scholarly journals Extended Multiple Aperture Mapdrift-Based Doppler Parameter Estimation and Compensation for Very-High-Squint Airborne SAR Imaging

Sensors ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 213 ◽  
Author(s):  
Zhichao Zhou ◽  
Yinghe Li ◽  
Yan Wang ◽  
Linghao Li ◽  
Tao Zeng
Keyword(s):  
Parameter Estimation ◽  
Cross Correlation ◽  
Image Generation ◽  
Third Order ◽  
Spatial Variance ◽  
Sar Imaging ◽  
Doppler Parameter ◽  
Aircraft Trajectory ◽  
Airborne Sar ◽  
Very High

Doppler parameter estimation and compensation (DPEC) is an important technique for airborne SAR imaging due to the unpredictable disturbance of real aircraft trajectory. Traditional DPEC methods can be only applied for broadside, small- or medium-squint geometries, as they at most consider the spatial variance of the second-order Doppler phase. To implement the DPEC in very-high-squint geometries, we propose an extended multiple aperture mapdrift (EMAM) method in this paper for better accuracy. This advantage is achieved by further estimating and compensating the spatial variation of the third-order Doppler phase, i.e., the derivative of the Doppler rate. The main procedures of the EMAM, including the steps of sub-view image generation, sliding-window-based cross-correlation, and image-offset-based Doppler parameter estimation, are derived in detail, followed by the analyses for the EMAM performance. The presented approach is evaluated by both computer simulations and real airborne data.

Third-Order Doppler Parameter Estimation of Bistatic Forward-Looking SAR Based on Modified Cubic Phase Function

2012 ◽  
Vol E95-B (2) ◽  
pp. 581-586 ◽  
Author(s):  
Wenchao LI ◽  
Jianyu YANG ◽  
Yulin HUANG ◽  
Lingjiang KONG
Keyword(s):  
Parameter Estimation ◽  
Phase Function ◽  
Cubic Phase ◽  
Third Order ◽  
Doppler Parameter ◽  
Cubic Phase Function ◽  
Forward Looking

A RELAX Based Method for Spotlight SAR Imaging

2012 ◽  
Vol 500 ◽  
pp. 362-367
Author(s):  
Xiao Zhen Ren ◽  
Yao Qin ◽  
Hong Liang Fu
Keyword(s):  
Parameter Estimation ◽  
Estimation Problem ◽  
Noisy Environment ◽  
Parameter Estimation Problem ◽  
Imaging Algorithm ◽  
Imaging Results ◽  
Sar Imaging ◽  
Simulation Results ◽  
Noisy Condition

The imaging problem of spotlight SAR is converted to a parameter estimation problem of several monochromatic signals in additive white Gaussian noisy condition in this paper. Moreover, a spotlight SAR imaging algorithm based on RELAX is presented in detail. Traditional polar format algorithm and the presented method are applied to spotlight SAR imaging respectively, and the imaging results are compared. Simulation results show that the polar format algorithm doesn’t give satisfactory imaging results, while the proposed method adapts the noisy environment better and obtains better results.

Investigation and Optimization of the Effects of Geologic Parameters on the Performance of Gravity-Stable Surfactant Floods

SPE Journal ◽  
2016 ◽  
Vol 21 (03) ◽  
pp. 761-775 ◽  
Author(s):  
Shayan Tavassoli ◽  
Gary A. Pope ◽  
Kamy Sepehrnoori
Keyword(s):  
Salinity Gradient ◽  
Horizontal Wells ◽  
Sensitivity Study ◽  
Third Order ◽  
Fine Grid ◽  
Heterogeneous Reservoirs ◽  
Vertical Permeability ◽  
Well Spacing ◽  
Optimization Schemes ◽  
Very High

Summary A systematic simulation study of gravity-stable surfactant flooding was performed to understand the conditions under which it is practical and to optimize its performance. Different optimization schemes were introduced to minimize the effects of geologic parameters and to improve the performance and the economics of surfactant floods. The simulations were carried out by use of horizontal wells in heterogeneous reservoirs. The results show that one can perform gravity-stable surfactant floods at a reasonable velocity and with very-high sweep efficiencies for reservoirs with high vertical permeability. These simulations were carried out with a 3D fine grid and a third-order finite-difference method to accurately model fingering. A sensitivity study was conducted to investigate the effects of heterogeneity and well spacing. The simulations were performed with realistic surfactant properties on the basis of laboratory experiments. The critical velocity for a stable surfactant flood is a function of the microemulsion (ME) viscosity, and it turns out there is an optimum value that one can use to significantly increase the velocity and still be stable. One can optimize the salinity gradient to gradually change the ME viscosity. Another alternative is to inject a low-concentration polymer drive following the surfactant slug (without polymer). Polymer complicates the process and adds to its cost without a significant benefit in most gravity-stable surfactant floods, but an exception is when the reservoir is highly layered. The effect of an aquifer on gravity-stable surfactant floods was also investigated, and strategies were developed for minimizing its effect on the process.

