scholarly journals GF-7 IMAGING SIMULATION AND DSM ACCURACY ESTIMATE

2017 ◽  
Vol XLII-1/W1 ◽  
pp. 353-356
Author(s):  
Q. Yue ◽  
X. Tang ◽  
X. Gao
Keyword(s):  
Ground Truth ◽  
Simulation Method ◽  
Geometric Error ◽  
Basic Data ◽  
Image Point ◽  
Physical Parameters ◽  
Stereo Images ◽  
Simulated Image ◽  
Accuracy Estimate ◽  
Imaging Simulation

GF-7 satellite is a two-line-array stereo imaging satellite for surveying and mapping which will be launched in 2018. Its resolution is about 0.8 meter at subastral point corresponding to a 20 km width of cloth, and the viewing angle of its forward and backward cameras are 5 and 26 degrees. This paper proposed the imaging simulation method of GF-7 stereo images. WorldView-2 stereo images were used as basic data for simulation. That is, we didn’t use DSM and DOM as basic data (we call it “ortho-to-stereo” method) but used a “stereo-to-stereo” method, which will be better to reflect the difference of geometry and radiation in different looking angle. The shortage is that geometric error will be caused by two factors, one is different looking angles between basic image and simulated image, another is not very accurate or no ground reference data. We generated DSM by WorldView-2 stereo images. The WorldView-2 DSM was not only used as reference DSM to estimate the accuracy of DSM generated by simulated GF-7 stereo images, but also used as “ground truth” to establish the relationship between WorldView-2 image point and simulated image point. Static MTF was simulated on the instantaneous focal plane “image” by filtering. SNR was simulated in the electronic sense, that is, digital value of WorldView-2 image point was converted to radiation brightness and used as radiation brightness of simulated GF-7 camera. This radiation brightness will be converted to electronic number n according to physical parameters of GF-7 camera. The noise electronic number n1 will be a random number between -√n and √n. The overall electronic number obtained by TDI CCD will add and converted to digital value of simulated GF-7 image. Sinusoidal curves with different amplitude, frequency and initial phase were used as attitude curves. Geometric installation errors of CCD tiles were also simulated considering the rotation and translation factors. An accuracy estimate was made for DSM generated from simulated images.

Calculation and Design Method Study of the Coil-Wound Heat Exchanger

2014 ◽  
Vol 1008-1009 ◽  
pp. 850-860 ◽  
Author(s):  
Zhou Wei Zhang ◽  
Jia Xing Xue ◽  
Ya Hong Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchanger ◽  
Design Method ◽  
Fluid Velocity ◽  
Exchange Process ◽  
Three Dimensional ◽  
Simulation Method ◽  
Physical Parameters ◽  
Numerical Result

A calculation method for counter-current type coil-wound heat exchanger is presented for heat exchange process. The numerical simulation method is applied to determine the basic physical parameters of wound bundles. By controlling the inlet fluid velocity varying in coil-wound heat exchanger to program and calculate the iterative process. The calculation data is analyzed by comparison of numerical result and the unit three dimensional pipe bundle model was built. Studies show that the introduction of numerical simulation can simplify the pipe winding process and accelerate the calculation and design of overall configuration in coil-wound heat exchanger. This method can be applied to the physical modeling and heat transfer calculation of pipe bundles in coil wound heat exchanger, program to calculate the complex heat transfer changing with velocity and other parameters, and optimize the overall design and calculation of spiral bundles.

An Optical Imaging Simulation Method for Inverted Microscope and its Application in Automatic Cell Manipulation

2012 ◽  
Vol 490-495 ◽  
pp. 1981-1985
Author(s):  
Qi Liang Du ◽  
Xue Song Lan ◽  
Ling Yuan ◽  
Rui Liang
Keyword(s):  
Optical Imaging ◽  
Forward Direction ◽  
Simulation Method ◽  
Considerable Effect ◽  
Cell Manipulation ◽  
Egg Cell ◽  
Virtual Image ◽  
Sensing Element ◽  
Inverted Microscope ◽  
Imaging Simulation

For a further understanding of the features of objects in the microscopic image during automatic cell manipulation, an optical imaging simulation method for inverted microscope was studied, with an assumption of parallel rays of light. The proposed method calculated the forward direction of every ray starting from the source until it reached the lens or disappeared from the effective range. A virtual image could be generated by an imitation of a CCD sensing element. Emulations in cases of a micro glass bar, a micro pipette and an egg cell which were commonly encountered in cell manipulation were carried out, whose gray-level virtual images were contrasted to real ones for verification. Results showed a considerable effect of the proposed simulation method

scholarly journals Estimation of sea-ice physical parameters using polarimetric SAR: results from Okhotsk and Lake Saroma campaign

