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- 摘要
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- 实验方案
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Screw-Shaped Plastic Optical Fibers for Refractive Index Sensing
摘要： This paper reports a novel nonlinear algorithm for retrieving near surface air temperature over a large area using support vector machines with satellite remote sensing and other types of data. The steps include the following. 1) Establish the 1st sub model learning dataset and validation dataset, then obtain the 2nd to f th sub model learning datasets and validation datasets, using unmanned weather station data and prede?ned in?uential variables. 2) Retrieve Ta of the target area. 3) Correct the generated Ta images based on prediction errors using the inverse distance weighting interpolation. The novelty of this algorithm is to apply multiple sources of remote sensing data combined with data of unmanned weather stations, topography, ground cover, DEM, and astronomy and calendar rules. The results indicated that the model has high accuracy, reliability, and generalization ability. Factors such as cloudiness, ground vegetation, and water vapor show little interference, so the model seems suitable for large area retrieving under natural conditions. The required high-performance computation was achieved by a CPU + GPU isomery and synergy parallel computation system that improved computing speed by more than 1000-fold, with easily extendable computing capability. We found that the current algorithm is superior to seven major split-window algorithms and their best combined algorithms based on prediction errors, root-mean-square errors, and the percentage of data points with <3 ?C absolute error. Our SVM approach overcomes shortcomings of classical temperature remote sensing technologies, and is the ?rst report of such application.
关键词： high-performance computation (HPC),moderate-resolution imaging spectroradiometer (MODIS),digital elevation model (DEM),Area-wide retrieving,GIS spatial analysis,remote sensing,satellite,multivariable analysis,support vector machine (SVM)
更新于2025-09-16 10:30:52
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Computational Investigation of Melt Pool Process Dynamics and Pore Formation in Laser Powder Bed Fusion
摘要： In the laser powder bed fusion additive manufacturing process, the presence of porosity may result in cracks and significantly affects the part performance. A comprehensive understanding of the melt pool process dynamics and porosity evolution can help to improve build quality. In this study, a novel multi-physics computational fluid dynamics (CFD) model has been applied to investigate the fluid dynamics in melt pools and resultant pore defects. To accurately capture the melting and solidification process, major process physics, such as the surface tension, evaporation as well as laser multi-reflection, have been considered in the model. A discrete element method is utilized to model the generation of powder spreading upon build plate by additional numerical simulations. Multiple single track experiments have been performed to obtain the melt pool shape and cross-sectional dimension information. The predicted melt pool dimensions were found to have a reasonable agreement with experimental measurements, e.g., the errors are in the range of 1.3 to 10.6% for melt pool width, while they are between 1.4 and 15.9% for melt depth. Pores are captured by both CFD simulation and x-ray computed tomography measurement for the case with a laser power of 350 W and laser speed of 100 mm/s. The formation of keyholes maybe related to the melt pool front wall angle, and it is found that the front wall angle increases with the increase in laser line energy density. In addition, a larger laser power or smaller scanning speed can help to generate keyhole-induced pores; they also contribute to produce larger sized pores.
关键词： additive manufacturing,melt pool,computational fluid dynamics (CFD),stainless steel,discrete element method (DEM),keyhole
更新于2025-09-12 10:27:22
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A New Lunar DEM Based on the Calibrated Chang’E-1 Laser Altimeter Data
摘要： To improve the lunar DEM accuracy derived from CE-1 altimeter data, CE-1 laser altimeter data are calibrated in this paper. Orbit accuracy and ranging accuracy are the two most important factors to affect the application of altimeter data in the lunar topography. An empirical method is proposed to calibrate CE-1 altimeter data, using gridded LOLA DEM to correct systematic errors of CE-1 altimeter data, and the systematic bias is about -139.52 m. A new lunar DEM grid model based on calibrated CE-1 altimeter data with the spatial resolution of 0.0625° × 0.0625° is obtained as well as a spherical harmonic model at 1400th order. Furthermore, the DEM accuracy is assessed through the comparison with the nearside landmarks of the Moon, and the results show that the DEM accuracy is improved from 127.3 m to 48.7 m after the calibration of laser altimeter data.
关键词： CE-1,LOLA,lunar DEM,calibration,laser altimeter
更新于2025-09-11 14:15:04
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Spaceborne Repeat-pass Interferometric Synthetic Aperture Radar Experimental Evaluation for the GaoFen-3 Satellite
摘要： High-precision DEM can be generated by SAR interferometry processing with GaoFen-3 repeat-pass data.This paper presents the first results from GaoFen-3 SAR Interferometry obtained with two interferometric SAR data pairs at the selected experiment sites. The temporal separations were 29 days. At the site the coherence requirements were met, resulting in high quality interferogram .The experimental results show that GaoFen-3 repeat-pass data have some good characteristics, such as high imaging quality, stable spatial baseline, high temporal correlation and spatial correlation, which has a good repeat-pass SAR interferometry application prospect.