scholarly journals THE USE OF THE STOKES-STRUIK APPROXIMATION FOR WAVES OF FINITE HEIGHT

2011 ◽  
Vol 1 (6) ◽  
pp. 16
Author(s):  
L. E. Borgman ◽  
J. E. Chappelear
Keyword(s):  
Wave Profile ◽  
Third Order ◽  
The Third ◽  
Finite Height ◽  
Particle Velocities ◽  
Relationship Of ◽  
The Relationship ◽  
Permanent Form ◽  
Very High ◽  
Water Depths

A formal approximate solution is derived for the profile and velocity components of a wave with permanent form of finite height m moderate water depths. The approximation is carried to the third order, sufficiently far to represent all except the very high "design" waves. The relationship of the formulas to others found in the literature is discussed. The wavelengths and the coefficients in the third-order series for the wave profile, and the water particle velocities and local accelerations are tabulated for approximately 2000 waves. The depths, heights, and periods for the listed wave conditions vary respectively from 10 to 500 feet, 5 to 40 feet, and 4 to 20 seconds. The range of applicability of the theory is discussed and approximate limits estimated. As an aid in calculations, tables of the trigonometric and hyperbolic sines and cosines for integral multiples of the argument are included.

Improved Adaptive Parameter Estimation for Sparse SAR Imaging Based on Complex Image and Azimuth-Range Decouple

2019 ◽  
Author(s):  
Mingqian Liu ◽  
Zhilin Xu ◽  
Zhongqiu Xu ◽  
Zhonghao Wei ◽  
Bingchen Zhang ◽  
...  
Keyword(s):  
Parameter Estimation ◽  
Adaptive Parameter ◽  
Complex Image ◽  
Sar Imaging

Rotating micro-doppler parameter estimation of ground wheeled vehicles based on SPWD and image enhancement

Optik ◽  
2020 ◽  
Vol 219 ◽  
pp. 165119
Author(s):  
Lingzhi Zhu ◽  
Si Chen ◽  
Qun Ma ◽  
Shuning Zhang ◽  
Huichang Zhao ◽  
...  
Keyword(s):  
Parameter Estimation ◽  
Image Enhancement ◽  
Doppler Parameter ◽  
Wheeled Vehicles

Stress Measurements in Polished Al-Mg Alloy and CrN Coating Using Multireflection Grazing Incidence Method

2014 ◽  
Vol 783-786 ◽  
pp. 2091-2096 ◽  
Author(s):  
Marianna Marciszko ◽  
Andrzej Baczmański ◽  
Krzysztof Wierzbanowski ◽  
Jean Paul Chopart ◽  
Alain Lodini ◽  
...  
Keyword(s):  
Lattice Strain ◽  
Stress Gradient ◽  
Grazing Incidence ◽  
Mg Alloy ◽  
Third Order ◽  
Crn Coating ◽  
X Ray ◽  
The Third ◽  
Microstructure Density ◽  
Very High

The multi-reflection grazing incidence X-ray diffrection was used to determine residual stress gradient in the mechanically polished Al-Mg alloy and CrN coating. Also, the root mean square values of the third order lattice strain was determined using Wiliamson-Hall method. The results obtained for Al-Mg alloy show that the stress field in the surface layer as well as the microstructure (density of dislocation) depend strongly on the sample preparation. A very high residual compressive stress, which does not change significantly with depth, was measured in the CrN coating. Moreover, a large value of the measured third order strains in the coating was found.

scholarly journals Correcting Spatial Variance of RCM for GEO SAR Imaging Based on Time-Frequency Scaling

Sensors ◽  
2016 ◽  
Vol 16 (7) ◽  
pp. 1091 ◽  
Author(s):  
Ze Yu ◽  
Peng Lin ◽  
Peng Xiao ◽  
Lihong Kang ◽  
Chunsheng Li
Keyword(s):  
Frequency Scaling ◽  
Spatial Variance ◽  
Time Frequency ◽  
Sar Imaging

Fast Fourier-Domain Optimization Using Hybrid L1−/L${}_{p}$ -Norm for Autofocus in Airborne SAR Imaging

2019 ◽  
Vol 57 (10) ◽  
pp. 7934-7954
Author(s):  
Jin-Woo Kim ◽  
Young-Dam Kim ◽  
Tae-Dong Yeo ◽  
Seung-Tae Khang ◽  
Jong-Won Yu
Keyword(s):  
Fourier Domain ◽  
Domain Optimization ◽  
Sar Imaging ◽  
Airborne Sar
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