scholarly journals An Improved Coordinate Registration for Over-the-Horizon Radar Using Reference Sources

Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3086
Author(s):  
Zhen Guo ◽  
Zengfu Wang ◽  
Yuhang Hao ◽  
Hua Lan ◽  
Quan Pan
Keyword(s):  
Electron Density Profile ◽  
Target Localization ◽  
Parabolic Model ◽  
Error Source ◽  
Ionospheric Electron Density ◽  
Registration Process ◽  
Simulation Results ◽  
Ray Path ◽  
Terrain Features ◽  
Improvement Ratio

In the target localization of skywave over-the-horizon radar (OTHR), the error of the ionospheric parameters is one main error source. To reduce the error of ionospheric parameters, a method using both the information of reference sources (e.g., terrain features, ADS-B) in ground coordinates and the corresponding OTHR measurements is proposed to estimate the ionospheric parameters. Describing the ionospheric electron density profile by the quasi-parabolic model, the estimation of the ionospheric parameters is formulated as an inverse problem, and is solved by a Markov chain Monte Carlo method due to the complicated ray path equations. Simulation results show that, comparing with using the a prior value of the ionospheric parameters, using the estimated ionospheric parameters based on four airliners in OTHR coordinate registration process, the ground range RMSE of interested targets is reduced from 2.86 to 1.13 km and the corresponding improvement ratio is up to 60.39%. This illustrates that the proposed method using reference sources is able to significantly improve the accuracy of target localization.

Error Source Diagnostics Using a Turning Process Simulator

1998 ◽  
Vol 120 (2) ◽  
pp. 409-416 ◽  
Author(s):  
Sung-Gwang Chen ◽  
A. Galip Ulsoy ◽  
Yoram Koren
Keyword(s):  
Process Simulation ◽  
Cutting Process ◽  
Force Model ◽  
Error Source ◽  
Turning Process ◽  
Cutting Force Model ◽  
Cnc Lathe ◽  
Computer Numerically Controlled ◽  
Simulation Results ◽  
Process Simulator

To improve productivity and quality in machining, it is necessary to understand the interactions among machine tool components and the cutting process. This paper presents a model that characterizes interactions among the subsystems of a computer numerically controlled (CNC) lathe. The model is combined with a cutting force model to obtain a comprehensive turning simulator that simulates the cutting forces and part dimensions. A series of calibration experiments are proposed and implemented for process simulation. The simulation results are good when compared with experimental measurements. The interactions among the subunits of a CNC lathe and the cutting process are found to be potentially important.

scholarly journals Energy-Level Jumping Algorithm for Global Optimization in Compressive Sensing-Based Target Localization

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2502
Author(s):  
Tianjing Wang ◽  
Xinjie Guan ◽  
Xili Wan ◽  
Guoqing Liu ◽  
Hang Shen
Keyword(s):  
Global Optimization ◽  
Energy Level ◽  
Initial Point ◽  
Target Localization ◽  
Global Minimizer ◽  
Wireless Sensor ◽  
Localization Algorithm ◽  
Simulation Results ◽  
Sparse Solutions ◽  
Recovery Problem

Target localization is one of the essential tasks in almost applications of wireless sensor networks. Some traditional compressed sensing (CS)-based target localization methods may achieve low-precision target localization because of using locally optimal sparse solutions. Solving global optimization for the sparse recovery problem remains a challenge in CS-based target localization. In this paper, we propose a novel energy-level jumping algorithm to address this problem, which achieves high-precision target localization by solving the globally optimal sparse solution of l p -norm ( 0 < p < 1 ) minimization. By repeating the process of energy-level jumping, our proposed algorithm establishes a global convergence path from an initial point to the global minimizer. Compared with existing CS-based target localization methods, the simulation results show that our localization algorithm obtain more accurate locations of targets with the significantly reduced number of measurements.

scholarly journals Ionospheric E–F valley observed by a sounding rocket at the low-latitude station Hainan

2013 ◽  
Vol 31 (8) ◽  
pp. 1459-1462 ◽  
Author(s):  
J. K. Shi ◽  
Z. Wang ◽  
K. Torkar ◽  
M. Friedrich ◽  
X. Wang ◽  
...  
Keyword(s):  
Electron Density ◽  
Density Profile ◽  
Physical Mechanism ◽  
East Asian ◽  
Electron Density Profile ◽  
Sounding Rocket ◽  
Low Latitude ◽  
Ionospheric Electron Density ◽  
Simultaneous Observation ◽  
Latitude Region