2001 ◽  
Vol 33 ◽  
pp. 120-124 ◽  
Author(s):  
Hiroyuki Wakabayashi ◽  
Takeshi Matsuoka ◽  
Kazuki Nakamura ◽  
Fumihiko Nishio
Keyword(s):  
Sea Ice ◽  
Correlation Coefficient ◽  
Ground Truth ◽  
Open Water ◽  
Physical Parameters ◽  
Dual Frequency ◽  
Ground Truth Data ◽  
National Space ◽  
Airborne Sar ◽  
Interferometric Sar

AbstractWe have acquired ground-truth data at Lake Saroma, northeast Hokkaido, Japan, and the surrounding area since 1993 in order to collect data on regional sea ice in the Sea of Okhotsk. The data were acquired in 1999 by polarimetric and interferometric SAR (Pi-SAR), the dual-frequency, fully polarimetric airborne SAR system jointly developed by the National Space Development Agency of Japan (NASDA) and the Communications Research Laboratory (CRL), simultaneously with ground experiments. This paper describes the results of polarimetric data analysis of typical sea ice observed in the offshore region near Lake Saroma. The polarimetric parameters used were correlation coefficient and phase difference. Based on the analysis of these parameters, we found that the correlation coefficient between RR and LL polarizations can discriminate four categories including three types of ice and open water.

scholarly journals Remote Cloud Ceiling Assessment Using Data-Mining Methods

2004 ◽  
Vol 43 (12) ◽  
pp. 1929-1946 ◽  
Author(s):  
Richard L. Bankert ◽  
Michael Hadjimichael ◽  
Arunas P. Kuciauskas ◽  
William T. Thompson ◽  
Kim Richardson
Keyword(s):  
Data Mining ◽  
Satellite Data ◽  
Weather Prediction ◽  
Ground Truth ◽  
Physical Parameters ◽  
Low Cloud ◽  
Ceiling Height ◽  
Mining Methods ◽  
Using Data ◽  
Automated Algorithms

Abstract Data-mining methods are applied to numerical weather prediction (NWP) output and satellite data to develop automated algorithms for the diagnosis of cloud ceiling height in regions where no local observations are available at analysis time. A database of hourly records that include Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) output, satellite data, and ground truth observations [aviation routine weather reports (METAR)] has been created. Data were collected over a 2.5-yr period for specific locations in California. Data-mining techniques have been applied to the database to determine relationships in the collected physical parameters that best estimate cloud ceiling conditions, with an emphasis on low ceiling heights. Algorithm development resulted in a three-step approach: 1) determine if a cloud ceiling exists, 2) if a cloud ceiling is determined to exist, determine if the ceiling is high or low (below 1 000 m), and 3) if the cloud ceiling is determined to be low, compute ceiling height. A sample of the performance evaluation indicates an average absolute height error of 120.6 m with a 0.76 correlation and a root-mean-square error of 168.0 m for the low-cloud-ceiling testing set. These results are a significant improvement over the ceiling-height estimations generated by an operational translation algorithm applied to COAMPS output.

Aerodynamic Heating Numerical Simulation of Terminal-Sensitive Projectile at Deceleration and Despinning Trajectory

2013 ◽  
Vol 376 ◽  
pp. 317-322
Author(s):  
Jun Zhang ◽  
Rong Zhong Liu ◽  
Rui Guo ◽  
Xiao Dong Ma
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Thermal Protection ◽  
Thermal Characteristics ◽  
Simulation Method ◽  
Aerodynamic Heating ◽  
Transient Temperature ◽  
Physical Parameters ◽  
Temperature Distributions ◽  
Infrared Signature

Aero-heating problem severely affects the performance of terminal-sensitive projectile (TSP) when projected out of the carrier capsule by the gunpowder gas at a high speed. In this paper, based on the typical ballistic data and airflow physical parameters at deceleration and despinning trajectory, the aerodynamic thermal characteristics of a TSP was simulated by Fluent, and the transient temperature distributions were obtained under the different flying conditions. Finally, we got stagnation temperatures by the numerical simulations which were similar to those by the engineering evaluation, and demonstrate the effectiveness of the simulation method. The results are valuable to the research of thermal protection and infrared signature of TSP.

scholarly journals Measuring the Solar Cell Parameters Using Fuzzy Set Technique

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Mohammed S. Rasheed ◽  
Mohammed Abdelhadi Sarhan
Keyword(s):  
Solar Cell ◽  
Fuzzy Set ◽  
Silicon Solar Cell ◽  
Simulation Method ◽  
Photovoltaic Cell ◽  
Comparison Method ◽  
Physical Parameters ◽  
Simple Method ◽  
Cell Parameters ◽  
Method Show

