scholarly journals In Situ Investigation of the 3D Mechanical Microstructure at Nanoscale: Nano-CT Imaging Method of Local Small Region in Large Scale Sample

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Bo Dong ◽  
Feng Xu ◽  
Xiao-fang Hu ◽  
Hong-yan Qu ◽  
Dan Kang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Small Region ◽  
Projection Data ◽  
Imaging Method ◽  
Reconstruction Method ◽  
Localization Property ◽  
Local Tomography ◽  
In Situ Investigation

To investigate the local micro-/nanoscale region in a large scale sample, an image reconstruction method for nanometer computed tomography (nano-CT) was proposed in this paper. In the algorithm, wavelets were used to localize the filtered-backprojection (FBP) algorithm because of its space-frequency localization property. After the implementation of the algorithm, two simulation local reconstruction experiments were performed to confirm its effectiveness. Three evaluation criteria were used in the experiments to judge the quality of the reconstructed images. The experimental results showed that the algorithm proposed in this paper performed best because (1) the quality of its results had improved 20%–30% compared to the results of FBP and 10%–30% compared to the results of another wavelet algorithm; (2) the new algorithm was stable under different circumstances. Besides, an actual reconstruction experiment was performed using real projection data that had been collected in a CT experiment. Two-dimensional (2D) and three-dimensional (3D) images of the sample were reconstructed. The microstructure of the sample could be clearly observed in the reconstructed images. Since much attention has been directed towards the nano-CT technique to investigate the microstructure of materials, this new wavelet-based local tomography algorithm could be considered as a meaningful effort.

AN IMPROVED 3DRP PET IMAGE RECONSTRUCTION METHOD WITH REBINNED DIRECT IMAGE ESTIMATE

2006 ◽  
Vol 18 (05) ◽  
pp. 237-245
Author(s):  
WEI-MIN JENG ◽  
HSUAN-HUI WANG
Keyword(s):  
Image Reconstruction ◽  
Image Quality ◽  
Three Dimensional ◽  
Simulation Software ◽  
Direct Image ◽  
Projection Data ◽  
Reconstruction Method ◽  
Two Dimensional ◽  
Dimensional Image

The quality of traditional two-dimensional image reconstruction for PET has been efficiently improved by three-dimensional image reconstruction, but the sensitivity of the data and the quality of the image are restricted by the limit of modality physics. In analytical image reconstruction algorithm, 3DRP method compensates the unmeasured events by forward projection based on the initial direct image estimate. However, the original 3DRP method merely depends on the parallel projections without taking into account the oblique projections. In our proposed 3DRP-SSRB method, we improve the first image estimate by incorporating the rebinned oblique data. SSRB method was used to perform the rebinning operation to make uses of the oblique projection data to improve the sensitivity information. And then project the improved image estimate forward and reconstruct the final image. Conflicting parameters of reconstructed image quality of 3DRP are experimented by simulated three-dimensional phantom study with regard to both system sensitivity and image quality factors. PET simulation software package was used to conduct the experiment along with the MATLAB software to evaluate the effectiveness of two-dimensional FBP, 3DRP, and our proposed 3DRP-SSRB methods. The result demonstrated its better image quality by having better mean squared error numbers in most of output image slices.

scholarly journals Reconstruction and Simulation of Stratospheric Ozone Distributions during the 2002 Austral Winter

2005 ◽  
Vol 62 (3) ◽  
pp. 748-764 ◽  
Author(s):  
C. E. Randall ◽  
G. L. Manney ◽  
D. R. Allen ◽  
R. M. Bevilacqua ◽  
J. Hornstein ◽  
...  
Keyword(s):  
Large Scale ◽  
Stratospheric Ozone ◽  
Three Dimensional ◽  
Stratospheric Aerosol ◽  
Equation Model ◽  
Transport Processes ◽  
Reconstruction Method ◽  
Austral Winter ◽  
Solar Occultation ◽  
Occultation Data

