惯性/卫星/里程计多信息融合方法及在铁路测绘中的应用

针对基于惯性技术对铁路基础设施进行精确测绘的需求提出一种多信息融合惯性基准方案,为测量测绘提供高精度位置和姿态参考。对载体运动特点和车载状态下惯性/里程组合导航航向角误差可观性进行分析,认为天向陀螺漂移和航向误差是导致测量精度下降的主要因素,针对该问题设计了基于双向滤波、双向平滑的多信息融合方案,针对缺乏绝对位置基准的应用情况,引入"正矢"概念和相对定位精度的评判方法。仿真及试验结果表明,在陀螺常值漂移0.2(°)/h条件下,该方案相对定位精度优于0.3 mm(300 m弦正矢),显著提高了车载铁路线路测绘位置、姿态基准精度,降低了对惯性器件的要求,利用中、低精度器件实现了高精度测量定位。     

一种飞机综合导航系统的研究

本文研究了某型飞机综合导航系统的组成及特点,重点研究并推导了大气数据系统、无 线电近程导航系统和光电雷达火控系统校正惯导的原理及其数学模型,并对其导航计算机的 软件进行分析破译。该综合导航系统的设计思想是很有借鉴价值的。     

集成光学陀螺及相关技术研究的现状与展望

陀螺技术作为惯性导航的重要组成部分已广泛应用于国民经济和军事工业的众多领域.文章综述了包括机械陀螺、光学陀螺和原子陀螺在内的 陀螺技术的发展过程和基本特点,着重论述了集成光学陀螺及其相关技术研究的现状与发展趋势.通过对比各种类型陀螺的性能特点,结合导 航技术的发展趋势,展望了各种陀螺在相应领域的发展前景.     

Application of Non-Destructive X-Ray Fluorescence Spectrometry to the Analysis of Suspended Matter in Sea Water

Abstract

In the framework of remote sensing studies concerning coastal transport of pollution in the Northern Adriatic Sea, a method has been developed for the quantitative determination of sulphur, iron, titanium, calcium, phosphorus, silicon, aluminium, magnesium in suspended matter of sea water.

The suspended material was collected by filtering on millipore membrane filters with pore width of 0.45 μ and directly analysed by X-ray spectroscopy. For calibration dried solution and particulate standard samples were used. Limits of sensitivity and precision of the method are reported.

Correlations between the concentration of these elements and the total suspended matter/chlorophyll are discussed.

The aim is to study the geochemical composition of particulate matter and its variations within the geographical site of the sea basin and the seasonal conditions. The approach is to consider aluminium and the other elements normalized on Al. On the basis of a matrix correlation analyses of some sets of data chosen in the restricted area for investigation, some hypothesis on superficial distribution of clay, carbonate, iron hydrous oxides and other mineral detrites, are taken into account. The results confirm the complex situation existing in the offshore area of the Venice lagoon from a geochemical point of view.

The suspended matter seem to be argillaceous in the Southern part of the investigated area and semi-argillaceous with hydrous oxides and carbonates in the Northern part which is influenced by the Piave river.     

Heteronuclear Cross‐Relaxation Effects in the NMR Spectroscopy of Hyperpolarized Targets

Dissolution dynamic nuclear polarization (DNP) enables high‐sensitivity solution‐phase NMR experiments on long‐lived nuclear spin species such as ¹⁵N and ¹³C. This report explores certain features arising in solution‐state ¹H NMR upon polarizing low‐γ nuclear species. Following solid‐state hyperpolarization of both ¹³C and ¹H, solution‐phase ¹H NMR experiments on dissolved samples revealed transient effects, whereby peaks arising from protons bonded to the naturally occurring ¹³C nuclei appeared larger than the typically dominant ¹²C‐bonded ¹H resonances. This enhancement of the satellite peaks was examined in detail with respect to a variety of mechanisms that could potentially explain this observation. Both two‐ and three‐spin phenomena active in the solid state could lead to this kind of effect; still, experimental observations revealed that the enhancement originates from ¹³C→¹H polarization‐transfer processes active in the liquid state. Kinetic equations based on modified heteronuclear cross‐relaxation models were examined, and found to well describe the distinct patterns of growth and decay shown by the ¹³C‐bound ¹H NMR satellite resonances. The dynamics of these novel cross‐relaxation phenomena were determined, and their potential usefulness as tools for investigating hyperpolarized ensembles and for obtaining enhanced‐sensitivity ¹H NMR traces was explored.     