关键词： SAR Interferometry,correlation,Repeat-pass,DEM,GaoFen-3
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Floodplain DEM Extraction Based on Swot HR Insar Data
摘要： The upcoming Surface Water and Ocean Topography (SWOT) mission, projected for launch in 2021, will provide global measurements of water elevation for ocean and continental water bodies with unprecedented resolution and accuracy. This article describes how the variations in height and extent of continental water surfaces, as measured by SWOT’s principal instrument, the Ka-band Radar Interferometer (KaRIn), can be used to derive floodplain Digital Elevation Models (DEMs), in principle with sub-meter accuracy. The proposed method is based on InSAR processing, refined geolocation, and the so-called bath-tub ring approach. Preliminary results obtained on multi-temporal simulated SWOT data are presented.
关键词： InSAR,DEM,SWOT,floodplain
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - SWAF-HR: A High Spatial and Temporal Resolution Water Surface Extent Product Over the Amazon Basin
摘要： Wetlands and open waters are key components of the hydrological and carbon cycles but their spatio-temporal dynamics are still not well known, mostly over tropical areas. In this paper, a new water surface product at high spatial resolution (30 arcsec) and high temporal resolution (3 days) over the Amazon basin for recent years (2010-2016) is presented. This product comes from the synergy between recent products: (1) water surface fraction at coarse spatial resolution from L-band microwave sensor (Soil Moisture and Ocean Salinity-SMOS), (2) Global Surface Water Occurrence (GSWO) from Landsat sensor and (3) the new Digital Elevation Model (DEM) Multi-Error-Removed-Improved-Terrain (MERIT) based on the Shuttle Radar Topography Mission (SRTM) observations.
关键词： microwave,MERIT DEM,water surface extent,L-band,SMOS,data synergy,GSWO
更新于2025-09-10 09:29:36
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Automatic Delineation of Seacliff Limits using Lidar-derived High-resolution DEMs in Southern California
摘要： Seacliff erosion is a serious hazard with implications for coastal management and is often estimated using successive hand-digitized cliff tops or bases (toe) to assess cliff retreat. Even if efforts are made to standardize manual digitizing and eliminate subjectivity, the delineation of cliffs is time-consuming and depends on the analyst’s interpretation. An automatic procedure is proposed to extract cliff edges from high-resolution lidar-derived bare-earth digital elevation models, generalized coastal shoreline vectors, and approximate measurements of distance between the shoreline and the cliff top. The method generates orthogonal transects and profiles with a minimum spacing equal to the digital elevation model resolution. The method also extracts the xyz coordinates for each profile for the cliff top and toe, as well as second major inflections along the profile. Over 75% of the automated cliff top points and 78% of the toe automated points are within 95% confidence interval of the hand-digitized top and toe lines, and over 79% of the digitized top points and 84% of the digitized toe points are within the 95% confidence interval of the automated top and toe lines along a stretch of coast in Del Mar, California. Outlier errors were caused by either the failure to remove all vegetation from the bare-earth digital elevation model or errors of interpretation. The automatic method was further applied between Point Conception and Los Angeles Harbor, California. This automatic method is repeatable, takes advantage of detailed topographic information within high-resolution digital elevation models, and is more efficient than hand-digitizing.
关键词： lidar,cliff limits,DEM,automatic procedures,southern California,Seacliffs
更新于2025-09-10 09:29:36
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High Resolution DEM Building with SAR Interferometry and High Resolution Optical Image
摘要： There have been many published articles describing Interferometry algorithms for DEM generation in different applications. The best uncertainty achieved in most of these articles is greater than ±1m calculating the elevation. Enabling scientists to gain experience with new techniques at low cost. Interferometry with Synthetic aperture radar (InSAR) is one of the best technique for measuring the altimetry surface, its different changes and degradation over time, and the characteristics detailed of the surface[9]. To take a better resolution of the surfaces, we propose our approach; it’s to merge the results of the interferometry and data from segmentation of an optical high resolution image. In this report we describe a procedure for hybridization of interferometry Algorithm (InSAR) and the use of geospatial data from the image segmentation, with Extraction of the building to calculate the zonal statistic parameter and mapping all segments comprising the highest elevations. This report is written in a step by step format to simplify the complicated steps described in the paper, with a focus on the Hybridization instead of the interferometry. The tests of this method were carried out on several sites, and showed good results.
关键词： co-registration,InSAR Interferometry,hybridization,Building High resolution,interferometric coherence,DEM Building
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Retrieval of Terrain Topography in Tropical Forests Using P-Band Sar Tomography
摘要： This paper presents the results achieved by SAR tomography in estimating digital terrain models under tropical forests. Several airborne data stacks have been processed, they have been gathered on dense forests in central Africa in the framework of the AfriSAR campaign and in South America. The joint exploitation of polarimetry and multibaseline interferometry enabled to separate ground from vegetation above and to analyze it alone. Also, airborne LIDAR measurements were available and provided a reliable comparison. Results indicate that terrain topography in tropical forests can be retrieved by P-Band SAR Tomography to within an accuracy at least comparable to that of LIDAR systems. Furthermore, few meaningful details visible in SAR derived DTMs are missing in LIDAR maps probably due to the high density of the vegetation layer.
关键词： SAR,Tropical,Forest,DEM,TomoSAR,Tomography,DTM
更新于2025-09-09 09:28:46