Abstract Satellite-based solar occultation measurements during the 2002 austral winter have been used to reconstruct global, three-dimensional ozone distributions. The reconstruction method uses correlations between potential vorticity and ozone to derive “proxy” distributions from the geographically limited occultation observations. Ozone profiles from the Halogen Occultation Experiment (HALOE), the Polar Ozone and Aerosol Measurement III (POAM III), and the Stratospheric Aerosol and Gas Experiment II and III (SAGE II and III) are incorporated into the analysis. Because this is one of the first uses of SAGE III data in a scientific analysis, preliminary validation results are shown. The reconstruction method is described, with particular emphasis on uncertainties caused by noisy and/or multivalued correlations. The evolution of the solar occultation data and proxy ozone fields throughout the winter is described, and differences with respect to previous winters are characterized. The results support the idea that dynamical forcing early in the 2002 winter influenced the morphology of the stratosphere in a significant and unusual manner, possibly setting the stage for the unprecedented major stratospheric warming in late September. The proxy is compared with ozone from mechanistic, primitive equation model simulations of passive ozone tracer fields during the time of the warming. In regions where chemistry is negligible compared to transport, the model and proxy ozone fields agree well. The agreement between, and changes in, the large-scale ozone fields in the model and proxy indicate that transport processes, particularly enhanced poleward transport and mixing, are the primary cause of ozone changes through most of the stratosphere during this unprecedented event. The analysis culminates with the calculation of globally distributed column ozone during the major warming, showing quantitatively how transport of low-latitude air to the polar region in the middle stratosphere led to the diminished ozone hole in 2002.

Research of Sludge Properties during Startup of Integrated Anoxic Aerobic Process

2012 ◽  
Vol 518-523 ◽  
pp. 3445-3449
Author(s):  
Yong Fu Guo ◽  
Jin Yu Chu ◽  
Yong Jian Liu ◽  
Wei Jia Zhang ◽  
Le Zhong Xu
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Sedimentation Velocity ◽  
The Novel ◽  
Dyeing Wastewater ◽  
Printing And Dyeing Wastewater ◽  
Aerobic Process ◽  
Sludge Properties ◽  
Last Stage

An integrated and three-dimensional anoxic-aerobic (A/O) process is put forward. The novel A/O process is used to treat printing and dyeing wastewater with concentrated sludge of sludge concentration tank as inoculated sludge. The experiment studies the sludge properties during startup of the A/O process. The results show that the inoculated sludge has completely adapted the quality of the wastewater after operation of 54 d. The average MLSS of A tank and O tank reach 7.26 g/L and 3.69 g/L at the end of the last stage, respectively. The ratios of MLVSS to MLSS in A/O reactor are stable at 0.63 - 0.75. And the sedimentation velocity of sludge has a large-scale promotion and reaches 34.2 m/h in A tank and 25 m/h in O tank, respectively. Simultaneously, the novel A/O reactor has high biodegradability for pollutants with CODcr removal efficiency of about 70%. The results indicate that the integrated A/O process will be a better method to treat printing and dyeing wastewater.

An algebraic algorithm for generation of three-dimensional grain maps based on diffraction with a wide beam of hard X-rays

2004 ◽  
Vol 37 (1) ◽  
pp. 96-102 ◽  
Author(s):  
T. Markussen ◽  
Xiaowei Fu ◽  
L. Margulies ◽  
E. M. Lauridsen ◽  
S. F. Nielsen ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Projection Algorithm ◽  
Reconstruction Method ◽  
Layer By Layer ◽  
X Rays ◽  
Spatial Accuracy ◽  
Wide Beam ◽  
Absorption Contrast ◽  
Better Than

A reconstruction method is presented for generation of three-dimensional maps of the grain boundaries within powders or polycrystals. The grains are assumed to have a mosaic spread below 1°. They are mapped by diffraction with a wide beam of hard X-rays, using a setup similar to that of parallel-beam absorption contrast tomography. First the diffraction spots are sorted with respect to grain of origin. Next, for each grain the reconstruction is performed by an algebraic algorithm known as three-dimensional ART. From simulations it is found that reconstructions with a spatial accuracy better than the pixel size of the detector can be obtained from as few as five diffraction spots. The results are superior to three-dimensional reconstructions based on the same data using a variant of the filtered back-projection algorithm. In comparison with layer-by-layer type reconstructions based on the two-dimensional ART algorithm, as introduced by Poulsen & Fu [J. Appl. Cryst.(2003),36, 1062–1068], the quality of the maps is found to be similar, provided that five to ten spots are available for analysis, while data acquisition with the three-dimensional method is much faster. The three-dimensional ART methodology is validated on experimental data. With state-of-the-art detectors, the spatial accuracy is estimated to be 5 µm.

scholarly journals Squint Model InISAR Imaging Method Based on Reference Interferometric Phase Construction and Coordinate Transformation