Methods of rapid orbit forecasting after maneuvers for geostationary satellites

A geostationary (GEO) satellite may serve as a navigation satellite, but there is a problem that maneuvers frequently occur and the forces are difficult to model. Based on the technique of determining satellite orbits by transfer, a predicted orbit with high accuracy may be achieved by the method of statistical orbit determination in case of no maneuver force. The predicted orbit will soon be invalid after the maneuver starts, and it takes a long time to get a valid orbit after the maneuver ends. In order to improve ephemeris usability, the method of rapid orbit forecasting after maneuvers is studied. First, GEO satellite movement is analyzed in case of maneuvers based on the observation from the orbit measurement system by transfer. Then when a GEO satellite is in the free status just after maneuvers, the short arc observation is used to forecast the orbit. It is assumed that the common system bias and biases of each station are constant, which can be obtained from orbit determination with long arc observations. In this way, only 6 orbit elements would be solved by the method of statistical orbit determination, and the ephemeris with high accuracy may be soon obtained. Actual orbit forecasting with short arc observation for SINOSAT-1 satellite shows that, with the tracking network available, the precision of the predicted orbit (RMS of O-C) can reach about 5 m with 15 min arc observation, and about 3 m with 30 min arc observation. Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA12Z322), the National Basic Research Program of China (Grant No. 2007CB815503), and the West Light Program of Chinese Academy of Sciences (Grant No. 2007LH01)     

Accelerating autonomous learning by using heuristic selection of actions

This paper investigates how to make improved action selection for online policy learning in robotic scenarios using reinforcement learning (RL) algorithms. Since finding control policies using any RL algorithm can be very time consuming, we propose to combine RL algorithms with heuristic functions for selecting promising actions during the learning process. With this aim, we investigate the use of heuristics for increasing the rate of convergence of RL algorithms and contribute with a new learning algorithm, Heuristically Accelerated Q-learning (HAQL), which incorporates heuristics for action selection to the Q-Learning algorithm. Experimental results on robot navigation show that the use of even very simple heuristic functions results in significant performance enhancement of the learning rate.     

S-curvature of isotropic Berwald metrics

Isotropic Berwald metrics are as a generalization of Berwald metrics. Shen proved that every Berwald metric is of vanishing S-curvature. In this paper, we generalize this fact and prove that every isotropic Berwald metric is of isotropic S-curvature. Let F = α + β be a Randers metric of isotropic Berwald curvature. Then it corresponds to a conformal vector field through navigation representation.     

降阶扩展卡尔曼滤波算法在船用INS/GPS组合导航系统中的应用

TNNS(真航向导航系统)由MS860接收机、INS及处理数据的PC/104架构的嵌入式工控机构成。针对TNNS推导了INS(惯性导航系统)的误差模型,提出了适合于TNNS的降阶扩展卡尔曼滤波算法组合GPS和INS。系统在东海作了三次海试,软件及滤波算法平台由C/C 编制。海上试验表明,组合滤波后,INS的位置误差由100m降低到40m以下;进行最优化滤波后的航向误差σ由原来的0.105°减小为0.034°,纵横摇的误差也大幅减小。整个海试结果表明,在TNNS中组合GPS/INS采用的降阶扩展卡尔曼滤波算法,大幅提高了系统精度和可靠性。     

A high-precision 1D dynamic angular measuring system based on linear CCD for Fengyun-2 meteorological satellite

The Fengyun-2 (FY-2) meteorological satellite uses a one-dimensional dynamic angular measuring system to evaluate the stepping accuracy of the scanning mirror. The basic principle of this angular measurement is detecting the light-spot position displacement using a linear charge-coupled device (CCD). This paper presents the design of this non-contact and non-destructive measuring system. To achieve high repeatability and accuracy the centroid method is employed to estimate the light-spot energy gravity, with 20-segment polygonal approximations as a nonlinear compensation. Experimental results show that the measurement system can achieve dynamic angular measurement with up to ±5″ accuracy and 3.5″ repeatability, which makes a credible evaluation for the scanning mirror of FY-2 meteorological satellite.