实时光测数据系统误差修正方法

由于测量设备本身或环境条件的影响,光测数据总存在一定的系统误差,如果不加以修正,将直接影响实时数据处理精度。依托靶场实际工程背景,对实时光测数据的光电波折射误差和轴系误差进行了分析,并提出了简化的误差修正方法,通过实测数据的计算分析可知,这些方法可以有效地减小实时光测数据处理的误差。

基于数据融合的靶场光测数据的实时剔野方法

基于数据融合的观点，提出一种融合算法，可实时确定光测数据的取舍，仿真结果表明此融合算法是有效的。

光度曲线反演空间目标形状的发展现状

光度曲线反演空间目标形状和姿态等参数为空间目标监视与识别提供了新的技术途径。首先分析了基于光度曲线反演空间目标信息的必要性,之后通过关注和跟踪国内外最新发展情况,全面总结了目前进行形状反演的3种主流方法的研究现状及优缺点,对3种反演方法进行了比较分析,指出基于非线性滤波技术的形状反演方法是未来的主要发展方向,并分析了3种非线性滤波技术的优缺点。最后针对反演存在的问题,指出了基于改进的实时性更好的粒子滤波算法,融合多种传感器信息反演几何形状和表面材料更为复杂的空间目标是下一步研究发展的主要方向。

光学航空、航天应用

V557.3 99032100光测和雷测常值系统误差的联合估计=Joint estimationsof constant systematic errors of radartesting data and optical testing data[刊,中]/周海银,王正明(国防科技大学701教研室.湖南,长沙(410073))//宇航计测技术.—1998,18(1).-36-43分析了目前通用的利用光测数据扣除连续波雷达测量数据中的常值系统误差方法存在的问题。

APPLICATION OF GREY SYSTEM THEORY TO PROCESSING OF MEASURING DATA IN REVERSE ENGINEERING

The processing of measuri ng data plays an important role in reverse engineering. Based on grey system the ory, we first propose some methods to the processing of measuring data in revers e engineering. The measured data usually have some abnormalities. When the abnor mal data are eliminated by filtering, blanks are created. The grey generation an d GM(1,1) are used to create new data for these blanks. For the uneven data sequ en ce created by measuring error, the mean generation is used to smooth it and then the stepwise and smooth generations are used to improve the data sequence.

Predictive Vegetation Mapping Approach Based on Spectral Data, DEM and Generalized Additive Models

This study aims to provide a predictive vegetation mapping approach based on the spectral data, DEM and Generalized Additive Models (GAMs). GAMs were used as a prediction tool to describe the relationship between vegetation and environmental variables, as well as spectral variables. Based on the fitted GAMs model, probability map of species occurrence was generated and then vegetation type of each grid was defined according to the probability of species occurrence. Deviance analysis was employed to test the goodness of curve fitting and drop contribution calculation was used to evaluate the contribution of each predictor in the fitted GAMs models. Area under curve (AUC) of Receiver Operating Characteristic (ROC) curve was employed to assess the results maps of probability. The results showed that: 1) AUC values of the fitted GAMs models are very high which proves that integrating spectral data and environmental variables based on the GAMs is a feasible way to map the vegetation. 2) Prediction accuracy varies with plant community, and community with dense cover is better predicted than sparse plant community. 3) Both spectral variables and environmental variables play an important role in mapping the vegetation. However, the contribution of the same predictor in the GAMs models for different plant communities is different. 4) Insufficient resolution of spectral data, environmental data and confounding effects of land use and other variables which are not closely related to the environmental conditions are the major causes of imprecision.

Dune dynamics in the southern edge of Dunhuang Oasis and implications for the oasis protection

The survival of Dunhuang Oasis is largely determined by the evolution of sand dunes in the southern edge of the oasis, mainly composed of shield dunes and mega pyramid dunes, which occupy twothirds and one-third of the area, respectively. However, few studies have focused on dynamics of these dunes, especially in terms of quantification. So the theoretical basis of sand-control engineering is relatively limited. Here we present the characteristics of dune dynamics of a shield dune and mega pyramid dune in the southern edge of Dunhuang Oasis during April 2014-April 2016 based on measurement data of a 3-D laser scanner. Results indicate that the volume of the shield dune decreased during the monitoring period of two years, and the gravity centers of the monitored shield dune moved windward, indicating that sand was transported toward the oasis. Conversely, the dune volume of the mega pyramid dune increased and the gravity center presented no prominent movement, indicating that the megapyramid dune was relatively stable and its migration toward the oasis was not notable. Thus, compared with mega pyramid dunes, shield dunes in the southern edge of Dunhuang Oasis are identified as a more significant sand source endangering the protection of the oasis, and sand-control engineering should mainly focus on these shield dunes.

