LMS滤波算法在连线干涉测量中的应用研究

对航天测控信号进行滤波处理将有利于提高系统的测量性能。针对连线干涉测量（connected elements interferometer,CEI）因以载波时延为测量量,使其测量精度与载波差分相位估计性能直接相关,且该性能主要受近载频噪声影响这一问题,提出了采用最小二乘法（least mean square,LMS）算法对测控信号进行滤波处理以提高载波差分相位估计精度的思路。首先给出了基于LMS算法的相位估计方案;然后分析了其可行性和存在的问题;最后将LMS算法应用于CEI测量仿真和同步卫星观测试验中。仿真和实测数据处理表明：LMS算法可提高CEI测量性能,在同样数据处理长度下,滤波处理后载波差分时延估计精度提高了大约1.42倍;或在同样数据情况下,滤波处理可以降低数据的信噪比为6dB。     

Hot dip fine Zn and Zn-Al alloy double coating for corrosion resistance at coastal area

A new hot dip Zn-7Al alloy coating was performed on a structural steel by double coating of fine Zn and Zn-7 wt.% Al alloy, to prevent severe corrosion in coastal area. The alloy-coated steels were exposed to seaside, quasi-industrial, and rural districts to compare with conventional Zn coating. Double coating was significantly effective in preventing corrosion, particularly in a seaside. It was estimated from the exposure test for 10 years that the life of the Zn-7Al alloy-coated steel would be almost four times that of the Zn-coated steel in the seaside. A bending test showed that no exfoliation occurred at the interface between the coated alloy and substrate steel. TEM observation revealed that the excellent adhesiveness of the doubly coated fine Zn and Zn-7Al alloy to the steel substrate was due to formation of the interface region consisting of heterogeneous fine phase mixture of zinc, aluminium and iron.     

IN-SITU OBSER VATION OF SINGLE-POINT WEAR OF PM Al-Ti ALLOY

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铝合金铸件充型过程及氧化膜卷入的数值模拟

对于直接有限差分法，提出了单元表面无量纲距离、表面充填比率和体积充填比率，以描述铸件充型过程中自由表面的形状，建立了相应的充型过程数学模型，考虑了自由表面形状对动量、质量和能量传输的影响；提出了充型过程自由表面碰撞中表面氧化膜破碎，及其后破碎氧化膜流动的计算模型。对实验铝合金铸件进行了模拟应用，通过实际铸件充型过程的特殊X射线实时观察和记录。及实际铸件的气孔、收缩缺陷分布的检测，对模拟结果进行了验证分析。结果表明：充型过程模拟结果与X射线实时观察结果吻合较好，尤其是自由表面的变化；氧化膜卷入模拟结果与实际铸件气孔、收缩缺陷的分布存在一定的对应关系。     

Crack initiation model for sensitized 304 stainless steel in high temperature water

To investigate the initiation behavior of stress corrosion cracking (SCC) for sensitized Type 304 stainless steel in high temperature water, a constant load SCC test method combined with in situ crack observation technique was employed. The in situ crack observation system allowed us to detect small cracks of at least 100 μm. As a result, a fracture time decreased with an increase in an applied stress. The first cracks were observed at most 3 h before the specimen was fractured under all the stress conditions. After that, many cracks were initiated in a short time to fracture. The fracture was caused by coalescence of multiple cracks rather than by growth of some primary cracks. The simulation model for surface crack initiation was newly developed using a Monte Carlo method, which was based on damage mechanics and stress analysis around the existing cracks. The simulation could represent the empirical results of changes in the crack distribution and the cumulative number of cracks during the SCC tests. It was concluded, therefore, that the crack initiation process should be considered in simulating the life prediction of the material in this SCC system.     

未知观测噪声时机器人同步定位与地图构建

对未知观测噪声的机器人同步定位与地图构建问题,提出基于神经网络PID自适应学习观测噪声的机器人同步定位与地图构建算法.已知系统噪声为高斯分布,噪声的方差未知,但其真值是在某个有限集合内.设计一个由神经网络PID控制器、观测噪声调整以及中值滤波构成的噪声在线辨识单元.通过自适应在线辨识观测噪声,并进行新息协方差平均值滤波,迭代修正观测噪声协方差,实现机器人同步定位精度的在线提高.实验表明,该算法可降低观测噪声先验信息不足的影响,减小定位误差.     

一种阵列式探空温度传感器设计

为降低传统探空温度传感器的横梁尾流热污染误差,设计了一种基于热电偶阵列的探空温度传感器。该传感器由铂电阻,四个热电偶组成的阵列,高精度测量电路等部分组成。采用计算流体动力学（CFD）软件FLUENT对探空温度传感器进行数值分析仿真计算。搭建了一套高空环境模拟实验装置。实验结果表明,使用阵列式热电偶作为探空温度传感器,可将横梁热辐射误差降低至横梁升温量的0.43%~8.72%,实验测量结果与仿真结果相差-3.02%~5.44%,吻合度较高。阵列式低辐射误差探空温度传感器和传统探空温度传感器相比,降低了横梁尾流在上升过程中对传感器探头的影响,具有较低的辐射误差。     

Toward Universal Design in Public Transportation Systems: An Analysis of Low‐Floor Bus Passenger Behavior with Video Observations

This study aims to investigate the relationship between ergonomic comfort and the provision of accessibility features for mobility‐impaired persons in the use of public transportation systems in Korea. To deal with mobility issues in a public transportation environment, we chose the low‐floor bus as our research subject because it is the representative of a barrier‐free design solution. We collected data via video observation, which can overcome the limitations of traditional accessibility‐focused studies and laboratory studies by providing data on real usage patterns. We developed a framework to analyze the gathered data which includes user, space, tools, activities, and context. As a result, we observed existing difficulties of mobility‐impaired persons in terms of moving and supporting their bodies on the bus, despite the application of accessibility features. Furthermore, the design only for accessibility of mobility‐disabled persons can cause unexpected predicaments for the passengers who do not have physical handicaps. Drawing on these findings, we concluded that the concept of universal design in public transportation environments must be introduced in Korea. This study suggests video observation as a useful methodology for collecting data in dynamic environments. Additionally, our study is expected to contribute to how the concept of universal design can be implemented, and stimulate issues for ergonomic research based on our behavior pattern analysis.     

引黄涵闸观测设施埋设预算定额编制论述

现行的水利工程概算编制工作中,观测设施埋设费用大部分采用指标估算的方法计价,准确性不高,导致报价与工程实际出现严重偏差,给建设部门造成不应有的损失.文章以黄河引黄涵闸测压管埋设预算定额为例,阐述观测设施预算定额的编制方法,并提供测算的单价水平,给建设单位、施工单位、设计单位提供参考.     

光伏电池最大功率点跟踪方法比较

根据太阳能光伏电池的工程数学模型,在Matlab环境下建立了光伏电池仿真模型,分析了光照强度和温度变化对光伏电池输出特性的影响。针对扰动观察法采用固定的扰动步长而难以获得较高跟踪精度和响应速度的问题,提出了一种基于变步长的改进的扰动观察法,并通过对光伏电池控制系统进行仿真,比较了这2种最大功率点跟踪方法的仿真曲线。结果表明,采用改进的扰动观察法的光伏电池控制系统能更快速跟踪最大功率点,且在最大功率点处稳定性较好。