Robust Pulmonary Nodule Segmentation in CT Image for Juxta-pleural and Juxta-vascular Case

2019 ◽  
Vol 14 (2) ◽  
pp. 139-147 ◽  
Author(s):  
Zhang Yang ◽  
Xie Yingying ◽  
Guo Li ◽  
Zhang Zewei ◽  
Ding Weifeng ◽  
...  
Keyword(s):  
Pulmonary Nodule ◽  
Geodesic Distance ◽  
Complex Structure ◽  
Numerical Approach ◽  
Graph Cut ◽  
The Other ◽  
Lung Nodules ◽  
Ct Image ◽  
Nodule Volume ◽  
Structure Boundary

Background: Lung cancer is a greatest threat to people's health and life. CT image leads to unclear boundary segmentation. Segmentation of irregular nodules and complex structure, boundary information is not well considered and lung nodules have always been a hot topic. Objective: In this study, the pulmonary nodule segmentation is accomplished with the new graph cut algorithm. The problem of segmenting the juxta-pleural and juxta-vascular nodules was investigated which is based on graph cut algorithm. Methods: Firstly, the inflection points by the curvature was decided. Secondly, we used kernel graph cut to segment the nodules for the initial edge. Thirdly, the seeds points based on cast raying method is performed; lastly, a novel geodesic distance function is proposed to improve the graph cut algorithm and applied in lung nodules segmentation. Results: The new algorithm has been tested on total 258 nodules. Table 1 summarizes the morphologic features of all the nodules and given the results between the successful segmentation group and the poor/failed segmentation group. Figure 1 to Fig. (12) shows segmentation effect of Juxta-vascular nodules, Juxta-pleural nodules, and comparted with the other interactive segmentation methods. Conclusion: The experimental verification shows better results with our algorithm, the results will measure the volume numerical approach to nodule volume. The results of lung nodules segmentation in this study are as good as the results obtained by the other methods.

scholarly journals A Study of the Effects of Rain, Snow and Hail on the Atmospheric Electric Field near Ground

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 996
Author(s):  
Athanasios Karagioras ◽  
Konstantinos Kourtidis
Keyword(s):  
Frequency Distribution ◽  
Complex Structure ◽  
Potential Gradient ◽  
Weather Conditions ◽  
The Other ◽  
Fair Weather ◽  
Northern Greece ◽  
Rain Events ◽  
The Impact ◽  
Bounce Back

The purpose of the present study is to investigate the impact of rain, snow and hail on potential gradient (PG), as observed in a period of ten years in Xanthi, northern Greece. An anticorrelation between PG and rainfall was observed for rain events that lasted several hours. When the precipitation rate was up to 2 mm/h, the decrease in PG was between 200 and 1300 V/m, in most cases being around 500 V/m. An event with rainfall rates up to 11 mm/h produced the largest drop in PG, of 2 kV/m. Shortly after rain, PG appeared to bounce back to somewhat higher values than the ones of fair-weather conditions. A decrease in mean hourly PG was observed, which was around 2–4 kV/m during the hail events which occurred concurrently with rain and from 0 to 3.5 kV/m for hail events with no rain. In the case of no drop, no concurrent drop in temperature was observed, while, for the other cases, it appeared that, for each degree drop in temperature, the drop in hourly mean PG was 1000 V/m; hence, we assume that the intensity of the hail event regulates the drop in PG. The frequency distribution of 1-minute PG exhibits a complex structure during hail events and extend from −18 to 11 kV/m, with most of the values in the negative range. During snow events, 1-minute PG exhibited rapid fluctuations between high positive and high negative values, its frequency distribution extending from −10 to 18 kV/m, with peaks at −10 and 3 kV/m.

Milling Curves Influence in Ring Rolling Processes

2014 ◽  
Vol 622-623 ◽  
pp. 956-963 ◽  
Author(s):  
Luca Giorleo ◽  
Elisabetta Ceretti ◽  
Claudio Giardini
Keyword(s):  
Numerical Approach ◽  
The Other ◽  
Ring Rolling ◽  
Roll Speed ◽  
Forming Process ◽  
Industrial Case Study ◽  
Industrial Environment ◽  
Ring Shape ◽  
Deformation Processes

Ring Rolling is a complex hot forming process used for the production of shaped rings, seamless and axis symmetrical workpieces. The main advantage of workpieces produced by ring rolling, compared to other technological processes, is given by the size and orientation of grains, especially on the worked surface which give to the final product excellent mechanical properties. In this process different rolls (Idle, Axial, Guide and Driver) are involved in generating the desired ring shape. Since each roll is characterized by a speed law that can be set independently by the speed law imposed to the other rolls, an optimization is more critical compared with other deformation processes. Usually, in industrial environment, a milling curve is introduced in order to correlate the Idle and Axial roll displacement, however it must be underlined that different milling curves lead to different loads and energy for ring realization. In this work an industrial case study was modeled by a numerical approach: different milling curves characterized by different Idle and Axial roll speed laws (linearly decreasing, constant, linearly increasing) were designed and simulated. The results were compared in order to identify the best milling curve that guarantees a good quality ring (higher diameter, lower fishtail) with lower loads and energy required for manufacturing.