A Laser Ranging System Using Chaotic Light

A novel laser ranging system using chaotic laser as probe light source is designed and presented.The system is made up of five components:chaotic light source,transmitter,receiver,data acquisition unit and data processing unit.Chaotic light is generated by an 808 nm,500 mW,single-mode laser diode with optical feedback cavity.Single target detection and multi-target detection are experimentally realized by correlating the chaotic reference light and the reflected or backscattered probe light.The performances,including the resolution of 18 cm within at least 130 m range and the sensitivity of-20 dB,are achieved and analyzed.

Segments-based progressive TIN densification filter for DTM generation from airborne LIDAR data

Airborne light detection and ranging( LIDAR) has revolutionized conventional methods for digital terrain models( DTMs) acquisition. Ground filtering for airborne LIDAR is one of the core steps taken to obtain a high quality DTM. This paper presents a segments-based progressive TIN( triangulated irregular network) densification( SPTD) filter that can automatically separate ground points from non-ground points. The SPTD method is composed of two key steps: point cloud segmentation and clustering by iterative judgement. The clustering method uses the dual distance to obtain a set of seed points as a coarse spatial clustering process. Then the rest of the valid point clouds are classified iteratively. Finally,the datasets provided by ISPRS are utilized to test the filtering performance.In comparison with the commercial software Terra Solid,the experimental results show that the SPTD method in this paper can avoid single threshold restrictions. The expected accuracy of ground point determination is capable of producing reliable DTMs in the discontinuous areas.

Effect of minimal shoes and slope on vertical and leg stiffness during running

Purpose： This study was designed to characterize and compare the vertical（kvert） and leg（kleg） stiffness measured during running in two different footwear conditions on negative, level, and positive slopes, using kinematic data only.Methods： Fourteen male recreational runners（age 23.4 4.4 years, height 177.5 5.2 cm, and body mass 69.5 5.3 kg） were tested on 2separate days within 1 week. At each session, subjects ran seven 5-min trials on a treadmill at 10 km/h, interspersed with 5 min of sitting passive recovery. Each trial was performed on a different slope gradient, ranging from 8%（downhill） to t8%（uphill）, assigned in a random order.Furthermore, each subject ran one 5-min trial wearing minimal shoes（MS） and the subsequent trial wearing traditional shoes（TS） in a counterbalanced randomized order ensuring that each slope was ran once in MS and once in TS. Kinematic data were collected using a photocell measuring system and high-speed video camera, with kvertand klegstiffness being calculated from these data.Results： Leg compression, contact times, and vertical displacement of the center of mass during running were significantly smaller in MS compared to TS across all slopes. In the two footwear conditions, step frequency significantly increased with a（positive） increase in slope.Kinematic analyses indicated that klegwas greater when running in MS than TS and this between-footwear difference remained similar across slopes. On the contrary, kvertdid not change on the basis of footwear, but increased with positive increases in slope.Conclusion： This study showed that kvertand klegduring running respond differently to change in footwear and/or slope. These two stiffness measures can hence provide a unique insight on the biomechanical adaptations of running under varying conditions and their respective quantification may assist in furthering our understanding of training, performance, and/or injury in this sport.

New Monitoring Technologies for Overhead Contact Line at 400 km.h-1

Various technologies have recently been developed for high-speed railways, in order to boost commercial speeds from 300 km.h： to 400 km.h-1. Among these technologies, this paper introduces the 400 km-h-1 class current collection performance evaluation methods that have been developed and demonstrated by Korea. Specifically, this paper reports details of the video-based monitoring techniques that have been adopted to inspect the stability of overhead contact line （OCL） components at 400 km.h-1 without direct contact with any components of the power supply system. Unlike conventional OCL monitoring systems, which detect contact wire positions using either laser sensors or line cameras, the developed system measures parameters in the active state by video data. According to experimental results that were obtained at a field-test site established at a commercial line, it is claimed that the proposed mea- surement system is capable of effectively measuring OCL parameters.

Aerosol Distribution of ASEAN Area Base on LIDAR Monitoring Data at Hanoi and Trajectory Statistics Simulation

Averaged fractional composition of aerosol in Vietnam and Belarus was obtained and the maps of the column on near-ground aerosol content were built on the basics of model calculations. The results show the complexity of the geographic ASEAN areas. It may cause variable of climate in local.

Reconstruction of Turbulent Swirling Flow in a Dump Combustor

Experimental data of the continuous evolution of fluid flow characteristics in a dump combustor is very useful and essential for better and optimum designs of gas turbine combustors and ramjet engines. Unfortunately, experimental techniques such as 2D and/or 3D LDV （Laser Doppler Velocimetry） measurements provide only limited discrete information at given points; especially, for the cases of complex flows such as dump combustor swirling flows. For this type of flows, usual numerical interpolating schemes appear to be unsuitable. Recently, neural networks have emerged as viable means of expanding a finite data set of experimental measurements to enhance better understanding of a particular complex phenomenon. This study showed that generalized feed forward network is suitable for the prediction of turbulent swirling flow characteristics in a model dump combustor. These techniques are proposed for optimum designs of dump combustors and ramjet engines.