2021 ◽  
Vol 13 (11) ◽  
pp. 2224
Author(s):  
Yu Li ◽  
Yunhua Zhang ◽  
Xiao Dong
Keyword(s):  
Coordinate Transformation ◽  
Cross Correlation ◽  
Three Dimensional ◽  
Image Distortion ◽  
Imaging Method ◽  
Phase Ambiguity ◽  
Correlation Algorithm ◽  
Interferometric Phase ◽  
Isar Imaging

The imaging quality of InISAR under squint geometry can be greatly degraded due to the serious interferometric phase ambiguity (InPhaA) and thus result in image distortion problems. Aiming to solve these problems, a three-dimensional InISAR (3D ISAR) imaging method based on reference InPhas construction and coordinate transformation is presented in this paper. First, the target’s 3D coarse location is obtained by the cross-correlation algorithm, and a relatively stronger scatterer is taken as the reference scatterer to construct the reference interferometric phases (InPhas) so as to remove the InPhaA and restore the real InPhas. The selected scatterer needs not to be exactly in the center of the coarsely located target. Then, the image distortion is corrected by coordinate transformation, and finally the 3D coordinates of the target can be accurately estimated. Both simulation and practical experiment results validate the effectiveness of the method.

scholarly journals RESEARCH ON THE MAPPING OF LARGE-SCALE TOPOGRAPHIC MAPS BASED ON LOW-ALTITUDE DRONE AERIAL PHOTOGRAPHY SYSTEM

2020 ◽  
Vol XLII-3/W10 ◽  
pp. 623-628
Author(s):  
R. S. Lu
Keyword(s):  
Aerial Photography ◽  
Large Scale ◽  
Control Point ◽  
Three Dimensional ◽  
Operator Method ◽  
Image Data ◽  
Aerial Survey ◽  
Least Square ◽  
Image Feature

Abstract. The field data collection and in-house data processing of the aerial photography system of the uavouring aircraft are studied, combined with their working examples in this paper. The aerial survey of the Bowen School of Management of Guilin University of Technology is carried out by using the Southern Sky Patrol AS1200 aerial survey system, and the obtained data is processed and studied in the internal and external industry. In order to successfully complete this research, this article (1) first of all to the external industry collected data inspection, that is, the quality of the aircraft film inspection, the main content of the inspection is the detection of the image of the tone, resolution, level, whether the film can clearly identify the main objects, such as houses, roads, etc. can be clearly identified; - Whether the film is ghosting, whether there is misalignment and fuzziness, etc. , if the film has blurred or other quality problems, it is necessary to carry out retest or retest, this step is mainly to ensure the quality of research data, for the industry processing data to do a basic guarantee. (2) For the processing of in-house data, this paper uses a correction model for image data distortion pre-processing, the method of arithmetic and the edge detection operator method of extracting the image feature, and the image matching method Greenfeld-Schenk method based on the feature, Bamard-Thompson method and jump method and other methods to match the image, at the same time, this paper also takes the aerial triangulation method of the processing of internal data, complete the measurement control point encryption work, so as to calculate the spatial coordinates of the encryption control point, reduce the field laying work like control points, and thus reduce the working time of the field. (3) For improving the accuracy of the topographic elevation point in the aviation area, this paper uses polymorphic curve to be legal, using the field elevation measured value of the checkpoint and the three-dimensional measurement value does not match the difference, using the least square-by-multiply method to fit, so that the elevation checkpoint curve fitting value change and the actual difference is the smallest, with the measurement area elevation accuracy.

scholarly journals Three-dimensional fast elemental mapping by soft X-ray dual-energy focal stacks imaging

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Limei Ma ◽  
Zijian Xu ◽  
Zhi Guo ◽  
Benjamin Watts ◽  
Jinyou Lin ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Materials Science ◽  
Three Dimensional ◽  
Dual Energy ◽  
Acquisition Time ◽  
Imaging Method ◽  
Reconstruction Method ◽  
Elemental Mapping ◽  
Contrast Imaging ◽  
X Ray

The three-dimensional (3D) dual-energy focal stacks (FS) imaging method has been developed to quickly obtain the spatial distribution of an element of interest in a sample; it is a combination of the 3D FS imaging method and two-dimensional (2D) dual-energy contrast imaging based on scanning transmission soft X-ray microscopy (STXM). A simulation was firstly performed to verify the feasibility of the 3D elemental reconstruction method. Then, a sample of composite nanofibers, polystyrene doped with ferric acetylacetonate [Fe(acac)3], was further investigated to quickly reveal the spatial distribution of Fe(acac)3 in the sample. Furthermore, the data acquisition time was less than that for STXM nanotomography under similar resolution conditions and did not require any complicated sample preparation. The novel approach of 3D dual-energy FS imaging, which allows fast 3D elemental mapping, is expected to provide invaluable information for biomedicine and materials science.