<p>This work studies the application of fuzzy set (FS) and fuzzy logic (FC) methods to determine the optimal operating point of solar cell. The physical parameters of the solar cell have been measured practically using silicon solar cell. The important parameters of the silicon cell are compared with each other using fuzzy set comparison method (FSCM) based on (I-V) characteristic curves of the voltage of photovoltaic cell and the maximum power resulting from the cell; which is a simple method for the measurement. The results of the simulation method show that, the fuzzy set comparison method (FSCM) is better measuring these parameters.</p>

scholarly journals DEM EXTRACTION FROM WORLDVIEW-3 STEREO-IMAGES AND ACCURACY EVALUATION

2016 ◽  
Vol XLI-B1 ◽  
pp. 327-332 ◽  
Author(s):  
F. Hu ◽  
X. M. Gao ◽  
G.Y. Li ◽  
M. Li
Keyword(s):  
Systematic Error ◽  
Large Scale ◽  
Test Area ◽  
Airborne Lidar ◽  
Image Point ◽  
Accuracy Evaluation ◽  
Stereo Images ◽  
Mountain Area ◽  
Mean Error ◽  
Check Points

This paper validates the potentials of Worldview-3 satellite images in large scale topographic mapping, by choosing Worldview-3 along-track stereo-images of Yi Mountain area in Shandong province China for DEM extraction and accuracy evaluation. Firstly, eighteen accurate and evenly-distributed GPS points are collected in field and used as GCPs/check points, the image points of which are accurately measured, and also tie points are extracted from image matching; then, the RFM-based block adjustment to compensate the systematic error in image orientation is carried out and the geo-positioning accuracy is calculated and analysed; next, for the two stereo-pairs of the block, DSMs are separately constructed and mosaicked as an entirety, and also the corresponding DEM is subsequently generated; finally, compared with the selected check points from high-precision airborne LiDAR point cloud covering the same test area, the accuracy of the generated DEM with 2-meter grid spacing is evaluated by the maximum (max.), minimum (min.), mean and standard deviation (std.) values of elevation biases. It is demonstrated that, for Worldview-3 stereo-images used in our research, the planimetric accuracy without GCPs is about 2.16 m (mean error) and 0.55 (std. error), which is superior to the nominal value, while the vertical accuracy is about -1.61 m (mean error) and 0.49 m (std. error); with a small amount of GCPs located in the center and four corners of the test area, the systematic error can be well compensated. The std. value of elevation biases between the generated DEM and the 7256 LiDAR check points are about 0.62 m. If considering the potential uncertainties in the image point measurement, stereo matching and also elevation editing, the accuracy of generating DEM from Worldview-3 stereo-images should be more desirable. Judging from the results, Worldview-3 has the potential for 1:5000 or even larger scale mapping application.

scholarly journals Ultrasonic liver steatosis quantification by a learning-based acoustic model from a novel shear wave sequence

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Xiudong Shi ◽  
Wen Ye ◽  
Fengjun Liu ◽  
Rengyin Zhang ◽  
Qinguo Hou ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Attenuation ◽  
Liver Steatosis ◽  
Ground Truth ◽  
Liver Fat ◽  
Physical Parameters ◽  
Acoustic Model ◽  
Related Field ◽  
Dispersion Slope ◽  
Wave Absorption

Abstract Background An efficient and accurate approach to quantify the steatosis extent of liver is important for clinical practice. For the purpose, we propose a specific designed ultrasound shear wave sequence to estimate ultrasonic and shear wave physical parameters. The utilization of the estimated quantitative parameters is then studied. Results Shear wave attenuation, shear wave absorption, elasticity, dispersion slope and echo attenuation were simultaneously estimated and quantified from the proposed novel shear wave sequence. Then, a regression tree model was utilized to learn the connection between the space represented by all the physical parameters and the liver fat proportion. MR mDIXON quantification was used as the ground truth for liver fat quantification. Our study included a total of 60 patients. Correlation coefficient (CC) with the ground truth were applied to mainly evaluate different methods for which the corresponding values were − 0.25, − 0.26, 0.028, 0.045, 0.46 and 0.83 for shear wave attenuation, shear wave absorption, elasticity, dispersion slope, echo attenuation and the learning-based model, respectively. The original parameters were extremely outperformed by the learning-based model for which the root mean square error for liver steatosis quantification is only 4.5% that is also state-of-the-art for ultrasound application in the related field. Conclusions Although individual ultrasonic and shear wave parameters were not perfectly adequate for liver steatosis quantification, a promising result can be achieved by the proposed learning-based acoustic model based on them.

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