Non-cooperative maritime target position and velocity measuring method based on monocular trajectory intersection for video satellite

2017 ◽  
Vol 233 (1) ◽  
pp. 44-56 ◽  
Author(s):  
Shengyi Chen ◽  
Haibo Liu ◽  
Xiaochun Liu ◽  
Qifeng Yu
Keyword(s):  
Target Position ◽  
Measuring Method ◽  
Observation Time ◽  
Measuring Error ◽  
Target Movement ◽  
Practical Applications ◽  
High Measurement ◽  
Velocity Measuring ◽  
Elevation Model ◽  
Intersection Method

This paper presents a passive measuring method based on monocular trajectory intersection, aimed at realizing the position and velocity measurement of a non-cooperative maritime target for video satellite. Due to the fact that the target’s moving range is relatively small in comparison to that of the satellite during the observation time, a large measuring error results when directly using the monocular trajectory intersection method for 3D motion measurement. Therefore, the dynamic sea surface elevation model is employed to increase the maritime target movement constraints, which simplifies the 3D spatial motion of the target to 2D surface motion. By combining the surface constraint and monocular trajectory intersection method, measurement robustness for a non-cooperative maritime target can be greatly improved. Furthermore, a line-surface intersection method is proposed to obtain the initial solution for motion parameters, which increases the nonlinear optimization efficiency. Simulation experiments are conducted to analyze the effect of different error factors on position and velocity accuracy. The results indicate that the proposed method achieves high measurement accuracy and is feasible in practical applications for video satellite.

Measuring Error of Phase Modulation Laser Doppler Shift Measuring Method

2014 ◽  
Vol 34 (7) ◽  
pp. 0712001 ◽  
Author(s):  
杜军 Du Jun ◽  
曲彦臣 Qu Yancheng ◽  
赵卫疆 Zhao Weijiang ◽  
耿利杰 Geng Lijie ◽  
刘闯 Liu Chuang ◽  
...  
Keyword(s):  
Doppler Shift ◽  
Phase Modulation ◽  
Measuring Method ◽  
Laser Doppler ◽  
Measuring Error

scholarly journals Effect of incorrect sound velocity on synthetic aperture sonar resolution

2019 ◽  
Vol 283 ◽  
pp. 04013
Author(s):  
Xia Ji ◽  
Lisheng Zhou ◽  
Weihua Cong
Keyword(s):  
Image Quality ◽  
Sound Velocity ◽  
Velocity Gradient ◽  
Phase Error ◽  
Synthetic Aperture ◽  
Measuring Error ◽  
Detection Range ◽  
Synthetic Aperture Sonar ◽  
Velocity Error ◽  
Velocity Measuring

Synthetic aperture sonar (SAS) is an imaging technique to produce centimeter resolution over hundreds-of-meter range on the sea floor, by constructing a virtual aperture whose length automatically adjusts itself for a given focusing range. SAS is near-field acoustic imaging, and this implies that the sound velocity should be accurately estimated for well focused imaging. Otherwise there will be image quality loss. However, sound velocity in the ocean varies with space and time, and there might also be measuring error of CTD (Conductivity, Temperature, and Depth) sensor, so sound velocity error has become one of the limiting factors to improve SAS resolution further. To characterize the effect of sound velocity error quantificationally, the practice SAS resolution is mode as the convolution of ideal seafloor reflectivity function and a phase error function in frequency domain, where the phase error is caused by incorrect sound velocity. Then the SAS resolution parameterized is calculated as a function of the sound velocity measuring error, or sound velocity gradient. It is shown that SAS azimuthally (along track) resolution loss, caused by sound velocity measurement error, increases linearly with detection range. Meanwhile the loss caused by sound velocity gradient increases squarely. It is simulated by considering the synthetic aperture data collection for a particular pixel, and results show that the point scatter response will defocus when the sound velocity measuring error is up to 1% at 200m range, or the sound velocity changes up to 2% over a typical gradient at 200m range, and be worse at a longer range. Furthermore, we demonstrate the influence of sound velocity errors on SAS imagery using a sea trial data and real CTD measurements at South China Sea. We evaluate the degradation in image quality with respect to sound velocity errors by using two plastic balls and a variable seafloor scene, and results also support the accuracy of theoretical conclusions above.

scholarly journals Topographic Exposure and its Practical Applications

2010 ◽  
Vol 3 (1) ◽  
pp. 42-51 ◽  
Author(s):  
Tomáš Mikita ◽  
Martin Klimánek
Keyword(s):  
Detailed Knowledge ◽  
Climatic Data ◽  
Practical Applications ◽  
Degree Of Protection ◽  
Power Stations ◽  
Snow Storage ◽  
Vegetation Zones ◽  
Digital Elevation ◽  
The Creation ◽  
Elevation Model

Topographic Exposure and its Practical ApplicationsTopographic exposure is a topographic characteristic representing a degree of protection by a surrounding topography of a certain site. Detailed knowledge of topographic exposure has broad use in a number of applications ranging from studying forest wind damage through research on snow storage dynamics to optimisation in positioning wind power stations. This paper describes a method for creation of topographic exposure on the basis of a digital elevation model (DEM) using GIS. In combination with other climatic data on wind direction and speed, this factor is used to define the degree of terrain ventilation. Low terrain ventilation has, among other things, a significant influence on the creation of valley inversions and related vegetation zoning inversions. By combining the degree of terrain ventilation with DEM and forest vegetation zones in the area of the Training Forest Enterprise Křtiny, a clear relationship between the influence of topographic exposure, or terrain ventilation, and the creation of the vegetation zoning inversion was determined.