Discrimination of Pulmonary Nodule Volume Change for Low- and High-contrast Tasks in a Phantom CT Study with Low-dose Protocols

2019 ◽  
Vol 26 (7) ◽  
pp. 937-948 ◽  
Author(s):  
Marios A. Gavrielides ◽  
Qin Li ◽  
Rongping Zeng ◽  
Benjamin Paul Berman ◽  
Berkman Sahiner ◽  
...  
Keyword(s):  
Volume Change ◽  
Pulmonary Nodule ◽  
Low Dose ◽  
High Contrast ◽  
Nodule Volume

Numerical Simulation of the Resistance and Self-Propulsion Model Tests

2018 ◽  
Author(s):  
Adrian Lungu
Keyword(s):  
Complex Structure ◽  
Turbulence Models ◽  
Numerical Approach ◽  
Local Flow ◽  
Complex Investigation ◽  
Grid Convergence ◽  
Flow Features ◽  
Sinkage And Trim ◽  
Thrust And Torque ◽  
Resistance Coefficients

The paper proposes a series of numerical investigations performed to test and demonstrate the capabilities of a RANS solver in the area of complex ship flow simulations. Focus is on a complete numerical model for hull, propeller and rudder that can account for the mutual interaction between these components. The paper presents the results of a complex investigation of the flow computations around the hull model of the 3600 TEU MOERI containership (KCS hereafter). The resistance for the hull equipped with rudder, the POW computations as well as the self-propulsion simulation are presented. Comparisons with the experimental data provided at the Tokyo 2015 Workshop on CFD in Ship Hydrodynamics are given to validate the numerical approach in terms of the total and wave resistance coefficients, sinkage and trim, thrust and torque coefficients, propeller efficiency and local flow features. Verification and validation based on the grid convergence tests are performed for each computational case. Discussions on the efficiency of the turbulence models used in the computations as well as on the main flow features are provided aimed at clarifying the complex structure of the flow around the stern.

A numerical approach for simulating two-dimensional dense-snow avalanches in global coordinate systems

2021 ◽  
Author(s):  
Daniel Zugliani ◽  
Giorgio Rosatti ◽  
Stefania Sansone
Keyword(s):  
Coordinate System ◽  
Finite Volume ◽  
Reference System ◽  
Source Term ◽  
Numerical Approach ◽  
The Other ◽  
Snow Avalanche ◽  
Two Dimensional ◽  
Snow Avalanches ◽  
Avalanche Models

<p>Snow avalanche models are commonly based on a continuum fluid scheme, on the assumption of shallow flow in the direction normal to the bed, on a depth-averaged description of the flow quantities and on different assumptions concerning the velocity profile, the friction law, and the pressure in the flow direction (see Bartelt et al, 1999, Barbolini et al., 2000, for an overview). The coordinate reference system is commonly local, i.e., for each point of the domain, one axis is normal to the bed while the other two axes lay in a tangent plane. When the bed is vertical and the flow is not aligned with the steepest direction (e.g., in case of a side wall), the flow depth is no longer defined considering the normal direction and the model based on the local coordinate system is no longer valid. In near-vertical conditions, numerical problems can be expected.</p><p>Another critical point, for numerical models based on finite volume schemes and Godunov fluxes, is the accurate treatment of the source term in case of no-motion conditions (persistence, starting and stopping of the flow) due to the presence of velocity-independent, Coulomb-type terms in the bed shear stress. </p><p>In this work, we provide a numerical approach for a Voellmy-fluid based model, able to overcome the limits depicted above, to accurately simulate analytical solutions and to give reliable solutions in other cases (Zugliani & Rosatti, 2021). Firstly, differently from the other literature models, the chosen coordinate reference system is global (an axis opposite the gravity vector and the other two orthogonal axes lay in the horizontal plane) and therefore, the relevant mass and momentum equations have been derived accordingly. Secondly, these equations have been discretized by using a finite volume method on a Cartesian square grid where the Godunov fluxes has been evaluated by mean of a modified DOT scheme (Zugliani & Rosatti, 2016) while source terms in conditions of motion have been discretized by using an implicit operator-splitting technique. Finally, a specific algorithm has been derived to deal with the source term to determine the no-motion conditions.  Several test cases assess the capabilities of the proposed approach.</p><p> </p><p><strong>References:</strong></p><p>Barbolini, M., Gruber, U., Keylock, C.J., Naaim, M., Savi, F. (2000), <em>Application of statistical and hydraulic-continuum dense-snow avalanche models to five real European sites.</em> Cold Regions Science and Tech. 31, 133–149.</p><p>Bartelt, P., Salm, B., Gruber, U. (1999), <em>Calculating dense-snow avalanche runout using a voellmy-fluid model with active/passive longitudinal straining.</em> Journal of Glaciology 45, 242-254.</p><p>Zugliani D., Rosatti G. (2021), <em>Accurate modeling of two-dimensional dense snow avalanches in global coordinate system: the TRENT2D<sup>❄</sup> approach. </em>Paper under review.</p><p>Zugliani, D., Rosatti, G. (2016), <em>A new Osher Riemann solver for shallow water flow over fixed or mobile bed</em>, Proceedings of the 4th European Congress of the IAHR, pp. 707–713.</p>