Extrusion Uniformity Optimization for Shaping Channel Design in Large-Scale Die-Plate of Underwater Pelletizing

2013 ◽  
Vol 275-277 ◽  
pp. 562-566 ◽  
Author(s):  
Bing Zhang ◽  
Xiao Feng Liu ◽  
Chao Bi
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Polymer Melt ◽  
Optimization Method ◽  
Three Dimensional Flow ◽  
Element Simulation ◽  
Bp Neural Network Model ◽  
Plate Channel ◽  
The Relationship

As an important component of large-scale extruder system for polymer material, Die-plate can be regarded as the final determinant for pelletization uniformity. Polymer melt was shaped in shaping channels and extruded from die-holes from Die-plate and then be diced. The design of shaping channels directly influences the uniformity for polymer-melt extrusion pressure and extrusion velocity of different die holes. In this paper, a three-dimensional flow model for polymer flow in Die-plate channel was presented, and then finite element simulation was used to analyze the distribution of extrusion velocity in each die-hole. Based on simulation result, a BP neural network model was applied to analyze the relationship between geometry factors of Die-plate, such as length of shaping channels, die hole extrusion velocity distribution, and extrusion uniformity. This optimization method can be used in the design of Die-plate to improve effect and quality of actual polymer production and processing.

scholarly journals Image Enhancement for Computational Integral Imaging Reconstruction via Four-Dimensional Image Structure

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4795
Author(s):  
Joungeun Bae ◽  
Hoon Yoo
Keyword(s):  
Image Enhancement ◽  
Visual Information ◽  
Three Dimensional ◽  
Adjustable Parameter ◽  
Reconstruction Method ◽  
Integral Imaging ◽  
Image Structure ◽  
Imaging Reconstruction ◽  
Computational Integral Imaging

This paper describes the image enhancement of a computational integral imaging reconstruction method via reconstructing a four-dimensional (4-D) image structure. A computational reconstruction method for high-resolution three-dimensional (3-D) images is highly required in 3-D applications such as 3-D visualization and 3-D object recognition. To improve the visual quality of reconstructed images, we introduce an adjustable parameter to produce a group of 3-D images from a single elemental image array. The adjustable parameter controls overlapping in back projection with a transformation of cropping and translating elemental images. It turns out that the new parameter is an independent parameter from the reconstruction position to reconstruct a 4-D image structure with four axes of x, y, z, and k. The 4-D image structure of the proposed method provides more visual information than existing methods. Computer simulations and optical experiments are carried out to show the feasibility of the proposed method. The results indicate that our method enhances the image quality of 3-D images by providing a 4-D image structure with the adjustable parameter.

scholarly journals Semantic segmentation of large-scale point clouds based on dilated nearest neighbors graph

2022 ◽  
Author(s):  
Lei Wang ◽  
Jiaji Wu ◽  
Xunyu Liu ◽  
Xiaoliang Ma ◽  
Jun Cheng
Keyword(s):  
Large Scale ◽  
Nearest Neighbor ◽  
Three Dimensional ◽  
Semantic Segmentation ◽  
Point Clouds ◽  
Sampling Point ◽  
Automatic Driving ◽  
Scale Point ◽  
Memory Efficient

AbstractThree-dimensional (3D) semantic segmentation of point clouds is important in many scenarios, such as automatic driving, robotic navigation, while edge computing is indispensable in the devices. Deep learning methods based on point sampling prove to be computation and memory efficient to tackle large-scale point clouds (e.g. millions of points). However, some local features may be abandoned while sampling. In this paper, We present one end-to-end 3D semantic segmentation framework based on dilated nearest neighbor encoding. Instead of down-sampling point cloud directly, we propose a dilated nearest neighbor encoding module to broaden the network’s receptive field to learn more 3D geometric information. Without increase of network parameters, our method is computation and memory efficient for large-scale point clouds. We have evaluated the dilated nearest neighbor encoding in two different networks. The first is the random sampling with local feature aggregation. The second is the Point Transformer. We have evaluated the quality of the semantic segmentation on the benchmark 3D dataset S3DIS, and demonstrate that the proposed dilated nearest neighbor encoding exhibited stable advantages over baseline and competing methods.

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