碰撞力反馈控制问题,建立碰撞力反馈模型、提出单个柔索驱动单元控制策略和机器人系统碰撞力反馈控制策略.利用Matlab/Simulink软件对碰撞力反馈模型和控制策略进行仿真验证,该模型和控制策略可以实现机器人碰撞力反馈,且具有计算量小、实时...     

捕获轨迹系统并联机构地面标定方法

捕获轨迹系统（CTS）是一种先进的预测外挂物投放轨迹的试验系统,普遍采用六自由度（6-DoF）串联机构作为其运动机构,串联机构因惯性力大和关节累积误差大使其定位精准度不足。相比串联机构,并联机构具有惯性力小和关节误差不累积等优点。采用6-PTRT并联机构作为CTS试验系统的六自由度运动机构,在空间受限的风洞环境中对CTS并联机构进行地面标定：提出动平台位姿的测量和计算方法,建立包含直线驱动平台安装夹角修正的标定模型,并基于非线性最小二乘法辨识结构参数。辨识后CTS并联机构的位移定位准度优于0.1 mm,姿态定位准度优于0.05°,最后以CTS并联机构和常规攻角机构进行8#标模的对比风洞试验。风洞试验结果表明,CTS并联机构的风载定位准度满足测力试验精准度要求。     

Space Weather Research in China

Recent progress in space weather research are briefly presented here from three aspects: establishment or improvement in observation systems, such as extra-soft X-ray detector and γ-ray detector onboard the spacecraft ‘Shen Zhou 2’, new solar radio broad-band spectrometer, magnetometer-chain, ionosonde and digisonde–chain, laser-lidar system and VHF radar; partial topic progresses included in CMEs, multi-streamer structures, evolution of interplanetary magnetic field B _z component, regional properties of traveling ionospheric disturbances, a fully-nonlinear global dynamical model for the middle and upper atmosphere, and a combined prediction method for geomagnetic disturbances; and space weather activity, such as ‘Meridian Project’ — a national major scientific project, ‘International Space Weather Meridian Circle Program’ — a suggestion of internationalization of ‘Meridian Project’, ‘Space Weather Research Plan’ — a major research plan from National Natural Science Foundation of China (NNSFC) and other space weather activities. This revised version was published online in August 2006 with corrections to the Cover Date.     

纳米SiO2基复合隔热材料吸水性能

考察了纳米SiO2基复合隔热材料各组分添加量对吸水率的影响,同时针对复合材料吸水率高的问题,通过热处理和添加疏水纳米SiO2的方式来降低吸水率.结果表明:纳米Al2O3和无碱超细玻璃纤维对复合材料吸水率影响不大,添加锆英石会使材料吸水率升高.高温热处理会在一定程度上降低吸水率,但温度应控制在800℃以下.添加疏水纳米S...