A Numerical Approach for Simulation of Rock Fracturing in Engineering Blasting

2012 ◽  
pp. 203-224
Author(s):  
Mani Ram Saharan ◽  
Hani Mitri
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modelling ◽  
Knowledge Base ◽  
Plane Stress ◽  
Numerical Approach ◽  
The Other ◽  
Brittle Rock ◽  
Rock Fracturing ◽  
Element Elimination

An approach for simulation of rock fracturing as a result of engineering blasting is presented in this paper. The approach uses element elimination technique within the framework of finite element method to capture the physics of engineering blasting. The approach does not require pre-placement of fracture paths which is the severe drawback of the other existing methodologies and approaches. Results of plane stress modelling for isotropic brittle rock behaviour are presented in this paper and these results are in good agreement with the existing knowledge base. The authors also review the existing approaches of numerical modelling to compare the efficacy of the element elimination technique. It is anticipated that the further developments with this approach can prove to be good experimental tool to improve engineering blasting operations.

Motion Segmentation and Matting by Graph Cut

2012 ◽  
pp. 95-117
Author(s):  
Jiangjian Xiao
Keyword(s):  
Video Sequence ◽  
Graph Cut ◽  
The Other ◽  
Robust Approach ◽  
Alpha Matting ◽  
Optical Flow Field ◽  
Segmentation Boundary ◽  
Clustering Approach ◽  
Multiple Frames ◽  
Layer Segmentation

Given a video sequence, obtaining accurate layer segmentation and alpha matting is very important for video representation, analysis, compression, and synthesis. By assuming that a scene can be approximately described by multiple planar or surface regions, this chapter describes a robust approach to automatically detect the region clusters and perform accurate layer segmentation for the scene. The approach starts from optical flow field or small corresponding seed regions and applies a clustering approach to estimate the layer number and support regions. Then, it uses graph cut algorithm combined with a general occlusion constraint over multiple frames to solve pixel assignment over multiple frames to obtain more accurate segmentation boundary and identify the occluded pixels. For the non-textured ambiguous regions, an alpha matting technique is further used to refine the segmentation and resolve the ambiguities by determining proper alpha values for the foreground and background, respectively. Based on the alpha mattes, the foreground object can be transferred into the other video sequence to generate a virtual video. The author’s experiments show that the proposed approach is effective and robust for both the challenging real and synthetic sequences.

scholarly journals Revising Stanley’s footsteps: encountering the ‘other’ in Darkest England (1996) by Christopher Hope

Literator ◽  
2000 ◽  
Vol 21 (1) ◽  
pp. 85-98
Author(s):  
H. Roos
Keyword(s):  
Nineteenth Century ◽  
Complex Structure ◽  
Frame Of Reference ◽  
Point Of View ◽  
The Other ◽  
Central Theme ◽  
Post Colonial ◽  
Black Africa ◽  
Colonial Texts ◽  
Travel Writings

As has now become a familiar image in Hope’s writings, once again ttie idea of looking at a society from the position of an outsider and an exile forms the central theme of Darkest England (1996). In this satirical novel, the tradition of nineteenth-century travel writings set in a colonial context is reversed, undermined, and then remarkably recreated to portray the present-day manifestation of encounters and relations between (black) Africa and the (white) West. Presenting the (fictional) journals of a Khoisan leader, David Mungo Booi, within a dynamic frame of reference to classical colonial texts by, among others, Livingstone and Stanley. Hope writes a new travel report. This essay discusses how, by the reversal of point of view, a change in time and space, and creating a satirical mood, the colonizer and the colonized are interchanged and the original texts are evoked to be rewritten. The notions of Self/Other, colonial /(post-)colonial and primitive/civilized are placed in new and disturbing contexts, adding to the complex structure of this fascinating text.

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