Abstract. According to the sounding rocket experiment conducted at Hainan ionospheric observatory (19.5° N, 109.1° E), a valley between the E layer and F layer in the ionospheric electron density profile is observed and presented. The sounding rocket was launched in the morning (06:15 LT) on 7 May 2011, and the observed electron density profile outside the valley agrees with the simultaneous observation by the DPS-4 digisonde at the same station. The width of the observed valley was about 42 km, the depth almost 50%, and the altitude of the electron density minimum 123.5 km. This is the first observation of the E–F valley in the low-latitude region in the East Asian sector. The results are also compared with models, and the physical mechanism of the observed valley is discussed in this paper.

A Calibration Approach for Installation Error of Multi-Axis Laser Interferometer

2017 ◽  
Author(s):  
Shengwu Du ◽  
Jinchun Hu ◽  
Yu Zhu ◽  
Chang Tian ◽  
Ming Zhang
Keyword(s):  
Laser Beam ◽  
Computational Model ◽  
Measurement System ◽  
Laser Interferometer ◽  
Measurement Information ◽  
Error Source ◽  
Reference Axis ◽  
Ultra Precision ◽  
Simulation Results ◽  
Calibration Approach

Multi-axis laser interferometer is generally employed in measuring multi-degree-of-freedom (M-DOF) displacement for many ultra-precision X-Y stages. In multi-axis measurement system, the installation deviation of interferometer laser beam is an important error source. In this paper, a novel calibration approach without other higher precision sensors has been presented, to calibrate the installation deviation in a 3-DOF displacement measurement system, with potential capability of calibrating 6-DOF measurement system. In the proposed method, one redundant measuring axis that is set as installation reference axis is added to the original 3-axis measurement system. Correspondingly, considering the installation deviations of 3-axis interferometer, a new displacement computational model with four equations is built. In this model, all installation deviations are constants and the displacement values are variable. Utilizing the redundant measurement information of three position points, the installation deviations are separated. The simulation results validate its feasibility. This approach can strictly ensure the parallelism and perpendicularity between measuring axes, and is easily applied to engineering.

scholarly journals Refining Inaccurate Transmitter and Receiver Positions Using Calibration Targets for Target Localization in Multi-Static Passive Radar

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3365 ◽  
Author(s):  
Yongsheng Zhao ◽  
Dexiu Hu ◽  
Yongjun Zhao ◽  
Zhixin Liu ◽  
Chuang Zhao
Keyword(s):  
Lower Bound ◽  
Closed Form Solution ◽  
Form Solution ◽  
Measurement Noise ◽  
Target Localization ◽  
Passive Radar ◽  
Localization Accuracy ◽  
Position Errors ◽  
Simulation Results ◽  
Calibration Step

Transmitter and receiver position errors have been known to significantly deteriorate target localization accuracy in a multi-static passive radar (MPR) system. This paper explores the use of calibration targets, whose positions are known to the MPR system, to counter the loss in target localization accuracy arising from transmitter/receiver position errors. This paper firstly evaluates the Cramér–Rao lower bound (CRLB) for bistatic range (BR)-based target localization with calibration targets, which analytically indicates the potential of calibration targets in enhancing localization accuracy. After that, this paper proposes a novel closed-form solution, which includes two steps: calibration step and localization step. Firstly, the calibration step is devoted to refine the inaccurate transmitter and receiver locations using the BR measurements from the calibration targets, and then in the calibration step, the target localization can be accurately achieved by using the refined transmitter/receiver positions and the BR measurements from the unknown target. Theoretical analysis and simulation results indicate that the proposed method can attain the CRLB at moderate measurement noise level, and exhibits the superiority of localization accuracy over existing algorithms.

Determination of the Ionospheric Electron Density Profile from FUV Remote Sensing Measurements

2013 ◽  
Vol 56 (2) ◽  
pp. 109-116
Author(s):  
WANG Jing ◽  
TANG Yi ◽  
ZHANG Zhi-Ge ◽  
ZHENG Xu-Li ◽  
NI Guo-Qiang
Keyword(s):  
Remote Sensing ◽  
Electron Density ◽  
Density Profile ◽  
Electron Density Profile ◽  
Ionospheric Electron Density
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