Velocity-Measuring Method for Vehicle using Magnetic Field

2017 ◽  
Vol 23 (8) ◽  
pp. 692-698
Author(s):  
Kwang-Il Han ◽  
Han-Sol Kim ◽  
Kwang Ryul Baek
Keyword(s):  
Magnetic Field ◽  
Measuring Method ◽  
Velocity Measuring

scholarly journals Spatial Downscaling of GPM Annual and Monthly Precipitation Using Regression-Based Algorithms in a Mountainous Area

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Chesheng Zhan ◽  
Jian Han ◽  
Shi Hu ◽  
Liangmeizi Liu ◽  
Yuxuan Dong
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Mountainous Area ◽  
Monthly Precipitation ◽  
Practical Applications ◽  
Precipitation Measurement ◽  
Digital Elevation ◽  
Elevation Model ◽  
Global Precipitation ◽  
Spatial Downscaling

As a fundamental component in material and energy circulation, precipitation with high resolution and accuracy is of great significance for hydrological, meteorological, and ecological studies. Since satellite measured precipitation is often too coarse for practical applications, it is essential to develop spatial downscaling algorithms. In this study, we investigated two downscaling algorithms based on the Multiple Linear Regression (MLR) and the Geographically Weighted Regression (GWR), respectively. They were employed to downscale annual and monthly precipitation obtained from the Global Precipitation Measurement (GPM) Mission in Hengduan Mountains, Southwestern China, from 10 km × 10 km to 1 km × 1 km. Ground observations were then used to validate the accuracy of downscaled precipitation. The results showed that (1) GWR performed much better than MLR to regress precipitation on Normalized Difference Vegetation Index (NDVI) and Digital Elevation Model (DEM); (2) coefficients of GWR models showed strong spatial nonstationarity, but the spatial mean standardized coefficients were very similar to standardized coefficients of MLR in terms of intra-annual patterns: generally NDVI was positively related to precipitation when monthly precipitation was under 166 mm; DEM was negatively related to precipitation, especially in wet months like July and August; contribution of DEM to precipitation was greater than that of NDVI; (3) residuals’ correction was indispensable for the MLR-based algorithm but should be removed from the GWR-based algorithm; (4) the GWR-based algorithm rather than the MLR-based algorithm produced more accurate precipitation than original GPM precipitation. These results indicated that GWR is a promising method in satellite precipitation downscaling researches and needed to be further studied.

Slag Thickness in Continuous Casting Tundish Measuring Method Based on Temperature Information

2012 ◽  
Vol 457-458 ◽  
pp. 804-809
Author(s):  
Jun Liu ◽  
Feng Yang ◽  
Jun Xie ◽  
Zheng Jun Zeng
Keyword(s):  
Continuous Casting ◽  
Slag Layer ◽  
Measuring Method ◽  
Thickness Measurement ◽  
Measuring Error ◽  
Steel Metallurgy ◽  
Continuous Casting Tundish ◽  
Steel Layer ◽  
Slag Thickness ◽  
Application Prospects

Acquiring the thickness of slag layer in continuous casting tundish accurately is beneficial to continous casting stably, and improves enterprise benefit. A new method to measure the thickness of slag layer in continuous casting tundish, based on temperature information is put forward in the papers. A measuring bar, made of Refractory Material, was inserted into the tundish to perceive the temperature. Then the thickness of slag layer may be obtained accurately by temperature interface between air layer and slag layer, and slag layer and molten steel layer. After applying to the slag layer thickness measurement in steel metallurgy field, it has a favorable application prospects because of the measuring error about less than 2.6mm.

Researches on Relationship between Dynamic Radius and Slip Ratio of Driving Wheel

2012 ◽  
Vol 159 ◽  
pp. 249-252
Author(s):  
Xi Qin Li
Keyword(s):  
Theoretical Analysis ◽  
Measuring Method ◽  
Measuring Error ◽  
Road Vehicles ◽  
Slip Ratio ◽  
Movement Characteristics ◽  
Driving Wheel ◽  
Experimental Researches

The dynamic radius of a driving wheel, especially for the off-road vehicles, has not been identified clear so far. This article reveals the relationships between the dynamic radius and the slip ratio of a driving wheel by theoretical analysis and experimental researches. The movement characteristics of a rigid driving wheel and an elastic pneumatic driving tire on soft roads are explained. There are many kinds of methods to measure the dynamic radius, and the magnitude of the dynamic radius is not the same according to the methods. A certain measuring method should be chosen for each kind of road conditions in order to reduce the measuring error.

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