Dosimetric evaluation of a beam matching procedure

Objective: The dosimetric characteristics for linear accelerators with the same model, and nominal energy are known to be very similar, as long as the machines are unaltered from the manufacturer's original specifications. In this preliminary study, a quantitative investigation of the similarity in the basic photon and electron dosimetry data from the Siemens Oncor linear accelerators at our hospital(Children's Cancer Hospital, Cairo, Egypt) was reported. Methods: The output factor(OF), wedge factors(WF), percentage depth dose(PDD), and beam profile for the 6 and 10 MV photon beams were measured. Results: The measured output factors varied by less than about 1% for each field size. The difference between the maximum and minimum PDD values at each depth was less than about 1%. The difference between the beam flattnes and symetry was no more than 1% at all off-axis distances. For electron the results showed that the PDD, OF, and the beam profiles were matched within 1% differences. Conclusion: These results strongly suggest that it is feasible to establish one reference photon and electron dosimetry data set for the two machines and nominal energies.

Analyses of Characteristics of Long-Term Monitoring of Arterial Pressure and Pulse

Long-term observations of pulse and arterial blood pressure taken from a patient＇s daily self-control diary have been analyzed in the paper. The diary was kept in the morning and in the evening. It contains regular observational data collected during over 13 years. Statistical estimates of series and their spectral responses were obtained. A difference between the morning and evening series was noted. Spectral harmonics with the period of 7 days was typical of the evening series. The morning series are characterized by a ＂lunar＂ component with the -27.35-day period. The examined series were also compared with the daily series of atmospheric pressure and daily Wolf numbers. Seasonal pulse and arterial pressure pattern and average monthly self-control tabulated data obtained during 13 years are presented in the paper.

Some Peculiarities of the Preprocessing of Spectral Data and Images

Remotely sensed spectral data and images are acquired under significant additional effects accompanying their major formation process, which greatly determine measurement accuracy. In order to be used in subsequent quantitative analysis and assessment, this data should be subject to preliminary processing aiming to improve its accuracy and credibility. The paper considers some major problems related with preliminary processing of remotely sensed spectral data and images. The major factors are analyzed, which affect the occurrence of data noise or uncertainties and the methods for reduction or removal thereof. Assessment is made of the extent to which available equipment and technologies may help reduce measurement errors.

基于Phong模型的地球同步轨道目标视星等仿真研究

地球同步轨道上运行着大量的空间目标,基于光度曲线反演空间目标信息为目标的跟踪、识别与监视提供了新的技术途径。利用STK软件,通过坐标变换获取不同轨道参数下太阳、卫星以及观测站的时空关系。根据视星等定义,利用面元法基于Phong模型推导出适用于立方体、棱柱体以及圆柱体空间目标的视星等模型。通过与实测数据对比,验证该视星等模型的仿真误差约为3%,仿真效果远好于仅采用漫反射率表征的视星等模型。基于Matlab软件,仿真研究了不同弧段、不同形状以及不同尺寸卫星光度曲线的变化规律。研究表明,当获取的光度曲线质量较高时采用非线性滤波技术反演,仅能获得特殊点的视星等信息时采用二面法理论反演,为下一步光度曲线反演提供了一定参考。

Performance Improvements in Temperature Reconstructions of 2-D Tunable Diode Laser Absorption Spectroscopy(TDLAS)

Performance improvement was attained in data reconstructions of 2-dimensional tunable diode laser absorption spectroscopy(TDLAS). Multiplicative Algebraic Reconstruction Technique(MART) algorithm was adopted for data reconstruction. The data obtained in an experiment for the measurement of temperature and concentration fields of gas flows were used. The measurement theory is based upon the Beer-Lambert law, and the measurement system consists of a tunable laser, collimators, detectors, and an analyzer. Methane was used as a fuel for combustion with air in the Bunsen-type burner. The data used for the reconstruction are from the optical signals of 8-laser beams passed on a cross-section of the methane flame. The performances of MART algorithm in data reconstruction were validated and compared with those obtained by Algebraic Reconstruction Technique(ART) algorithm.

A 3D measurement method based on multi-view fringe projection by using a turntable

In order to get the entire data in the optical measurement, a multi-view three-dimensional(3D) measurement method based on turntable is proposed. In the method, a turntable is used to rotate the object and obtain multi-view point cloud data, and then multi-view point cloud data are registered and integrated into a 3D model. The measurement results are compared with that of the sticking marked point method. Experimental results show that the measurement process of the proposed method is simpler, and the scanning speed and accuracy are improved.